What is compressor noxious space?

 During the ejection phase of the compressed vapor a certain amount of refrigerant can not be expelled either because the piston reaches its PMS or because there is no more pressure differential between the chamber and the outlet network. This amount that is high pressure in the compressor occupies a volume called noxious space and we must expend energy so we can expand it and allow pressure a little lower than the net to allow suction. In general this value is 5%.