Abstract:
A self-contained beverage chilling apparatus including a refrigerant cooling system comprising a refrigerant reservoir in a fluid communication with a cold plate, a refrigerator accumulator, a compressor and a refrigerant condenser mounted within a housing unit. The housing unit further included beverage inlet means in fluid communication with the cooling system cold plate, and beverage dispenser means in fluid communication with the cold plate wherein the beverage to be dispensed is chilled to a desired temperature as it passes through the cold plate to the beverage dispensing means.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is related generally to beverage dispensing systems employing a cooling subsystem, and more particularly to a self-contained, table top beverage dispenser incorporating a refrigerant-chilled cold plate for cooling the beverage.  
         [0003]     2. Description of Related Art  
         [0004]     In a large number of restaurants, taverns, pubs, and clubs where beer is sold at a bar, beer kegs are stored in a cold room where they can be maintained at a reduced temperature along with other perishable food items and beverages. These cold rooms are typically maintained at a temperature of approximately 40° F. The beer is conducted from the cold rooms to serving towers at the bar through plastic tubes or beer lines that extend within a thermally insulated jacket, or trunk line. The distance between the cold room and the tower can be as little as fifteen feet and as great as two hundred feet, depending on the layout of the particular establishment. To move the beer through the lines, such systems require a pressurization subsystem that forces the beer from the cold room down the length of beer line to the beer tower for dispensing. The pressurization subsystem introduces a gas such as nitrogen or carbon dioxide into the beverage, pressurizing the beverage to enable it to be pumped through the beer lines.  
         [0005]     As the beer is communicated from the cold room to the dispensing tower, it gains heat from the ambient atmosphere and warms to a temperature above the original 40° F. Even enveloped in the thermally insulated trunk line, traveling seventy five feet the beer in the trunk line can result in a beer temperature increase of 8° F. at the end of the trunk line. Thus, where the length of the beer lines from the cold room to the dispensing towers is not minimal, the beer dispensing system will traditionally include one or more refrigerated glycol chillers that incorporate glycol re-circulating lines of plastic tubing that extend within the thermally insulated trunk line carrying the beer lines. The presence of the glycol recirculation lines can reduce the warming of the beer by five to six degrees, resulting in an end temperature as low as 42° F., or a two degree rise from cold room to the end of the trunk line.  
         [0006]     The trunk lines may lead to a counter top supporting cabinetry such that their downstream ends terminate below the counter tops, where they connect with balance lines that extend from the down stream end of the trunk line to the delivery tubes adjacent the respective dispensing valve. In practice the beer flowing from the beer lines, through the balance lines and stainless steel tubes can be expected to further warm from 2° F. to 4° F. Accordingly, in the example above beer initially at 40° F. in the cold room is warmed to 42° F. at the downstream end of the trunk line, and further warmed to approximately 45° F. by the time it reaches the dispensing valve.  
         [0007]     When beer is charged with a gas such as carbon dioxide to move the beer through the various lines, the gas is entrained or dissolved in the fluid and resides in a stable state for temperatures below or at approximately 30° F. That is, the gas does not bubble out of the fluid but is carried by the fluid and gives the beverage its distinctive effervescence when consumed. However, as the temperature of the beer rises above 30° F., absent an increase in pressure on the system, the gas gradually becomes increasingly unstable and begins to bubble or foam out of the flowing beer. Further warming of the beer increases the foaming effect as the gas bubbles coalesce and propagate downstream, and foaming is further exacerbated by disturbances in the beer such as the turbulence generated when the beer is dispensed from the dispensing valve. When beer is warmed to 45° F. or more, when exposed to normal ambient room pressure, the gas becomes so unstable and so much foam is generated when it is dispensed through the valves that it can often times cannot be served to patrons. As a result, the beer dispensed through the valve must be discarded as waste resulting in significant erosion of the owner&#39;s profit.  
