Kılıç, MustafaUllah, Atta2025-01-062025-01-0620212148-784710.18186/THERMAL.10512872-s2.0-85123768849https://doi.org/10.18186/THERMAL.1051287https://search.trdizin.gov.tr/tr/yayin/detay/1172257https://hdl.handle.net/20.500.14669/1551The heat loads on electronic systems of an unmanned air vehicle are a significant problem. So enhancing heat transfer is a critical key to solve these thermal problems. This study is focused on increasing heat transfer rate in a crossflow heat exchanger by using nanofluids numerically. Effects of different Reynolds number of hot fluid (Re = 6000, 8000, 10000, 12000), different inlet velocity (Vair,inlet = 30, 45, 60, 90 m/s) of cooling fluid, temperature of cooling air at different altitude (Tair,inlet = 15, 10, 4, ?17°C) and different types of nanofluids (Cu-H2O, CuO-H2O, TiO2-H2O, H2O) on heat transfer were studied numerically. Realizable k-? turbulence model of ANSYS FLUENT computational fluid dynamics code was used for numerical analysis. It was obtained that increasing Reynolds number from Re = 6000 to 12000 causes an increase of 44.65% on average Nusselt Number. Increasing inlet velocity of cooling air from 30 m/s to 90 m/s causes an increase of 6.96% on average Nusselt number. Increasing or decreasing air inlet temperature at different attitude does not cause any significant change on average Nusselt number. Using Cu-H2O nanofluid, which shows the best performance, causes an increase of 6.63% on average Nusselt number according H2O. Numerical results were also compared with experimental results at literature. It was obtained that numerical model can represent experimental results in a good level. © 2021. Yıldız Technical University. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).eninfo:eu-repo/semantics/openAccessComputational Fluid DynamicsHeat exchangerNanofluidUnmanned Air VehiclesArticle1989Supplement14Q3198011722577