US2463835A - Refrigerator having an air-pump circuit - Google Patents

Description

mah w49., v. WARREN, 'E

REFRIQERATOR HAVING AN AIR PUMP CIRCUIT Filed Jan. s, 1947 Patented Mar. 8, 1949 REFRIGERATOR `HAVIN G AN AIR-PUMP CIRCUIT Virgil P. Warren, II, Atlanta, Ga., assignor to The Warren Company, Incorporated, Atlanta,

Application January 3, 1947, Serial No. 720,048

2 Claims. 1

This invention relates -to a cold storage refrigerator or air flow cooler unit and more particularly to the type which is usually referred to as reach-in or walk-in coolers. It is particularly adapted for the open storage of unwrapped or unpackaged meat.

In the art of refrigeration of meats, and especially-in the type of coolers herein contemplated, there has been a common difficulty resulting fromrthe accumulation of warm bodies of air in the tops of the coolers which gave rise to undesirable temperature conditions around the upper portions of the stored meat, as well as so-called dead spots in the circulation of air streams in the cooler. Furthermore, if the circulating air stream is allowed to impinge upon the meat itself, a de-humidifying action takes place, resulting in the meat being given a dark appearance, which reduces its salability. In order to provide a more uniform flow of air throughout the cooled storage space, it is desirable to arrange the cooling coils so that the air will not be in contact with the cooling coils long enough for frost to form thereon. The de-humidcation of the meat and the formation of frost on the coils is reduced if the difference in temperature between the air approaching and passing from the coils is kept to a minimum. In other words, instead of sharply reducing the temperature of the air circulating past the coil, I have found that it is preferable to reduce the temperature of all of the air in the storage chamber by relying primarily on convection currents rather than sharply chilling the circulated air and then relying on conduction between the strata of air to eiect cooling of the adjacent air. I accomplish this result by reducing the temperature of the circulated air a lesser amount and continuously circulating a larger volume of air at lower velocities.

The correlation between the actual and relative temperature of the air and cooling coils, and the volume and velocity of the air is such that the air immediately in contact with the cooling coils is not so -chilled as to give up any substantial amount of moisture upon contact with the coils. In this way, the frost does not form on the coils, and consequently the circulating air is not deprived oi moisture, thus minimizing the de-humidication of the meat in the cold storage chamber.

In PatentNo. 2,251,725, issued to Virgil P. Warren, air cooling unit directed to overcoming the problems mentioned above is disclosed. However, I have discovered that even better results can be accomplished by arranging the cooling unit 2 against the upper part or ceiling of the cooler storage chamber in accord-ance with the present invention. An air-flow cooler according to the present invention comprises a cooling uni-t which is located in the space and which wouldV normally be occupied by the upper layer of the warmest air in the storage chamber. 'Ihe air,` intake for the cooling unit is arranged -adjacent the center of the cooling unit and the discharge of the cooled air is at the opposite end-s of the unit adjacent the side walls of the storage chamber, thus reducing the time during which the air is in contact with the cooling unit at any one traverse of the air-now and so that the circulation of the air will be facilitated by gravity ow. The forced draft from the fan produces an induced draft of the air so that as a result all of the airwithin the storage chamber is eventually circulated by the fan over the cooling coils. Since the cooling u nit is arranged immediately adjacent the upper part of the storage chamber, the air will be coolest where it would normally be the warmest, and accordingly, as the air is discharged from adjacent the cooling unit and circulates towards the bottom of the chamber under action of gravity, it will spread out and drift toward the center so that there is a substantially uniform temperature and uniform flow ofithe air maintained throughout the space in the storage chamber, thus avoiding local drafts and consequent discoloration of the meat. In effect, the present invention relies upon a curtain of slow moving air to insulate air in the storage chamber from the temperature of the outside air,` rather than relying upon the sharp reduction of temperature of localized areas of air inside of the storage chamber to eiect cooling of the inside air through conduction between the adjacent areas of air.

Accordingly, one of the major objects of the present invention is the provision of an improved cooler of the class described wherein the movement of the circulating air is effected in such a manner as to preclude localized drafts of chilled Another object is to provide an air-flow cooler in which the coolingunit is so arranged as to obtain the maximum advantage of gravity in iacilitating the circulation of the air.

A further object is toy provide such a coolerin whichthe cooling unit is so constructed and arranged that the cooling unit occupies a space normally occupied by the upper layer of the warmestair in the chamber, whereby a more uniform temperature of the air is effected throughout the storage area.

A still further object is to provide an improved air cooler in which the air is circulated over `the coils in such a manner as to avoid the formation of frost on the coils of the cooling unit.

A still further object is to provide an improved air flow cooler in which the correlation between the actual and relative temperature of the air and the cooling coils and the volume and velocity of the circulating air is such that the air in immediate contact with the cooling coils is not so chilled as to give up any substantial amount of moisture upon contact with the coils.