         [0008]     In the recent past, the purveyors of beer using systems such as that described above have resorted to the inclusion of jacketed heat exchangers in the beer distribution systems just prior to the dispensing valves to chill beer to a low temperature at the down stream end of the trunk lines. The heat exchangers are thermally insulated cast aluminum or aluminum alloy cold plates that incorporate stainless steel tubular beer conducting coils for communicating beer from the downstream end of the trunk lines to the upstream end of the balance lines. Within the cold plates next to the beer conducting coils are a series of coolant re-circulating coils used to remove heat from the beer in a heat exchanger relationship. Typically the coolant used in such systems has been glycol.  
         [0009]     The chilled glycol carries heat away from the cold plate and the beer lines within the cold plate in a continuous manner to lower the temperature of the beer entering the balance lines. If the glycol is chilled to, for example, 28° or 29° F. where it enters the cold plate it can be expected that the beer flowing through the cold plate will be chilled to about 29° F. In such case, the beer as it leaves the cold plate will be conducted to the dispensing valve via the balance lines and will be dispensed at about 29° F. At this temperature, the generation of foam can be minimal if attention and care is applied when the delivery is carried out through the dispensing valve and profits can be preserved.  
         [0010]     A system such as that described above is disclosed in U.S. Pat. No. 5,694,787, entitled “Counter Top Beer Chilling Dispensing Tower,” issued Dec. 9, 1997 and which the present inventor was a co-inventor. The &#39;787 patent described a glycol recirculating coil unit or basket including elongate tubular glycol inlet and outlet tube sections having upstream ends connected to an upstream manifold and downstream ends connected to a downstream manifold.  
         [0011]     Although the system disclosed in the &#39;787 patent provided for a counter-top chilling and dispensing apparatus, it required the use of a glycol reservoir and glycol pump which take up significant space and require proper maintenance for efficient operation.  
         [0012]     A need therefore exists for a tabletop chilled beverage dispensing system which is compact, easy to maintain and does not require the utilization of a glycol reservoir or pump.  
       SUMMARY OF THE INVENTION  
       [0013]     The present invention is directed to a beverage dispensing system for dispensing chilled beverages comprising a housing with one or more beverage inlet connections extending from said housing and one or more beverage dispensers extending from said housing. A beverage cooling system is positioned within said housing, said cooling system comprising a reservoir containing a supply of refrigerant, a cold plate in fluid communication with said refrigerant reservoir wherein the refrigerant lines extend through said cold plate. The cooling system further includes an accumulator, a compressor, a refrigerant condenser and a thermal expansion valve positioned between said refrigerant reservoir and said cold plate to adjust the flow of refrigerant depending upon the temperature of the cold plate, wherein beverage lines extend between said beverage inlet connections and beverage dispensing outlets, said beverage lines passing through said cold plate in a heat exchange relationship with the refrigerant lines.  
         [0014]     An electronic control system is provided for controlling the operation of the beverage cooling system. The electronic control system includes an on/off switch controlling the operation of the beverage dispenser, and a pressure switch controlling the operation of the compressor. A second pressure switch is provided for controlling the beverage evaporator coil, a liquid line coil and a time delay relay. A manual defrost switch is provided for operating a defrost line in the event the cold plate becomes frozen. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a perspective view of the subject invention;  
         [0016]      FIG. 2  is a diagram of the refrigerant cooling system of the subject invention;  
         [0017]      FIG. 3  is a diagram of the electrical control system of the subject invention;  
         [0018]      FIG. 4  is a front view of a beverage line coil basket used in the cold plate in one embodiment of the subject invention; and  
         [0019]      FIG. 5  is an end view of the coil basket shown in  FIG. 4 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     The stand alone, self-contained beverage dispenser  1  of the present invention is shown in  FIG. 1 . Although the subject invention will be described in the context of the beverage to be dispensed being beer, it is to be understood that the invention is not limited to the dispensing of beer. The dispenser of the subject invention may be utilized to chill and dispense any other beverage that may be desired. Beverage dispensing outlets  10   a  and  b  extend out of the front end of housing  14 . The beverage dispensing outlets may be beer taps or other such dispensers known to those skilled in the art. A beverage spill tray  16  is positioned beneath the dispensing outlets  10   a  and  b.    
         [0021]     Beverage dispenser  1  may be mounted on a counter-top or other support surface. Beverage inlet connections  18  (not shown) are provided on the rear of beverage dispenser  1 . The beverage dispenser  1  may be easily installed at the desired location. One need simply run the beverage lines from the beverage supply, i.e. beer keg, to the location for connection to the beverage dispenser unit.  
