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Heat and Mass Transfer
Journal Prestige (SJR): 0.448  Citation Impact (citeScore): 1 Number of Followers: 28  Hybrid journal (It can contain Open Access articles)ISSN (Print) 1432-1181 - ISSN (Online) 0947-7411 Published by Springer-Verlag  [2468 journals]
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- Bubble energy nanogenerators
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Abstract: Demands for sustainable and efficient energy solutions are increasing globally every day. This has led to significant advances in nanotechnology-based energy harvesting. Bubble Energy Nanogenerators (BuNGs) are one of the latest emerging technologies to convert the kinetic and potential energy of air bubbles in water into electrical energy. This review is based on a comprehensive review of theoretical principles, instability mechanisms, and recent technological developments in bubble-based nanogenerators, with a particular focus on triboelectric nanogenerators (TENGs), piezoelectric nanogenerators (PENGs) and hybrid nanogenerators. The article aims to critically evaluate bubble dynamics and stability by combining fundamental instability models, including Ledinegg, Taylor, and Henry instability theories, to improve the understanding of bubble-induced energy conversion. Additionally, advances in nanomaterial integration, such as using surface-modified electrodes, surface coatings, and hydrophobic nanostructures to optimize energy efficiency, are discussed. According to the literature, it is understood that BuNG designs can achieve high voltage outputs with large bubble sizes, but there are difficulties in controlling energy dissipation, unstable bubble behavior, and charge transfer efficiency. New approaches, pressure-induced bubble collapse, charge separation mechanisms, and modified surfaces for improved performance have been presented as solutions. This work is intended to bridge the gap between fundamental bubble physics and applied nanotechnology and draw a clear roadmap for future research on self-powered energy systems, underwater sensing, and renewable energy harvesting applications.
PubDate: 2025-03-29
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- Experimental analysis using thermocouple and infrared thermography of the
temperature evolution of lithium-ion polymer cells at different charging
rates-
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Abstract: An experiment was designed to investigate the temperature revolution of lithium-ion polymer (LiPo) cells using two different approaches, thermocouples and infrared thermography. The cells were charged under controlled conditions at rates of 2.0 A, 4.0 A, 6.0 A, 8.0 A, and 10.0 A. The analysis focused on the maximum surface temperature, temperature changes over time, and surface temperature distribution. The findings revealed that higher charging rates result in increased heat generation, causing greater temperature rises, steeper temperature gradients, and higher maximum temperatures. During the charging process, the study also observed endothermic behavior and uneven temperature distribution across the cells. However, upon completing the charging, the surface temperature became evenly distributed without any critical hotspots. Notably, maximum temperatures were observed in the lower regions of the cells for lower charging rates (2.0 A, 4.0 A, and 6.0 A) and in the upper regions for higher rates (8.0 A and 10.0 A). Additionally, infrared thermography provided a clearer and more precise method for measuring surface temperatures compared to thermocouples, as indicated by experimental uncertainty analysis. IR imaging also showed a faster temperature increase at higher charging rates, offering deeper insights into the thermal characteristics of LiPo cells.
PubDate: 2025-03-27
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- A hybrid method based optimal FOPID parameters for air heater temperature
and humidity control system in industrial drying application-
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Abstract: Drying is a critical process in various industries such as agriculture, food processing, and textiles, where maintaining precise temperature and humidity is essential for product quality and shelf life. Traditional methods often struggle with inefficiencies due to the interdependence of temperature and humidity. This study proposes a novel hybrid control approach that integrates the Reptile Search Algorithm and Random Forest Algorithm to optimize the variables of a Fractional-Order Proportional-Integral-Derivative controller. Additionally, an Adaptive Neuro-Fuzzy Inference System is used to model the relationship between temperature and humidity. Implemented in MATLAB/Simulink, the approach was evaluated across four testing scenarios: constant, step, saw tooth, and random responses. The findings show that the proposed strategy works significantly outperforms traditional techniques by reducing errors and maintaining more stable temperature and humidity control. For food dryers, it achieved humidity stability from 0 to 70%, with grain dryers reaching peak humidity of around 90% and wood dryers maintaining lower humidity levels. Key performance improvements include faster rise times, reduced overshoot, and lower steady-state errors. These findings illustrate the efficiency of the proposed approach in enhancing drying efficiency and system stability.
