A portion of the disclosure of this patent document contains material which is subject to copyright or mask work protection. The copyright or mask work owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright or mask work rights whatsoever.
This disclosure relates to the use of new refrigerants in vending machines.
Governments across the globe are limiting the refrigerants that are potentially harmful to the earth. As a result, companies are starting to use r290 (propane) as a refrigerant including vending machine manufacturers. However, a problem with r290 is that it's flammable.
Vending machines offer unattended sales of commodities such as snacks, canned or bottled beverages, or any of a variety of other articles. Frequently, these vended articles need to be kept cold or refrigerated and internal coils with refrigerants have traditionally been used to accomplish that cooling.
In the global transition away from high-global warming potential (GWP) hydrofluorocarbon (HFC) refrigerants, R-290 (aka propane) has emerged as an increasingly viable alternative.
Offering excellent thermodynamic properties and a very low GWP (GWP=3), this natural hydrocarbon refrigerant has potentially widespread uses in commercial refrigeration. But with its classification as an A3 (flammable) refrigerant, R-290's inherent safety concerns have always been a barrier to wider adoption.
Originally introduced in the early 1900s, R-290 was a commonly used refrigerant until it was replaced by chlorofluorocarbons (CFCs) in the 1930s. Since the 2000s, global regulatory actions to phase down high-GWP HFCs have led to a resurgence in the use of R-290 in smaller, self-contained applications.
Because R-290 is more combustible than HFCs special use considerations for using it in refrigeration applications can include use of sealed, gas tight, or fire and explosion proof electrical components, spark free fan motors, and ventilation and leak sensors or detectors.
In addition, there are UL specifications for refrigerated vending machines which have been published under a designation UL-541. One part of what is defined as being a protected system under subsection SA2.6 of Supplement SA states that any part of the refrigeration system located inside a vender, and in which the refrigerant is contained, in an enclosure which itself is contained within a separate protective enclosure. If leakage from the containing enclosure occurs, the leaked refrigerant is contained within the separate protective enclosure and the vender will not function as in normal use. The protective enclosure contains no joints within the vender.
These regulations do not specify specifically what any protective enclosure should be, nor its design.
The invention is better understood by reading the following detailed description with reference to the accompanying drawings in which:
To gain a better understanding of the invention, a preferred embodiment will now be described in detail. Frequent reference will be made to the drawings. Reference numerals or letters will be used throughout to indicate certain parts or locations in the drawings. The same reference numerals or letters will be used to indicate the same parts and locations throughout the drawings, unless otherwise indicated.
One preferred embodiment will now be described with respect to a vending machine refrigeration system. The scale of the embodiment, therefore, is to be understood with respect to this type of article and environment. It is to be understood as well, however, that the invention is applicable to other articles and its scale can vary accordingly.
Turning to
Since this particular vending machine is refrigerated, the outer walls are each insulated by sheets of insulation 40 as shown in
The internal portion 50 of the refrigeration system is comprised of an outer frame 52, shown in
Additional structural details of the internal evaporator assembly a simplified version of the approach is show in in
Also shown in
The space 66 between tubes 62 and 64 can be left open to provide a fail-safe way to capture therein any leaks of the R290 refrigerant from the inner tube 64 to prevent any leaking of the flammable R290 refrigerant into the vending machine and from potentially resulting in a fire within the vending machine. However, as suggested above, it is preferred to provide a good conductor material within that space 66, or some other heat exchange media within the space 66 which can be, for example, a solid, liquid or a gas. Ideally, a great media material would be one that could be installed as a liquid through fill hole 72 and then become more solid after the inner space 66 is filled so there would not be any leakage. Among the preferred media material is ethylene glycol, propylene, or silicone. To achieve the desired level of cooling within the interior of the vending machine the inner tube 64 should have an inner volume of about 24 cubic inches and the outer tube 62 should have a surface area of about 1900 square inches. The surface area of the outer tube 62 can be greatly reduced if fins are added such as those shown in
The interior portion of the heat exchanger includes the evaporator coil assembly 56 as shown in more detail in
The half section 82 are preferably made from aluminum, but other materials could also be used such as steel, copper, or other desired material.
Referring again to
It should be understood that the plurality of half or mating blocks 82 could be formed as multiple pairs, as shown, or from two appropriately sized opposing units, to accommodate the desired number of coils in the tubing so that in either case opposing structures would encase a set of coils from opposing sides of the coiled tubing. Alternatively, material encasing each of the separate opposing sides of the dual walled tubing could be provided in the form of a heat removing structure otherwise formed there around, or the whole of the coiled double walled tubing could be encased within a molded structure formed with suitable evaporative heat removing surfaces.
This exterior section 100 includes an outer cover 102 that has a bottom structure including air inlet perforations 104, and similarly perforated areas 106 at the top of the outer cover 102. These perforated areas permit ambient air to flow in from the bottom and exit the top due to air flow induced by an air circulation condenser fan 110 that is preferably mounted to an angled plate 112 within the exterior portion 100.
As was shown in
In operation, the refrigerant, as a low-pressure gas, passes through a compressor 122, mounted on a shelf 124 that is itself secured within the exterior portion 100 or directly to rear wall 20. The refrigerant flows from compressor 122 as a hot, high-pressure gas that is routed to and through the condenser coil assembly 120 which cools the high-pressure gas by which it becomes a high-pressure liquid. That high-pressure liquid is routed through a metering device, for example an expansion valve 76, causing a downstream pressure drop transforming the high-pressure liquid into a low pressure gas. The low-pressure gas then flows through the evaporator apparatus 80 within the vending machine 10 during which the refrigerant absorbs heat from within the vending machines interior. The refrigerant then flows as warmer, low-pressure gas passes back to compressor 122 for a continuation of the cycle.
When introducing elements of various aspects of the present invention or embodiments thereof, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements, unless stated otherwise. The terms “comprising,” “including” and “having,” and their derivatives, are intended to be open-ended terms that specify the presence of the stated features, elements, components, groups, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, and/or steps and mean that there may be additional features, elements, components, groups, and/or steps other than those listed. Moreover, the use of “top” and “bottom,” “front” and “rear,” “above,” and “below” and variations thereof and other terms of orientation are made for convenience, but does not require any particular orientation of the components. The terms of degree such as “substantially,” “about” and “approximate,” and any derivatives, as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. For example, these terms can be construed as including a deviation of at least +/−5% of the modified term if this deviation would not negate the meaning of the word it modifies.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.