Responding to the applied air-conditioning requirements for electric cars

an experimental bench for the R290 heat pump system with a secondary medium cycle was established. The cooling and heating performances of the system were tested under various working conditions. As the compressor speed increases from 1800 r/min to 6600 r/m

the cooling capacity increases from 1789 to 4027 W under standard conditions (35 ℃)

while the COP decreases from 3.65 to 1.82. As the compressor speed increases from 2700 r/min to 4500 r/min

the cooling capacity increases from 1973 to 3031 W under extremely warm conditions (45 ℃)

while the COP decreases from 2.10 to 1.88. Under cold conditions (?20 ℃)

the heating capacity of the system reaches 2911 W at 6000 r/min

and the corresponding COP is 1.80. Under extremely cold conditions (?25 ℃)

the heating capacity reaches 1685 W at 3600 r/min

and the COP is 2.16. Meanwhile

the system adopted the form of secondary heat transfer

which improved the safety and reliability. However

compared with the primary circuit

the cooling capacity is attenuated by 300–500 W

and the heating capacity is attenuated by 200–400 W.