         [0022]     A refrigerant cooling system  20  is contained within the housing  14  so as to provide a self-contained beverage dispenser which does not require a separate glycol chiller and pump as required in prior art systems.  
         [0023]     The refrigerant cooling system  20  of the subject invention is shown in  FIG. 2 . The cooling system  20  includes receiver  22  which acts as the reservoir for the refrigerant, which is in fluid communication with cold plate  24  via refrigerant line  25 . Refrigerant cooling lines extend through cold plate  24  to cool corresponding beverage lines which also extend through cold plate  24 . The cold plate utilized is a standard cold plate known to those skilled in the art wherein the beverage and refrigerant lines may be wound within the cold plate to increase the length of the lines positioned within said cold plate. The cooling system  20  also includes accumulator  26 , compressor  28  and refrigerant condenser  30 . As shown, refrigerant exits the cold plate  24  and flows to accumulator  26  via refrigerant line  27 . From the accumulator  26 , the refrigerant travels to the compressor  28  via refrigerant line  29 . The refrigerant flows from the compressor  28  to the condenser  30  via refrigerant line  31 .  
         [0024]     The operation of the refrigerant system is described below, in connection with  FIGS. 2 and 3 .  
         [0025]     The refrigerant, in a preferred embodiment type  404   a  is used, enters the compressor  28  at point A as a low pressure gas and is discharged from the compressor as a high pressure gas at point B. It then enters the top of the condenser  30  at point C.  
         [0026]     The refrigerant is cooled in the condenser, exiting it as a high pressure liquid, and passes through a drier  32  (which retains unwanted scale, dirt and moisture) to the liquid line valve  34 , which is open whenever the cold plate  24  is warm enough to require cooling, as determined by a pressure switch PSW 2 .  
         [0027]     The refrigerant, still in a high pressure liquid state, flows through the liquid line valve and enters the receiver tank  22 , which serves as a storage tank for the refrigerant at point D.  
         [0028]     At point E, the refrigerant exits the receiver tank, passes through a sight glass  36  (where bubbles will be observed if the system is low on refrigerant) and encounters the thermal expansion valve  38 .  
         [0029]     A pressure differential is provided across the thermal expansion valve. This valve includes a sensor bulb that measures the degree of superheat of the suction gas exiting the cold plate and expands or contracts to allow the flow of refrigerant to be varied according to need. The refrigerant leaving the thermal expansion valve will be in a low pressure liquid state.  
         [0030]     At the thermal expansion valve  38  there is also a small equalizer tube  39  connected to the outlet of the cold plate  24 . The equalizer tube  38  helps to equalize the pressure between the inlet and outlet side of the cold plate  24 .  
         [0031]     After passing through the thermal expansion valve  38 , the refrigerant enters the cold plate  24  at point G. As the liquid refrigerant enters the cold plate it is subjected to a much lower pressure due to the suction created by the compressor and the pressure drop across the expansion valve. Thus, the refrigerant tends to expand and evaporate. In doing so, the liquid refrigerant absorbs energy (heat) from beverage lines within the cold plate  24 .  
         [0032]     The low pressure gas leaving the cold plate  24  encounters the evaporator valve  40 , whose function is to trap refrigerant in the cold plate, thus helping to keep the cold plate cold while it is absorbing heat from the beverage, i.e. beer in a preferred embodiment. From the evaporator valve  40 , the gas passes into the accumulator  26 , which prevents any slugs of liquid refrigerant from passing directly into the compressor, and continues back to the compressor  28 .  
         [0033]     The thermal expansion valve  38  mentioned above is used instead of a capillary tube in order to provide improved response to the cooling needs of the cold plate  24 .  
