Publisher: Elsevier   (Total: 3206 journals)

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Showing 1 - 200 of 3206 Journals sorted alphabetically
Academic Pediatrics     Hybrid Journal   (Followers: 39, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 27, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 106, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 28, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 44, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 8)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 6)
Acta Astronautica     Hybrid Journal   (Followers: 450, SJR: 0.758, CiteScore: 2)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 30, SJR: 1.967, CiteScore: 7)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 3)
Acta de Investigación Psicológica     Open Access   (Followers: 2)
Acta Ecologica Sinica     Open Access   (Followers: 11, SJR: 0.18, CiteScore: 1)
Acta Histochemica     Hybrid Journal   (Followers: 5, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 337, SJR: 3.263, CiteScore: 6)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.504, CiteScore: 1)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.542, CiteScore: 1)
Acta Oecologica     Hybrid Journal   (Followers: 12, SJR: 0.834, CiteScore: 2)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 2, SJR: 0.307, CiteScore: 0)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2, SJR: 1.793, CiteScore: 6)
Acta Psychologica     Hybrid Journal   (Followers: 26, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access   (Followers: 1)
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.052, CiteScore: 2)
Acta Urológica Portuguesa     Open Access   (Followers: 1)
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3, SJR: 0.374, CiteScore: 1)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.344, CiteScore: 1)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 7, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 8)
Acute Pain     Full-text available via subscription   (Followers: 15, SJR: 2.671, CiteScore: 5)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.53, CiteScore: 4)
Addictive Behaviors     Hybrid Journal   (Followers: 18, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 9, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 14, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 22)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 193, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 13, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 20, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 30, SJR: 0.126, CiteScore: 0)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 12, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 12, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 24, SJR: 2.089, CiteScore: 5)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 15, SJR: 0.572, CiteScore: 2)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.61, CiteScore: 7)
Advances in Botanical Research     Full-text available via subscription   (Followers: 2, SJR: 0.686, CiteScore: 2)
Advances in Cancer Research     Full-text available via subscription   (Followers: 35, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 1.453, CiteScore: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 1.992, CiteScore: 5)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 5)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 14)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 29, SJR: 0.156, CiteScore: 1)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 11, SJR: 0.713, CiteScore: 1)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 11, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 27, SJR: 1.562, CiteScore: 3)
Advances in Clinical Radiology     Full-text available via subscription   (Followers: 1)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 21, SJR: 1.977, CiteScore: 8)
Advances in Computers     Full-text available via subscription   (Followers: 14, SJR: 0.205, CiteScore: 1)
Advances in Cosmetic Surgery     Full-text available via subscription   (Followers: 1)
Advances in Dermatology     Full-text available via subscription   (Followers: 16)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 14)
Advances in Digestive Medicine     Open Access   (Followers: 14)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 7)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Ecological Research     Full-text available via subscription   (Followers: 44, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 30, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 9)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 51, SJR: 5.39, CiteScore: 8)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 2)
Advances in Family Practice Nursing     Full-text available via subscription   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 69, SJR: 0.591, CiteScore: 2)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Genetics     Full-text available via subscription   (Followers: 21, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11, SJR: 12.74, CiteScore: 13)
Advances in Geophysics     Full-text available via subscription   (Followers: 8, SJR: 1.193, CiteScore: 3)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 26, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 4, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 37, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 10, SJR: 1.163, CiteScore: 2)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.938, CiteScore: 3)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6, SJR: 0.176, CiteScore: 0)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 10, SJR: 0.682, CiteScore: 2)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Marine Biology     Full-text available via subscription   (Followers: 21, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 17, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 9, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 5, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 26)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Pathology     Hybrid Journal   (Followers: 1)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.182, CiteScore: 0)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 5)
Advances in Oncobiology     Full-text available via subscription   (Followers: 2)
Advances in Ophthalmology and Optometry     Full-text available via subscription   (Followers: 1)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18, SJR: 1.875, CiteScore: 4)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.174, CiteScore: 0)
Advances in Parasitology     Full-text available via subscription   (Followers: 6, SJR: 1.579, CiteScore: 4)
Advances in Pediatrics     Full-text available via subscription   (Followers: 27, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 19)
Advances in Pharmacology     Full-text available via subscription   (Followers: 17, SJR: 1.536, CiteScore: 3)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 10, SJR: 0.574, CiteScore: 1)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.109, CiteScore: 1)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 10)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 6)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 69)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 7, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (Followers: 3, SJR: 0.263, CiteScore: 1)
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.101, CiteScore: 0)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 7)
Advances in Space Research     Full-text available via subscription   (Followers: 434, SJR: 0.569, CiteScore: 2)
Advances in Structural Biology     Full-text available via subscription   (Followers: 6)
Advances in Surgery     Full-text available via subscription   (Followers: 13, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 36, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 20)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 15)
Advances in Virus Research     Full-text available via subscription   (Followers: 6, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 57, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 398, SJR: 0.796, CiteScore: 3)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.42, CiteScore: 2)
African J. of Emergency Medicine     Open Access   (Followers: 6, SJR: 0.296, CiteScore: 0)
Ageing Research Reviews     Hybrid Journal   (Followers: 12, SJR: 3.671, CiteScore: 9)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 485, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (Followers: 1, SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 18, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 32, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 47, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 4)
Agriculture and Natural Resources     Open Access   (Followers: 3)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 58, SJR: 1.747, CiteScore: 4)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.589, CiteScore: 3)
Air Medical J.     Hybrid Journal   (Followers: 8, SJR: 0.26, CiteScore: 0)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.19, CiteScore: 0)
Alcohol     Hybrid Journal   (Followers: 12, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 12)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 2, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 11, SJR: 1.142, CiteScore: 4)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.504, CiteScore: 1)
Allergology Intl.     Open Access   (Followers: 5, SJR: 1.148, CiteScore: 2)
Alpha Omegan     Full-text available via subscription   (SJR: 3.521, CiteScore: 6)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 11, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 56, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 6, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 6, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 5)
American Heart J.     Hybrid Journal   (Followers: 59, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 67, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 48, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 13)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 17, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 40, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 35, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 37, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 51)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3, SJR: 1.967, CiteScore: 2)
American J. of Obstetrics & Gynecology MFM     Hybrid Journal   (Followers: 1)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 275, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 67, SJR: 3.184, CiteScore: 4)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5, SJR: 0.265, CiteScore: 0)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.289, CiteScore: 1)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, CiteScore: 1)
American J. of Pathology     Hybrid Journal   (Followers: 32, SJR: 2.139, CiteScore: 4)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 29, SJR: 2.164, CiteScore: 4)
American J. of Surgery     Hybrid Journal   (Followers: 39, SJR: 1.141, CiteScore: 2)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.767, CiteScore: 1)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 7)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 67, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 26, SJR: 0.411, CiteScore: 1)
Anales de Cirugia Vascular     Full-text available via subscription   (Followers: 1)
Anales de Pediatría     Full-text available via subscription   (Followers: 3, SJR: 0.277, CiteScore: 0)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription  
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 6, SJR: 4.849, CiteScore: 10)
Analytica Chimica Acta     Hybrid Journal   (Followers: 44, SJR: 1.512, CiteScore: 5)
Analytica Chimica Acta : X     Open Access  
Analytical Biochemistry     Hybrid Journal   (Followers: 224, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 13, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 14)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 25, SJR: 0.683, CiteScore: 2)

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Similar Journals
Journal Cover
International Journal of Thermal Sciences
Journal Prestige (SJR): 1.429
Citation Impact (citeScore): 4
Number of Followers: 20  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1290-0729 - ISSN (Online) 1290-0729
Published by Elsevier Homepage  [3206 journals]
  • Heat transfer comparison between branching and non-branching fins in a
           latent heat energy storage system
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Jonas Skaalum, Dominic GroulxAbstractThermal energy from sustainable sources is a growing percentage of the global energy budget, one which requires storage technologies for effective use. For thermal energy, latent heat energy storage systems (LHESSs) offer the potential for significantly improved energy density and quality compared to traditional sensible storage systems. Most materials suitable for use in LHESSs, however, have very low thermal conductivities leading to limited heat transfer rates and requiring advances in heat exchanger design for these systems. Therefore, the first ever experimental study was performed comparing a heat exchanger using bifurcated fins and heat exchangers with straight fins within a shell-and-pipe LHESS. The bifurcated fins transferred less energy than the straight fins during charging tests due to their reduced ability to form convective cells of molten phase change material. During discharge the bifurcated geometry provided a lower but steadier rate of heat transfer, exchanging slightly more energy over an 8-h period than the straight fins. With the additional manufacturing cost required to obtain the bifurcated fins, it was found that their implementation in this shell-and-pipe LHESS offers no energetic nor economic advantages.
       
  • Nucleate boiling on nanostructured surfaces using molecular dynamics
           simulations
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Longyan Zhang, Jinliang Xu, Guangling Liu, Junpeng LeiAbstractNanostructures have significant impacts on incipient nucleation time and onset temperature during nucleate boiling. This study compares three types of surfaces, namely smooth, concave structured, and convex structured to investigate the mechanism of nucleate boiling via molecular dynamics simulations. The results show that nanostructured surfaces enhance bubble nucleation compared to smooth surfaces, provide fixed nucleation sites for initial embryo generation and shorten incipient nucleation time. Furthermore, nucleate boiling occurs more quickly on concave nanostructured surfaces than on convex ones regardless of the nanostructure size. However, with decreasing nanostructure size, the difference between them gradually decreases. A further analysis of the onset temperature is performed under various surface conditions. The onset temperature of nucleate boiling on the large concave nanostructured surface is much lower than on large convex nanostructured surface, owing to the stronger heat accumulation effect of the cavity. However, the onset temperature on the small concave nanostructured surface is higher, because liquid atoms are strongly absorbed into the small cavity and crystallized with the hydrophilic surface. The results improve the understanding of nanoscale nucleate boiling and provide a reference for the design of microelectronic devices.
       
