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- MakaleAçık Erişim2022Scopus SJRQ1Analysis of turbulent wall jet impingement onto a moving heated body
Coşanay, Hakan; Öztop, Hakan F.; Gür, Muhammed; Bakır, Eda
Purpose: The purpose of this study is to make a numerical analysis of a wall jet with a moving wall attached with a heated body. The hot body is cooled via impinging wall jet. Thus, a jet cooling problem is modeled. The Reynolds number is taken in three different values between 5 × 103 ≤ Re ≤ 15 × 103. The h/H ratio for each value of the Re number was taken as 0.02, 0.04 and 0.0, respectively. Design/methodology/approach: Two-dimensional impinged wall jet problem onto a moving body on a conveyor is numerically studied. The heated body is inserted onto an adiabatic moving wall, and it moves in +x direction with the wall. Governing equations for turbulent flow are solved by using the finite element method via analysis and system Fluent R2020. A dynamic mesh was produced to simulate the moving hot body. Findings: The obtained results showed that the heat transfer (HT) is decreased with distance between the jet outlet and the jet inlet. The best HT occurred for the parameters of h/H = 0.02 and Re = 15 × 103. Also, HT can be controlled by changing the h/H ratio as a passive method. Originality/value: Originality of this work is to make an analysis of turbulent flow and heat transfer for wall jet impinging onto a moving heated body.
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İncele - MakaleAçık Erişim2021Experimental Analysis of PV/T Collectors Assisted with PCM for Off-Grid Domestic Applications
Bayrak, Fatih; Oztop, Hakan; Bakır, Eda
An experimental study was carried out to examine the efficiency of solar energy in photovoltaic thermal collectors (PV/T) with energy storage. A photovoltaic thermal collector was used to generate both electrical energy and hot water. The effects of inclination angle of PV/T collectors on power, temperature, energy and exergy values were investigated. Also, effects of cellular shading are tested and discussed. PV/T was compared with the conventional PV/T collector by adding phase change material (PCM) for one of the collectors. In addition, the effect of different shading conditions (small, medium and large circle) on the power and hot water output of the PV/T collector at optimum slope angle were investigated. It is found that 7 ºC temperature differences are occurred in the hot water outlet between the PV/T collector and the PV/T-PCM collector. The highest energy efficiencies of PV/T-PCM collectors are obtained as 73.26%, 84.70% and 68.96% for slope angle 25º, 30º and 35º, respectively. The highest exergy efficiencies of shaded collectors are obtained as 11.92% for PV/T and 23.38% for PV/T-PCM.
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İncele - MakaleAçık Erişim2021Numerical Investigation of the Effect of Using Nanofluids on Thermal Performance in an Energy Storage Pipe
Bayrak, Fatih; Işık, Erdem; Uçar, Aynur; Bakır, Eda
Considering the advances in technology, new approaches and heatsinks with good thermal performance are needed to achieve the efficiency and reliability expected from high-efficiency electronic devices. In this numerical study, an aluminum pipe with the same hydraulic diameter, channel length and cross-section geometry was used. To increase the heat transfer rate of the system; Al2O3/water nanofluids with water, 1% and 2% concentrations were used in the pipe, and a 5mm thick RT25HC phase change material (PCM) was used on the outer surface of the pipe. The fluids passed through the aluminum pipe were analyzed using the ANSYS 20.2 package program at four different speeds and four different Reynolds numbers. According to the results obtained, the mass melting ratio and Nusselt number were calculated for each fluid. When the results obtained from the study were examined, it was seen that the best Nusselt and liquid fraction was Reynolds 1500 and 2% Al2O3/water. For all refrigerants, it was concluded that the mass melting rate of the refrigerants and the Nusselt number increased with the increase of the fluid velocity.