         [0034]     The electrical control system  50  is illustrated in  FIG. 3 . Refrigeration on/off switch SW 1  provides power to the entire system by manually depressing the switch. Pressure switch SW 2  monitors the refrigerant pressure in the compressor and cycles of the compressor and condenser fan (not shown) when the pressure drops to a predetermined level, 15 psi in a preferred embodiment, and cycles the compressor and fan back on when the pressure reaches a second predetermined level, 30 psi in a preferred embodiment. The pressure switch PSW 2  normally will be set to monitor refrigerant pressure with a range in the low pressure side of the compressor and cycles off the compressor and condenser fan (not shown) when refrigerant pressure drops to approximately 10 to 20 psi and cycles the compressor back on at approximately 25 to 30 psi. Pressure switch SW 3  monitors refrigerant pressure in the beverage cold plate. When the pressure drops to a predetermined level, approximately 62-65 psi in a preferred embodiment pressure switch SW 3  cycles off the beverage evaporator coil, liquid line solenoid coil and time delay relay TM-1. When the refrigerant pressure rises to a second predetermined level, approximately 72-75 psi in a preferred embodiment, the switch SW 3  cycles on the beverage (beer) evaporator solenoid coil, liquid line solenoid and the time delay relay TM-1. A push-button defrost switch SW 4  is provided to cycle on the hot gas solenoid and cycle off the condenser fan to deliver hot gas to the cold plate should the cold plate become frozen.  
         [0035]     Pressure switch SW 3  responds to the cold plate  24  temperature by reading the pressure of the refrigerant as it is discharged from the cold plate. When the cold plate becomes warm enough the liquid line valve and the evaporator valve open, thereby allowing refrigerant to flow throughout the system. When the cold plate becomes cool enough these valves will close, trapping most refrigerant in the system but allowing gaseous refrigerant to pump from the accumulator into the compressor. Pumping from the accumulator into the compressor extends the life of the compressor by preventing it from having to start against a high pressure differential.  
         [0036]     The time delay relay TM-1 causes the liquid line valve and the evaporator valve to remain open for about 10 seconds after the pressure switch SW 3  tells them to close. It allows some time for the system to stabilize and prevents short cycling of the compressor.  
         [0037]     As shown in  FIG. 2 , defrost valve  42  is installed between the compressor discharge tube and the cold plate inlet. A manually operated momentary switch SW 4  may be deployed to open the defrost valve, which allows high pressure gas from the compressor to be pumped into the cold plate to thaw it, should it freeze up. To prevent damaging the system, the switch should not be held on for more than two minutes.  
         [0038]     The refrigerated beverage system described herein is capable of producing 16 ounce draws on a continual basis at a dispensing of temperature of approximately 29° F. based upon a beverage (beer) inlet temperature of 60° F. and ambient room temperature of 70° F.  
         [0039]     In an alternate embodiment of the invention, the cold plate disclosed in co-pending application Ser. No. 10/633,728, for Coil Basket having the same inventor as the subject invention may be utilized. The disclosure of application Ser. No. 10/633,728 is hereby incorporated by reference in its entirety.  
         [0040]     As show in  FIGS. 4 and 5 , this cold plate utilizes a beverage line coil basket having a plurality of clips or Y-connectors to take a single inlet line and separate it into a plurality of lines within the cold plate and then reduce the plurality of lines back down to a single outlet line. This allows for greater exposure of the beverage to the refrigerant lines within the cold plate to maximize the cooling effect of the cold plate on the beverage.  
         [0041]     The beverage line circulation system shown in isolation in  FIGS. 4 and 5  includes an inlet  50  formed with a connector portion  58  that connects to the beverage line. The inlet  50  further includes a straight pipe portion  60  leading to a cylindrical compartment  65  with a longitudinal axis traverse with the longitudinal axis of the straight pipe portion  60 . The cylindrical compartment  65  has an inlet  70  at a centered position on its top surface where the straight pipe portion  60  is welded, such that beverage conducted through the straight pipe portion  60  enters and fills the cylindrical compartment  65 . The cylindrical compartment  65  includes two outlets  75  on the bottom surface equally spaced from the central inlet location, and each outlet  75  is welded to an intermediate inlet tubing element  80  such that each intermediate inlet tubing element  80  receives an equal distribution of the beverage flow entering the cylindrical compartment  65 . Here, the internal diameter of each intermediate segment  80  is smaller compared with the inner diameter of the straight pipe section  65 , and the pair of intermediate segments  80  are preferably arranged in a parallel orientation having conforming curvatures forming an elbow section  88 . The transition from a single flow through the straight pipe  60  of the inlet  50  to the pair of intermediate segments  80  constitutes a first stage.  
