Numerical investigation of heat transfer and pressure drop characteristics on the hot fluid side of the plate-fin precooler under negative pressure conditions

Abstract

Plate-fin heat exchangers are widely employed in aerospace and many other fields due to the advantage of high efficiency and low resistance. However, they usually operate at atmospheric or high-pressure conditions. In this study, The commercial CFD solver Fluent 16.0 was used to evaluate the overall performance of the plate-fin precooler whose hot fluid is nitrogen under negative pressure and high temperature conditions. The characteristics of the hot fluid flow field inside the precooler with and without fins were investigated. The effect of fin number on the heat transfer and pressure drop characteristics of the hot fluid side was analyzed. Furthermore, the comprehensive performance of the precooler under different pressure conditions was compared quantitatively. The results showed that under negative pressure conditions, the hot fluid flow field features inside the precooler without fins was regular, while that of the precooler with fins took on a “<” shaped flow features, indicating the evolving of thermal boundary layer. It was also found that the comprehensive performance of the precooler did not increase with an increase in the number of fins when the hot fluid was in a low-density and high-speed flow state. Moreover, pressure conditions did not affect the heat transfer performance of the precooler but had a significant impact on the pressure drop performance.