PubDate: 2025-03-24
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- Extension of a simplified physical flushing process model to realistic
fluid property variation of chocolates-
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Abstract: Experiments and fully resolved numerical simulations are reliable, yet costly ways of designing safe and efficient flushing processes. An alternative is the use of a simplified algebraic model. In this work a model previously developed by the present authors for combinations of fluids with identical properties is extended to different fluid properties of previous and flushing fluid. A realistic range of fluid properties is determined using chocolate as an example. The results from the simplified model are compared to highly resolved numerical data. The simplified model is able to predict the flushing process well, for phases where only the removal of previous fluid near the wall is relevant. This is achieved quickly, when the previous fluid has a lower apparent viscosity than the displacing one. In the opposite case, the prediction quality of the model for the preceding phase is low and other approaches should be considered.
PubDate: 2025-03-21
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- Comparison of kinetics, energy, and thermal properties processing
hackberry fruits by hot air-
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Abstract: Hackberry fruit is used as a snack and animal supplement feed after drying due to its nutritious properties. It needs to be dried in order to be consumed for a long time as a snack or feed additive. In this study, the effects of drying temperatures of 50, 60, and 70 ºC on the drying rate, modeling, effective moisture diffusion-activation energy, exergy energy, energy efficiency, thermodynamics, heat-mass transfer and color properties of hackberry fruit processing by conventional type dryer were investigated. The effective moisture diffusion value was determined as 3.42 × 10–9—1.56 × 10–8 m2/s and the activation energy was determined as 69.36 kJ/mol. The color properties of dried hackberry fruits were determined best at 60 ºC drying temperature. The Exin, Exout, and evaporation energy values were determined as 0.183—0.531 J/s, 0.162—0.486 J/s and 5.240—8.627 J/s, respectively. Mass and heat transfer values were calculated as 1.93—5.32 × 10–7 m/s and 4.271—4.202 × 10–13 W/m2K, respectively. The enthalpy, entropy, and Gibbs Free energy values of the drying processes were determined as 2.56—2.72 kJ/mol, 0.63—0.93 kJ/molK and 2264.03—2431.84 kJ/mol, respectively. By increasing the drying temperatures, the drying kinetics and thermodynamic properties of hackberry fruit improved and energy consumption decreased.
PubDate: 2025-03-20
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- Experimental and simulation study of flow and heat transfer
characteristics of the leaf-veined mini-channel heat sink-
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Abstract: In order to enhance the heat dissipation effect of high heat flow density electronic devices and prolong the service life of electronic devices. In this paper, a new type of the leaf-veined mini-channel heat sink (LVMCHS) was proposed based on the bionic blade structure. Numerical simulation technology was used to study the fluid flow, heat transfer and entropy generation characteristics of the LVMCHS. The experimental test platform was constructed for experimental verification. The orthogonal experiment was designed by using water as the coolant. The effects of Re, coolant inlet temperature Tin and heat flux Qw on the pressure drop ΔP, total thermal resistance Rth, average Nusselt number Nuavg and total entropy generation Sgen of the LVMCHS were studied. Polar deviation analysis showed that the order of the influence of each factor on the temperature uniformity (TUF) was Qw>Re > Tin, and the order of the influence of each factor on Nuavg was Re > Tin>Qw. When the Re was in the range of 300 ~ 10,000, with the increase of Re, the Rth decreased by 92.59%, and Sgen decreased by 15.764%. At Re = 9970, its Sgen reached the lowest value of 171.57, the integrated heat transfer performance of the LVMCHS was optimal. Through the trend of the influence of each factor level, the better combination of programmer levels was obtained: when the Qw was 35 W/cm2, the Re was 9970 and the Tin was 5 °C. This study provided a novel approach and guidance for the design and analysis of heat sink.
