Refrigerant flow control for improving low capacity efficiency

Claim 1

IN A CENTRIFUGAL REFRIGERATION SYSTEM, THE COMBINATION OF A HIGH PRESSURE SIDE INCLUDING A CENTRIFUGAL COMPRESSOR AND A CONDENSER; A LOW PRESSURE SIDE INCLUDING AN EVAPORATOR HAVING A TUBE BUNDLE THEREIN; A REFRIGERANT METERING DEVICE COMPRISING A FLOAT VALVE DISPOSED IN THE HIGH PRESSURE SIDE OF THE SYSTEM TO METER PASSAGE OF REFRIGERANT FROM THE CONDENSER TO THE LOW PRESSURE SIDE, SAID FLOAT VALVE BEING OPERABLE IN RESPONSE TO LIQUID REFRIGERANT LEVEL IN THE HIGH PRESSURE SIDE TO PASS REFRIGERANT TO THE EVAPORATOR TO MAINTAIN A CONSTANT LIQUID LEVEL IN THE HIGH PRESSURE SIDE UNDER NORMAL OPERATING CONDITIONS; AND AN ACTUATING ASSEMBLY FOR ACTUATING SAID FLOAT VALVE, SAID ASSEMBLY BEING RESPONSIVE TO AN OPERATING CHARACTERISTIC OF THE SYSTEM AT LOW LOAD TO HOLD SAID VALVE OPEN IRRESPECTIVE OF THE REFRIGERANT LEVEL IN THE HIGH PRESSURE SIDE TO PASS GASEOUS REFRIGERANT FROM THE HIGH PRESSURE SIDE TO THE EVAPORATOR TO AGITATE LIQUID REFRIGERANT IN THE EVAPORATOR THEREBY WETTING SUBSTANTIALLY ALL THE TUBES OF THE BUNDLE WITTH LIQUID REFRIGERANT TO INCREASE EVAPORATOR EFFICIENCY UNDER LOW LOAD CONDITIONS.