  • Performance evaluation and optimization of design parameters for twisted
           conical strip inserts in tubular laminar flow Using Taguchi approach
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Mahdi Pourramezan, Hossein Ajam, Mohammad Amin Raoufi, Abazar AbadehAbstractNumerical simulation of flow structure and heat transfer augmentation of laminar flow in a circular tube fitted with the novel twisted conical strip inserts is investigated in this paper. The mechanism of heat transfer and the effects of geometrical parameters on thermo-hydraulic characteristics of the flow are studied through the utilization of performance evaluation criteria and performance ratio R3. In addition, the optimized cases and contribution of each parameter to heat transfer and friction factor are obtained from Taguchi analysis. The results show that higher values of Nusselt number, friction factor, and performance evaluation criteria occur due to lower pitches, lower twist angles, and non-staggered alignment. It was also observed that the Nusselt number and friction factor of the enhanced tube respectively vary in the range of 2.4–14.66 and 2.3–51.22, compared to the similar parameters of the plain tube, while performance evaluation criteria and performance ratio R3 locate in the range of 1.82–3.94 and 1.37–7.75, respectively. It was found that the twist angle is the most effective geometrical parameter on both friction factor and Nusselt number. Moreover, the effect of all investigated parameters on Nusselt number, friction factor, and performance evaluation criteria declines at higher levels of the parameters.
       
  • Natural convection heat transfer and fluid flow around a thick hollow
           vertical cylinder suspended in air: A numerical approach
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Manoj Kumar Dash, Sukanta Kumar DashAbstractThe present study reports numerical investigation on natural convection heat transfer and fluid flow from a thick hollow vertical cylinder suspended in air within laminar regime for a Rayleigh number (Ra) of 104 to 108. Numerical simulations have been performed by changing the length to outer diameter ratio (L/Do) of the cylinder from 0.2 to 20 and thickness ratio (Di/Do) from 0.5 to 0.9. Variation of average Nusselt number (Nu) and local Nusselt number with the above parameters has been elucidated graphically. Subsequently, the influences of Ra, L/Do, Di/Do on mass-flow rate and velocity profile inside the cylinder has also been investigated. Temperature contour and velocity vector plot around the cylinder have been represented pictorially to describe the thermal and velocity field around the vertical thick hollow cylinder. It has been observed that the average Nu of a thick hollow cylinder increases with L/Do, attains a peak and then decreases to a minimum and then again increases with L/Do. This phenomenon is very well observed at high Ra of 106 compared to lower Ra of 104. The Nu of the inner surface is found to be always lower compared to the outer surface and as L/Do increases beyond 8 the inner surface Nu falls drastically at high Ra compared to lower Ra. It has also been observed that the non-dimensional mass-flow rate due to buoyancy driven flow inside the thick hollow cylinder increases with L/Do, attains a peak and then decreases for all Ra. Cooling curve and a correlation for Nusselt number as a function of geometrical and thermal parameter have been presented which are useful for industrial purposes.
       
  • Mathematical modelling of conjugate laminar and turbulent heat transfer in
           a cavity: Effect of a vertical glazed wall
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Y. Olazo-Gómez, J. Xamán, M. Gijón-Rivera, F. Noh-Pat, E. Simá, Y. ChávezAbstractA numerical analysis of the laminar and turbulent natural convection combined with surface thermal radiation in a square cavity with a glazed wall is presented. The enclosure is composed of one left vertical isothermal wall, two horizontal adiabatic walls, and one right vertical partially semitransparent wall (clear glass sheet). Different values of the aspect ratio of the right vertical glazed wall (A=0.15,0.25,0.5,0.75,1.0) are analyzed, and the incoming solar irradiation (G) over the glass is varied from 0 to 750 W/m2 at intervals of 150 W/m2. Three different case studies were considered based on the position of the clear glass sheet on the right wall: (a) located at bottom side/Case 1 (C1), (b) located at the middle side/Case 2 (C2), and (c) located at the upper side/Case 3 (C3). The numerical solution was carried out using an in-house code based on the finite volume method. The numerical code was validated against experimental data for the turbulent natural convection problem. A comparison between the predicted and measured dimensionless vertical velocity, temperature profiles and local and average Nusselt numbers are presented, obtaining good agreement. Results show that convective heat transfer increases from about 70 to 250 as the aspect ratio increases from 0.15 to 1.0, for all solar radiation intensities, and all cases of turbulent flow. Also, radiative heat transfer decreases as the aspect ratio and solar radiation increase, which implies that it could become lower than convective heat transfer for some aspect ratio values set. When a laminar flow regime is considered, lower average convective and radiative heat transfer rates are obtained regarding the case of turbulent flow. In general, they are between 2.0
       
  • Predicting the vertical buoyant spill-plume temperature along building
           facade with an external sloping facing wall
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Tong Xu, Fei TangAbstractThis study focuses on the vertical buoyant spill-plume temperature along building facades under the effect of external sloping walls having different angles. Experiments were conducted using a reduced-scale room model [0.4 m (height) × 0.4 m (width) × 0.4 m (length)] under various heat-release rates (HRRs) with different opening dimensions and angles of the sloping facing wall. K-type thermocouples were installed in a vertical position along the facade wall. We observed that for a given HRR, the vertical buoyant spill-plume temperature along the building facade decreased with increasing height, and the external flow velocity of the ejected plume along the facade wall became more intense with the increase in the inclination angle of the sloping facing wall. A new dimensionless correlation was proposed to characterize the vertical temperature along the facade wall; this correlation considers the various opening sizes and angles of the sloping facing wall. Thus, this study provides both basic data and new information on the correlations of the vertical buoyant spill-plume temperature along the building facade with an external sloping facing wall.
       
  • Thermal analysis of heat transfer in pipe cooling concrete structure by a
           meshless RBF-FD method combined with an indirect model
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Yongxing Hong, Ji Lin, Alex H.-D. Cheng, Yuan Wang, Wen ChenAbstractNumerical simulation of heat conduction in the concrete structure with cooling pipes is meaningful and full of challenges. In this paper, the radial basis function finite difference method (RBF-FD) combined with a self-correcting prediction model (SCM) is proposed for thermal analysis of heat transfer in concrete structures with pipe cooling system. Using the Multiquadric radial basis function (MQ-RBF), the SCM is proposed to give full play to advantages of the localized meshless method. This technique allows use of more number of nodes in the whole domain to solve the ill-conditioning problem associated with multiple regions of rapid variation and increases the accuracy of models. A multiple-scale technique is applied to determine the shape parameter in the MQ-RBF and the fictitious nodes method is modified by using just one fictitious node outside the domain to deal with boundary conditions of the third kind in tiny holes. To show the flexibility and efficiency of the proposed scheme, we consider several examples with different number, size, and positions of pipes. Meanwhile, a guidance of determination of effected area near a tiny hole is provided and a simple optimization design of cooling pipe system is performed. The results demonstrate advantages of the proposed model which can effectively handle heat conduction problem with multiple holes subjected to the third kind boundary conditions.
       
  • Experimental investigation on heat transfer characteristics of
           supercritical nitrogen in a heated vertical tube
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): He Cheng, Liang Yin, Yonglin Ju, Yunzhun FuAbstractThe rapid variations of physical properties near the pseudocritical points and the unique heat transfer and resistance characteristics of supercritical fluids have gained a great deal of attentions in recent years. In this paper, the heat transfer characteristics of supercritical nitrogen in a heated vertical tube are investigated experimentally. The test section is an aluminum alloy tube of 6.6 m in length and 0.02 m in inner diameter with a wall thickness of 0.0085 m. The effects of different operating parameters, including pressure and mass flow rate of nitrogen, inlet temperature and mass flow rate of water, on the heat transfer characteristics are investigated. Meanwhile, the experimental data are compared with the predict values by different existing correlations, and all of them show large differences. Therefore, a new correlation has been developed to accurately predict the heat transfer coefficient based on the experimental data. The new correlation works well with 95% of the experimental data captured with a deviation of 20%. The experimental study and the new correlation may provide reference for the study of the heat transfer of supercritical fluid flow and design and operation of open rack vaporizer (ORV).
       
  • Buoyancy-driven convection in a horizontal porous layer saturated by a
           power-law fluid: The effect of an open boundary
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Michele Celli, Andrea Natale Impiombato, Antonio Barletta An infinitely wide horizontal porous layer saturated by a power-law fluid is heated from below by an imposed heat flux. The basic stationary state is characterised by a horizontal throughflow and a constant temperature gradient along the vertical direction. A linear stability analysis is performed by employing the method of normal modes. The eigenvalue problem obtained is solved by employing two different approaches: a hybrid analytical/numerical technique and a fully numerical technique. The critical values defining the threshold configurations for the onset of thermal convection are presented. These threshold values display a non monotonic dependence on the basic flow rate while they are monotonically increasing functions of the power-law index.
       
  • Numerical investigation on the effect of tunnel width and slope on ceiling
           gas temperature in inclined tunnels
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Zhiyong Wang, Long Ding, Huaxian Wan, Jie Ji, Zihe Gao, Longxing Yu A series of simulations are conducted in full-scale inclined road tunnels to explore the effect of tunnel width and slope on ceiling gas temperature pattern in fire. Firstly, characteristic temperature pattern in inclined tunnel fires due to the presence of stack effect are indicated. The buoyancy induced airflow velocity at the inlet increases with tunnel slope and stays almost invariable with tunnel width, and the location of impinging point is blown downstream with the increasing tunnel slope and changes little with tunnel width correspondingly. However, the maximum ceiling gas temperature area stays almost unmovable with the change of tunnel width and slope because of the effect of the buoyancy induced airflow at the inlet on the upstream gas back-layering. Then a correlation of the maximum gas excess temperature with tunnel width and slope is proposed by dimensional analysis. Finally, taking the position and value of maximum ceiling gas temperature as references, downstream ceiling gas temperature data can be correlated well by an exponential expression. In addition, the correlation is compared with previous experimental results and simulated results in the tunnels with longer length and different fire source locations.
       
