OIL RETURN FROM EVAPORATOR TO COMPRESSOR IN A REFRIGERATION SYSTEM

摘要

A refrigeration system (10) employing a screw compressor (12) and a falling film evaporator (20) makes use of high-side pressure to drive lubricant, which escapes the compressor (12) and collects as a lubricant-rich mixture of lubricant and refrigerant in the system evaporator (20), back to the compressor (12). The mixture is cyclically exposed to high-side pressure for a period of time which (i) varies in accordance with the difference between a sensed condenser-related pressure a nd a sensed evaporator-related pressure and (ii) is calculated to maintain a predetermined oil concentration in the lubricant-rich mixture in the evaporator (20) so as to minimize the oil return process.