Abstract:
An apparatus and methodology are provided for advantageously increasing heat transfer between the evaporator/oil separator (“accumulator”) and condenser of a refrigerant recovery/recycling system, to increase the efficiency of the system and to simplify the system. Embodiments include a refrigerant recovery/recycling device comprising a compressor having a suction inlet and a discharge outlet; an accumulator fluidly connected to a refrigerant source and to the compressor suction inlet; a recovery tank fluidly connected to the compressor discharge outlet; and a heat exchanger for transferring heat from the recovery tank to the accumulator, for raising the temperature of the accumulator and lowering the temperature of the recovery tank.

Description:
[0001]    This application is a Divisional of application Ser. No. 11/641,105 filed Dec. 19, 2006, now U.S. Pat. No. 7,845,178 issued Dec. 7, 2010. 
     
    
     TECHNICAL FIELD 
       [0002]    The disclosure relates to refrigerant handling systems and, in particular, to systems and methodology for recovering and recycling refrigerant from a refrigeration system and recharging recycled refrigerant to the refrigeration system. The disclosure has particular application to techniques and apparatus for improving the efficiency of such refrigerant recovery/recycling systems. 
       BACKGROUND ART 
       [0003]    Heretofore, when refrigerant-charged refrigeration systems, such as automotive air conditioning systems, were repaired, the refrigerant charge was simply vented to atmosphere to accomplish, the repairs. More recently, it has become increasingly important to capture and reuse the refrigerant charge in such refrigeration systems, both to avoid pollution of the atmosphere and to minimize the increasing costs of disposal and replacement of the refrigerant charge. As used herein, “recover” means to remove used refrigerant from refrigeration equipment and collect it in an appropriate external container. “Recycle” means to reduce the amount of contaminants in used refrigerant so that it can be reused. Systems for recovering and recycling used refrigerant typically extract it from a refrigeration system in gaseous form, remove oil and moisture from the refrigerant, condense the refrigerant to liquid form, and store it in a recovery tank. 
         [0004]    A block diagram of a conventional refrigerant recovery/recycling system, in the form of a vehicle air conditioning maintenance system, is shown in  FIG. 1 . The air conditioning maintenance system  100  includes ports  101 ,  102  which are respectively connected to the high pressure side and low pressure side of a refrigeration system, such as a vehicle air conditioning system (not shown). A compressor  110  pulls the refrigerant from the air conditioning system through the ports  101 ,  102 , past gauges  103 ,  104 , and valves  105 ,  106  into an evaporator/oil separator  120 , also called an accumulator. In accumulator  120 , any lubricant (usually an oil) which has flowed along with the refrigerant from the vehicle to the maintenance system  100  drops to the bottom of its oil separator. At the end of a recovery operation, any oil that has been collected is drained into a bottle. Accumulator  120  becomes cool during operation, because liquid refrigerant in accumulator  120  changes to the gaseous phase as it passes through. In fact, conventional accumulators  120  can become cold enough for ice to form on their outer surfaces. However, accumulator  120  is more efficient when warm. Consequently, a heat blanket (not shown) or the like is usually employed to warm accumulator  120  to help vaporize any liquid refrigerant. 
         [0005]    The vaporized refrigerant is pulled out of accumulator  120  and passes through filter/dryer  130 , where any moisture is removed, before entering the suction side of compressor  110 . Refrigerant is pushed out of compressor  110  as a high-pressure, high-temperature gas. Some of compressor  110 &#39;s oil may be pushed out in solution with the refrigerant. The refrigerant and oil from compressor  110  flows into the top of a compressor oil separator  111 , where any oil drops to the bottom and is later returned to compressor  110  via a solenoid  112 . 
         [0006]    The pressurized, hot vaporous refrigerant then flows through a check valve  113  and into the finned tubing of a condenser  140 . A fan (not shown) pushes relatively cool ambient air through the fms of condenser  140 , which transfers heat from the refrigerant to the atmosphere, causing the gaseous refrigerant to condense into a liquid. The liquid refrigerant then flows to a recovery tank  150 . 
