JournalTOCs

Journal of Power Technologies
Journal Prestige (SJR): 0.361

Citation Impact (citeScore): 1
Number of Followers: 6

This is an Open Access Journal

Open Access journal
ISSN (Print) 2083-4187 - ISSN (Online) 2083-4195
Published by Warsaw University of Technology

[2 journals]

An improved Müller-Steinhagen and Heck model for two phase pressure drop
modelling at high reduced pressures
- Authors: Dariusz Mikielewicz, Jarosław Mikielewicz
  Pages: 81 - 87
  Abstract: A better understanding of the two-phase fluid behaviour is necessary to optimize the design models of the components containing a two-phase refrigerant especially in the light of the fact that more and more applications are sought in the region of high reduced pressure values, for instance a vapor generator, a key heat exchanger in Organic Rankine Cycle system or high temperature heat pump. Nowadays we seek implementations at high evaporation saturation temperatures where the refrigerant transformation to vapour occurs at temperatures higher than 90oC. However, a literature analysis shows that there is a gap in knowledge of the two-phase flow for synthetic refrigerants at high saturation temperatures. The reliable prediction of pressure drop in two-phase flows is an important prerequisite to accurate optimization of thermal systems. The total pressure drop of a fluid is due to the variation of potential and kinetic energy of the fluid and to the friction on the channel walls or between the phases (60-120oC) and moderate reduced pressures (0.2-0.5). In the paper a modification to the established Müller-Steinhagen and Heck (1986) model for two phase pressure drop in relation to high values of reduced pressures has been presented. Model validation has been done in comparison to a reliable experimental data due to Charnay et al (2015) for R245fa at reduced pressures above 0.5. Postulated in the paper modification exhibit a significant improvement to the calculations presented in the literature, also by the authors of experimental data.
  PubDate: 2022-11-25
  Issue No: Vol. 102, No. 3 (2022)
Mathematical analysis of mass and heat transfer through arterial stenosis
- Authors: azad hussain, Lubna Sarwar, Sobia Akbar, Muhammad Yousaf Malik
  Pages: 88 - 95
  Abstract: In current article a steady state flow of an in-compressible fluid which appertains Williamson fluid through stenoised region in the shape of cosine constriction is investigated. Blood is supposed as Williamson fluid. Mathematical formulation leads us to nonlinear compatibility and energy equations then deciphered by shooting technique to obtain the numerical solution. Suitable resemblance transfiguration's are accustomed to metamorphose partial differential equations into embellish form of ordinary differential equations. Further the consequences of different involved parameters are shown by graphs and an arrogate conclusion is also presented. Velocity and temperature fields are canvassed graphically for the distinct values of emerging parameters and discussed in tabular form. Skin friction and coefficient of heat transfer are also debated in under discussion investigation. The results shows Nusselt number curve exhibits negative deflection for variational values of λ and height of the stenosis δ.
  PubDate: 2022-11-29
  Issue No: Vol. 102, No. 3 (2022)
A New Generalized Basic Structure for Multilevel Inverter with Reduced
Power Electronic Components Count
- Authors: rasoul shalchi alishah
  Pages: 96 - 107
  Abstract: In this paper, a new multilevel inverter topology is presented which can generate every number of levels at the output stage. This proposed topology composed from six unidirectional switches, several bidirectional switches, and DC voltage sources. In order to show advantages and disadvantages, the proposed topology is compared with other presented topologies. This comparison exclaims that the proposed topology generates more voltage levels without the need for an excess number of switches and DC voltage sources. Also, the reduced number of switches in the current flow leads to a decreased conductive loss in the proposed topology in comparison with other topologies. For the purpose of assurance of correct operation of the proposed topology, it is simulated with the aid of PSCAD/EMTDC software and the results are discussed.
  PubDate: 2022-12-06
  Issue No: Vol. 102, No. 3 (2022)
Energy analysis and optimizing of hybrid WT/ PV cell in power systems
- Authors: reza alayi, Mehrdad Ahmadi Kamarposhti, Mohsen Ghafari, Salamoulah Mohammadi Aylar
  Pages: 108 - 120
  Abstract: The importance placed on renewable energy is growing exponentially due to rising demand for energy, concerns about the environmental impact of burning fossil fuels and fears about the world’s limited fossil fuel reserves. This study features an optimal combination of scattered production sources (wind-solar), an IEEE 33-bus system, and beta distribution to model wind speed. The load and production planning period is 24 hours. The aim of this study is to improve voltage profiles, increase reliability and reduce losses. The resulting model forecast a 39% loss-improvement in the presence of wind turbines and a 40% loss-improvement in the presence of photovoltaic cells, which highlights the role of these renewable resources in the grid.
  PubDate: 2022-12-28
  Issue No: Vol. 102, No. 3 (2022)