         [0042]     The two intermediate segments  80  at the end of the elbow  88  each terminate in a Y-connector or splitter clip  90  that further divides the flow in each intermediate segment  80  into two smaller, beverage tubes  95 . Again, the outlets  98  of the Y-connector  90  are spaced equal distant from the inlet  94  so as to equalize the flow between the two beverage tubes  95 . It may be necessary to stagger the location of the Y-connecters  90  in the vertical direction as shown in  FIG. 5  in order to minimize the profile of the basket  10 , since the Y-connectors  90  have a width greater than the width of two beverage tubes  95 . Placing the two Y-connectors  90  at the same vertical location could unnecessarily widen the basket  10  at that point, so slightly staggering the position of the Y-connectors provides a more compact configuration. The creation of the four beverage lines  95  from the two intermediate segments  80  comprises the second stage.  
         [0043]     The four beverage tubes  95  are preferably arranged substantially in a common plane as shown in  FIG. 2 , and assimilate into the grouping of the refrigerant conducting tubes. Because the beverage flow has been reduced in two stages, each stage exactly doubling the lines of the previous stage, the resultant flows are equally balanced and each beverage (beer) line is subjected to the same heat exchanging conditions.  
         [0044]     The four tubes  95  conducting the beverage converge into two intermediate outlet segments  115  in the same manner as that described for the inlet stage two. That is, two Y-connectors  120  each consolidate two beverage tubes  95  into an intermediate segment  115  having an inner diameter larger than the inner diameter of the heat exchanger tubes  95 . The two intermediate outlet segments  115  feed to a cylindrical compartment  120  along a bottom surface thereof, where the inlets  118  to the cylindrical compartment  120  are equally spaced from a centrally disposed outlet  125 . The outlet  125  feeds a single straight pipe section  130  leading to beverage outlet  140  of the cold plate with connector portion  142  that carries the end of a beverage line connecting the cold plate with beverage dispenses  10   a, b  shown in  FIG. 1 .  
         [0045]     In describing the above beverage circulating system, the term Y-connector or splitter should be interpreted broadly as any fluid dividing member that has either one inlet line and two outlet lines, or two inlet lines and one outlet. Thus, the cylindrical compartments described with respect to the first stage division and consolidation should be considered Y-connectors for purposes of this application. Likewise, clips or other flow dividers that provide a 2 for 1 flow division or flow consolidation are also properly considered Y-connectors.  
         [0046]     Each stage of the beverage flow subdivision is preferably accompanied by a reduction in the inner diameter of the downstream tubing, but in a preferred embodiment the cross-sectional area of the two downstream tubing is greater than the cross sectional area of the upstream tubing. This increase in the flow capacity of the downstream tubing results in a slowing of the fluid flow through the cold plate leading to more efficient heat exchange conditions. That is, the resident time for the beverage in the cold plate is increased and thus the efficiency of the heat exchange is improved when compared to faster moving beverage flow.  
         [0047]     While the description above discloses two stages of beverage subdivision forming four discrete beverage tubes  95 , the present invention can be expanded to a third stage of subdivision wherein the four beverage tubes are replaced with four transitional tubes that each incorporate a Y-connector at a staggered position with respect to each other to yield eight individual beverage conducting tubes in a manner similar to that described above. Employing eight beverage lines increases the available contact area with the refrigerant conducting lines and can further slow the flow of beverage in the manner described above. However, machining smaller tubes can be more expensive and increase the overall cost of the cold plate. Further, because the walls of the tubing are minimized in the beverage portion of the basket to facilitate heat transfer, smaller tubes may be susceptible to crimping which can block flow and negatively impact heat transfer. Those skilled in the art will recognize that additional stages of subdivision can be provided to allow for additional beverage lines if desired. The ultimate number of beverage lines N can be characterized as N=2 S , where S is the number of stresses and S is greater or equal to 2.  
         [0048]     It is to be understood that the subject invention is not to be limited to the specific embodiment disclosed herein but is to be accorded the full breadth and scope of the appended claims.