         [0007]    Accumulator  120  becomes cool when operating, but is more efficient when warm. Conversely, condenser  140  and recovery tank  150  are heat-producing components that are more efficient when cool, Moreover, when operating in high ambient temperatures, the efficiency of conventional refrigerant recovery/recycling systems decreases significantly. To meet efficiency goals over a range of operating temperatures, conventional systems warm their accumulators using a heat blanket and cool their condensers using a fan and air flow controls, which consume energy and complicate the system, thereby raising the cost of production and operation. There exists a need for an apparatus and methodology for a simplified, less costly, more efficient refrigerant recovery/recycling system. 
       SUMMARY OF THE DISCLOSURE 
       [0008]    An apparatus and methodology is disclosed for advantageously increasing heat transfer between the evaporator/oil separator and condenser of a refrigerant recovery/recyling system to increase the efficiency of the system and to simplify the system, thereby reducing operating costs and production costs. 
         [0009]    The foregoing and other advantages are achieved in part by a refrigerant recovery/recycling device comprising an accumulator fluidly connected to a refrigerant source and to a compressor suction inlet, and a recovery tank fluidly connected to a compressor discharge outlet. The accumulator and the recovery tank are disposed for transferring heat from the condenser to the recovery tank, for raising the temperature of the accumulator and lowering the temperature of the recovery tank. 
         [0010]    Another aspect of the disclosure is a refrigerant recovery/recycling device comprising an accumulator fluidly connected to a refrigerant source and to a compressor suction inlet, and a condenser fluidly connected to a compressor discharge outlet. The accumulator and the condenser are disposed for transferring heat from the condenser to the accumulator, for raising the temperature of the accumulator and lowering the temperature of the condenser. 
         [0011]    Additional advantages will become readily apparent to those skilled in this art from the following detailed description, wherein only exemplary embodiments are shown and described. As will be realized, the present disclosure can include other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure, Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent like elements throughout, and wherein: 
           [0013]      FIG. 1  is a diagram of a conventional air conditioning maintenance system. 
           [0014]      FIGS. 2   a - c ,  3 , and  4   a - c  are block diagrams of refrigerant recovery/recycling systems according to embodiments of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    The present disclosure provides a heat transfer mechanism between an evaporator/oil separator, hereinafter “accumulator” (a component that becomes cool during operation but is more efficient when warm), and a recovery tank (a component that becomes warm but is more efficient when cool). The heat transfer mechanism improves the recovery efficiency of the refrigerant recovery/recycling system and the purity of the recovered refrigerant. Moreover, systems incorporating the present disclosure are simplified because certain conventional heating and cooling mechanisms, such as the accumulator heat blanket and the condenser, are eliminated, 
         [0016]    Several embodiments utilize the principle of using heat loss and heat gains of the accumulator and condenser, respectively, to improve the performance of the other. One embodiment uses a block of material having good thermal conductivity properties, such as aluminum, as a heat transfer mechanism located between the accumulator and the recovery tank. This heat transfer mechanism provides a thermal transfer path between the two components, as well as mechanical stability. In other embodiments, the accumulator, recovery tank, and condenser are all directly connected together to promote heat transfer, or the accumulator and the condenser are connected together, In a further embodiment, the accumulator is located in the recovery tank. This is done, for example, using concentric tanks, i.e., a small accumulator inside of the recovery tank. 
         [0017]    A block diagram of a refrigerant recovery/recycling system according to an exemplary embodiment is shown in  FIG. 2   a . The system  200   a  is connected to a refrigeration system, such as a vehicle air conditioning system (not shown). A conventional compressor  210  having a suction inlet  210   a  and a discharge outlet  210   b  pulls refrigerant (which can be in a liquid and/or gaseous form) from the air conditioning system into an accumulator  220 , which includes a conventional oil separator  221 . In accumulator  220 , lubricant (i.e., oil) which has flowed along with the refrigerant from the vehicle to recovery/recycling system  200  drops to the bottom of oil separator  221 , At the end of a recovery operation, any oil that has been collected is drained into a bottle. The refrigerant becomes vaporized as it passes through accumulator  220 . 
