TY - JOUR
TI - Effects of electronic expansion valve superheat on refrigeration performance of new vehicle heat pump air conditioning system at high temperatures
AU - Li Haijun
AU - Chen Gang
AU - Su Zhiyong
AU - Zhang Yibo
AU - Gao Jiayang
JN - Thermal Science
PY - 2025
VL - 29
IS - 3
SP - 1961
EP - 1969
PT - Article
AB - In response to the problem of serious deterioration in the refrigeration  performance of the heat pump air conditioning system at high temperatures,  the impact of the electronic expansion valve of the new refrigerant R1234yf  on the vehicle low-voltage air conditioning heat pump system was  investigated with regard to its refrigeration performance. In order to  ascertain the effect of refrigeration performance parameters at a high  temperature of 50°C, the superheat of the main valve and the supplement  valve was analyzed. To illustrate, when the primary valve was subjected to  superheating by 3°C at a temperature of 9°C, the exhaust temperature  exhibited an increase of 9.82°C, while the opening degree exhibited a  decrease of 7.8%. In addition, both the evaporation temperature and  condensing temperature decreased by 3.97°C and 11.25°C, respectively.  When the primary valve was subjected to superheating by 5°C, the maximum  refrigeration and COP were 3.201 kW and 1.769, respectively. This represents  an increase of 13.96% and 10.91%, respectively. Upon the increase of the  supplement excess heat by 15°C, the exhaust temperature exhibited an  increase of 7.23°C, while the opening degree demonstrated a decrease of  20.7%. The evaporation temperature and condensing temperature have  decreased by 1.8°C and 6.15°C, respectively. When the auxiliary valve was  superheated at 10°C, the cooling capacity and COP were 3.315 kW and 1.889,  respectively. The values in question exhibited an increase of 3.01% and  7.51%, respectively, in comparison to the baseline conditions. The optimal  temperature for the main valve is 5°C, while the optimal temperature for  the auxiliary valve is 10°C.