Design of a Microchannel Heat Exchanger for Extreme Environments (MHXEE)

Abstract

The development of low-cost, high-performance, and compact heat exchangers for extreme environmental conditions will benefit multiple sectors, especially applications in power electronics and aerospace. These heat exchangers enable efficient thermal exchange systems with strict size, weight, and power consumption (SWaP) requirements. In this study, a counter-flow heat exchanger was designed using microchannels to achieve a high-power density (31.1 kW/kg and 195 kW/L) and is capable of operating in high-temperature (800 °C) and high-pressure (80 bar) environments. Two critical aspects of this microchannel heat exchanger for extreme environments (MHXEE) are included: (1) creep resistance associated with operating at high temperatures and (2) pressure drop associated with the microchannels. CFD and stress analyses were conducted to characterize the heat exchanger's thermohydraulic and mechanical performances. By adding internal ribs inside the manifold area, the heat exchange strength was improved at its design condition while the pressure drops remained at acceptable levels. In order to improve this design further, a topology optimization approach was developed using a 2D model, where different optimal material distributions could be determined that focused on optimizing either: (1) the uniformity of the velocity field or (2) the uniformity of the heat flux. This study demonstrated the potential for further using a robust and reliable yet simple topology optimization approach to improve the thermal and mechanical performance of the MHXEE.