         [0018]    The vaporized refrigerant is pulled out of accumulator  220  and passes through a conventional filter/dryer  230 , where any moisture is removed, before entering the suction inlet  210   a  of compressor  210 . Refrigerant is pushed out of discharge outlet  2101 ) of compressor  210  as a high-pressure, high-temperature gas. The pressurized, hot vaporous refrigerant then flows through a conventional check valve  213  and into the finned tubing of a condenser  240 . A fan (not shown) pushes relatively cool ambient air through the fins of condenser  240 , which transfers heat from the refrigerant to the atmosphere, causing the gaseous refrigerant to condense into a liquid. The liquid refrigerant then flows to a recovery tank  250 . 
         [0019]    In this embodiment, accumulator  220  is fixedly mounted to recovery tank  250  via a heat exchanger  260  comprising a block of thermally conductive material, such as aluminum. Accumulator  220 , heat exchanger  260  and tank  250  are connected together in a conventional manner, such as by bolts, so that their surfaces contact each other and accumulator  220  is stably supported. Heat is thereby transferred from recovery tank  250 , which becomes warm during operation of the system, through heat exchanger  260 , to accumulator  220 , which becomes cool during operation of the system. In other embodiments, no separate heat exchanger  260  is used, but accumulator  220  and tank  250  are connected directly together and their outer walls form the heat exchanger. 
         [0020]    As a result of the heat transfer between tank  250  and accumulator  220 , whether or not a separate heat exchanger  260  is employed, efficiency of the system  200   a  is increased. Since the temperature of recovery tank  250  is reduced, the refrigerant is more readily condensed to liquid form inside tank  250 . Since the temperature of accumulator  220  is increased, the refrigerant flowing through it is more readily vaporized. Moreover, the need for a heat blanket to vaporize the refrigerant is eliminated, thereby simplifying system  200   a  and reducing its cost. 
         [0021]    Condenser  240 , located between compressor  210  and recovery tank  250 , is used to liquefy and cool the refrigerant before going into recovery tank  250 . In further embodiments, heat exchanger  260  cools recovery tank  250  sufficiently to eliminate condenser  240  and its associated fan and controls, thereby further simplifying system  200   a  and reducing its cost. 
         [0022]    In a further embodiment, shown in  FIG. 2   b , accumulator  220  is fixedly, directly mounted to recovery tank  250 , and condenser  240  is also fixedly directly mounted to recovery tank  250 . In this embodiment, ho separate heat exchanger is employed as in the embodiment of  FIG. 2   a ; rather, the walls of the accumulator  220 , recovery tank  250 , and condenser  240  are employed as heat exchangers. Accumulator  220 , tank  250 , and condenser  240  are connected together in a conventional manner, such as by bolts, so that their surfaces contact each other and accumulator  220  and condenser  240  are stably supported. Heat is thereby transferred from recovery tank  250  and condenser  240 , which become warm during operation of the system, to accumulator  220 , which becomes cool during operation of the system. 
         [0023]    As a result of the heat transfer between condenser  240 , tank  250  and accumulator  220 , efficiency of the system  200   b  is increased. Since the temperature of recovery tank  250  is reduced, the refrigerant is more readily condensed to liquid form inside tank  250 . Since the temperature of accumulator  220  is increased, the refrigerant flowing through it is more readily vaporized. Moreover, the need for a heat blanket to vaporize the refrigerant is eliminated, thereby simplifying system  200   b  and reducing its cost. All other components of system  200   b  are similar or identical to like-numbered components of system  200   a  described hereinabove. 
         [0024]    In another embodiment, shown in  FIG. 2   c , accumulator  220  is directly fixedly mounted to condenser  240 . Accumulator  220  and condenser  240  are connected together in a conventional manner, such as by bolts, so that their surfaces contact each other and both are stably supported. Heat is thereby transferred from condenser  240 , which becomes warm during operation of the system, to accumulator  220 , which becomes cool during operation of the system. 
         [0025]    As a result of the heat transfer between condenser  240  and accumulator  220 , efficiency of the system  200   c  is increased. Since the temperature of condenser  240  is reduced, the temperature of the refrigerant entering recovery tank  250  is also reduced, so the refrigerant is more readily condensed to liquid form inside tank  250 . Since the temperature of accumulator  220  is increased, the refrigerant flowing through it is more readily vaporized. Moreover, the need for a heat blanket around accumulator  220  to vaporize the refrigerant is eliminated, thereby simplifying system  200   c  and reducing its cost. 
