In conventional refrigeration systems, if pressure buildup within the system exceeds a predetermined value, a safety valve will open to release refrigerant to the atmosphere. This relieves pressures within the system and therefore avoids damage to the refrigeration system and a possible explosion. A refrigeration system which employs a safety valve (23) which releases refrigerant to the atmosphere is disclosed in U.S. Pat. No. 1,703,299 to Copeman.
However, release of refrigerants to the atmosphere, while saving the equipment, unfortunately may contribute to pollution of the atmosphere. The U.S. and more than 80 other countries have reached a pact to halt the production of chlorofluorocarbons, or CFC's after 1995. The leading coolants slated for replacing CFC's in the next generation of industrial air conditioners, or chillers, are HFC 134a and HCFC 123. Even these CFC substitutes have been accused of exhibiting some global warming effect, or small ozone-depletion effect, or causing benign tumors in rats. CFC's may be used after the production deadline, but costs for the refrigerants will greatly increase as the supply decreases. CFC's have already increased from about 50 cents a pound ten years ago to about $7.00 per pound. It is estimated that the pool of CFC's after the ban on production will supply only about 25% of current needs.
Thus, there exists a great need for conserving refrigerant, whether it be the banned CFC's or their proposed replacements, both from an ecological view and from an economic one.
European patent no. 250,914 employs a valve 8 and a container 1 downstream of the valve to collect refrigerant and prevent the refrigerant from being released to the atmosphere during refrigerant draining.
Japanese patent no. 28,967 discloses an expansion tank 11 which communicates with the high pressure side of the refrigerant system via line 17. The tank is connected to the inlet of a compressor by a capillary tube 14 and a check valve 15. A valve is opened when a discharge pressure of the compressor exceeds a specified value. The valve actuator 13 is controlled by element 12 which in turn communicates with the discharge of the compressor 1.
U.S. Pat. No. 5,186,017 to Hancock et al employs tanks 16 (FIGS. 1 and 2) and 316 (FIGS. 6 to 8) to accept refrigerant from the high pressure side of the refrigerant system. Condition responsive controlled compressors 172 (FIGS. 1 and 2) and 372 (FIGS. 6 to 8) return vapor from the tank to the refrigerant system.
U.S. Pat. No. 3,736,763 to Garland illustrates the employment of condition responsive control means (FIG. 2) to control a compressor motor 28 and valves 21, 37 and 39 in response to pressure switches 38 and 40 which communicate with receiver 16. The tank 33 located between valves 37 and 39 contains a non-condensible gas.
U.S. Pat. No. 3,238,737 to Schrader et al discloses (FIG. 2A) a check valve 26 which releases refrigerant from liquid line 13A to a tank 17 (column 4, lines 27 to 53).
U.S. Pat. No. 1,815,962 to Andrews discloses a pressurized refrigerant container 40 to charge the refrigerant system. The patent also discloses opening valve 38 to allow the compressor 20 to pump reserve from the evaporator into the receiver.
However, none of these references disclose shutting down the compressor and collecting refrigerant which would be released to the atmosphere if it were not collected during a high pressure system failure.
The present invention provides a method and apparatus for delivering refrigerant from the high pressure and/or low pressure side of the refrigerant system to an evacuated sealed receiver and denying operating current to the compressor to prevent its operation when the high pressure safety valve opens so as to contain refrigerant which would otherwise be discharged into the atmosphere.