Influences of compressor displacement ratio on dual-loop heat pump system for ventilation heat recovery

The performance of heat pump ventilation heat recovery system can be effectively improved using multiple-loop independent compression cycle. The influence of the DR change on the performance of dual-loop system was predicted through calculation to explore the influence of the change in displacement ratio (DR) on the performance of the system and the direction of further improving the performance of the system. The optimum DR in dual-loop system was calculated. The performance differences of two dual-loop heat pump systems with different DR values were compared by experiments. Results show that the optimum DR is between 0.8040 and 0.9206, and this optimum DR maximizes the COP of the system. Experimental results show that, compared with the COP of the system with the DR of 2, that of the system with the DR of 0.5 can be increased by 14.8%. Compared with the overall COP of the triplex loop system with the same displacement in each loop, that of the system with the DR of 0.5 is even higher under certain test conditions. The comparison results of COP changes are in accordance with the prediction of simulation calculation. Therefore, a reasonable increase in the displacement of the low-pressure loop in the multi-loop heat recovery heat pump system will improve the system performance. (c) 2020 Elsevier B.V. All rights reserved.