| abstract |
A vapor compression system (20, 400, 420, 440, 460, 480) has: a compressor (22) having a suction port (40) and a discharge port (42); a heat rejection heat exchanger (58) coupled to the discharge port to receive compressed refrigerant; a heat absorption heat exchanger (88); a first lubricant flowpath (120, 126; 120) from the heat rejection heat exchanger to the compressor; a second lubricant flowpath (121, 126; 121) from the heat absorption heat exchanger to the compressor; at least one lubricant pump (190; 190, 191); at least one liquid level sensor (180, 181; 180, 181, 330); and a controller (900) configured to control lubricant flow along the first lubricant flowpath and the second lubricant flowpath based output of the at least one liquid level sensor. |