A method and apparatus for controlling the capacity of a multi-stage cooling system is disclosed. The system of the invention utilizes a plurality of commonly piped compressors being a variable speed compressor, means for establishing a single predetermined cooling state "cut-in" pressure and a single predetermined cooling state "cut-out" pressure, a plurality of condenser fans and a microprocessor based control means for controlling the operation of the system.

Method and apparatus for controlling capacity of a multiple-stage cooling system

A heat pump system is presented having a primary compressor, a booster compressor, a multi-step thermostat, an indoor coil, an outdoor coil, a refrigerant flow conduit connecting these elements is a closed loop system, and at least one pressure sensor positioned to always sense the refrigerant system low side pressure, which is commensurate with outdoor ambient air temperature in all heating modes of operation. The pressure sensor functions as an override and safety control to prevent or permit operation of the compressors, and also other system components, depending on outside air temperature. The primary compressor is preferably a multi-capacity compressor. A defrost energy transfer fluid is used in a defrost cycle.

Boosted air source heat pump

There is disclosed a refrigerant cycle apparatus capable of avoiding occurrence of an abnormal rise in a pressure on a high-pressure side in advance, comprising: a throttling mechanism including a first capillary tube, and a second capillary tube which is connected in parallel to the first capillary tube and whose flow path resistance is smaller than that of the first capillary tube; and a valve device for controlling refrigerant circulation into the first and second capillary tubes, so that a refrigerant is passed into the second capillary tube at the time of starting of a compressor.

Refrigerant cycle apparatus

A primary compressor (12) and a booster compressor (10) connected in series are presented. A first conduit (14) connects the low side of a heating/cooling or refrigeration system to the inlet (18) of the booster compressor (10), the outlet (22) of the booster compressor (10) and the inlet (24) of the primary compressor (12). A second conduit (28) connects the outlet (26) of the primary compressor (12) to the high side of the system. The first conduit (14) includes a check valve (16) for closing or opening the connection between the first conduit (14) and the outlet (22) of the booster compressor (10). A sump conduit (30) is positioned near the bottom of the primary and booster compressors (10, 12) to allow lubricant to flow from the booster compressor (10) to the primary compressor (12).

Series connected primary and booster compressors

In a system having low and high stage compressors with an oil separator downstream of each stage there can be a tendency for oil from the first stage to collect in the second stage So, responsive to a low level of oil in the first stage oil system, oil is supplied from the second stage oil system to the first stage oil system

Makeup oil system for first stage oil separation in booster system

A two-stage refrigeration system including a condensor, a receiver, an evaporator, a low-stage dry-wall compressor and a high-stage dry-wall compressor, the low-stage compressor including an oil-draining assembly for automatically draining oil from the suction chamber to the crankcase chamber, and a pressure-equalizing connection between the suction chamber and the crankcase chamber, the high-stage compressor having an oildraining assembly for automatically draining oil from the highstage suction chamber to the high-stage crankcase chamber, and a pressure connection between the high-stage crankcase chamber and the low-stage crankcase chamber; and a pressure-responsive regulating valve interposed in the connection between the highstage crankcase chamber and the low-stage crankcase chamber, the pressure-responsive valve being connected to respond to the highstage suction chamber pressure to maintain a predetermined pressure differential of one pound per square inch between the high-stage suction chamber and the high-stage crankcase chamber.

Grant Whitney I

Papers

Two-stage refrigeration system having crankcase pressure regulation in high stage compressor