US1698810A - Refrigerating apparatus - Google Patents

Description

Jam l5, 1929. 1,698,810

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Patented Jan. 15, 1929.

UNITED STATES y 1,698,810 PATENT OFFICE.

SIDNEY CLABORNE, OF FORT WORTH, TEXAS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO FRIGIDAIRE CORPORATION, A CORPORATION .OF DELAWARE.

REFRIGERATING APPARATUS.

Application led April 30, 1927.' Serial No. 187,928.

This invention relates to mechanical refrigeration and particularly to mechanically refrigerated refrigerating devices for cooling various types of commercial refrigerator '5 Cabinets such as show-case refrigerators.

Onevobject of the invention is to improve the efficiency of the transfer of heat from the air circulating within the cabinet to the refrigerant by preventing the frosting of.

erant more rapidly than heretofore. By l using relatively large metal surfaces in contact with the circulating air the average temperature of the brine may be higher than in the conventional brine tank; consequently there will be less accumulation of frost upon these surfaces during the active periods of the operation of the refrigerating machine, and the metal surfaces will be defrosted during the idle periods. By providing relatively narrow brine passages between the metal heat transfer surfaces, substantially all of the brine is caused to circulate actively so that heat will be conducted from the metal walls to the refrigerant evaporator more rapidly than heretofore, with the result thatthe duration of the active period of the machine 4is reduced.

It is therefore apparent that refrigeration can be obtained more economically 4than heretofore, because the heat transferring.

mediathe metal walls and the brine, are

caused to operate more eiliciently, and because the machine is not required to reduce the pressure upon the refrigerant to the low point necessary heretofore, since the'average brine temperature is higher.

One object of the present invention is to minimize the 'accumulation of frost upon the metal heat-transfer surfaces of the refrigerating device during the active period of operation of the refrigerating machine while maintaining the device in relatively small and compact form. This object is accomplished by providing the m-ain, narrow brine ducts with spur ducts or hollow fins projecting into the air ues of the revfrigerating device. By using spur ducts the average temperature of the brine ma be even higher than in the apparatus in W ich the spur ducts are not provided; consequently .there will be substantially no accumulation of frost upon the metal heattransfer surfaces to hinder the transfer of heat thereto even during the active period of machine operation. Although the heat transfer walls of the main and spur ducts are maintained at a` temperature higher than the freezing point of the moisture which condenses thereon, the temperature of the circulating air will be sufliciently low for satisfactory refrigeration by reason of the presence of the relatively large Ametallic heat-transfer surface maintained free of frost at all times. i

vFurther objects and advantages of the prcsent'invention will be apparent from the following description, reference' being had to the accompanying drawings, wherein a preferred form of embodiment of 'the present invention is clearly shown.

In the drawings:

Fig. l is a vertical lon itudinal sectional view of a show-case re rigerator cabinet equipped with a refrigerating device embodying the presentinvention; the device being shown partly in section on line 1-1 o f Fig. 2.

Fig. 2 is a top view partly broken away, of the device; and

Fig. 3 is a sectional view on the'line 3-'3 of Fig. 2. y

In Fig. l, 2O designates a cabinet havin solid insulating walls 21,22 and 23 an other insulating walls provided by dead air spaces between a plurality of plates of glass 24 and 25. A partition 26 divides the interior of the cabinet into a coolin partment 28 and a food or otherv display compartment 27. l y

The refrigerating device 30 includes a shell brine tank of tin-plated copper or galvanized iron and formed to provide a brine chamber 31 communicating with relatively narrow brine ducts 32, 33, 34, 35 and 36 which surround relatfv'ely large air iues 37 and 38.

^ The chamber 31 is provided with a tightly boiler 40 extends through an opening 4Z in the Ioutside wall of the chamber 3l and is secured by'a flanged collar 43 and a clamping disc 44 forming one end of the boiler. Pipes 46 and 47 conduct refrigerant respectively into and out of the boiler 40. The chamber and ducts should be filled with brine or other low freezing-point liquid up circulate and be cooled. Preferably the top of the boiler should be about one inch below the' level of the brine. It has been found that with a cooling unit located low in a deep tank, the brine above the coil does not cool down to the temperature desired, it remaining above the freezing point even when the rest of the brine may be at or below freezing temperature.

The device is supported above the bottom of the cooling chamber 28 and is spaced from the chamber walls and baffle 26 so that air may circulate freely around the unit as well as through its fines. The combined vsurface of the exposed vertical walls of the unit should at least be equal to the exposed surface of the block of ice which would be required to cool the cabinet. By providing relatively narrow brine ducts and relatively large liue openings, a relatively greater exposed area may easily be provided by a refrigerating device which will occupy a smaller space than the ice block. The space required by the device need be no more than approximataely.two-thirds of the cubical content of the cooling chamber 28, and may be slightly less if necessary to provide at least three inches of space between the walls of the device and the cooling chamber walls so that air may circulate freely about and through the device. The matter of clearance is important, because frosting of the tank and ducts tends to decrease the clearance and might even close it off entirely, preventing free circulation of the air. Unless the air can circulate freely adjacent the walls of the refrigerating device, it can not absorb the heat from the air. For the same reason the liue openings should be at least four inches in width. As an example of construction of one form of the invention,