  • Efficient design of curved solar air heater integrated with semi-down
           turbulators
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Ajeet Pratap Singh, Akshayveer, Amit Kumar, O.P. Singh Recent investigations reveal that curved solar air heaters (SAH) thermo-hydrodynamically performs better in comparison to flat SAH design. Further, it has been observed that down-configurations of turbulators or extended surfaces on the flat plate solar collector significantly enhance the thermal performance. However, scientific literature on thermal performance investigations with down-configurations of ribs in curved SAH are rare. In the paper, we systematically investigate using experimentally validated computational fluid dynamics model for different shapes of down-configuration of ribs. It was observed that half-trapezoidal and quarter-circular shape ribs shows maximum increase in thermal performance i.e. 17% and 16%, respectively, however frictional loss for quarter-circular ribs was observed to be less by about 10% when compared to trapezoidal shape ribs. The exergy recovery is maximum for trapezoidal and circular shape ribs and it is about 35% more than the smooth flat SAH. A new correlation has been developed for Nusselt number variation which has the form as Nu=f[Re,erH] where er is the height of quarter-circle groove. Observed data from the model matches well with the prediction from the developed correlation.Graphical abstractImage 1
       
  • Gas temperature rise and flame length induced by two buoyancy-controlled
           propane burners aligned parallel to the cross wind
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Jie Ji, Bo Li, Huaxian Wan, Long Ding, Zihe Gao This paper investigates the gas temperature rise and flame length of buoyant turbulent diffusion flames under cross wind, which does exist in fuel leakage fire accidents. Two identical propane burners with the same heat release rate were employed as fire sources. The burner spacing, heat release rate and cross wind velocity were changed. The results show that with the increase of the cross wind velocity, the gas temperatures in downwind region are strongly increased, resulting in a strong heat transfer to nearby energy loads. On the other hand, the non-monotonic trend of the flame length is caused by the cross wind effect. In addition, a segmented function predicting the flame length under cross wind is developed for merging and non-merging flames, which involves the heat release rate, burner spacing, pool size and cross wind velocity. The findings of this work have potential practical applications for optimal arrangements of energy loads, which allow predictions to be made regarding the possible threat and the establishment of the necessary safety distance to prevent the damage of multiple fires.
       
  • A modal substructuring method for non-conformal mesh. Application to an
           electronic board
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Sébastien Grosjean, Benjamin Gaume, Frédéric Joly, Karine Vera, Alain Neveu This paper deals with the coupling of modal models computed independently from each other (non-conformal substructuring). The proposed approach is inspired by the mortar methods initially written for finite elements, and here adapted to modal formalism. Mortar methods combine efficiently with the modal method described hereafter as Steklov modes introduced in this study dissociate volume and surface contributions. A realistic example illustrates the method: a library of electronic components reduced models is built, then used to create two electronic cards. Results meet high expectations: the substructured reduced model is 2500 times faster to solve than a finite elements one, while keeping a precision below 1∘C on the critical parameters.
       
  • Cooling solutions for an electronic equipment box operating on UAV systems
           under transient conditions
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Giovanni Tanda The thermal behaviour of an electronic equipment box under transient conditions is investigated. The box consists of a cabinet designed to contain electronic devices (such as infrared and visible cameras, hyperspectral sensors, etc.) carried on UAV systems and thermal control has to be assured only for the short duration (15–20 min) of each flight. Experiments were performed by considering a single component as electronic unit and different cooling systems, including forced convection of external or internal air and use of phase change/storage units (cold gel packs) inside the box. The best cooling solution was obtained by placing cold gel packs inside the box in combination with the internal ventilation, without any air exchange with external environment. A simple mathematical model was devised to simulate the thermal response of the component during the cooling transient and calculated results were successfully compared with experimental results. As a result, it is expected that the developed model could be used as a reliable tool for transient thermal management of an array of components inside the box, as encountered in UAV remote sensing applications.
       
  • Dynamics of liquid drops levitating on superheated surfaces
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Junseok Park, Dong Eok Kim The determination of the spreading dynamics and Leidenfrost temperature of drops impacting on a superheated surface is very complicated because it needs the rigorous determination of relevant time and length scales. We experimentally measured the parameters related to these phenomena for different fluid drops (water, ethanol, and FC-72). Although the drop spreading dynamics, which are represented by the maximum spreading ratio, can be qualitatively modeled by existing energy (kinetic, surface, and viscous dissipation energies) conservation theory, we find that the estimates for the surface area of the drop and the relevant length and time scales should be modified for the accuracy and generality of the model. For drops with a low Weber number, the side surface area should be considered. Further, using experimental data, we reveal that the minimum drop thickness and time scale expressed by the thickness are more suitable for describing the spreading dynamics than the drop diameter and relevant time scale. Moreover, we present a scaling procedure for the Leidenfrost temperature, for which a proper scale for the vapor film thickness is essential. As a result of the scaling analysis, the vapor film thickness scale is expressed in terms of the drop diameter and as a power function of the Weber number. Together with the scaling result, we propose a Leidenfrost temperature scale relation.
       
  • Thermal enhancement of baseboard heaters using novel fin-tube arrays:
           Experiment and simulation
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): N. Bagheri, A. Moosavi, M.B. Shafii Baseboard heaters are a type of building heating systems that are placed along the base of the interior wall, instead of the traditional skirting. Baseboard heaters meet all the requirements of modern buildings such as thermal comfort, well-architected appearance, space-saving, efficient energy consumption, and fast thermal response. In the present study, we investigate the enhancement of the thermal output of hydronic baseboard heaters. For this purpose, several novel fin-tube arrays such as convector fins and fin-clips are proposed and the thermal performance of each array is evaluated experimentally. In addition, two different types of materials for the tubes, namely, copper and aluminum are examined during the experiment. The computational fluid dynamic simulations are used to carefully analyze the mechanism of the heat transfer enhancement in the baseboard heaters. The results indicate that the novel fins may considerably increase the performance. For instance, for low and high water temperatures, the convector fins can increase the performance by up to 42% and 94%, respectively, compared to the conventional fins. A baseboard heater with a convector fin and a copper tube exhibits the highest performance.
       
  • Numerical and experimental studies on an optimum Fin design problem to
           determine the deformed wavy-shaped heat sinks
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Cheng-Hung Huang, Po-Wei Tung A three-dimensional wavy-shaped fin array design problem is considered in this study using a software package CFD-ACE+ and the Levenberg-Marquardt method (LMM). The wavy shape of fin is expressed as a deformed sinusoidal function with increasing amplitude and period characteristics, which was suggested as the best combination of wave shape in Ref. [1]. The objective is to estimate the optimal shape of a wavy-shaped fin array to minimize the average temperature of the base plate of fin array under a fixed fin volume constraint. The results of the numerical analysis indicate that only when the design variables of deformed sinusoidal function can be estimated correctly, the optimal design of wavy-shaped fin can be obtained. The estimated optimal design fin array (Fin#4) has better heat dissipation characteristic than Straight-shaped (Fin#1), deformed sinusoidal-shaped (Fin#2), and regular sinusoidal-shaped (Fin#3) fin arrays since the average relative temperature (in the Celsius scale) of the base plate can decrease 8.78%, 1.45% and 1.35%, respectively, besides, the performances of both heat dissipation and power consumption of Fin#4 are better than those of Fin#3. Finally, experimental verifications are performed on the fabricated wavy-shaped fin array modules. The measurement results illustrate that the maximum relative error of temperatures between the numerical solutions and experimental data at inlet velocity wo = 1.0 m/s for Fin#1, Fin#3 and Fin#4 along four specified measurement lines are calculated as 2.54%. It implies an excellent agreement between the numerical and experimental temperature distributions on those wavy-shaped fin array modules.
       
  • Heat transfer modification of a natural convection flow in a
           differentially heated cavity by means of a localized obstacle
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): P. Chorin, F. Moreau, D. Saury In this experimental study, a natural convection flow in a differentially heated cavity has been disturbed in order to modify heat transfers. The disturbance is achieved by introducing a localized obstacle which acts as a small spatial extent passive system. The obstacle is placed inside the hot boundary layer of the cavity flow. Measurements have been carried out in terms of velocity fields, temperature profiles and heat transfers. The influence of the length and the vertical location for an insulating and a conducting obstacle have been analyzed. For the insulating obstacle, a part of the flow is deviated inside the colder core region in front of the obstacle, which leads to an increase of the downstream heat transfers as the deviated colder flow returns along the hot wall. For the conducting obstacle, a hot thermal plume is generated, which counters the obstacle effect observed for the insulating obstacle. In that case, the downstream heat transfer is increased or reduced depending on the vertical location of the obstacle. Relative changes on heat transfers compared to the case without obstacle are larger for longer obstacles and for higher vertical locations of the obstacle, for any conductivity. For instance, a relative heat transfer increase up to 83% is observed downstream the insulating obstacle for the largest length and highest vertical location.
       
