US1993325A - Refrigerating device for displaying and preserving perishable goods such as foods, delicacies and the like - Google Patents

Description

March 5, 1935. w. HAMEL TING DEVICE FOR DISPLAYING AND PRESERVING PER 1,993,325 ISHABLE REFRIGERA GOODS SUCH AS FOODS, DELICACIES, AND THE LIKE Filed Oct. 4, 1933 Patented Mar. 1935 means UNlTED STATES PATENT OFFICE REFRIGEBATING DEVICE FOR DISPLAYING AND PBESEBVING PEBISHABLE GOODS 15.11%): AS FOODS, DELICACIES AND THE Wilhelm Hamel, Amsterdam, Netherlands, as-

signor to Johan Robert Carp, Amsterdam, Netherlands, and Arthur Abraham Ruben,

Berlin-Charlottenburg, Germany Application October 4, 1933, Serial No. 692,211

In Great Britain September 18, 1933 8 Claims. (01. 62-895) The invention relates to a refrigerating device for displaying and preserving perishable goods such as foods, delicacies and the like, but which may of course be used also for other cooling purposes. Particularly the invention relates to devices comprising a surface disposed freely in open air, on which surface the goods to be cooled are fully exposed to view and which may be of any convenient form, the said surface constituting the member of a refrigerating apparatus that gives 01f the cold, the capacity of said refrigerating apparatus preferably being so great that the temperature of the surface can be kept so low that due to the humidity of the air white frost is formed thereon, the cooling or the white frosted area being sharply restricted by means of suitable insulation. In a usual construction hereof the cooling surface on which the goods to be cooled are to be placed is surrounded by a frame which restricts the cooling or the white frostedarea and which is so well insulated from the surface that it will never attain a temperature which is as low as that of the surface or which is so low that white frost is formed on it. Preferably this frame is made of metal which can easily assume the temperature of the surrounding air.

In apparatus of the kind referred to the cooled e. g. the white frosted surface may be used directly for instance as a table, display board, or the like. The appearance of such a surface is rendered particularly attractive if white frost is formed thereon, while the cooling effect can be sufliciently powerful and the use of the apparatus is not associated with a single difficulty.

In practice it has been shown to be very well possible to insulate theframe surrounding the white frosted area so well from the cooling surface that the frame is never covered by white frost itself, when the apparatus is in use. Thus the white frosted area is always sharply restricted .by the non-frosted frame which results in the beautiful appearance of the device. It has now appeared, however, that if the atmospl ere is very humid, that is when the air contains a great quantity of water, this water sometimes condenses on the frame. This fact will be understood because the cold which is transmitted from the cooling surface through the insulation to the frame is given off to the surrounding air and the frame has a temperature which is a little under that of the surrounding air. The temperature of the frame may, however, be below the dew point of the air and thus water will condense on the frame. This is injurious to the beautiful appearance of the whole apparatus, as

the frame, when it is made for example of a bright metal, such as chromium, will look very beautiful only if it is dry.

The improvement according to this invention, therefore, resides in the provision of means for so heating the frame that deposition thereon of moisture from the atmosphere is prevented or that such moisture is removed by evaporation without influencing the white frost on the cooling surface. It will be understood that moisture will be deposited from a relatively humid atmosphere upon objects which are colder than the. surrounding air, and that a deposition of moisture upon the frame can be prevented by heating the frame to approximately the room temperature.

Heating of the frame can be done in many ways. In the first place it is possible to do it electrically by means of electrical resistances. Furthermore, it is possible to heat the frame by means of the compressed gaseous refrigerating medium, such as S02, which has a considerable temperature when leaving the compressor of the refrigerating plant belonging to the. cooling device, and before being cooled down in the ordinary manner.

In the drawing a device according to the invention and some details of forms of construction are illustrated by way of example.

Fig. 1 is a diagrammatical representation of a cooling apparatus according to the invention which operates with a compressor and in which the frame is electrically heated.

Fig. 2 shows a cross section of a construction of the frame surrounding the cooling surface and restricting the white frosted area, a heating element being provided in the form of a special electric cable.

Fig. 3 shows the same construction of insulated frame, but another manner of providing an electric heating wire.

Fig. 4 also shows the same cross section, but comprising a tube for guiding the compressed warm refrigerating medium.

In Fig. 1, 1 is the electro-motor, which drives a compressor 3 by means of a belt transmission 2. The motor 1 also directly drives a fan 4 which is arranged opposite an air cooled condenser 5. If necessary, this air cooled condenser may of .course be replaced by a water cooled condenser,

in which case the fan 4 may be omitted. The gas (S02, NH: or the like), compressed by the compressor, passes through the piping 6 into the-cooler 5, from there passes through the piping '7 and then arrives in the expansion valve (throttling nozzle or the like) 8. The compressed refrigerhereinafter.

ant is liquefied in the condenser 5 and expands in the expansion valve 8 in known manner, thus producing cold which is given off to the plate 9. The expansion valve 8 may, of course, be constructed in various manners and may, for instance, also be self-regulating. In this case the adjustment can-be controlled either by the gas pressure or by the temperature of plate 9. After the working medium has given off its cold, it flows through the piping 10 to the suction side of the compressor. The piping 10 is of such length, if necessary arranged in one or more coils 11, that the working medium is always able, even when the temperature of the surroundings is low, to give 011 its excessive cold to the surrounding air, (when this cannot be done completely by the plate 9) before it again reaches the compressor 3. At the same time it is thus also possible to give the plate an inclined position, for instance, because the pipes can then yield suificiently to permit it.

