Refrigeration – Refrigeration producer – With lubricant handling means
Reexamination Certificate
1999-09-27
2001-02-06
Doerrler, William (Department: 3744)
Refrigeration
Refrigeration producer
With lubricant handling means
C062S471000, C062S505000, C062S513000
Reexamination Certificate
active
06182467
ABSTRACT:
BACKGROUND OF THE INVENTION
In closed refrigeration and air conditioning systems, the refrigerant and lubricant are normally in contact. Because there is an affinity between lubricants and refrigerants, they are present in refrigeration and air conditioning systems as a mixture of varying composition. The composition will depend upon many factors such as the temperature, whether the system is running or not, whether oil is separated by flow through an oil separator or circuitous path, whether the refrigerant undergoes a phase change, etc. The lubricant in the refrigerant tends to coat the surfaces of the system and deteriorates the heat transfer properties of the system. The refrigerant not only dilutes the lubricant, but is subject to outgassing which results from a pressure reduction and produces a froth which can interfere with lubrication.
SUMMARY OF THE INVENTION
A small heat exchanger is preferably located below the cooler or evaporator of a closed refrigeration or air conditioning system and defines an oil rich generator or still. Alternatively, the still may be located at a higher level but would require a pump, or the like. The oil rich generator takes mixed liquid made up of refrigerant and oil from the cooler. A portion of the relatively warm liquid from the condenser is diverted into the generator vessel. In flowing through the tubes in the generator vessel, heat is given up by the flow from the condenser causing the refrigerant in the generator vessel to boil. Alternatively, a supplemental heat source such as electric resistance heat may be used. The resulting refrigerant vapor is vented from the vessel and flows to the compressor suction due to the pressure differential between the compressor suction and the cooler. The boiling off of refrigerant results in an “oil rich” liquid. The oil rich liquid is supplied to the lubrication system via one, or more, ejectors which cause the oil rich liquid to be entrained in high pressure gas diverted from the compressor. The pressure driving the ejectors is, preferably, the higher of the discharge pressure or the last closed lobe rotor pressure.
In passing through the generator, the refrigerant flow from the condenser is subcooled. This relatively high pressure, subcooled flow is supplied to the motor for cooling. In cooling the motor, the subcooled flow is heated and expanded and is subsequently supplied to the suction flow to the compressor.
It is an object of this invention to generate an oil rich fluid to lubricate screw compressor bearings.
It is an additional object of this invention to provide separate lubrication circuits for the rotors and bearings of a screw compressor.
It is another object of this invention to reduce the refrigerant content of an oil-refrigerant mixture.
It is an object of this invention to eliminate the complexity of typical oil separation systems thereby lowering the cost and improving the system reliability.
It is a further object of this invention to generate subcooled liquid for motor cooling. These objects, and others as will become apparent hereinafter, are accomplished by the present invention.
Basically, supplemental heat or a portion of the condensed liquid in a condenser is diverted to a generator or still where it supplies heat to boil off refrigerant from a refrigerant oil mixture and is thereby subcooled. The subcooled liquid is supplied to the motor for cooling. The boiling off of refrigerant in the generator results in an “oil rich” liquid which is supplied to the bearings for lubrication. One, or more, jet or ejector pumps are preferably used to supply the oil rich liquid to the lubrication distribution system for lubricating the bearings. Preferably, an oil rich zone in the cooler supplies lubricant for lubrication and/or sealing of the rotors via a second lubrication distribution system.
REFERENCES:
patent: 1922942 (1933-08-01), Gay
patent: 3336762 (1967-08-01), Patterson
patent: 3777509 (1973-12-01), Muench
patent: 4419865 (1983-12-01), Szymaszek
patent: 4497185 (1985-02-01), Shaw
patent: 5016447 (1991-05-01), Lane et al.
Huenniger Edward A.
Maalouf Fadi S.
Yannascoli Donald
Zhong Jianping
Carrier Corporation
Doerrler William
Norman Marc
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