-if the tank and ducts are made of sheet metal sufficiently thin to permit making the jointsv by lock-seaming and soldering, the width of the ducts need be only one inch or less. If heavier sheet material is required on account of the size of the cooling unit, and the joints must therefore be riveted, the ducts may be two inches wide to allow for introducing riveting tools between the metal sheets forming the ducts. There is no object in making the ducts wider than one inch except to facilitate manufacture. Generally, the brine ducts should be from about one to tWo inches wide and the flues preferably at least four times as wide as the ducts. v

The circulation of air within the cabinet is indicated roughly by the'arrows 50, 5l. 52 and 53. Shelves or other baffles (not shown) may be provided in the food chamber 27 for securing a fairly even distribution of the air circulating therein.

If more than one device is used in a cooling chamber, at least four inches andpreferably six inches should be left between the tank for circulation and to prevent the space from being stopped up with frost.

One of the features of the shell brine tank is the use of such a relatively large metal heat-absorbing surface adjacent which the air may circulate freely, that it is possible to effect satisfoctory refrigeration by brine or other heat transfer medium working at temperatures higher than permissible in brine tanks used heretofore. Although, during the active period of operation Yof the re-' frigerating machine frost may collect upon the metal surfaces, these surfaces will be defrosted during the idle period of the machine. Another feature is the circulation of brine through relatively narrow ducts between the metal heat-absorbing surfaces. Substantially all of the brine which is cooled by the evaporator is caused to circulate actively so that heat will be conducted from the metal walls to the evaporator, more rapidly than heretofore, with the result that the duration of the active period of the refrigerating machine is reduced.

The present invention solves the problem of preventing the accumulation of frost upon the metal surfaces surrounding the air lfilles during the operation of the refrigeraing machine. The main brine ducts 33, 34,

35 and 36 and the chamber 3l are connected with spur ducts or hollow fins 60 and 61 which project, respectively, into flues 37 and 38. The metal, heat-absorbing walls of the main and spur ducts have a greater area exposed tothe air circulating through the fiues than in the cooling unit having no spur ducts. The brine is distributed within the flues so that heat from the air circulating through the iues will be quickly transferred to the brine. Consequently the temperature of the brine may be maintained above the ,freezing point while effecting satisfactory refrigeration. Besides operating as means for transferring heat to the brine, the hollow fins operate as plates upon which the moisture circulating with the air may be condensed without freezing. Since the fins prevent freezing of condensed moisture, the fins may be spaced relatively close within the flues in order to present the maximum heat transfer area, without danger of obstructing air circulation.

In my-copending application Serial No.

187,927, liledApril 30, 1927, I have disscribed lierem.

lDue to more rapid and effective circulation of the brine and to keeping the metal surfaces free of'frost at all times, the average working temperature of. the brine. is higher than heretofore. Thereforethe refrigerating machine may be .operated more economically since it is not necessary to re-l duce the pressure upon the refrigerant in the evaporator to that low point required by apparatus in which the working tempera,- ture of the brine is lower.

The refrigerating device may be provided with horizontal or vertical {iues accordingto the type of refrigerator cabinet with which they are intended to be used. Vertical flues are preferable, owing to the natural tendency of air to descend on being chilled. However, the invention is not limited to cooling units or tanks with vertical flues, as a' refrigerating device with horizontal flues ma be used advantageously in some types ofy show-case cabinet not provided with a baille to separate the food compartment from the cooling compartment'.v

Where the term brine i's used in the specification and claims, it refers to any low freezing point liquid or solution which.v is suitable for transferring heatafrom the heat transfer walls of the device to the evaporator. l

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be undercabinets; for example, a i

stood that other forms mightbe adopted, all 'coming within the scope of the claims which` follow. '-4

What is claimed is as follows; v

. l. Refrigerating apparatus comprising a shell tank having hollow walls adapted to form a narrow chamber and adapted to contain a refrigerating medium, said walls being arranged to form a flue and a heat absorbing member extending into said flue,1said member being hollow and communicating with said chamber.

2. In a refrigeratingdevice, a shell tank .comprising a plurality of vertically extend,-

ing hollow walls arranged to form a chamber ada ted to contain refrigerating medium, sai "-walls being arranged to form a vertically extending iue' and a vertically extending heat absorbing member in thermal contact with a wall of said tank and extending into said flue, v,said member being hollowand communicating with said chamber.

3. In a refrigerating apparatus having chambers adapted to contain refrigerating medium air flues formed by the walls of said chambers, said air ilues belng providedl` with i hollow heat absorbing members integral and communicating with -said ducts, and a cooling unit disposed Within-the body portion for cooling said brine.

In testimony whereof AI hereto aflx my y SIDNEY CLAIBORNE,

signature.

eat'absorbing members integral and 80

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