Economized Refrigerant System with Vapor Injection at Low Pressure

摘要

A refrigerant system with an economizer cycle incorporates a time dependant vapor injection scheme to reduce losses and enhance performance. The benefits of such an approach are particularly pronounced at low pressure ratios typical of air conditioning applications. The injection of refrigerant occurs during a limited time interval and at a particular point of time into a compression cycle. The vapor injection preferably occurs when the compression chamber are sealed (or about to be sealed off) from a suction port and continues until refrigerant pressure in the compression chambers is equal (or about to be equal) to the pressure at the injection line. This communication time constitutes about 35% of time of one revolution. In one embodiment, such time dependence of refrigerant vapor injection is provided by a specific compressor design. In another embodiment, a fast-acting solenoid valve is placed at the vicinity of the injection port to control the initiation and duration of the injection process. The benefits for an unloading scheme are disclosed as well.