The thermal performance and applicability analysis of the composite ventilation system with heat recovery in ultra-low energy buildings

Abstract

By analyzing the energy transfer process of building ventilators with heat recovery, a novel building ventilator with exhaust air heat pump enhanced by pump-driven loop heat pipe system was proposed and experimentally compared with the dual-loop heat pump and traditional heat pump system. During the test, the thermal performance of the prototype under three different operating modes was comprehensively studied, and then the energy-saving potential and applicability of the heat recovery units in the ultra-low energy buildings (ULEBs) were analyzed by using the DEST and MATLAB tools. Results showed that compared with the heat pump system, the composite system presented the highest energy efficiency ratio (EER) in the whole year, at 12.6 for winter and 4.8 for summer conditions, respectively. What's more, the energy recovered by the composite system is in line with the fresh air load, which can solve the problem of energy recovery attenuation of traditional ventilators in cold climate conditions. In addition, the composite system had great applicability in ULEBs, and the energy-saving ratio was 35.3% and 14.5% in Harbin and Kunming, respectively. Future works are to improve the performance of the pump-driven loop heat pipe and heat pump unit under all operating conditions for better adaptability of the ventilators.