In Fig. 1 the plate 9 is surrounded by a frame 12 which is insulated from the plate and thus cannot assume a low temperature.

The piping coming from the expansion valve 8 may be arranged under the plate 9 in the form of pipe coils, passages or channels in the interior of the plate 9 or the like. It is recommendable to combine the points where the said piping enters and leaves the plate structure in such a manner that only one opening ought to be made in the table. It is much easier then to make the tubes fitting airtight in the opening, which is very necessary as will, be pointed out It is, of course, important that the pipe coil under the plate 9 should be in good thermally conductive connection with the said plate 9. This can be done e. g. by soldering or welding (for example spot welding) when the pipe coil is made as a separate unit. If necessary, however, the pipe coil may also be integral with the plate 9, so that so to speak a hollow plate is obtained and the refrigerating medium circulates directly in the plate itself.

It is evident that it is also possible by means of the refrigerating plant to cool a solution of sodium chloride or the like to, for instance, 15 C. below zero, and then cause this solution to run along the bottom of the plate 9 or to circulate therein. There is therefore a certain accumulation of cold available, and it is then also possible to fit the plate 9 on already existing refrigerating plants. Moreover, the latter is possible in any case.

In Fig. 1 the plate structure 9, 12 is provided with a cord 31 and a plug 32 for switching on the electrical heating of the frame 12.

Also in Figs. 2, 3 and 4 the plate 9 forms the cooling surface intended to be covered with white frost and being cooled by means of the pipe coils 22 soldered to the underside of it. The plate 9 is surrounded by a frame 12 preferably made of metal, for example of brass coated with chromium. On the upper side the plate 9 is surrounded by a strip of rubber or the like 16 (in some cases, for example, also by a rubber tube filled with cork) against which the plate 9 is pressed by means of the screws 17. Immediately against the under side of the plate 9 there are disposed small strips 18 of cork, supported by small strips 19. of wood, against which small plates 20 of fibre, bakelite or the like are pressed. The screws 1'7 co-operate with nuts 21 likewise made of insulating material such as fibre or the like. Those nuts 21 are engaged in a groove in the frame 12 in which they can slide endwise. In this manner the plate 9 can be exactly adjusted and engaged waterand air-tight while a very great resistance is offered to the transmission of heat between the plates 9 and the frame 12. The resistance is still further increased in that the plate 9 is allowed to come into contact with the rubber 16 and the cork 18 only along a very narrow edge.

The space below the plate 9 and, therefore, about the pipecoil 22 is filled with an insulating mass 23, for example cork, the joints of which are carefully filled up with finer insulating material such as cork powder, slag wool or the like.

Furthermore, the whole is closed by a plate 24 so as to form an airand water-tight unit. It is of importance, of course, that no air can enter into the space between the plates 9 and 24 because if there should arise some circulation of air white frost would be formed there also and this would decrease the cooling action at the upper side considerably, while as well a lot of condensation water could be formed within the insulating mass.

In Fig. 2 there is located at the inner side of the frame, thus hidden from view, an electric cable, 25 which e. g. is connected to the cord 31 in Fig. 1. This cable may be, for example, a lead covered cable comprising a core of asbestos on which a wire is helically wound, the said wire being made of a high resistant metal. This heating element is surrounded by specially prepared rubber and then covered with the lead. The cable also could be formed, of course, by a simple straight wire, embedded in the specially prepared rubber and covered by the lead. Dependent on the electric voltage used, the temperature 01' the frame can be regulated. Also electric resistances, switches or the like can be provided to control the heating of the frame or the cord 31 may be connected to the circuit of the motor 1, so that heating of the frame only is switched on when this motor is running.

It is not necessary, moreover, to provide the heating cable 25 or the like along the whole length of the frame and often it is sufficient to heat only one part of the frame which it is particularly desired should not become wetted. In Fig. 1 it is shown furthermore how the cable 25 is fastened by means of a strip 26 of insulating material.

In Fig. 3 is shown how a simple electric heating wire 30 can be enclosed between two strips of asbestos 27 and 28 for the purpose of the invention.

In Fig. 4 a tube 29 adapted to be connected to the outlet of the compressor of the refrigerating plant is soldered to the inner side of the frame. In this event the piping 6 in Fig. 1 immediately after leaving the compressor 3 is connected to the tube 29 in Fig. 4, the outlet of which thereafter is connected to the cooler 5, or directly to the valve 8 if the refrigerating medium after having passed the tube 29 and being cooled down therein, needs no further cooling in a cooler such as 5.

