Bakır Gür, Eda; Işık, Erdem; Uçar, Aynur

Solar dryers using phase change materials buffer heat, yet the combined influence of airflow regime and PCM placement on melting remains underexplored. A controlled like-for-like study fixed geometry and PCM properties while varying placement and operating conditions. A 3D transient CFD model simulated a forced-convection dryer with RT28HC over Re = 3000–9000 and inlet temperatures Ti = 50–60 °C. Raising either Re or Ti shortened melt time, and three-wall coverage melted faster and more uniformly than a rear-wall-only layout. For three walls, melt time dropped from 13 h (50 °C, Re = 3000) to 7 h (60 °C, Re = 9000) (−46 %) for the rear wall it fell from 19 h to 11 h (−42 %). A 10 °C increase in Ti reduced overall melt time by 4 h across Re. Practically, three wall PCM with Re ≥ 6000 at Ti = 60 °C achieved reliably 7–9 h melting, enabling late afternoon heat release without auxiliary heating.

AtıfScopus17·WoS16·OpenAlex12

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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.

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