PubDate: 2025-03-20
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- Enhancing air conditioning performance: effects of direct evaporative
cooling with various pad materials on condensing temperature of R-22 and
cycle efficiency-
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Abstract: This study investigates and compares the performance of an air conditioning system with conventional air-cooled condenser (CV-AC) and an air conditioning system with direct evaporative cooling on the condenser side (DEC-AC) utilizing four different cooling pad materials such as honeycomb structured cellulose, banana fibre, jute fibre, and cotton thread. The experiments were conducted at varying ambient air temperatures at 30 °C, 35 °C, 40 °C, and 45 °C DBT. The analysis focuses on key performance parameters including temperature drop across the cooling pad, cooling pad efficiency, heat rejection rate from the condenser, refrigerant condensing temperature and COP of the air conditioning system. Experimental results indicate that the DEC-AC system, utilizing all tested cooling pad materials, outperforms the CV-AC system. Regarding pad cooling efficiency under varying ambient air conditions, the cellulose pad exhibits the highest efficiency, ranging from 55.11 to 76.58%, followed by the banana fiber pad with an efficiency range of 38.4 to 54.62%, the jute fiber pad ranging from 31.68 to 47.51%, and the cotton thread pad demonstrating the lowest efficiency, ranging from 26.58 to 39.57%. Under the same ambient conditions, an air conditioning system employing direct evaporative cooling with a cellulose pad (aDEC-AC) demonstrated the highest performance, with a significant increase in heat rejection from the condenser of up to 68.33% and a reduction in condensing temperature of up to 8.41%. Followed by systems employing banana fibre (bDEC-AC), jute fibre (cDEC-AC), and cotton thread pads (dDEC-AC) recorded heat rejection improvements of up to 59.10%, 51.67%, and 43.17%, respectively, along with corresponding reductions in condensing temperature of up to 6.88%, 5.97%, and 5.46% all in comparison with CV-AC. Furthermore, the study also reveals that, as ambient air temperature increased, the COP of DEC-AC improved, with aDEC-AC achieving the highest increment in COP up to 27.93%, Followed by bDEC-AC, which achieved an increase of up to 18.81%, cDEC-AC showing an improvement of up to 17.17%, and dDEC-AC demonstrating the least increase of up to 15.8% compared to CV-AC. The operating costs for all cooling pads are approximately similar, with only minor variations. The cellulose pad incurs the highest cost of INR 7156, while the banana fibre pad has the lowest cost of INR 7046. These findings emphasize that incorporating direct evaporative cooling (DEC) system with air conditioning systems can substantially improve energy efficiency and system performance.
PubDate: 2025-03-20
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- PCM-integrated windows for enhanced passive cooling: an experimental and
numerical investigation-
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Abstract: Buildings account for a significant share of global energy consumption, with heating and cooling demands driving high carbon emissions and environmental impact. This study investigates the potential of phase change material (PCM)-based windows as a passive cooling solution to reduce indoor temperatures and minimize energy consumption. Experimental and numerical analyses were conducted using paraffin wax as the PCM, comparing conventional windows, PCM-filled windows, and PCM-filled windows with copper tubes. Results indicate that PCM-filled windows lower indoor temperatures by up to 12 °C compared to conventional windows, while the integration of copper tubes accelerates the solidification process by 27%. Heat transfer analysis reveals a 40% reduction in the heat transfer coefficient and a higher heat flux of 130.06 Wm− 2 for PCM-filled windows, compared to 81.16 Wm− 2 for conventional glazing. Numerical simulations using ANSYS Fluent validate these findings, with a minor 3% deviation in liquid fraction from experimental results. These findings underscore the enhanced thermal performance of PCM-based windows, demonstrating their potential for energy-efficient building design and sustainable cooling applications.
PubDate: 2025-03-17
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- Effect of gas injection location on bubble size from Venturi bubble
generators-
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Abstract: To explore the potential performance of Venturi in the field of bubble generation, the effect of gas injection location on the bubble generation performance was investigated. This study aims to utilise the liquid kinetic energy to minimise the bubble size. Compared to the gas injection before converging region, the gas injection at the throat exhibits smaller bubble size with the gas-to-liquid ratio (GLR) ranging from 0.01 to 0.08. The bubble size with the gas injection at the throat at GLR of 0.01 is about 0.05 ~ 0.6mm. An improved Venturi bubble generator with gas injection in the divergent region has a smaller bubble size when the GLR exceeds 4.3. The bubble size with the gas injection in the divergent region at GLR of 24 is about 3.7 mm while the bubble size with the gas injection at the throat exhibits 8 mm. For small GLR, gas injection location was recommended at the throat to improve bubble generation frequency. For large GLR, gas injection location was recommended in the divergent region to achieve less bubble coalescence. This study provides the valuable insights for advancing bubble generation technologies and the design guidelines for Venturi bubble generators.