  • Critical assessment of a new mathematical model for hysteresis effects on
           heat and mass transfer in porous building material
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Julien Berger, Thomas Busser, Thibaut Colinart, Denys Dutykh The reliability of mathematical models for heat and mass transfer in building porous material is of capital importance. A reliable model permits to carry predictions of the physical phenomenon with sufficient confidence in the results. Among the physical phenomena, the hysteresis effects on moisture sorption and moisture capacity need to be integrated in the mathematical model of transfer. This article proposes to explore the use of an smooth Bang–Bang model to simulate the hysteresis effects coupled with heat and mass transfer in porous material. This model adds two supplementary differential equations to the two classical ones for heat and mass transfer. The solution of these equations ensures smooth transitions between the main sorption and desorption curves. Two parameters are required to control the speed of transition through the intermediary curves. After the mathematical description of the model, an efficient numerical model is proposed to compute the fields with accuracy and reduced computational efforts. It is based on the Du Fort–Frankel scheme for the heat and mass balance equations. For the hysteresis numerical model, an innovative implicit–explicit approach is proposed. Then, the predictions of the numerical model are compared with experimental observations from literature for two case studies. The first one corresponds to a slow cycle of adsorption and desorption while the second is based on a fast cycling case with alternative increase and decrease of moisture content. The comparisons highlight a very satisfactory agreement between the numerical predictions and the observations. In the last Section, the reliability and efficiency of the proposed model is investigated for long term simulation cases. The importance of considering hysteresis effects in the reliability of the predictions are enhanced by comparison with classical approaches from literature.
       
  • Numerical experiment of turbulent transfer of thermal energy using the
           immersed boundary method and adaptive mesh refinement
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Rafael Romão da Silva Melo, Denise Kinoshita, Millena Martins Villar, Ricardo Serfaty, Aristeu da Silveira Neto This paper presents the mathematical modeling and numerical simulations of turbulent flows with thermal convection. Cartesian numerical meshes are used for non-Cartesian problems thanks to the dynamic and thermal immersed boundary methods. Turbulence modeling was performed using the LES (Large Eddy Simulation) methodology with dynamic Smagorinsky subgrid-scale modeling. All of the simulations were carried out using a computational code that was developed at home (MFSim - Multiphysic Simulator). Two kinds of thermal immersed boundary conditions were proposed, implemented, and validated. To exemplify the functionalities of this computational tool, simulations of turbulent natural convection were performed on a horizontal cylinder. Consistent qualitative results were obtained, which reveal the dynamic structures characterizing the transition to turbulence. The corresponding statistical results compare well with the reference results that have been published by other authors.
       
  • Numerical investigation of the fluid flow distribution for the
           hydrofluidisation food freezing method
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Michal Stebel, Jacek Smolka, Michal Palacz, Wojciech Adamczyk, Edyta Piechnik The food freezing method of hydrofluidisation is based on submerging small food products in an appropriate water-based solution, which is pumped into the tank through orifices in order to increase the heat transfer between the food products and the liquid by creating agitating jets. The highly turbulent refrigerating medium flow, which can be analysed using Computational Fluid Mechanics (CFD), creates significantly higher heat transfer coefficients in comparison to other techniques offering effective freezing, e.g. immersion or impingement jet methods. Therefore, rapid freezing of food products may occur. The aim of this study was to investigate the turbulent refrigerating medium flow within a hydrofluidisation freezing unit. The liquid used for the process was an aqueous solution of ethanol with a mass concentration of 5%. An axisymmetric CFD model has been developed to analyse the configuration with a single orifice and a spherical-shaped artificial food product located at different positions. The parameters being analysed were the orifice diameter (2–5 mm), sphere diameter (5–30 mm), position of the product above the orifice (20–80 mm) and the refrigerating medium mass flow rate (0.00267–0.15 kg⋅s−1). All cases covered the Reynolds number range of 1700–93,000. The developed model employed two turbulence models: k-ω SST and Reynolds stress model (RSM) which are appropriate for modelling an impinging flow over spherical objects. Validation has been performed using the PIV technique on a hydrofluidisation freezing unit designed for this study. The results being compared were the angle of the boundary layer separation and velocity profiles along the impinging jet and around the spherical object. The results of the CFD simulations confirmed by PIV measurements proved that the refrigerating medium flow is highly agitating around the samples. In addition, the preliminary results of sphere shape potato samples during the cooling process have been presented in this paper.
       
  • Heat transfer enhancement by localised time varying thermal perturbations
           at hot and cold walls in a rectangular differentially heated cavity
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): N. Thiers, R. Gers, O. Skurtys The objective of this work it is to determine the optimal properties of a thermal disturbance to enhance the heat transfer in a rectangular differentially heated cavity of aspect ratio 4. So, we study numerically the effect on the heat transfer of one or two small thermal actuators (5% of active plate surface) applied at the active walls of this kind of cavity. Thermal disturbances are sine or square waves. Influences of wave characteristics (amplitude, frequency, phase shift) and the vertical location of the disturbance area are investigated for various Rayleigh numbers below its first critical value (RaH=1.02×108). Only a fluid with Prandtl number equal to 0.71 (air) is considered. Flows are calculated solving the 2D unsteady Boussinesq–Navier–Stokes equations using the Spectral Element Method programmed in the Nek5000 opencode. A detailed description of the coupling between one or two thermal disturbances and cavity flow is presented. The main contribution of this work is that the best position to enhance the heat transfer is 70% of the hot plate height or 30% of the cold plate height, and not 0.1 for the hot plate (0.9 for the cold one) which is generally admitted. At this position this increase reaches 5.5% by disturbing at both active walls with local synchronised square waves of amplitude ε=1, of frequency f=0.403 and at a state slightly below the first critical Rayleigh number.
       
  • Effects of friction heating on a half space involving ellipsoidal
           inclusions with non-uniform eigentemperature gradients
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Wanyou Yang, Cenbo Xiong, Qinghua Zhou, Yanyan Huang, Jiaxu Wang, Jinxuan Zhu, Li Ma, Leon M. Keer Performance of material containing inhomogeneities/inclusions is severely affected by frictional heat resulting from contact behaviors between two mechanical components. An effective method for dealing with thermal field of a half space with distributed non-uniform ellipsoidal inclusions subjected to frictional heating load was proposed in the current investigation, which can be simplified to handle problems of uniform ellipsoidal inclusion and extended to deal with inhomogeneity problems. Two categories of non-uniform inclusions with Gaussian and exponential eigentemperature gradients are modeled. Temperature rise and thermal stress are analogously solved via the equivalent inclusion method (EIM). Results obtained by the proposed method totally correspond to those of the benchmarks. Parametric studies on eigentermperature gradient distribution and thermal field of a half space involving a non-uniform spherical inclusion are carried out. Surface convection effect is further taken into consideration to extend the application scope of the proposed method, and the influence of surface heat-transfer coefficients on the thermal field of a semi-infinite medium is explored.
       
  • Sensitivity study of the influence of the water boiling parameters on
           aluminum semi-continuous DC casting
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Sébastien Bolduc, László I. Kiss The thermal aspect is dominant in semi-continuous direct chill (DC) casting. In steady state, 80% of the total energy contained inside the ingot is evacuated by secondary cooling. For this reason, water is often suspected as a potential cause for the issues related to ingot quality. In the secondary cooling zone, the ingot is cooled by jet impingement boiling. Opinions in the literature about the influence of water quality on the boiling curve are conflicting. This can be associated mainly to the difficulties that experimenters meet during the measurement of the boiling curve repeatedly. Furthermore, published works present the entire boiling curve rather than identifying what are the significant parameters in it. This understanding is nonetheless essential in order to improve the measurement repeatability by focusing on the most significant boiling parameters as well as to ensure that the measured variations of the boiling curve are those that have an impact on the process. Considering this lack of knowledge, a sensitivity study has been completed to compare the relative influence of four parameters that characterize the boiling curve (Leidenfrost temperature, film boiling heat flux, critical heat flux and the temperature that belongs to the critical heat flux) on three issues responsible for the diminution of the recovery rate (hot tearing, bleed-out, butt curl). The study has shown that except the critical heat flux temperature, every tested boiling parameter plays a significant role on the three recovery rate obstacles. Moreover, for every case, a mutual interaction exists between the three significant boiling parameters. The latter demonstrates that the variation of each of the three most important boiling parameters is relevant and needs to be measured following a modification of the water quality. This study is the first step in the framework of a project aimed at the conception of an appropriate device for measuring the variation of the cooling capacity of water and its role on ingot quality.
       
  • Performance evaluation of charging process in a cascade latent heat
           storage system (C-LHSS) based on heat flux DSC results
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Rupinder Pal Singh, S.C. Kaushik, Dibakar Rakshit Thermal energy storage systems using phase change materials (PCMs) provides isothermal output with high energy storage density. But, these systems exhibit poor rate of heat transfer due to very low thermal conductivity. Cascade LHSS with varying melting temperatures are capable of providing a nearly constant heat flux condition between the flowing heat transfer fluid (HTF) and the PCM's. The mathematical model of any LHSS needs correct inputs of specific heat which is continuously varying with the temperature to predict the thermal performance accurately. The main objective of this study is to analyze the charging process of a medium temperature cascade LHSS with radial and longitudinal configurations, using two low cost phase change materials with experimentally evaluated thermo-physical properties. Dynamic Differential scanning calorimetry DSC tests are performed to evaluate the cyclic stability, phase change temperature and specific heat of PCM's namely HDPE and Carnauba wax. CFD model has been developed using precise specific heat–temperature relationship throughout the working temperature range including the phase change region. Effect of different heating rates on the DSC results and their impact on system performance has also been discussed. Geometric optimization along with parametric study with varying inlet temperature & mass flow rate has been carried out. The melting time is reduced by 26% using cascade system as compared to single PCM storage system. It is found that radial placement of PCM's increases the melting time by 96%.
       
  • Measuring anisotropic thermal conductivity of aluminum nitride films with
           the ultra-fast hot strip technique
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): B.E. Belkerk, J. Camus, B. Garnier, H. Al Brithen, S. Sahli, M.-A. Djouadi In this work, we report the implementation of the ultra-fast transient hot strip (THS) technique for measuring the anisotropic thermal conductivity of aluminum nitride (AlN) thin-films. AlN films were produced by reactive DC magnetron sputtering grown at low temperature (>250 °C) on silicon oxide (SiO2) thin-film produced on a silicon substrate. Precise measurement of thermal conductivity was performed with an experimental device generating ultra-short electrical pulses, and subsequent temperature increases were electrically measured on nanosecond and microsecond time scales. The electrical pulses were applied within metalized strips patterned on SiO2 before AlN elaboration and the temperature increases were analyzed within time periods selected in the range [0.1–10 μs]. AlN thermal conductivity of cross-plane (in-plane) increased from 60 to 90 W m−1K−1 (33–44 W m−1K−1) when thickness was raised from 1 to 2 μm, respectively. This shows clearly the anisotropy in thermal conductivity of AlN films. In addition, the volumetric heat capacity of AlN was estimated to be ~2.5 × 106 J K−1 m−3.
       
