Influences of the flow rate and fluid volume in air-kerosene cross-flow heat exchangers using Gyroid-typed triply periodic minimal surfaces

Abstract

• A crossflow Gyroid heat exchanger is designed with air and kerosene as working fluid. • Effects of the volume and flow rate ratios on fluid-thermal characteristics are studied. • Increasing the volume ratio highly improves the overall performance of heat exchangers. • Air-kerosene Gyroid heat exchangers present superiority in efficiency and compactness. Characterized by high specific surface area and intrinsic intricate topology, triply periodic minimal surfaces (TPMS) have been identified as an extremely promising configuration for the efficient and compact heat exchanger (HEX). In aircraft engines, the gas–liquid heat exchange scenario suffers from a thermal disparity between hot and cold fluids due to the intrinsic difference in the heat removal capacity between gas and liquid phases. Using hot air and cold aviation kerosene as the working fluids, this work designs a crossflow HEX equipped with Gyroid TPMS structures and studies the effects of the volume and flow rate ratios of the cold-to-hot fluid on the fluid-thermal characteristics and performances. The results indicate that profiting from the continuous and interwoven smooth paths, the Gyroid structure typically induces secondary helical, split-merge, parallel, and circulation flows, accordingly enhancing the fluid disturbance and rendering the HEX an outstanding performance. It is notably discovered that the overall thermal performance of the HEX strongly depends on the heat transfer level of the hot-air side with the relatively low specific heat. By adjusting the volume and flow rate ratio, enhancing convection heat transfer of the air-side channel can substantially improve the overall heat transfer coefficient of the HEX by up to 65.2 %∼75.7 %. Considering the simultaneous pressure drop penalty, a relatively small volume and flow rate ratio is recommended to reduce the thermal disparity between hot and cold fluids, hence an improved overall thermal performance. Finally, compared with typical HEX configurations, this air-kerosene Gyroid HEX provides a significant improvement in the volume-based power density and normalized pressure drop by approximately an order of magnitude.