摘要
A series of experiments on the dynamic performance of the HPWH （heat pump water heater） unit with EXV （electronic expansion valve） under different environmental conditions were conducted. The dynamic heating capacity and COP （coefficient of performance） of the HPWH unit under different EXV openings were measured. The effects of the EXV opening on the performance of the HPWH unit were analyzed. Meanwhile, the dynamic performance of the HPWH with EXV was simulated and the results were compared with the experimental one. The experimental results indicate that during heating process, the COP increases firstly and then decreases for a fixed EXV opening, which is in good agreement with the numerical result. For different EXV openings, the COP and heating capacity of the system using larger EXV opening are superior to those using the smaller one in the initial heating stage. While in the late stage, the performance of system using smaller EXV opening is better. It is found that the system performance is improved significantly by changing the EXV opening in the different heating period and the average COP of the HPWH system is increased by 7.6%.