  • Smoothed iterative enthalpy approach for solid-liquid phase change
    • Abstract: Publication date: Available online 12 February 2020Source: International Journal of Thermal SciencesAuthor(s): R.R. Kasibhatla, D. Brüggemann Numerical modelling of solid-liquid phase change problems has a wide range of applications. Here, the fictitious source based method is one of the most implemented iterative approaches to account for non-linear temperature-enthalpy coupling despite its slow convergence. In the present work a method based on the optimum approach is implemented to model the solid-liquid phase change with a fast convergence. The complete numerical model involving the heat transfer and fluid flow is implemented in the open source computational fluid dynamics software OpenFOAM. The numerical results have fairly agreed with the benchmark experiments from Gau and Viskanta. Parameters like dimensional simplification, porosity constants and the influence of temperature correction step are studied to understand the consistent deviations in the numerical modelling. The optimum approach has also shown a fast convergence compared to the fictitious source-based method. For thin melting ranges, the temperature correction step ensures energy conservation.
       
  • Natural convection of water-based nanofluids near the density maximum in
           an annulus
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Yu-Peng Hu, You-Rong Li, Liang Lu, Yong-Jian Mao, Ming-Hai Li This paper presents a series of numerical simulations on natural convection of a water-based nanofluid near its density maximum in an annulus. The volume fraction of the nanoparticles ranged from 0 to 0.08, the nanoparticle diameter from 10 nm to 100 nm, the radius ratio of the annulus from 0.1 to 0.8, and the density inversion parameter from 0 to 1. The results indicate that Brownian motion should be considered in natural convection of water-based nanofluid with the density inversion phenomenon. Both the solid volume fraction and the radius ratio affect greatly the flow and thermal fields, while the nanoparticle diameter has a little impact. Adding nanoparticles can weaken or even overcome the negative effect of the density inversion phenomenon on the heat transfer performance, possibly making it higher than that of the common fluid. Additionally, the heat transfer performance of the nanofluid with metal or metal oxide nanoparticles is better than that of the nanofluid with non-metallic compound nanoparticles.
       
  • Optimization of pin perforation(s) induced flow dynamic for effective
           thermal dissipation
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Wong Jin Cheng, Chew Irene Mei Leng, Foo Ji Jinn This study numerically investigates the 3D perforated pin-fin heat sink forced convection and the induced flow dynamics at Reynolds number ranging between 10 × 103
       
  • Convective heat transfer characteristics of twin-web turbine disk with pin
           fins in the inner cavity
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Lei Li, Zhonghao Tang, Honglin Li, Wenjing Gao, Zhufeng Yue, Gongnan Xie In order to enhance the convective heat transfer effect of high pressure turbine disk, a novel twin-web turbine disk with pin fins in the inner cavity is developed. The convective heat transfer characteristics of the traditional TWD and the TWD with pin fins are analyzed by numerical method verified by a hollow disk model. The results show that there is a circular flow in the inner cavity which impacts the back and front web to enhance the local convective heat transfer coefficient. The Nusselt number of the back web is remarkably higher than that of the front web, and the temperature of the back web is visibly lower than that of the front web. The pin fins in the inner cavity compress the circular flow and make it move downward, so that the Nusselt number in the region below the pin fins is improved; meanwhile, local convective heat transfer coefficient and the area of heat exchange have both increased to improve the convective heat transfer effect. The convective heat transfer characteristics of the developed TWD with six Reynolds numbers are analyzed, the average Nusselt number of the inner cavity surface with pin fins are as much as about 10% larger than that of the traditional TWD, the flow resistance coefficients of the inner cavity of TWD with pin fins is about 11% higher than that of the traditional TWD.
       
  • Experimental study on the effect of ceiling mechanical smoke extraction
           system on transverse temperature decay induced by ceiling jet in the
           tunnel
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Fei Tang, Lei Chen, Yuhang Chen, Huanping Pang This paper focused on studying the transverse temperature distributions induced by ceiling jet under the effect of ceiling mechanical smoke extraction system. Many test conditions were investigated by conducted reduced tunnel model experiments. These changes in fire heat release rates (HRRs) and ceiling mechanical smoke extraction velocities were all taken into consideration. The longitudinal and transverse temperature distributions beneath the ceiling were also compared in this paper, it was found that the transverse temperature decays more slowly than the longitudinal temperature without ceiling extraction. In order to reveal the effect of ceiling mechanical smoke extraction system on the transverse temperature distributions induced by ceiling jet in a tunnel, the attenuation rate of transverse temperature increases as the increasing ceiling mechanical smoke extraction velocities. The modified model for transverse temperature attenuation under the ceiling induced by tunnel fire with different ceiling mechanical smoke extraction velocities was developed by modified the characteristic radius. And the dimensionless transverse temperature decay mainly shows a piecewise function.
       
  • Numerical analysis of rectangular fins in a PCM for low-grade heat
           harnessing
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Abdur Rehman Mazhar, Ashish Shukla, Shuli Liu Harnessing waste thermal energy from greywater (GW) in non-industrial buildings is becoming necessary to reduce energy demands, make heating/cooling technologies more efficient and to increase the share of renewables in the consumption. Harnessing this low grade energy to heat incoming cold water (CW) linked with phase change materials (PCMs) would decouple demand and supply along with integrating heat recovery with storage in a single unit, unlike technologies of the past.Radially installed rectangular copper fins around the GW and CW pipes of such heat exchanger (HE) enhance the thermal conductivity of the PCM which is the biggest obstacle in this high-impulse application, with the flow rate being high only for a short duration of time. Initially an experimental test rig is used to validate a numerical model as the basis of a sensitivity analysis to find the optimum geometric parameters of the finned HE for this application. A 40 × 90 mm fin with a 10 mm pitch provides complete phase change for both melting and freezing in the constrained time duration of 900s. Compared to a non-finned geometry this optimized fin configuration enhances the effective thermal conductivity of the PCM by a factor of 1.38 for melting and 4.75 for freezing. Although the development of buoyancy induced natural convection vortices are inhibited by fins the eventual heat transfer is enhanced due to a lower overall thermal resistance compared to a non-finned configuration. The GW to CW energy transfer efficiency is 72.4% with higher fluid flow temperature increments, compared to only 47.3% for a non-finned version.
       
  • Determination of thermal resistance at mould-strand interface due to
           shrinkage in billet continuous casting – Development and application of
           a novel integrated numerical model
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Saurav Chakraborty, Suvankar Ganguly, Prabal Talukdar An industrial continuous casting process of steel billet is analysed using a novel, integrated numerical model for the heat transfer and solidification of the molten metal as it passes through the mould. One of the major difficulties related to determination of thermal resistance at the mould-strand interface is addressed in the present study. Contrary to empirical or semi-empirical methods commonly used in the industry for determination of the heat transfer at the interface, the present work deals with the determination of the interfacial thermal resistance by adopting a novel mathematical approach. A two-dimensional, transient, finite difference method based code is developed for a plane slice of molten steel moving with a given casting speed down the mould. The resultant solidification and thermal shrinkage are calculated from the temperature distribution and knowledge of the temperature dependent density of steel. The heat transfer from the cast strand to the cooling water is modelled by a network of thermal resistance. The model is validated against experimental data obtained from literature. The numerical results reveal a dominant role of advection of the gaseous mixture of air and other components from pyrolysis of casting oil, in the interfacial gap formed due to the shrinkage of steel, which has not been considered previously in the formulation of thermal resistance. The numerical model is also used to analyse the heat transfer in the mould and the growth of the solidified shell as the strand moves down the mould. In particular, the corner regions of the strand are found to be hotter than the off-corner regions, due to non-uniform heat transfer across the periphery. Also, the effect of casting speed in the mould is found to be dominant in comparison to other casting parameters, such as mould thickness and cooling water velocity.
       
  • Study on the relationship between interfacial heat transfer coefficient
           and interface pressure in squeeze casting by using microscopic contact
           model
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Feifan Wang, Xueting Zhao, Jiahao Liu, Qingxian Ma, Jue Sun, Shanxin Xu, Zhiqiang Han In this paper, the relationship between interface heat transfer coefficient (IHTC) and interfacial pressure in squeeze casting was studied by using microscopic contact model. First, through deducing the geometrical characteristics of rough surfaces using the standard procedure for roughness and waviness parameters and analyzing the thermo-mechanical behavior of the contacting surfaces, the relationship between the mean surface plane separation and the interface pressure and interface temperature was established. Then, based on the data acquired from squeeze casting experiments and microscopic heat transfer analysis, the IHTC and the mean surface plane separation was correlated. By combining the above relationships, the dependence of the IHTC on the interface pressure and the interface temperature was determined quantitatively. Comparison between the calculated and the experimental IHTC showed a good accordance. Besides, the relationship between the IHTC after the interfacial pressure at the casting-die interface decreased to zero and the interface temperature was also fitted through the experimental data.
       
