Fluent material handling – with receiver or receiver coacting mea – Processes
Reexamination Certificate
2002-08-19
2003-11-04
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
Processes
C141S067000, C141S082000, C141S098000, C141S065000, C252S068000
Reexamination Certificate
active
06640841
ABSTRACT:
FIELD OF INVENTION
The present invention relates generally to methods of introducing environmentally desirable refrigerants into refrigeration systems. More specifically, this invention relates to methods for removing chlorofluorocarbons and hydrochlorofluorocarbons from refrigeration systems and charging refrigeration systems with environmentally desirable refrigerant compositions.
BACKGROUND
The use of chlorine-containing refrigerants, such as chlorofluorocarbons (“CFC's”), hydrochlorofluorcarbons (“HCFC's”) and the like, as refrigerants in air conditioning and refrigerating equipment has become disfavored due to the ozone-depleting properties associated with such compounds. As a result, it has become desirable to “retrofit” chlorine-containing refrigeration systems by replacing chlorine-containing refrigerants with non-chlorine-containing refrigerant compounds which will not deplete the ozone layer, such as hydrofluorocarbons (“HFC's”).
Unfortunately, many non-chlorine-containing refrigerants, including HFC's, are relatively insoluble and/or immiscible in the types of lubricants used traditionally with CFC's (“hydrocarbon-based lubricants”) including, for example, mineral oils, alkylbenzenes or polyalphaolefins. This is problematic because in order for a refrigerant/lubricant system to work efficiently within a refrigeration or air conditioning system, the refrigerant must be sufficiently soluble in the lubricant over a wide range of operating temperatures. Such solubility lowers the viscosity of the lubricant and allows it to flow more easily throughout the system. In the absence of such solubility, lubricants tend to become lodged in the coils of the refrigeration system evaporator, as well as other parts of the system, and thus reduce the system efficiency.
To avoid such problems, traditional methods for retrofitting refrigeration systems require the steps of: (a) removing all chlorine-containing refrigerant and at least 95% of the hydrocarbon-based lubricant from the system; followed by (b) introducing to the system a new non-chlorine-containing refrigerant composition and a replacement lubricant compatible therewith.
The present inventors have come to appreciate that such traditional methods are disadvantageous for several reasons. For example, one disadvantage is that removal of lubricants, and particularly hydrocarbon-based lubricants which have heretofore frequently been used, from a refrigeration system via flushing or other methods tends to be time-consuming and costly. Another disadvantage is that many replacement lubricants, such as esters, are very sensitive to moisture and must be handled with great care. Yet another disadvantage is that replacement lubricants do not perform efficiently certain functions, such as noise reduction, which are associated with hydrocarbon-based lubricants.
Recognizing these and other drawbacks of the prior art, the present inventors have perceived a need for a new, efficient and more desirable method for introducing environmentally desirable refrigerants into refrigeration systems. These and other objects are achieved by the present invention as described below.
DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
The present invention is directed to methods of introducing environmentally desirable refrigerants into refrigeration systems. The methods of the present invention overcome the disadvantages of the prior art by facilitating the introduction of environmentally desirable, non-chlorine-containing refrigerant compositions into refrigeration systems without the removal of hydrocarbon-based lubricant already present in the system. Accordingly, non-chlorine-containing refrigerant compositions can be added to existing refrigeration systems containing hydrocarbon-based oils, such as mineral oils or alkyl benzenes, to form efficient and environmentally desirable refrigerant/lubricant systems with greater ease and less expense than traditional methods.
According to certain embodiments, the present methods involve recharging a refrigerant system that contains a chlorine-containing refrigerant and a lubricant comprising the steps of (a) removing the chlorine-containing refrigerant from the refrigeration system while retaining a substantial portion of the lubricant in said system; and (b) introducing to said system a composition comprising: (i) a refrigerant; (ii) a surfactant; and (iii) a solubilizing agent. As used herein, the term “substantial portion” refers generally to a quantity of lubricant which is at least about 50% (by weight) of the quantity of lubricant contained in the refrigeration system prior to removal of the chlorine-containing refrigerant. Preferably, the substantial portion of lubricant in the system according to the present invention is a quantity of at least about 60% of the lubricant contained originally in the refrigeration system, and more preferably a quantity of at least about 70%.
According to certain alternative embodiments, the present methods involve generally the steps of (a) providing a refrigeration system comprising a chamber having therein a hydrocarbon-based lubricant and substantially no chlorine-containing refrigerant; and (b) introducing to said chamber a composition comprising: (i) a refrigerant; (ii) a surfactant; and (iii) a solubilizing agent.
As used herein the term “refrigeration system” refers generally to any system or apparatus, or any part or portion of such a system or apparatus, which employs a refrigerant to provide cooling. Such refrigeration systems include, for example, air conditioners, electric refrigerators, chillers, transport refrigeration systems, commercial refrigeration systems and the like.
Those of skill in the art will recognize that the refrigeration systems used in the methods of the present invention generally comprise a chamber in which both a refrigerant and lubricant are contained and through which the refrigerant and lubricant can be circulated. According to certain embodiments of the present invention, the removal step (a) comprises removing a chlorine-containing refrigerant from a refrigeration system, especially from a chamber within the system, while leaving a substantial amount of lubricant, and preferably a hydrocarbon-based lubricant, in the system.
Any of a wide range of known methods can be used to remove chlorine-containing refrigerants from a refrigeration system while removing less than a major portion of the lubricant contained in the system. According to preferred embodiments, the lubricant is a hydrocarbon-based lubricant and the removal step results in at least about 90%, and even more preferably at least about 95%, of said lubricant remaining in the system. For example, because refrigerants are quite volatile relative to traditional hydrocarbon-based lubricants (the boiling point of refrigerants are generally under 10° C. whereas the boiling point of mineral oils are generally over 200° C.), the removal step may readily be performed by pumping chlorine-containing refrigerants in the gaseous state out of a refrigeration system containing liquid state lubricants. Such removal can be achieved in any of a number of ways known in the art, including, the use of a refrigerant recovery system, such as the recovery system manufactured by Robinair of Ohio. Alternatively, a cooled, evacuated refrigerant container can be attached to the low pressure side of a refrigeration system such that the gaseous refrigerant is drawn into the evacuated container and removed. Moreover, a compressor may be attached to a refrigeration system to pump the refrigerant from the system to an evacuated container. In light of the above disclosure, those of ordinary skill in the art will be readily able to remove chlorine-containing lubricants from refrigeration systems and to provide a refrigeration system comprising a chamber having therein a hydrocarbon-based lubricant and substantially no chlorine-containing refrigerant according to the present invention.
The introduction step (b) of the present invention comprises introducing to a hydrocarbon-base
Robinson Roy P.
Singh Rajiv R.
Thomas Raymond H. P.
Wilson David P.
Chess Deborah M.
Douglas Steven O.
Honeywell International , Inc.
Szuch Colleen D.
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