Pressure drop and heat transfer performance of microchannel heat exchanger with different reentrant cavities

Abstract

The shape of the reentrant cavities has a great effect on the pressure drop and heat transfer performance of microchannel heat exchanger (MHE). In present study, MHEs with three reentrant cavity, i.e. circular, trapezoidal, and rectangular, were designed and manufactured. The influence of the cavity shape on the pressure drop performance, heat transfer performance and comprehensive performance of the MHEs were investigated. The pressure drop and Darcy friction coefficients were largest for the rectangular reentrant cavities, indicating that it exhibited the best pressure drop performance. At the same flow rate, the MHE with circular reentrant cavities had the lowest hot water outlet temperature and the MHE with rectangular reentrant cavities had the highest temperature, whereas the results were the opposite for the cold water outlet temperature. The Nusselt number was largest for the circular reentrant cavities. This indicates that the MHE with circular reentrant cavities had the best heat performance. Finally, the comprehensive performance index η was put forward. And the result found that the MHE with circular reentrant cavities had the highest comprehensive performance.