  • A comparative analysis of shielding of thermal radiation of fires using
           mist curtains containing droplets of pure water or sea water
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Leonid A. Dombrovsky, Vladimir Yu Levashov, Alexei P. Kryukov, Siaka Dembele, Jennifer X. Wen The paper is focused on comparative computational modelling of the attenuation of fire radiation by water mists of pure water or sea water. The use of sea water in fire protection could be a more convenient and practical choice in coastal areas, on offshore installations or transported ships. The spectral absorption and scattering properties of both water droplets and salt particles formed by evaporation of sea water droplets are considered. A combined heat transfer problem is based on a combination of the spectral radiative transfer in a mist curtain, the kinetics of water evaporation, and convective heat transfer along the curtain. The developed computational model is used to analyze the radiative heating and evaporation of droplets of pure water and more complex multi-phase processes in droplets of sea water at all stages of the process. The numerical results for the case problem indicate sufficiently good shielding quality of a sea-water mist curtain. The suggested approach is expected to be useful for important engineering applications in fire protection.
       
  • Effects of undulated wall on the hydrodynamic and thermal transport
           characteristics of turbulent jet
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Shrirang Shivankar, Pitambar R. Randive, Sukumar Pati The present study investigates numerically the effect of wall undulation on the thermo-hydraulic transport characteristics of turbulent jet. In order to explore the influence of position of the nozzle exit from the wall, both wall jet and offset jet are considered. The theoretical model is numerically solved using shear stress transport (SST) model to predict the effects of height of undulation of the wall and the offset jet ratio on the re-attachment length, the velocity profile at different downstream locations, the coefficient of friction and the Nusselt number. The results indicate that the undulation of wall has a strong influence in altering the friction coefficient, Nusselt number and re-attachment length for offset jet. It further reveals that there is an intricate interplay between undulation height and offset ratio in dictating the flow and heat transfer characteristics.
       
  • Thermal properties of a novel form-stable phase change thermal interface
           materials olefin block copolymer/paraffin filled with Al2O3
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Changqing Liu, Cheng Chen, Wei Yu, Mao Chen, Dongyi Zhou, Huaqing Xie Thermal contact resistance (TCR) between the thermal interface materials (TIMs) and the upper and lower contact surfaces plays an important role in the heat dissipation process of electronic devices. Moreover, TCR is mainly affected by temperature, pressure and fluidity of TIMs. When the critical operating temperature of the electronic device is reached, if solid-solid contact between two contact surfaces is changed into solid-liquid contact, TCR will be greatly reduced. Based on this idea, a novel form-stable phase change TIMs is proposed. The thermal conductivity of paraffin wax (PA) is improved by filling Al2O3 particles. The addition of olefin block copolymer (OBC) improves the stability and solves the leakage problem of PA. In addition, the effects of temperature and pressure on the TCR, especially near the phase transition point, are systematically studied. These results confirm that TCR of phase change Al2O3/OBC/PA is very sensitive to temperature. When the temperature rises from 37 °C to 41 °C, TCR of all samples decreases sharply from 10~20 K⋅cm2/Wto 1~2K⋅cm2/W. TCR of all samples decreases slowly with the increase of pressure (10~50 Psi, 45 °C) and is very close to the TCR of common thermal grease. Finally, when the mass fraction of Al2O3 is higher than 60 wt%, the thermal conductivity of the Al2O3/OBC/PA increases sharply with the increase of Al2O3. Therefore, form-stable Al2O3/OBC/PA is an important development direction to solve the heat dissipation in electronic technology.
       
  • Analytical and numerical investigation of combined convection-radiation
           heat transfer from conical spine extended surface
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Mishaal A. Abdulkareem, Aouf A. Al-Tabbakh The steady-state, one-dimensional, Cartesian coordinate, non-linear ordinary differential energy equation of heat conduction through a conical spine extended surface of a thermal conductivity temperature dependent property that is proposed by an available quadratic function of a computer fitted model of a published experimental data is solved analytically using Kirchhoff's transformation and numerically using the finite volume method. It is assumed that this extended surface is subjected with a Dirichlet and Neumann's boundary conditions of temperature at its base and tip respectively. The combined convection-radiation mode of heat transfer is imposed along the surface of the conical spine. Three case studies are investigated. The thermal conductivity is assumed constant in the first case and it is variable with temperature in the second and third cases, while the radiation heat transfer is neglected in the first and second cases and it is taken into account in the third case. In addition, the effect of the conical spine aspect ratio on its performance is investigated. Aluminum Alloy (A319) material of extended surface is selected. Excellent agreement between the predicted results of the numerical and analytical solution of the present work (case study 1) when compared with the experimental measurement of previously published paper. In addition, excellent agreement between the analytical and numerical results of the present work for all case studies. It shows a maximum error of temperature difference of less than (0.022%). It is found that the dissipated heat due to combined convection-radiation mode from the surface of the conical spine extended surface to the environment is greater than that due to convection mode only. In addition, increasing the value of aspect ratio of the conical spine extended surface will decrease its efficiency.
       
  • Numerical study on the performance of a two-nozzle spray cooling system
           under different conditions
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Zhiyu Zhang, Suoying He, Mingxuan Yan, Ming Gao, Yuetao Shi, Yuanshen Lu, Jiayou Liu, Cong Guo, Xiang Huang The cooling performance of natural draft dry cooling towers (NDDCTs) would significantly be reduced when the ambient air is hot. To address this problem, the spray pre-cooling technology has been introduced to cool the inlet air of the tower. The effect of two-nozzle distance on the evaporative cooling performance will instruct the arrangement of multi-nozzle for industrial applications. This paper is therefore to study two nozzles vertically arranged in a wind tunnel by the numerical simulation. A 3-D model was developed and validated for simulation studies. The effects of two-nozzle distance, inlet air speed, inlet air dry-bulb temperature and humidity on the evaporative cooling performance were investigated. Besides, a modified cooling efficiency was proposed to effectively evaluate the cooling performance with considering both the cooling affected region and the air temperature drop. The simulation results indicate that the modified cooling efficiency is more or less affected by the two cooling affected regions generated by two nozzles at the wind tunnel exit. The modified cooling efficiency of the tangent region is similar to that of the separating region, and it is 2.5% higher than the partially overlapping region. Generally, the high modified cooling efficiency is accompanied with the high air dry-bulb temperature and the low humidity. The modified cooling efficiency increases with the decreasing inlet air speed.
       
  • Experimental investigation on shell-side performance of a novel shell and
           tube oil cooler with twisted oval tubes
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Shijie Liu, Yingde Yin, Aimin Tu, Dongsheng Zhu The lubrication oil cooler is widely used in many industries. The lubrication oil is usually operated in a laminar state with Reynolds number less than 1000 due to its high viscosity characteristic. It is hard to augment the heat transfer performance of high viscosity fluids without obvious pressure drop. A lot of researches have been conducted on the shell-side heat transfer and fluid flow characteristics of twisted oval tube heat exchangers. However, the previous study mainly focused on the high Reynolds number regime and the correlations obtained are not suitable for low Reynolds flow. In the present paper, a novel self-supported shell-and-tube oil cooler with twisted oval tube bundles (OCTT) is designed. Experiments are conducted to investigate the shell-side heat transfer and pressure drop of OCTT compared to the conventional shell-and-tube oil cooler with round tube bundles (OCRT) in low Reynolds number flow. The experimental results indicate that at identical oil volume flow rate, the shell-side pressure drop of OCTT is lower than that of OCRT. Furthermore the shell-side heat transfer coefficient per unit pressure drop of OCTT is larger than OCRT. The empirical equations for Nusselt number and friction coefficient of OCTT in low Reynolds number ranging of 50–600 are also deduced from the experimental data, which could provide a beneficial guidance for the design of OCTT.
       
  • Numerical investigation on flow pattern transformation and heat transfer
           characteristics of two-phase flow boiling in the shell side of LNG spiral
           wound heat exchanger
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Jianrui Li, Haitao Hu, Haoxian Wang The flow pattern transformation and heat transfer characteristics of refrigerant flow in the shell side of LNG spiral wound heat exchangers (SWHEs) have a significant influence on the performance of SWHEs. A numerical model was developed to predict the flow pattern and heat transfer characteristics of two-phase flow boiling in the shell side of SWHEs. In the model, a submodel for simulating flow pattern was developed by employing Volume of Fluid combined with a Continuous Surface Force (VOF-CSF model), and a submodel for the mass transfer rate was developed; the forces and the heat and mass transfer rates were introduced into the control equations as the source terms. The experimental validation of the model shows that, the deviation of heat transfer coefficient is within ±20%, and the predicted flow patterns are consistent with those observed ones. Based on the proposed model, the flow pattern maps were developed, and the flow pattern transformation principles and heat transfer characteristics in SWHE shell side under different conditions were analyzed. The maximum heat transfer coefficient for SWHE shell side is enhanced by 10.5% as the longitude tube pitch increases from 1 mm to 3 mm, and reduced by 8.9% as the tube diameter decreases from 12 mm to 8 mm.
       
  • Enhancement heat transfer analysis of supercritical hydrogen fuel in
           small-scale channels with spherical concave
    • Abstract: Publication date: June 2020Source: International Journal of Thermal Sciences, Volume 152Author(s): Pengyong Xie, Xiaobing Zhang Thermal protection is a key issue for rocket engines. To effectively protect the combustion chamber wall, this paper mainly proposes a novel enhancement heat transfer device of using a spherical concave surface in a small-scale cooling channel, and numerically analyzes the hydrogen flow and heat transfer characteristics under supercritical conditions. The spherical concaves with a depth-to-diameter ratio of 0.2 (D = 1 mm, H = 0.2 mm) are applied on the inner wall of the regenerative cooling channel. The numerical study results show that the spherical concave can significantly improve cooling capacity, increase convective heat transfer coefficient, and reduce the maximum heat wall temperature. The new structure will be conducive to reducing the influence of the non-uniform temperature distribution caused by single-side heating, resulting in the more uniform temperature distribution and the better enhancing heat transfer capacity. For Re = 42000, the average Nu of the spherical concave channel can be improved by 40%, but the pressure drop only increases 14% than the smooth channel.
       
