Heretofore, it is known, in for example, a beverage or ice unit or dispenser to have a freeze portion or chamber provided with compressed refrigerant which is discharged from a compressor, then sent through a condenser, and an expansion valve to provide cold refrigerant to form ice or semi-frozen beverage in the freeze portions or chambers. For packaging reasons and/or ease of replacement, the freeze portion or chamber is part of a “foam pack.” That is, one or more freeze portions or chambers is encircled or surrounded by refrigerant lines, encased in foam insulation, and generally further enclosing the freeze chamber and its refrigeration lines and surrounding foam in a protective metal box or casing. The latter protective casing is generally formed of non-rusting material, such as aluminum or stainless steel. While such foam pack freeze chambers are successful, they have had the disadvantage of causing moisture and humidity to collect on the cold foam pack, and particularly its protective outer metal surface. Thus, humidity due to the low temperature may collect into droplets which can fall from the foam pack upon other components, such as electrical components, causing damage to such components, and can require additional maintenance. The condensate can also cause corrosion and loss of electrical continuity, shorting, component damage and water collecting on the floor. Typically, attempts to manage condensate have required a drip pan, a drain line and additional maintenance of the same.
A rule of thumb in the refrigeration is that the condenser is responsible for removing the heat off the hot gas refrigerant (coming from the compressor), while the liquid leaving the condenser can be sub-cooled further either in a liquid to suction heat exchanger or through external means. While it is known to use the hot gas from the compressor, as for example, in residential refrigerators to keep the surfaces around the freezer door warm and prevent freezing of the magnetic seals, usually this is just a small diverted refrigerant flow and that the capacity/mass flow of this refrigeration door system is typically small, hence needs to use the highest enthalpy media (hot gas).
While using hot gas from the compressor and before the condenser has the advantage that the gas is in its highest energy state (highest enthalpy) and temperature, it also has disadvantages. If, for example, such hot gas was used in the dispenser foam pack as there is limited surface area (in the foam pack to dissipate heat) for the full capacity/mass flow of the refrigeration system, in such instance, too much heat would be passed through the foam pack. Therefore, some of the excess heat would heat the evaporator coils and reduce performance, and is absolutely not desired.
The present invention provides an apparatus and method for solving the above difficulties, while further increasing the refrigeration efficiency and cooling capacity of the unit or dispenser, be it ice, beverage, frozen carbonated beverage (FCB), or frozen uncarbonated beverage (FUB) dispensers. Instead of hot gas, in the present invention, warm liquid refrigerant after the condenser is used. This has the advantage of lower energy state (lower enthalpy and temperature). Almost all of the heat will be dissipated to keep the foam pack bottom warm to prevent condensation. Thus, the heat will not reach the evaporator coils, but instead, will also further cool the liquid refrigerant before its expansion to increase cooling capacity. The present invention comprises a freeze chamber (including its surrounding refrigeration lines), enclosed in insulation, surrounded by a protective metal casing and supplied with compressed liquid refrigerant, from a compressor and after the condenser, but before the evaporator, and more particularly through an auxiliary coil or sub-cooler located after the compressor and condenser but before an expansion means or valve supplying refrigerant to the sub-cooler. The sub-cooler is located or included in a portion of the condenser discharge line before the expansion means or valve and is preferably located in a lower portion of the foam pack to further cool the compressed or liquid refrigeration before its expansion and to also transfer heat from the liquid refrigerant to the protective enclosure, usually metal, of the foam pack to prevent or reduce condensation of humidity on the same. Thus, with the present invention, the advantages of eliminating or reducing condensation and associated problems and increased cooling capacity are achieved.
The method of the present invention comprises the steps of providing a dispenser with a compressor, condenser and freeze chamber surrounded by insulation and, usually a protective metal, enclosure, and an expansion means, comprising the steps of providing an auxiliary coil or sub-cooler adjacent the freeze chamber, supplying the sub-cooler with compressed liquid refrigeration from the condenser, locating said sub-cooler upstream of said expansion means, using the heat from liquid refrigerant in the sub-cooler to reduce or prevent condensation on the foam pack and its protective casing, and using the heat give up to the freeze chamber to lower the temperature of the liquid refrigerant provided to the expansion means, and then subsequently to the freeze chamber. The heat given up in the sub-cooler from the compressed liquid refrigerant prior to its expansion reduces or eliminates condensation and lowers the temperature of the liquid refrigerant going into the expansion valve to cause increased cooling in the freeze chamber.
The primary function of the sub-cooler or auxiliary coil is to keep the bottom of the foam pack warm (its temperature above the dew point). As a desirable side effect, we also get a small amount of sub-cooling of the liquid refrigerant in the sub-cooler after it leaves the condenser.
It is an object of the present invention to provide a method and apparatus for reducing condensation from the freeze chambers of an ice and/or beverage dispenser.
Yet another object of the present invention is to provide a method and apparatus for increasing the freeze chamber cooling capacity of the unit it is incorporated therein.
Still another object of the present invention is a method and apparatus that provides a sub-cooler coil between a condenser and expansion means located adjacent the freeze chamber.
These and other objects of the present invention will become apparent from the following written description and the accompanying figures of the drawing wherein in:
Referring to
All these components are mounted to a frame 42 and provided with FCB output face plates 51 and 43 having FCB output valves 46 and 48. As is shown the compressor 14 is driven by a motor 48′. The compressor 14 is supplied by a refrigerant gas line 52, from an accumulator 54. The accumulator 54, in turn, is supplied with discharged cooled gas from the evaporator 28, and in this instance its two freeze chambers 32 and 34. It should be understood that there could be fewer or more freeze chambers.
