Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 18Citation - Scopus: 20Cold Plate Enabling Air and Liquid Cooling Simultaneously: Experimental Study for Battery Pack Thermal Management and Electronic Cooling(Elsevier, 2023) Coşkun, Turgay; Çetkin, ErdalThe temperature of cells varies greatly during dis/charge while their performance and lifetime are greatly affected by this fluctuation. Elevated temperatures may yield battery fire due to thermal runaway as well they accelerate ageing and capacity fade of cells. Thermal management systems are a necessity for electric vehicles to extend the lifetime of battery cells and eliminate any fire risks, especially for fast dis/charging applications. Here, we document a hybrid cold plate with a working fluid(s) of sole air or liquid as well as both of them. Hybridization of air and liquid cooling promises to minimize energy consumption requirements during a charge/ discharge cycle by combining the benefits of both thermal management strategies if energy management is controlled accordingly. The temperature of each cell can be kept below 30 degrees C with the proposed hybrid cooling heat exchanger, and the temperature difference between the cells is reduced by 30 % relative to liquid cooling. The maximum temperatures are decreased by 18 % and 3 % in hybrid cooling when compared to air and water cooling, respectively. Furthermore, a step function combining various discharge rates (1C and 3C) was employed in experiments to mimic a realistic situation, i.e. variable C-rate rather than constant. The results show that the temperature of the battery cells can be kept below 30 degrees C with air cooling for variable discharge rate and the effect of contact resistance should not be overlooked for liquid cooling. Furthermore, the possible use of the proposed hybrid cold plates is surveyed in the cooling of electronic devices which produce more and continuous heat than cells. Therefore, three resistance heaters with a capacity of 50W are used in experiments as well. The results show that the proposed cold plates could be used in both electronics cooling and battery thermal management with a control algorithm to switch between sole working fluid and combination modes which could be developed based on the results of this paper.Article Citation - WoS: 18Citation - Scopus: 22A Review of Heat and Fluid Flow Characteristics in Microchannel Heat Sinks(John Wiley and Sons Inc., 2020) Coşkun, Turgay; Çetkin, ErdalHeat transfer and flow characteristic in microchannel heat sinks (MCHS) are extensively studied in the literature due to high heat transfer rate capability by increased heat transfer surface area relative to the macroscale heat sinks. However, heat transfer and fluid flow characteristics in MCHS differ from conventional ones because of the scaling effects. This review summarizes the studies that are mainly based on heat transfer and fluid flow characteristic in MCHS. There is no consistency among the published results; however, everyone agrees on that there is no new physical phenomenon in microscale that does not exist at macroscale. Only difference between them is that the effect of some physical phenomena such as viscous dissipation, axial heat conduction, entrance effect, rarefaction, and so forth, is negligibly small at macroscale, whereas it is not at microscale. The effect of these physical phenomena on the heat transfer and flow characteristics becomes significant with respect to specified conditions such as Reynolds number, Peclet number, hydraulic diameter, and heat transfer boundary conditions. Here, the literature was reviewed to document when these physical phenomena become significant and insignificant.Article Citation - WoS: 35Citation - Scopus: 38Heat Transfer Enhancement in a Microchannel Heat Sink: Nanofluids And/Or Micro Pin Fins(Taylor & Francis, 2020) Coşkun, Turgay; Çetkin, ErdalHere, we show that overall thermal conductance in a rectangular microchannel heat sink can be maximized with the combination of nanofluids and micro pin fins. We uncover the effect of micro pin fins and nanofluids both separately and simultaneously in order to uncover their effect on the thermal conductance (i.e., thermal resistance). Both nanofluids and micro pin fins decrease the overall thermal resistance due to increase in the average thermal conductivity of the flow system. In addition, they increase the heat transfer surface area of the solid interacting with the fluid. However, the pumping power (pressure drop) increases in both methods due to the increase in the resistances to the fluid flow. The results document what should be the nanoparticle volume fraction mixed into the base fluid and the micro pin fin volume in order to minimize thermal resistance. If the thermal conductivity of the nanoparticles and micro pin fins are the same, the thermal conductance becomes the maximum with 4% and 0.14% volume fractions for the nanofluid and micro pin fins, respectively. This result shows that inserting micro pin fins and using nanofluids with a given volume fraction ratio maximize the overall thermal conductance. © 2019, © 2019 Taylor & Francis Group, LLC.Conference Object Citation - WoS: 6Citation - Scopus: 8The Effect of Spatial Interventions on Historic Buildings' Indoor Climate (case Study: Tire Necip Paşa Library, Izmir-Turkey)(Elsevier Ltd., 2017) Coşkun, Turgay; Gülhan, Özcan; Şahin, Cem Doğan; Durmuş Arsan, Zeynep; Gökçen Akkurt, GüldenThe indoor climate of historic libraries should meet rigorous requirements related to human thermal comfort and conservation of books, manuscripts and cultural proper-ties. Paper based collections in historic libraries can be deteriorated chemically, mechanically and biologically because of inadequate indoor climate conditions. In this paper, Necip Paşa Library, the historic library located in Tire-Izmir, Turkey, was selected as a case study. The chemical, mechanical and biological degradation risks on the manuscripts were evaluated based on the indoor climate parameters measured for one year period. The Library, consisting of a main hall, a manuscript zone and an entrance hall, was modelled via the dynamic simulation software, Design Builder. Calibration of the model was conducted with respect to the measured indoor temperature and relative humidity values. The portico/Revak at the south facade of Library was converted into the entrance hall by wooden framed windows in 1930. To be able to see the effect of that intervention on the indoor climate (correspondingly on degradation risk of the manuscripts), a new model, namely semi-open model, was created and simulated. A remarkable change has not been observed on chemical degradation risk when the results of semi-open and existing library models were compared, while mechanical and biological degradation risks were less in semi-open model.Article Citation - WoS: 7Citation - Scopus: 7The Importance of Internal Heat Gains for Building Cooling Design(Yıldız Teknik Üniversitesi, 2017) Coşkun, Turgay; Turhan, Cihan; Durmuş Arsan, Zeynep; Gökçen Akkurt, GüldenThis paper aims to investigate the effect of internal heat gains on the cooling load of a building. The house occupied by three adult men is selected as the case study for paper. The house is in the third floor of the apartment. The apartment has four flats and it has no insulation around the external walls. The heat dissipation from lighting devices, electrical equipment and the occupants are calculated by using the DesignBuilder v4 Beta release simulation program. The temperature of the house is observed during three weeks by using hobo data loggers and calibration of the measurements is made with respect to weather data file of the flat. Detailed schedule based on time of operation and occupancy is prepared to get more accurate results. Annual energy consumption and cooling load of the house is determined by using the dynamic simulation program.