  • Measuring the in-plane thermal diffusivity of moving samples using laser
           spot lock-in thermography
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): M. Colom, A. Bedoya, A. Mendioroz, A. Salazar In this work we deal with samples that move at constant speed and are illuminated by a modulated and focused laser beam. We have obtained a general expression for the surface temperature of these moving samples: it is valid not only for opaque and thermally thick materials, but also for thermally thin and semitransparent samples. Moreover, heat losses by convection and radiation are taken into account in the model. Numerical calculations indicate that the temperature (amplitude and phase) profiles in the directions parallel and perpendicular to the sample motion are straight lines with respect to the distance to the laser spot. The slopes of these straight lines depend on sample speed, modulation frequency and in-plane thermal diffusivity of the sample. Provided the two first experimental parameters are known, the in-plane thermal diffusivity can be retrieved in a simple manner. Measurements performed on materials covering a wide range of thermal diffusivity values, from insulators to good thermal conductors, confirm the validity of these linear methods.
       
  • Experimental investigation of effect of different tube row-numbers, fin
           pitches and operating conditions on thermal and hydraulic performances of
           louvered and wavy finned heat exchangers
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Abdulkerim Okbaz, Ali Pınarbaşı, Ali Bahadır Olcay Heat exchangers are used in air conditioners, heat pumps, marine, land and air vehicles, refrigeration systems, thermal and nuclear power plants, etc. Increasing heat transfer capacity of a heat exchanger means that the volume of the heat exchanger and the material used will be reduced. Besides, effects of some geometric parameters on heat transfer and pressure drop are more complex depending on the fin structure in fin and tube heat exchangers. In this study, three of the most dominant parameters affecting the thermal-hydraulic performance of a finned and tube heat exchanger were experimentally investigated. These are fin-type (louvered and wavy fins), fin pitch and number of tube-rows. The intermittent geometric structures of louvered fins break growing of the boundary layer and reduce its thickness yielding heat transfer enhancement. On the other hand, wavy fins cause an increase in the heat transfer area due to its large flow length and create instabilities in the flow due to flow separations increasing the heat transfer coefficient. In the present study, specifically five louvered finned and three wavy finned and round tube heat exchanger prototypes were manufactured. Heat transfer and pressure drop experiments of these heat exchangers were performed at a wind tunnel in a conditioned room. Heat transfer and pressure drop characteristics were presented as heat transfer coefficient ho, Stanton number St, Nusselt number Nu, dimensionless pressure drop coefficient Cp, Colburn-j factor, Fanning friction factor f, jlouver/jwavy, flouver/fwavy, j/f1/3 ratios and JF factor. The results were examined from the point of heat transfer and pressure drop mechanisms of louvered and wavy fins for the different number of tube-rows, fin pitches and air inlet velocities. It is found that Colburn-j factors and Fanning friction f factors of the LFRTHXs are higher than those of the WFRTHXs for all the studied cases. Colburn-j factors of the LFRTHXs are higher by 16.4–6.9%, 28.5–18.3% and 25–11.7% than those of the WFRTHXs for the cases of two tube-rows, three tube-rows and four tube-rows, respectively. On the other hand, pressure drops of the LFRTHXs are significantly higher than those of WFRTHXs. However, the thermal-hydraulic performances of the LFRTHXs are still higher than that of WFRTHXs. The thermal-hydraulic performance criteria j/f1/3 ratios of the LFRTHXs are higher by 9.6–4.1%, 22.1–16% and 16.8–7.4% than those of the WFRTHXs for the cases of two tube-rows, three tube-rows and four tube-rows, respectively.
       
  • Effect of temperature modulation on natural convection in a horizontal
           porous annulus
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Jabrane Belabid, Karam Allali The effect of temperature modulation on natural convection in a horizontal porous annulus is investigated in this paper. The porous medium is confined between the inner and outer cylinders of the annulus which is subjected to time-dependent temperature. It is assumed that the time-dependent modulation is periodic with frequency σ and amplitude λ. The model consists of the heat equation and the equations of motion under the Darcy law. The derived problem with the stream function-temperature formulation is solved numerically using the alternating direction implicit method. It is shown that a stabilizing effect can be gained for appropriate values of the frequency σ and the amplitude λ.
       
  • Fouling evolution on ribbed surfaces under EGR dry soot conditions:
           Experimental measurements and 3D model validation
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): C. Paz, E. Suárez, J. Vence, A. Cabarcos This study presents the development of an experimental procedure to validate a novel computational fluid dynamics (CFD) model that was presented in a previous study. This model reproduces the fouling phenomenon caused by soot particles inside exhaust gas recirculation (EGR) coolers. The aim of this study is to verify the model results by using a numerical tool to improve the study of deposits created inside EGR coolers.By employing an experimental layout that emulates dry soot fouling, the deposit formation and evolution are recreated inside three probes designed ad hoc to enable local thickness measurements. An optical profiler is used to determine the topography of the soot deposit, thereby circumventing destructive tests. A sequential validation process is conducted by comparing the actual fouling profiles and the CFD results at different instants of the test. The results obtained under the studied conditions reveal that on average, 73.4% of the area analysed exhibits a low level of relative error. This verifies that the proposed model and its numerical implementation constitute a valuable tool for studying the performance of heat exchangers exposed to fouling.Graphical abstractImage 1
       
  • Experimental study and numerical simulation of thermal hydraulic
           characteristics of a finned oval tube at different fin configurations
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Alireza Hashem-ol-Hosseini, Mehran Akbarpour Ghazani, Mohsen Davazdah Emami Finned tube heat exchangers are among the most common types of heat exchangers that are used in engineering applications. Most of the tubes used in finned-tube heat exchangers are of circular type, but the oval tubes have more desirable features as they impose lower pressure drops with approximately the same amount of heat transfer. In this paper, a finned oval tube is studied experimentally and numerically to obtain temperature fields around the tube at different locations. Moreover, several 3D numerical simulations are performed to study the effects of fin length, fin spacing and diameter ratio of the tube cross section. Based on the obtained results, fin spacing of 1 mm is the optimum at all tube aspect ratios and fin lengths when Reynolds number is low while at high Reynolds numbers, fin spacing of 3 or 4 mm is the better choice. As to the fin length considerations, for a short fin, a spacing of 3 or 4 mm is the best choice at high Reynolds numbers. For larger fin lengths, sensitivity to fin spacing is less but a fin spacing of 3 or 4 is preferable at high Reynolds numbers.
       
  • Phase change heat transfer in a rectangular enclosure as a function of
           inclination and fin placement
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Dominic Groulx, Pascal H. Biwole, Maha Bhouri In this paper, melting of a phase change material (PCM) inside a rectangular enclosure, possibly finned and inclined, is studied numerically. The application of this work is related to the temperature control of a finned PV panel filled with PCM and installed at different tilt angles. The studied system is modeled as a 2D rectangular enclosure filled with PCM (RT25) and packed between two aluminum plates, where the front side is exposed to a constant heat flux of 1000 W/m2 for 2 h. Four geometries were considered including a non-finned PCM enclosure, a PCM enclosure with one centered full-width fin, one half-width fin attached to the front plate, and one half-width fin attached to the back plate. Results have shown that the most efficient thermal management of the PV-PCM panel is obtained when the PCM enclosure is equipped with a full-width fin simultaneously attached to the front and back plates. With such a PV panel design, the PCM melting is dominated by natural convection heat transfer from both sides of the PCM enclosure at an early stage, with added heat losses from the back plate to the external environment. Accordingly, low values of the front and back plates temperatures can be maintained during a stabilization time of 80 min as long as the tilt angle is varied from 0° to 75° from the vertical. The efficient temperature control resulting from the full-width fin geometry is mainly related to the high overall heat transfer coefficient obtained during the whole melting process.
       
  • Augmentation and diminution of non-Boussinesq effects due to non-Newtonian
           power-law behavior in natural convection
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Jacob Koshy Mulamootil, Sukanta Kumar Dash This study investigates the extent and significance of augmentation and diminution of non-Oberbeck–Boussinesq (NOB) effects due to power-law rheology in natural convection. The relative significance of each temperature dependent thermophysical property of a non-Newtonian power-law fluid was first evaluated using an order of magnitude analysis. The limiting criteria were derived for a class of fluids having an Arrhenius-type thermodependent consistency index, and a constant power-law index. Significant fluid property dependencies were identified, incorporated into the conservation equations, and solved numerically. The benchmark problem of natural convection around an isothermal vertical flat plate, immersed in a quiescent power-law fluid, was re-investigated from the viewpoint of NOB effects. It was found that power-law rheology significantly augmented or diminished the acceleration of flow caused by NOB effects. Compared to the Newtonian case, strong shear thinning behavior more than doubled the NOB acceleration of the flow field, and shear thickening inhibited the acceleration by nearly half. Numerical solutions facilitated the visualization of velocity and temperature distributions, and thus provided insights to the underlying physics. It is demonstrated that the cumulative effect of the power-law behavior and temperature dependence of properties is more than a mere superposition of the individual effects. Important contributions from the present work include modifications to the OB approximation’s limiting criteria applicable to power-law fluids, insights into the effect of temperature dependent properties on the flow field and consequent heat transfer, and their correspondence to the results of the order of magnitude analysis. The present investigation of the underlying physics of augmentation and diminution facilitate a better understanding for future studies of NOB effects combined with non-Newtonian behavior.
       
