Assessment and optimization assistance of entropy generation to air-side comprehensive performance of fin-and-flat tube heat exchanger

Abstract Fin-and-flat tube heat exchanger (FFTHE) is widely utilized in the cooling system of construction vehicle for its high efficiency and easy maintenance. To reduce irreversible energy loss in performance optimization, an elementary unit of the FFTHE was numerically investigated for heat transfer coefficient and pressure loss, which were validated by experimental data later. Simultaneously, a specific expression of entropy generation per mass flow rate (EGPMFR), also a criterion, was derived with them when cold air was treated as working medium. Its independent variables involve the physical performance of working medium, working condition, and structural parameters. The effect of physical performance on heat exchange was analyzed with iterations to reduce related error. Then, the EGPMFR was employed to select the results from a traditional multi-object genetic algorithm (MOGA) based optimization. Finally, the EGPMFR, entropy generation under the same mass flow rate (EGSMFR), local entropy generation (LEG) and the JF factors of original and improved schemes were compared to shed light on the assistance of EGPMFR in performance optimization. It is found that the accuracy of numerical analysis could be validated by experimental data over a certain range of error. As for the effect of physical performance on bulk temperature, it could be kept under 0.01 °C with two iterations before the structural optimization starts, and with this determination, EGPMFR could be introduced to screen optimization results by assessing their irreversible energy loss. Among optimized schemes in this paper, scheme 2 owning a better JF factor presents the highest LEG, EGPMFR and EGSMFR, whose deviation increases by 4.36% at 12 m/s compared to the original data. The conclusions of this work might provide helpful assistance for the further optimization of FFTHE, and remind designers that a suitable optimum scheme would meet the requirements from heat exchange and energy conservation at the same time.