Numerical study on heat transfer performance of printed circuit heat exchanger with anisotropic thermal conductivity

Printed Circuit Heat Exchangers are compact and efficient heat exchangers, widely used in nuclear engineering, very high-temperature reactors, and aerospace systems. This study investigates the heat transfer performance of a heat exchanger with anisotropic thermal conductivity, such as fiber reinforced composites. Numerical simulations were conducted to examine the synergistic effect of three-dimensional thermal resistance on heat exchanger performance. The most significant impact on performance is the z-direction thermal resistance, followed by the y-direction, while the x-direction has the least impact. Contrary to traditional design thinking, increasing the overall heat exchanger thermal resistance under the same thermal resistance ratio improves heat transfer efficiency at the studied conditions. The results suggest that it is necessary to design the lowest thermal conductivity direction as the z-direction and increase the y-direction thermal conductivity to enhance heat exchanger performance. In the numerical investigation presented in this study, the efficiency of the heat exchanger was improved by approximately 23 % under specific operating conditions by adjusting the thermal conductivity of anisotropic materials to control the thermal resistance in the x, y and z directions. It is evident that the manipulation of anisotropic material properties has a substantial influence on the performance of heat exchangers.