         [0026]    Although condenser  240  and accumulator  220  are shown in  FIG. 2   c  as abutting each other, in further embodiments, shown in  FIG. 4   a , the coils of condenser  440   a  are wrapped around accumulator  420   a , such that condenser  440   a  surrounds accumulator  420   a  to further improve heat transfer. In another embodiment, shown in  FIG. 4   b , accumulator  420   b  is located inside condenser  440   b . In still another embodiment, shown in  FIG. 4   c , condenser  440   c  is located inside accumulator  420   c . All other components of systems of these embodiments are similar or identical to like-numbered components of system  200   c  described hereinabove. 
         [0027]    In another embodiment shown in  FIG. 3 , a refrigerant recovery system  200   d  comprises an apparatus  300  comprising a refrigerant recovery tank  250   a  and an accumulator  220   a  inside recovery tank  250   a  for transferring heat from recovery tank  250   a  to accumulator  220   a . Accumulator  220   a  includes a conventional oil separator  221   a , and has a fluid inlet  220   b  and a fluid outlet  220   c  accessible at an outside surface of recovery tank  250   a . In certain embodiments, accumulator  220   a  and recovery tank  250   a  are concentric, All other components of system  200   d  are similar or identical to like-numbered components of system  200   a  described hereinabove. 
         [0028]    As a result of the heat transfer between tank  250   a  and accumulator  220   a , efficiency of the system  200   d  is increased, Since the temperature of recovery tank  250   a  is reduced, the refrigerant is more readily condensed to liquid form inside tank  250   a , Since the temperature of accumulator  220   a  is increased, the refrigerant flowing through it is more readily vaporized. The need for a heat blanket to vaporize the refrigerant is eliminated, thereby simplifying system  200   d  and reducing its cost. In further embodiments, the heat transfer between recovery tank  250   a  and accumulator  220   a  cools recovery tank  250   a  sufficiently to eliminate condenser  240  and its associated fan and controls, thereby further simplifying system  200   d  and reducing its cost. 
         [0029]    The increased efficiency of refrigerant recovery/recycling systems employing the heat transfer techniques of the embodiments enables systems using the embodiments to meet strict efficiency standards. For example, the Underwriter&#39;s Laboratories (UL) 120 Degree Ambient Test requires a system to meet limits for oil, air, and moisture contamination in the recovery process (i.e., purity) while maintaining a refrigerant recovery efficiency of 90%. The present disclosure provides a way to use heat generated by the refrigerant recycling/recovery system, which is disadvantageous in conventional systems, to warm the accumulator, thereby increasing overall recovery efficiency and purity of the recovered refrigerant. 
         [0030]    The above-described embodiments can be practiced by employing conventional materials, methodology and equipment. Accordingly, the details of such materials, equipment and methodology are not set forth herein in detail. In the previous descriptions, numerous specific details are set forth, such as specific materials, structures, chemicals, processes, etc., in order to provide a thorough understanding of the embodiments. However, it should be recognized that the embodiments can be practiced without resorting to the details specifically set forth. In other instances, well known processing structures have not been described in detail, in Order not to unnecessarily obscure the present disclosure. 
         [0031]    Only exemplary embodiments are shown and described in the present disclosure. It is to be understood that the embodiments are capable of use in various other combinations and environments and are capable of changes or modifications. 
         [0032]    The embodiments described herein may include or be utilized with any appropriate voltage or current source, such as a battery, an alternator, a fuel cell, and the like, providing any appropriate current and/or voltage, such as about 12 Volts, about 42 Volts and the like. 
         [0033]    The embodiments described herein may be used with any desired system or engine. Those systems or engines may comprise items utilizing fossil fuels, such as gasoline, natural gas, propane and the like, electricity, such as that generated by battery, magneto, fuel cell, solar cell and the like, wind and hybrids or combinations thereof. Those systems or engines may be incorporated into other systems, such as an automobile, a truck, a boat or ship, a motorcycle, a generator, an airplane and the like.