It will be understood that at all events it is not permitted that the heat developed by the means described above be so great that white frost on the surface of the plate 9 is influenced.

A special advantage of the heating elements above described is in the following:

If by some reason, say accidentally, humidity has deposited within the plate unit, so that, for example, the insulating mass 23 contains water, it is possible to remove this water by evaporation by heating the frame and thus the plate by the heating means described above. Preferably cooling is interrupted then, that is to say the refrigerating machine is stopped and the snow layer removed. It is also possible to heat more strongly in this event, for example by increasing the electric voltage in apparatus as shown in Figs. 2 and 3.

It is not necessary, of course, to heat the frame for the reasons mentioned above by means arranged internally of the frame (electric resistance wires, compressed medium piping). Heating may also occur by external means, e. g. there may be arranged electric or other lamps along the outside of the frame forthis purpose. Besides giving under circumstances a very decorative effect, the radiating or direct heat of these lamps may be used for heating the frame.

What I claim is:-

1. In a refrigerated device for displaying and preserving perishable goods, a cooling member having its upper surface freely exposed in open air and adapted to have the goods placed thereon, refrigerating means for cooling said member to below that temperature at which moisture will be deposited on said member from air circulating over the same, a frame surrounding said member to define the limits of the exposed cooling surface thereof, heat insulating means between said frame and cooling member, and means for heating said frame to prevent the deposition of moisture thereon from the atmosphere.

2. In a refrigerated device for displaying and preserving perishable goods, a cooling member having its upper surface freely exposed in open air and adapted to have the goods placed thereon, refrigerating means for cooling said member, a heat-conducting frame surrounding said member to define the limits of the exposed cooling surface thereof, heat insulating means between said frame and cooling member, and heating means concealed from view within said frame for heating the latter to prevent the deposition of moisture thereon from the atmosphere.

3. In a refrigerated device for displaying and preserving perishable goods, a cooling member having its upper surface freely exposed in open air and adapted to have the goods placed thereon, refrigerating means for cooling said membeer to maintain a deposit of frost thereon by moisture withdrawn from air circulating over said cooling member, a frame surrounding said member to define the limits of the frosted area thereof, heat insulating means between said frame and cooling member, and electrical heating means concealed from view within said frame for heating the latter to prevent the deposition of moisture thereon from the atmosphere.

4. In a refrigerated device for displaying and preserving perishable goods, a cooling member having its upper surface freely exposed in open air and adapted to have the goods placed thereon, refrigerating means for cooling said member, a metallic frame surrounding said member to define the limits of the exposed cooling surface thereof, heat insulating means between said frame and cooling member, and insulated cables containing electrical heating wires within said frame and extending along the inner side thereof.

5. In a refrigerated device for displaying and preserving perishable goods, a cooling member having its upper surface freely exposed in open air and adapted to have the goods placed thereon, refrigerating means for cooling said member, a metallic frame surrounding said member to define the limits of the exposed cooling surface thereof, heat insulating means between said frame and cooling member, electric heating wires within said frame, and a lead covering enclosing and insulated from said wires, said heating wires extending along and with the lead covering thereof adjacent the inner side of said frame.

6. In a refrigerated device for displaying and preserving perishable goods, a cooling member having its upper surface freely exposed in open air and adapted to have the goods placed thereon, refrigerating means including a compressor and condenser for cooling said cooling member by the expansion of a gaseous refrigerating medium, said refrigerating means being of sufficient capacity to maintain a coating of white frost on said cooling member by moisture withdrawn from air circulating over the same, a frame surrounding said cooling member to define the limits of the exposed cooling surface thereof, thermal insulation between said frame and cooling member, and means for passing the compressed gases from said compressor through said frame, thereby to heat the latter to a temperature above the dew point of the surrounding air.

7. A device for displaying and preserving perishable goods comprising a display surface freely exposed in open air, means for refrigerating said surface, a metallic frame surrounding said surface to define the exposed cooling portion upon which goods may be placed, thermal insulation between said frame and surface, and heating means concealed from view within said frame to prevent the formation of dew upon the metallic frame.

8. In a device for the preservation and display of perishable goods, the combination with a substantially air-tight body comprising a frame, a plate forming the upper surface of the body, refrigerating conduits within the body and in heattransfer relationship to said plate, a layer of heat insulating material within said frame beneath said plate and adjacent said conduits, and means insulating said frame from said plate to prevent cooling of said frame low enough for the deposition of hoar frost thereon, of refrigerating apparatus for supplying a refrigerating medium to said conduits in quantity sufficient to maintain a coating of white frost upon said plate by moisture withdrawn from air circulating over the same, and heating means within said body to evaporate therefrom any moisture which may collect within the same and to heat the frame to a temperature above that at which moisture may deposit upon the same from the surrounding air.

WILHELM HAMIEL.

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