| A new ejector heat pump air conditioning（EHPAC）system for electric vehicle was proposed by our research group,in order to improve the heating capacity and COP of the traditional heat pump air conditioning（THPAC）system for electric vehicle.The indoor and outdoor heat exchangers were designed as separated front and rear rows to increase the heat exchange area,and the ejectors were installed between the front and rear rows of the indoor and outdoor heat exchangers to provide a higher evaporation temperature in the front rows of the evaporator,so that increase the suction pressure of the compressor and the enthalpy difference between the inlet and outlet of the evaporator,thereby improving the performance of the system.The system can realize four modes of cooling,heating,defogging and defrosting through the switch of four-valve.In this paper,the performance simulation and experimental study of the EHPAC system were carried out.Firstly,the simulation model of each component of the system was established,and the sequential module method was used to simulate the performance of the EHPAC system by using MATLAB software.The effects of the evaporation temperature,condensation temperature and compressor speed on the performance of the EHPAC system in cooling and heating modes were studied respectively.Secondly,the effects of outdoor and indoor parameters on the refrigeration and heating performance of the EHPAC system under summer and winter conditions were experimentally studied,and compared with the performance of the THPAC system.The conclusions were obtained as follows:（1）The simulation results show that as the evaporation temperature increases by 2°C in cooling and heating modes,the entrainment ratio of the ejector decreases by about10.88%～12.11% and 13.27%～14.99%,respectively.As the condensation temperature increases by 2°C in cooling and heating modes,the entrainment ratio of the ejector increases by about 10.73%～11.25% and 15.16%,respectively.Within the range of simulation cooling conditions in this paper,the higher the compressor speed,the greater the entrainment ratio of the ejector,but when the evaporation temperature in cooling mode is lower than-2℃ or in heating mode is lower than-7℃,the compressor speed has little effect on the entrainment ratio of the ejector.（2）The simulation results show that the performance of the EHPAC system is better than that of the THPAC system in both cooling and heating modes.Within the range of simulation working conditions in this paper,the refrigeration COP of the EHPAC system is about 16.66%～31.97% higher than that of the THPAC system,and the heating COP of the EHPAC system is about 11.63%～21.24% higher than that of the THPAC system.（3）The experimental results indicated that the entrainment ratio of the ejector of the EHPAC system increases with the increase of the pressure difference between the high and low sides of the system.As the outdoor temperature in summer or indoor temperature in winter increases by 2°C,the entrainment ratio of the ejector increases by about13.1%～16.12%.Within the range of the experimental conditions in this paper,the indoor temperature has a greater impact on the COP of the EHPAC system.The COP of the EHPAC system increases by about 5.29%～5.88% as the indoor temperature increases by2°C in summer or decreases by 2°C in winter.（4）The experimental results indicated that the performance of the EHPAC system is better than that of the THPAC system in both summer and winter conditions.Within the experimental conditions in this paper,the refrigeration capacity and the refrigeration COP of the EHPAC system are about 21.48%～35.77% and 13.02 %～21.61% higher than those of the THPAC system,respectively,while the heating capacity and the heating COP of the EHPAC system are about 4.42%～14.45% and 11.33%～18.34% higher than those of the THPAC system,respectively.（5）The comparison between the simulation and the experimental results shows that the variation trends of simulated refrigeration capacity,refrigeration COP,heating capacity and heating COP under different working conditions are in good agreement with the experimental results,and the error is less than 15.02%.The correctness of simulation is verified by experiment. |