PubDate: 2025-03-12
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- Preserving bioactive compounds in wheat germ through drying: A kinetic
study-
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Abstract: In this study, wheat germ was dried at three different temperatures (80 °C, 90 °C, and 100 °C) using an oven. The drying characteristics of the samples were analyzed, and the experimental data were fitted to five different thin-layer drying models: Logarithmic, Lewis, Henderson and Pabis, Page, and Modified Page. Among these models, the Page and Modified Page models provided the best fit, yielding the highest R2 values and the lowest RMSE and χ2 values. The overall drying process occurred in the falling rate period in all experiments. Bioactive compound degradation was also assessed during drying process. Lutein content decreased by 37.24–49.22%, total phenolic content decreased by 41.41–43.67%, and total antioxidant activity decreased by 31.25–45.70%. The degradation kinetics of lutein content, total phenolic content, and total antioxidant activity were evaluated, yielding activation energy values of 34.03, 61.89, and 63.55 kJ/mol, respectively. Lutein degradation followed a second-order kinetic model, changes in total phenolic content adhered to a zero-order kinetic model, and total antioxidant activity followed a first-order kinetic model. Considering the Q10 values, it was determined that the effect of increasing the temperature from 80 °C to 90 °C was less significant than the effect of increasing the temperature from 90 °C to 100 °C on all bioactive components.
PubDate: 2025-03-10
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- Thermodynamic analysis of shell and tube heat exchanger by using
AgNO3-Graphene/H2O hybrid nanofluid-
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Abstract: Hybrid nanofluids are proven as the emerging next generation heat transfer fluids due to their superior thermophysical properties. Current study focuses on dispersion of silver-carbon based nanoparticles (AgNO3 and graphene) in base fluid (water) to develop hybrid nanofluid (HNF) at varying concentrations (0.01 vol% to 0.03 vol%) using a two-step technique and their thermodynamic performance investigations on shell and tube heat exchanger (STHX). Prepared HNFs are found stable by conducting Zeta potential stability measurement. Experimental investigations are performed to examine the effects of flow rate (115 lph to 155 lph) on heat transfer rates, energy (ηen) and exergy (ηex) efficiencies for both shell and tube sides of the heat exchanger. Additionally, significant dimensionless quantities like the Reynolds number (Re), Prandtl number (Pr), Nusselt number (Nu), friction factor (Ff), pressure drop, and thermal performance factor (TPF) are examined. Results reveal that, the actual, average, overall heat transfer rate, ηen and ηex are found higher as 39.21%, 39.55%, 50.87%, 39.52%, and 70.01% respectively on the shell side and as 47.02%, 37.36%, 22.96%, 47.05%, and 32.72% respectively on the tube side than that of base fluid at mean flow rate for 0.03 vol%. The shell side exhibits a 12.76% increase in convective heat transfer compared to the tube side. A reduction in friction factor leads to an increase in pressure drop at particular flow rate for all prepared HNFs and water. Finally, TPF of prepared HNFs are evaluated and found more than one, which recommends their long-term utilization in different heat transfer applications.
PubDate: 2025-02-27
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- Study on the cooling performance of spray cooling system integrated with
color recognition-
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Abstract: Effective thermal management is a key to ensure the normal operation and long-term stability of high-power equipment. Spray cooling technology demonstrates robust thermal management performance and enables efficient utilization of coolant. This study proposes a spray cooling system that integrated with color identification. Hardware and software design of a color distinguish device based on STM32F407 microcontroller is presented. The impact of different spray pressures and different nozzles of various size on heat transfer characteristics is evaluated. The result reveals that, as spray pressure increasing, the average temperature of heating surface decreases significantly. The results show that the maximum temperature is reduced by 5%, when spray pressure ranges from 3.0 MPa to 4.5 MPa. However, at the same cooling duration, higher pressure requires more injection cycles than lower pressure to avoid the emergence of dry-out points. The injection cycle is shortened by 18 s. The cooling effect of three aperture nozzles are compared. It was observed that increasing nozzle aperture size substantially improves cooling performance, while reducing injection interval time. With the increase of nozzle aperture, the maximum temperature is reduced by 18% and the injection cycle is shortened by 27 s.
