Refrigeration – Processes – Separating or preventing formation of undesirables
Reexamination Certificate
1999-06-01
2001-06-12
Buiz, Michael (Department: 3744)
Refrigeration
Processes
Separating or preventing formation of undesirables
C062S077000, C062S149000, C062S474000
Reexamination Certificate
active
06244055
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and method for recovering and recycling refrigerant from an air conditioning unit; to a combined heat exchanger and oil separator and for use in an apparatus for recovering and recycling refrigerant from an air conditioning unit; and to a method for improving the efficiency of a combined oil separator and heat exchanger for use in an apparatus for recovering and recycling refrigerant from an air conditioning unit.
BACKGROUND OF THE INVENTION
Most modem air conditioning equipment employ one of several organic solvent compositions, commonly referred to as chlorofluorocarbon compounds (CFCs), as a working fluid (refrigerant). For various reasons, such as wearing of the seals in the air conditioning equipment's compressor, the refrigerant in the equipment may eventually become contaminated with dirt, oil and/or moisture. These contaminants affect the efficiency of the equipment and may eventually lead to damage of the compressor and other components in the equipment. Thus, it is desirable to replace the refrigerant periodically to avoid damaging the equipment and to restore the equipment's overall efficiency. Also, in the event of a failure of the equipment, it is typically required that the refrigerant be removed from the equipment prior to servicing.
Previously, the most common method of removing the refrigerant from the equipment was to vent the refrigerant into the atmosphere and to replace it with virgin refrigerant as required. However, problems exist with this method of removing the refrigerant. The release of CFC compounds into the atmosphere results in the depletion of the ozone layer therein. As the ozone layer is the principal filter in the atmosphere for removing the sun's ultraviolet radiation, much concern has been expressed about its depletion as it is expected to lead to many problems. For example, it is expected that an upturn in related health problems such as skin cancer will occur. Accordingly, many governments are passing legislation restricting or prohibiting the use of and/or releases of CFC compounds into the atmosphere. These restrictions pose a serious problem to refrigeration equipment manufacturers and servicers who no longer can release CFC-type refrigerants into the atmosphere. Another problem in regard of venting of refrigerants to the atmosphere is that the virgin refrigerant compounds required for replacement of vented refrigerants are expensive and may be difficult to obtain.
Refrigerant recovery and recycling systems are described in, for example, U.S. Pat. Nos. 3,699,781; 4,285,206; 4,364,236; 4,805,416; 4,768,347; 4,809,520; 5,072,593; 5,245,840; 5,335,512; 4,809,520; 5,353,603; and 5,617,731.
Most automobile air conditioning units utilize either R-134a refrigerant or R-12 refrigerant. The R-12 refrigerant is often referred to as ozone depleting refrigerant and was commonly used in automobile systems until about the year 1993. Modem automobile systems use the R-134a refrigerant which is more environmentally friendly. Because of the use of different types of refrigerant, it is desirable to provide an apparatus that will recover and recycle each type of refrigerant.
SUMMARY OF THE INVENTION
The invention relates to an apparatus for recovering and recycling refrigerants from an air conditioning unit. The apparatus includes a contaminated refrigerant recovery line for conveying contaminated refrigerant, a combined oil separator and heat exchanger, a dryer for removal of moisture from vapor refrigerant, a compressor for compressing refrigerant, and a receiver tank for receiving condensed purified refrigerant. The combined oil separator and heat exchanger includes a canister having a top wall, a bottom wall, and a substantially cylindrical side wall. The canister additionally includes a high pressure region and a low pressure region. The high pressure region includes heat exchange coils and has a high pressure inlet through the top wall for providing purified refrigerant vapor, and a high pressure outlet through the top wall for removing purified refrigerant liquid. The heat exchange coils are provided in the lower region of the canister. The low pressure region includes a low pressure inlet through the bottom wall for introducing contaminated refrigerant proximate to heat exchange coils, and low pressure outlet through the top wall for removal of refrigerant vapor, and condensed oil outlet through the top wall for removal of condensed oil. By providing the combined oil separator and heat exchanger of the present invention, the Applicants believe they have achieved enhanced separation and efficiency between refrigerant and oil.
The low pressure inlet includes an evaporator injector having a tube for conveying contaminated refrigerant inside the combined oil separator and heat exchanger, and orifices directed downward for spraying contaminated refrigerant onto the coils. Preferably, the orifices are provided within about 5 inches of the coils, and more preferably within about 4 inches of the coils. It is an advantage of the present invention that the evaporator injector sprays the contaminated refrigerant onto the heat exchange coils in order to enhance the separation efficiency between the vapor refrigerant and the oil. By spraying the contaminated refrigerant onto the coils, enhanced agitation of fluid on the coils is provided resulting in increased heat transfer. Furthermore, the proximate location of the spray to the coils reduces the condensation problem associated with having cold liquid fall through vapor which accumulates in the upper region of the canister.
The dryer is provided for removal of moisture from vapor refrigerant from the low pressure outlet of the combined oil separator and heat exchanger. The compressor is provided for compressing the purified refrigerant from the dryer to provide a warm, high pressure refrigerant line for feeding through the high pressure inlet in the combined oil separator and heat exchanger, and through the heat exchange coils. The receiver tank is provided for receiving condensed purified refrigerant from the high pressure outlet of the combined oil separator and heat exchanger.
The invention relates to a method for recovering and recycling refrigerant from an air conditioning unit. The method includes steps of providing a source of contaminated refrigerant for conversion to purified refrigerant; introducing the contaminated refrigerant into a lower region of a combined oil separator and heat exchanger; feeding separated volatile component to a dryer for removal of moisture and to a compressor for compressing refrigerant from the dryer to provide compressed, purified refrigerant; and feeding the compressed, purified refrigerant from the compressor to the high pressure inlet in the combined oil separator and heat exchanger to provide a condensed refrigerant. The method can include a step of charging purified refrigerant into an automobile air conditioning unit.
The invention further relates to a combined oil separator and heat exchanger for use in an apparatus for recovering and recycling refrigerants from an air conditioning unit. It is this combined oil separator and heat exchanger which provides enhanced refrigerant and oil separation compared with prior art devices. In addition, the invention relates to a method for improving the efficiency of a combined oil separator and heat exchanger for use in an apparatus for recovering and recycling refrigerant from an air conditioning unit.
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pate
Chandler Thomas Donald
Hanson Arnold M.
Buiz Michael
Century Manufacturing Company
Jiang Chen Wen
Merchant & Gould
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