High-efficiency cooling solution for exhaust air heat pump: Modeling and experimental validation

Abstract

The cooling performance of exhaust air heat pumps is limited by the high condensing temperatures owing to insufficient exhaust air volume. In this study, a high-efficiency solution for an exhaust air heat pump was developed and numerically studied. In this novel system, the exhaust air is stepped energy recovered by an indirect evaporative cooler and a heat pump with an evaporative condenser. It is considered that the combination of these two heat transfer components can provide a system with a significantly high cooling efficiency. To explore the application potential of this system further, a detailed mathematical model was established. Meanwhile, a prototype based on this design was developed, and its performance in four operating modes was tested for model validation. When the test results are compared with those of a conventional system of the same size, they show that the cooling capacity and energy efficiency ratio of the novel system increased by 53% and 135%, respectively. Subsequently, to clarify the principles underlying the design of this system, parameter sensitivity analysis and system matching optimization were conducted numerically.