PubDate: 2025-02-26
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- Fluid flow and heat transfer characteristics in minichannels - CFD
calculations in simcenter STAR-CCM+-
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Abstract: The paper presents an experimental and numerical analysis on heat transfer during distilled water flow in an asymmetrically heated minichannel. The experimental study was conducted in a horizontally oriented test section, where the temperature of the external surface of the minichannel heated wall was measured by an infrared camera. The experimental data were used to validate the results of numerical simulations performed in Simcenter STAR-CCM + software. The governing equations for mass, momentum, and energy conservation were considered, along with the Reynolds-Averaged Navier-Stokes (RANS) turbulence model. Numerical results were presented as distributions of temperature, velocity, and heat transfer coefficients along the channel length. A decrease in the heat transfer coefficient was identified with increasing distance from the channel inlet. The innovative aspect of this study lies in combining experimental data with advanced CFD simulations, enabling comprehensive validation of the models, rarely achieved in the literature on minichannels. The results demonstrate that the numerical models accurately describe the experiment, with the mean temperature difference between the simulation results and the thermographic measurements being 2.12 K. These findings can contribute to the optimisation of heat transfer processes in cooling devices for electronics applications.
PubDate: 2025-02-25
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- Study on the possibility of maintaining ice in an ice hole using
numerical modeling of phase change and meteorological digitized data-
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Abstract: This work is devoted to studying some natural geological cavities named ice holes. Because few studies have investigated this phenomenon, our goal is to provide a coherent explanation for it. It is representative of the presence of ice inside some ground cavities at shallow depths during short unfavorable meteorological periods—spring or summer—in some European geographical zones of mean altitude (600 ~ 900 m) that are not subjected to very cold temperatures. However, to date, this phenomenon has not been well explained. The goal of our research is to verify whether the results obtained in a previous simplified study could be confirmed on the basis of the phase change phenomenon and digitalization of local meteorological data observed during a total year. The ice and water contained inside these “ice holes” are representative of a phase change (solidification, fusion, or vaporization), of which water is a well-known model.The first approach, whose results were published in a previous paper Batina (Environ Water Sci Public Health Territorial Intell J 7(1), 2023), was performed on the basis of a theoretical model involving sinusoidal temperature fluctuations whose mean amplitudes corresponded to 4 seasons: “severe winter”, “winter”, “spring” and “summer”. Natural measurements—physical and structural ice-hole dimensions, depth in relation to the ground level, and material nature—have been equally reported. Currently, digitized local meteorological temperature data play an important role in our numerical modeling. Then, on an identical volume with an equivalent ice content, temperature amplitudes issuing from digitized local meteorological data were applied on the top level of the ice hole. These temperature values will be modified in relation to the depth of the ice-hole top level, which refers to the soil level and the imposed bottom temperature.From this numerical approach, it appears that many conditions need to be considered and can lead to ice formation and maintenance in this type of hole.
