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US 4,136,528 AGranted
Refrigeration system subcooling control
AssigneeMcQuay-Perfex Inc.
InventorsKenneth E. Vogel, Jerome D. Powlas
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AssigneeMcQuay-Perfex Inc.
InventorsKenneth E. Vogel, Jerome D. Powlas
Estimating the term…
A control system for a refrigeration system having an air-cooled condenser exposed to normal year round ambient temperatures. Head pressure is controlled in response to sensed subcooling of the refrigerant in the liquid line near the entrance to the expansion device, so as to prevent the occurrence of flash gas at the expansion device, while still allowing minimum head pressures so as to improve energy efficiency. In alternate embodiments, additional controls are provided for assuring at least a predetermined minimum pressure differential across the thermostatic expansion valve. In one preferred embodiment a two-bulb sensing technique is used for subcooling and pressure differential sensing. Both series and parallel condenser-receiver connection systems are disclosed, as are a number of different subcooling sensing and control embodiments.
A control system for a refrigeration system of the type including a compressor, a condenser, an expansion device, an evaporator, and interconnection means connected to form a refrigerant flow path therethrough including a liquid line connected between the condenser and the expansion device, said control system comprising means for sensing the subcooling of liquid refrigerant in the liquid line at the warmest point thereof that will assure subcooling at the expansion device, and control means connected to said subcooling sensing means and connected for controlling system head pressure in response to the sensed subcooling.
A control system for a refrigeration system of the type including a compressor, a condenser, an expansion device, an evaporator, and interconnection means connected to form a refrigerant flow path therethrough including a liquid line connected between the condenser and the expansion device, said control system comprising means for sensing the subcooling of liquid refrigerant in the liquid line at a point that will assure subcooling at the expansion device, and control means connected to said subcooling sensing means and including means for controlling condenser flooding so as to control system head pressure in response to sensed subcooling.
A control system for a refrigeration system of the type including a compressor, a condenser, a receiver, an expansion device, an evaporator and interconnection means connected to form a refrigerant flow path therethrough including a liquid line connected to conduct liquid refrigerant to the expansion device, said control system comprising subcooling sensing means including a refrigerant filled sensing bulb in thermal contact with said liquid line at a point that assures subcooling at the expansion device and a pressure tap in communication with the pressure in said liquid line, a control valve connected to said receiver and said condenser and operable for controlling condenser flooding so as to control system head pressure, said control valve including a diaphragm for actuation thereof, and means for connecting said sensing bulb and said pressure tap to said control valve for operation of the diaphragm thereof, whereby to control system pressure to maintain subcooling at the expansion device.
A control system for a refrigeration system of the type including a compressor, a condenser, a receiver, an expansion device, an evaporator, and interconnection means connected to form a refrigerant flow path therethrough including a liquid line connected to conduct liquid refrigerant to the expansion device, said control system comprising a control valve connected to control condenser flooding so as to control system head pressure, and subcooling sensing means including a fluid pressure tap in said liquid line and a refrigerant filled sensing bulb in thermal contact with said liquid line at a point that assures subcooling at the expansion device, a force balance device, means for connecting said pressure tap and said sensing bulb to said force balance device in opposition to each other, and means connecting said force balance device to said control valve for controlling the operation thereof.
A control system for a refrigeration system of the type including a compressor, a condenser, a control valve connected to receive the output of the condenser, a bypass conduit connecting from the compressor to the control valve, a receiver, a subcooler, an expansion valve, an evaporator, and interconnection means connected to form a refrigerant flow path therethrough including a liquid line connected to carry liquid refrigerant to the expansion device, said control system comprising:
A control system for a refrigeration system of the type including a compressor, a condenser, a control valve connected to receive the output of the condenser, a bypass conduit connecting from the compressor to the control valve, a receiver, a subcooler, an expansion valve, an evaporator, and interconnection means connected to form a refrigerant flow path therethrough including a liquid line connected to carry liquid refrigerant to the expansion device, said control system comprising:
Dependencies are inferred from the claim text.