From the compressor high pressure and temperature gas refrigerant is supplied by a line 60 to a pair of tees 62 and 64, which provides outputs to hot gas (say 120° F. to 160° F. or even and up to and including 240° F.) by pass valves 65 and 67 and the inlet for condenser 18. Refrigerant is cooled in the condenser and becomes a warm liquid (say about 95° F. to 125° F. or even and up to and including about 135° F.). From there this refrigerant is sent via line 66 to the auxiliary sub-cooler 68 of the present invention. The sub-cooler 68, as will be further made clear below, is located in the foam pack containing the evaporator 28 and its freeze chambers 32 and 34.
From the sub-cooler 68, the refrigerant flow is provided, via a tee 72, to two branches 74 and 76 to expansion means 26, in this instance separate expansion valves 36 and 38, preferably one for each of the freeze chamber 32 and 34. This construction provides for independent operation of each freeze chamber. That is each freeze chamber 32 or 34 can independently be provided with condensed refrigerant from its respective expansion valve 36 or 38 for cooling. Alternatively, hot compressed refrigerant gas from the compressor can be supplied via hot gas by pass valves 65 and 67 and their respective lines which connect to the respective freeze chambers 32 and 34, below or downstream of the respective then closed expansion valves 36 and 38 for defrosting or heating one or the other or both the freeze chambers. In the latter case this hot gas is not sent through the auxiliary sub-cooling coil 68.
From the freeze chamber 32 and 34, the cooled refrigerant gas (or heated gas) can be provided and flows through to the refrigerant lines 90 and 92 surrounding the freeze chambers 32 and 34.
In normal operation, the expanded and warmed gases are then collected and provided back to the accumulator 54 and then to the compressor 14 to be recycled and reused.
Referring to
Referring to
Referring to
With the dispenser described, the refrigeration system could use R404A refrigerant for maximum capacity and efficiency.
The dispenser would have typical compressor cooling capacity of about 14200 Btu/hr, but could range from about 11500 to 16700 Btu/hr or even up to and including about 19100 Btu/hr. See
Typical refrigerant mass flow through the system (including through the sub-cooler coil) is about 310 lbm/hr, but could range from about 300 to 320 lbm/hr or even up to and including about 350 lbm/hr.
Typical heat rejection from the condenser coil is about 24400 Btu/hr, but could range from about 23800 to 25200 Btu/hr. or even up to and including about 27100 Btu/hr.
The sub-cooler coil diameter is ⅜ inch, (but ¼ to ½ inch could be used) and coil length mainly in contact with the sheet metal bottom is about 80 inches, but could be say from about 60 to 100 inches or even up to and including about 150 inches.
Typical heat rejection from sub-cooler coil is about 620 Btu/hr, but could range from about 600 to 640 Btu/hr or even up to and including about 1200 Btu/hr.
The ratio between sub-cooler heat rejection and condenser coil heat rejection, “heat rejection ratio” is about 2.5% (but could be up to and including about 4%) throughout the operating range of the dispenser. For example: (1−((24400−620)/24400))*100=2.5%. One would want to appropriately size the sub-cooler coil for if it is too big requires more tubing, is difficult to package, also requires larger refrigeration charge, therefore the cost is higher, and if its too small the heat to keep the foam pack bottom warm may be insufficient, therefore failing to eliminate/reduce condensation under all operating conditions.
The frozen beverage dispenser sub-cooler is optimized to provide an even temperature distribution to and/or on the bottom surface of the foam pack 112 (
If the dispenser is operating in a tropical environment the ambient temperature could be 90° F. (line 130) and the relative humidity is 90% and the dew point for this condition is 86.5° F. (line 132). In this case the foam pack with the sub-cooler coil of the present invention will not form condensation, because the bottom of the foam pack is warmer (97° F. to 106° F.) than the ambient 90° F. temperature (line 130) therefore it will always be warmer than the dew point temperature (line 132). However, the form pack without the sub-cooler would form water condensation and would sweat because the surface temperature (85° F. to 83° F.) (line 146) would be lower than the dew point (86.5° F.) (line 132).
As noted the supply of compressed condensed liquid to the foam pack 112 can prevent formulation of condensation on the exterior of the foam pack, while the additional cooling provided to the refrigerant liquid enhances the cooling in the freeze chamber.
While the present invention shows the sub-cool internally, there are other ways to accomplish the invention objectives, such as using a coil attached to the outside sheet metal surface of the foam pack. The present invention reveals an economical, energy efficient well designed and manufacturable method.
While the preferred embodiment has been disclosed and illustrated, it should be understood that the equivalent elements and steps of those set forth in the following claims.
This is a United States Non-Provisional, Continuation-in-Part patent application claiming the benefit of and the priority of U.S. Provisional patent application No. 61/003,279, filed Nov. 15, 2007, and relates to a refrigerated ice or beverage dispenser, and more particularly to an auxiliary sub-cooler in the refrigerant line after the condenser but before the refrigerant expansion means, provided with condensed liquid refrigerant used to heat the enclosure for a frozen beverage freeze chamber to reduce or eliminate condensation on the enclosure while also increasing freeze chamber cooling capacity.
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Number | Date | Country | |
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61003279 | Nov 2007 | US |