PubDate: 2025-02-15
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- Evaluation and quantification of mixing uniformity of gas-liquid two-phase
flow by Gini coefficient-
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Abstract: In the heat transfer process, the liquid disturbance caused by the phase change will affect the spatial position of the bubbles in the liquid and thus affect the heat transfer efficiency. The Gini coefficient is proposed as a theoretical tool to characterize the degree of uniformity of bubble mixing in the heat transfer process and the evaluation method of the stability of the working conditions. The gas-liquid phase transition process under different operating conditions is taken as the object of study, and the degree of bubble distribution uniformity and the Stability of the spatial positional distribution of bubbles in the heat transfer process are quantified. This study has done an effective validation of the method to characterize the homogeneity of bubble mixing. The characteristic law parameter δ of the operating conditions was established, the correlation coefficient between δ and the volumetric heat transfer coefficient $$\:{U}_{v}$$ was 0.72, and the cosine similarity between δ and $$\:{U}_{v}$$was 0.995. In this study, it was found that among the nine conditions, the heat transfer process was more stable in condition L1, and the time required to reach the stable condition was the shortest in condition L6. The method of Gini coefficient provided in this study can effectively characterize the mixing uniformity of two-phase flow during heat transfer process. Graphical Abstract
PubDate: 2025-02-14
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- Experimental study on the heat transfer characteristics of dry ice
sublimation spray cooling on ribbed surfaces with high thermal loads-
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Abstract: Dry ice sublimation spray cooling technology provides significant advantages for thermal management and efficient heat dissipation in high-power electronic chips because of its high latent heat of sublimation, high heat flow density, and rapid cooling speed. A ribbed structure of the surface increases the overall effective area that may be used for convective heat transfer. Such a structure can be used for the heat dissipation of electronic components, as it simultaneously lowers the thermal resistance. This study uses ribbed structures and dry ice sublimation spray cooling to examine the effect of ribbed heat sources on heat transfer. A two-phase flow theoretical model is built on the basis of the dry ice sublimation spray cooling heat transfer process for ribbed surfaces with high heat sources. Heat source copper blocks with a smooth surface, a straight-rib surface, and a cylindrical-rib surface are designed and processed accordingly. For the different influencing factors of the cooling process, the effect of these three heat source copper blocks on the heat transfer characteristics of dry ice sublimation spray cooling was investigated. Our research demonstrates that identical parameter settings, a heat source with a ribbed surface shows better heat transmission performance than the heat source without a ribbed surface. Additionally, the cylindrical-rib surface shows better heat transfer effectiveness than the straight-rib surface. The cooling efficacy of dry ice spray on ribbed surfaces may be improved by increasing the mass flow rate of carbon dioxide and decreasing the continuous heating power while keeping all other parameters constant. As a result, the heat transfer coefficient and flux both increase. The cylindrical-rib surface requires the shortest amount of time (60 s) to reach equilibrium from the initial temperature of 345 K for the spray height, mass flow rate of dry ice spray, and the constant heating power of 5 cm, 17 g/s, and 30 W, respectively. The ideal average temperature of heat source surface upon attaining equilibrium is 275.3 K, and the heat flow and heat transfer coefficients are 860,406 W/m2 and 8653.6 W/(m2·K), respectively.
PubDate: 2025-02-10
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- Experimental and numerical studies of laminar natural convection heat
transfer from an isothermally heated narrow flat plate oriented at
different angles of rotation-
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Abstract: The laminar natural convection heat transfer from isothermally heated, narrow flat plates oriented at different angles of rotation is experimentally and numerically studied. The heated flat plate is narrow, i.e., has a relatively small width, w, to length, l, ratio, and is embedded in a plane adiabatic surface within which the heated plate can be oriented at different angles of rotation. The three-dimensional governing equations for geometrical assessment were solved numerically in terms of non-dimensional variables using finite volume-based solution. Model results for the average Nusselt number were obtained for a relatively wide range of non-dimensional variables included the Rayleigh number ranging from 1 × 103 ≤ Ra ≤ 1 × 108, non-dimensional plate width ranging from 0.15 ≤ W ≤ 1, and angle of rotation ranging from 0° ≤ α ≤ 90°. On the other hand, experimental results for the average Nusselt number were obtained for a narrower range of non-dimensional variables included the Rayleigh number ranged from 5.98 × 103 ≤ Ra ≤ 1.18 × 105, the angle of rotation ranged from 0° ≤ α ≤ 90°, and the non-dimensional plate width was fixed at 0.4. Additionally, air with a Prandtl number of 0.7 was used as the working fluid in the study. Model results were validated against present experimental results and existing correlations. The effects of these non-dimensional variables on the average and local Nusselt numbers for the heated flat plate were investigated. It was found that in some situations the non-dimensional variables have a significant effect on heat transfer rate from the heated flat plate. Correlations to calculate the average Nusselt number for the heated flat plate were developed.
