Twin-screw refrigeration compressor has been widely applied because of its unique advantage in air-source heat pump. In this paper

the performance variation of the twin-screw refrigeration compressor during the reverse cycle defrost process has been studied by experiment. The results showed that the twin-screw refrigeration compressor would receive a marked impact because of the reverse cycle defrost behavior of the system. The discharge pressure of compressor would drop sharply to 0.65MPa and then rise gradually during the first half of reverse cycle defrost process

but the suction pressure would rise perpendicularly and then decrease rapidly

even to 0.1MPa

after that it would go up gradually in this period of time. In the second half of reverse cycle defrost process

the discharge pressure and the suction pressure would have a strong oscillation and then tend to steady. During the reverse cycle defrost process

the variation of the discharge temperature and the suction temperature would be slow and lag behind the changing of pressure. The discharge temperature would drop firstly from 90℃ to 75℃

and then up to 100℃

finally

decrease and tend to steady. However

the suction temperature would rise and keep the high temperature for some time

and drop finally. The consumption power of compressor would have the similar experience as the discharge pressure. The heat capacity of this system would decrease and offer cooling capacity to environment. At that time

the frost on the fins would be melted.