  • Numerical investigation on heat transfer of water spray cooling from
           single-phase to nucleate boiling region
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Chang Cai, Hong Liu, Ming Jia, Hongchao Yin, Rong Xie, Peiliang Yan In the present study, spray cooling heat transfer characteristics were numerically investigated under the heat flux ranging from 50 to 170 W/cm2. Effect of nozzle height and spray pressure was also studied in order to reveal the microscopic mechanisms of the heat transfer enhancement from single-phase to nucleate boiling regions. A two-phase flow heat transfer model was adopted based on the Euler-Lagrangian approach. The dependence of thermo-physical properties of fluid on the temperature was also taken into account. The comparison between simulated wall temperature and experimental data demonstrates a satisfactory agreement. The results show that the heat transfer coefficient increases monotonously with the heat flux. In the nucleate boiling region, the wall film is thinner with a smaller velocity compared with those in the single-phase region. Spray cooling heat transfer is enhanced evidently as the nozzle height decreases and the spray pressure increases. The most important feature which separates the present study from the literature is that the numerical simulation in this paper presents some detailed microscopic characteristics, e.g. the wall film thickness and velocity, which play an important role in spray cooling heat transfer.
       
  • Numerical investigation of heat transfer from a plane surface due to
           turbulent annular swirling jet impingement
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Farhana Afroz, Muhammad A.R. Sharif The heat transfer characteristic of an annular turbulent swirling jet impingement on a heated plane surface is investigated numerically. The annular jet configuration causes instabilities and fluctuations in the flow. Depending on the combinations of different parameters, the annular jet impingement may have positive or negative effects on the heat transfer from the impingement surface. Swirl, on the other hand, introduces vorticity and fluid mixing in an impinging jet, which is desirable in some applications. The axisymmetric two-dimensional flow domain on a radial-axial plane is considered in the numerical model. Both non-swirling and swirling jet impingement is studied. The numerical computations are performed using the ANSYS Fluent CFD code. The Realizable k-ε turbulence model with enhanced wall treatment is used in the computation. The computational process is validated against other published data on similar flow configuration for non-swirling annular impinging jets. The flow and geometric parameters are the jet exit Reynolds number, Re (5000 to 25,000), the swirl strength Sw (0–0.77), the jet exit to the impingement surface distance, H (0.5–4.0), and the moderate blockage ratio of the annular jet, BR (0.4–0.6). The thermal-hydraulic field in the domain is computed for various combinations of these parameters. The effects of these parameters on the Nusselt number distribution on the impingement surface are analyzed. For short separation distance (H = 0.5), the swirling motion positively affects the overall heat transfer, and the average Nu is increased as high as 8% for certain combinations of Re, Sw, and BR; compared to the non-swirling annular jet impingement. For higher separation distances, the average and peak Nusselt number is initially reduced and then increased with increasing swirl strength.
       
  • Approximate Bayesian computation applied to the identification of thermal
           damage of biological tissues due to laser irradiation
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Bruna R. Loiola, Helcio R.B. Orlande, George S. Dulikravich This paper deals with the solution of an inverse bioheat transfer problem, by using Approximate Bayesian Computation (ABC). A Sequential Monte Carlo (SMC) method is applied for simultaneous model selection and model calibration (estimation of the model parameters) by using synthetic measurements. Two competing models are considered in the analysis of the thermal damage of biological tissues. The results show that the ABC-SMC algorithm provides accurate results for the model selection and estimation of the thermal damage model parameters.
       
  • Ignition of polymers under exponential heat flux considering both surface
           and in-depth absorptions
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Junhui Gong, Chunjie Zhai, Lizhong Yang, Zhirong Wang Analytical models addressing ignition of solids under constant heat flux have been developed in previous studies utilizing surface or in-depth absorption or combination of them. When encountering time-dependent heat flux, the majority of the studies focused on polynomial heat flux and surface absorption assumption. However, in-depth absorption also should be taken into account under time-dependent heat flux in analytical models especially for infrared translucent solids. In this work, an analytical model aiming at revealing the ignition mechanism of translucent polymers under exponential time-increasing heat flux is established considering both surface and in-depth absorptions. Critical temperature is employed as ignition criterion. Four typical non-charring polymers, polymethyl methacrylate (PMMA), polyoxymethylene (POM), polyamide 6 (PA 6) and polypropylene (PP), are utilized as the reference materials, and a numerical solver is employed to validate the analytical model. The results show that the developed analytical model provides accurate predictions of surface temperature and ignition time. Surface heat loss by convection and reradiation has little effect on surface temperature, ignition time and critical energy, but it affects the ignition heat flux greatly. Thermal penetration depth differs from the one under constant heat flux, and it gets smaller as the surface heat loss is considered. The ignition time, thermal penetration depth and critical energy decrease as the heat flux increasing rate gets larger. Meanwhile, the ignition heat flux for in-depth absorption is higher than that for surface absorption, and both increase with heat flux increasing rate. Furthermore, the linearity between ignition time and the squared critical energy, proposed in constant and linear heat flux scenarios, is also found valid under this exponential heat flux condition.
       
  • Experimental and numerical investigation of air-side forced convection on
           wire-on-tube condensers
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Alişan Gönül, Özden Ağra, Ş. Özgür Atayılmaz, Hakan Demir, M. Kemal Sevindir, İsmail Teke In this study, wire-on-tube condensers used frequently in industrial cooling applications have been investigated experimentally and numerically, which are exposed to forced convection. Five different coils with different geometric properties were studied in the experimental study. The numerical study has been validated by the experimental data obtained through these coils. After validation, the effect of wire diameter (Dw), tube diameter (Dt), wire pitch (Sw) and tube pitch (St) have been investigated parametrically for five different air velocities (0.5, 1.0, 1.5, 2.0 and 2.5 m/s). The parametric study was performed for the variation for wire diameter (1.2 mm–2.0 mm), tube diameter (4.2 mm–7.2 mm), wire pitch (5.5 mm–9.5 mm) and the tube pitch (20 mm–50 mm) to determine their effects on wire-on-tube condensers in terms of heat transfer. It is observed that the increase of the wire diameter decreased the heat transfer coefficient on the wire by 10–12% while the heat transfer coefficient on the tube increased by 10–15%. It is determined that the effect of increasing tube diameters on the convection coefficient on the wire is very low. When the distance between the wires is increased from 5.5 mm to 9.5 mm, the average convection coefficient on both tubes and wires is decreased by 5%. When the distance between the tubes is increased from 20 mm to 50 mm, it is concluded that there is a decrease in the convection heat transfer coefficient on both the tube and the wires by approximately 7–8% depending on the velocities. As a result, the correlations are proposed to determine the amount of heat transfer generated over both the wire and the tube. The proposed correlations yield accurate results in the error range of 10% with CFD results and %15 with experimental results.
       
  • Evaporation of a sessile oil drop in the Wenzel-like regime
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Dorra Khilifi, Walid Foudhil, Souad Harmand, Sadok Ben Jabrallah In this work, we present an experimental study of the evaporation of oil drops deposited on both textured and smooth silicon substrates at two different temperatures (20 °C and 270 °C). We show that the sessile drops take a hexagonal form and are linked by an oil film (a droplet sitting on a mixture of solid and liquid). This wetting regime represents the Wenzel-like regime. We are particularly interested in the propagation of the oil film on the textured surface over time. The effect of the surface fraction of the micro-textures ∅ and the temperature of the substrate Th on the film propagation were also studied. We reveal that the spreading length of the oil drops increases as ∅ decreases and Th increases. We also demonstrate that the textured surface favors oil drop evaporation.
       
  • Modelling the stability of Marangoni convection in a layer of nanofluid
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): A.A. Abdullah, N.M. Alraiqib, K.A. Lindsay A linear stability analysis is undertaken for the onset of Marangoni convection in a horizontal layer of a nanofluid heated from below. The model employed for the nanofluid incorporates the effects of Brownian motion and thermophoresis. The lower boundary of the layer is assumed to be a rigid surface at fixed temperature while the top boundary is assumed to be a non-deformable free surface cooled by convection to an exterior region at a fixed temperature. The lower boundary of the layer is assumed to be impenetrable to nanoparticles with their distribution being determined from a conservation condition. Material properties of the nanofluid are modelled by the non-constant constitutive expressions developed by Kanafer and Vafai based on experimental evidence. The steady state solution across the layer is shown to be well approximated by a linear distribution of temperature and an exponential distribution of nanoparticle volume fraction. Constitutive properties are assumed to be non-constant functions of temperature and the volume fraction of nanoparticles. New behavior is introduced which in turn leads to significantly different stability boundaries from those predicted by historical analyses.
       
  • Heat transfer performance evaluation of a novel concept of the core-hole
           heat exchanger for polymer foaming process
    • Abstract: Publication date: May 2020Source: International Journal of Thermal Sciences, Volume 151Author(s): Waqas Mughal, Chunling Xin, Jiangnan Li, Masroor Abro, Zhaoping Yang, K.H. Solangi, Yadong He The tandem extrusion method is quite famous for polymer foaming production in up-scale. In this method, two extruders coupled together for different functionality. The primary extruder used for melting, homogenizing the foaming agent in the melt. The secondary extruder used for reducing the melt temperature to the required foaming temperature limit. In this study, propose newly developed core-hole heat exchanger by replacing secondary extruder as an alternative solution. The heat transfer performance of the core-hole structure investigated in this work. According to heat transfer performance mainly focus on heat transfer rate, temperature distribution, local heat transfer coefficient, Nusselt number, and overall heat transfer coefficient in this work. The experiments were carried out on 180 °C, 190 °C, and 200 °C inlet temperature, whereas the flow rate was 08 to 20 kg/h with 4 unit of the interval. Non-homogeneous temperature distribution resulted in 08 kg/h and 180 °C of the inlet temperature, but overall average temperature approximately similar to surface temperature. Good mix ability and the uniform temperature achieved on 12 and 16 kg/h in all range of temperatures in this study. Whereas, 20 kg/h of mass flow rate reduces the temperature distribution quality of the melt. Because of the higher temperature difference and flow rate, higher heat transfer rate achieved on 200 °C and 20 kg/h. Convective heat transfer coefficient has been increased concerning flow rate and local point temperature difference. In this work, it investigated that 190 °C of inlet temperature gives a higher overall heat transfer coefficient on 16 and 20 kg/h of mass flow rate.
       
 
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