PubDate: 2025-01-24
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- Analysis of cooling performance of compact regenerative evaporative
coolers for practical applications-
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Abstract: This study investigates the performance of a compact regenerative evaporative cooler (REC). Compactness and cooling performance are important factors for practical REC applications. To improve compactness, an REC prototype with reduced length was designed and fabricated by inserting fins into both the dry and wet channels. The prototype performance was evaluated under various operating conditions. A numerical model was developed to analyze the axial conduction effect through the solid part of the REC, wettability on the wet water channel surface, and thermal capacity of the evaporating water stream. The model was validated by comparing the predicted results with the experimental data. Through a numerical simulation based on the model, the performance of the REC was analyzed, and methods were suggested to improve its cooling performance. Finally, the performance of the proposed REC was compared with the results of previous experimental studies. The proposed REC prototype was the most compact and achieved the best cooling performance.
PubDate: 2025-01-07
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- Thermo-hydraulics flow investigation and heat performance augmentation
evaluation in 3d tube based on novel corrugated, varying insert tape and
dimple configurations-
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Abstract: High performance heat exchangers are becoming necessary for a range of industrial applications. the consequent loss of energy resources in systems like power plants, air conditioners, and food processing facilities. Improving thermal performance was a critical area for energy saving since it can lead to high-performance heat exchangers. It is possible to distinguish between three modified types of present-enhancing method for passive approaches. The dimple, tape twisted, as well corrugated tube passive heat enhancement techniques all include more surface extensions. Validating computational estimations of flow in heat exchanger tube for varying pipe surface is, thus, the primary objective of this research project. The numerical results indicate that the properties of heat and flow are more affected by differences in dimple, tape twisted, and corrugated configurations. The dependability of the simulation technique employed in this work can be confirmed by comparing the experimental and numerical results consistently. The deviation errors are smaller than 6.7% and 7.5% for Nu and f, respectively, as compared to the average pipe. The pressure decrease that results from increasing width as well thickness of twisted tape also improves fluid mixing, secondary and swirl flows in pipe. Because there is a larger difference in the velocities between the liquid layers next to tape surfaces, tube walls, and pipe core flow layers, the f value increases as tape geometrical parameters increase. As such, in comparison to conventional pipe, twisted topologies may increase from 5.4 to 33.5%. The 1 × 1 mm twisted tape has a higher thermal evaluation factor. The range of thermal assessment factor was higher than 1.7.
PubDate: 2025-01-03
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- Experimental Investigation of vermicompost masses with initial and
continuous water supply in a direct evaporative cooling system-
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Abstract: Evaporative cooling, an eco-friendly and energy-efficient technique, mitigates the environmental damage caused by mechanically driven air-conditioners. Recent studies have shown that rotating humidifiers are useful for large space cooling applications due to their higher efficiency. Despite the benefits, it leads to an increase in the electrical energy consumption. Vermicompost, an excellent water storage medium, replaces the pad of conventional air coolers, thereby eliminating the pump used for water circulation and the motor used in centrifugal humidifiers. However, the amount of water storage depends on the mass of the vermicompost. The supplied water should produce continuous cooling if the vermicompost is completely soaked and operated. If all the water evaporates over a period, vermicompost may dry, necessitating additional water supply. Hence, the need arises to study the influence of the mass of vermicompost and the water supply method on the performance of vermicompost-based direct evaporative cooling systems. The present study proposes to experiment with three different masses and two modes of water supply: initial and continuous. Experimental results showed that the system produced an average effectiveness of 82 % using '500 g' and '1000 g' of vermicompost through the continuous water supply, while the effectiveness augments to 85 % using '1500 g' of vermicompost with only the initial water supply. The studies reveal that a lower mass of vermicompost with a continuous water supply is preferable for cooling in small spaces. A higher mass of vermicompost with an initial water supply is helpful for large spaces like greenhouses and livestock buildings. Hence, the present system is energy-efficient, showing an energy savings of 69.43% by neglecting the pump and motor, as in centrifugal humidifiers. Moreover, it is eco-friendly as it eliminates the pump and sump that lead to the transmission of diseases like dengue and malaria caused by insect breeding in the sump.
PubDate: 2024-12-17
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