Other and further objects will become more readily apparent from the following description when considered in connection with the accompanying drawings illustrating an embodiment of the invention, and in which:

Figure 1 is a partial cross section of an air owcoolerin accordance with the present invention;

Figure 2 is a partial worms-eye view of the cooling unit shown in Figure l;

Figure 3 is a partial sectional elevation of a modified. form of the invention shown in Figure l;

Figure 4 is a schematic diagram of the refrigerating unit; and

Figure 5 is a sectional elevation of an air flow cooler made in accordance with this invention and illustrating the manner in which the air circulates within the storage area and also illustrating the manner in which the temperature gradient due to the location of the refrigerating unit tends to neutralize the temperature gradient due to the action of gravity.

The form of the invention shown for the purpose of illustrating the invention comprises a cooling cabinet or room Il] having a cooling unit I I fixed to the upper part or ceiling of the cooling room. The walls of the cooling room are provided with suitable insulation I2. The cooling unit Il, per se, comprises a plurality of cooling conduits I3 in a transverse sinuous arrangement to form in effect a plurality of interconnected U- shaped elements. The conduits I3 are supported by and extend transversely through a plurality of. spaced baiiies Ill which are suitably secured as by spot welding to a horizontal upper plate I6. The plate I6 is suitably attached to the ceiling of the cabinet or room IE) by means of suitable brackets I'I. The lower part of the cooling unit is closed by a suitable plate i8 attached to the underside of the vertical baliies ill. A cylindrical shield 23 having a baiiie 24 is carried by and arranged over an aperture in the central part of the plate I8 for the purpose of directing the flow of air past a suitable fan 25. Suitable side plates I9 and 2I extend between the plates I 5 and I 8 and serve to complete the enclosure of the cooling conduits I3. As shown the plates i6 and I8 stop short of the side walls of the cabinet or room I and form the air discharge outlet for the cooling unit II. Suitable deflectors 26 and 2,1.are arrangedat the opposite ends of the cooling unit for the purpose of directing the flow of the air downwardly along the sides of the cabinet and to prevent the air from impinging directly against the side Walls of the room I0.

The fan 25 driven by any appropriate means, such as an electric motor (not shown), is adapted to rotate about a vertical axis for the purpose of creating a draft of air upwardly through the cylindricalshield 23 at the center of the cooling unit I I, and outwardly past the cooler conduits I3. Suitable bales 28 and 28a. arranged behind the fan 25 are adapted to direct the air from the ian outwardly against the conduits I3. A suitable thermostat 29 is attached in heat exchange relation to the end of the conduits I3 which returns the refrigerant to the compressor 3l, The thermostat 2g is so positioned and arranged to maintain the appropriate temperature conditions by automatically adjusting an expansion valve 3l. Although only one cooling unit I I is described it will be readily apparent that the entire ceiling ofl the cabinet or room i8 can be covered with similar units arranged side by side. By this arrangement, it will be readily apparent that it will be substantially impossible for any pockets of warm air to exist in the cabinet or room l0. The temperature of the cooling conduits I3 is so adjusted and correlated to the velocity and volume of the flow of the air through the fan 25 and over the conduits i3 so that the temperature of the entire body of the air within the room or cabinet is reduced and maintained at a lower temperature by a series of steps rather than by the sharp reduction of temperature of only a small part of the air which is immediately adjacent and surrounds the cooling conduits I3. Cooling of the entire body of the air in the cabinet or room I0 is accomplished by the progressive lowering of the temperature of the large volume of air which is continuously recirculated and whereby all of the air eventually passes over the cooling conduits E3. As the air ilows outwardly over the cooling conduits i3, the temperature of the air will be reduced making the air denser and heavier so that it will flow downwardly in a thin insulating curtain along the inner surfaces of the walls of the cabinet. As the cool air progresses toward the bottom its temperature will gradually rise as the air absorbs heat from the meat stored in the cabinet or room and from the heat which passes throughthe walls of said cabinet. The inside air will expand and get lighter and a part thereof will migrate toward the center of the chamber where the slight induction draft from the fan 25 will cause it to be recirculated over the cooling conduits I3. The other cooler portions of the air will continue toward the bottom of the cabinet until it receives sufficient heat to cause it to expand and migrate toward the center of the cabinet and eventually upwardly into the induction draft of the fan where it is again recirculated past the cooling coils. The general nature of the circulation of the air in the chamber i is roughly illustrated in Figure 5. It will be readily apparent that the air near the inner surface of the curtain of cooler air may be cooler than the air in the outer part of the curtain, and will travel in a longer` path than the air which is not so cooled. ln this manner there is a continual interchange and diffusion of all of the air within the cabinet so that air which is recirculated at any one time will not come from the same part of the cabinet. The natural stratification of the air due to gravity will tend to force or squeeze any layer of warm air which might tend to form immediately under the cooling unit so that the air Will be drawn into the circulating air.

By reason of the fact that the cooling unit is arranged immediately adjacent the ceiling of the cabinet or room and occupies the space which would normally be occupied by the layer of the warmest air in the cabinet, it is found possible to reduce the thickness of the insulation in the ceiling of the cabinet without reducing the eiliciency of the cooling cabinet as a whole. This construction is illustrated in Figure 3 where it is shown that the thickness of the insulation I2a is thinner than the insulation in the side walls of the cabinet. Also in this modied form of the invention the .cooling unit is completely enclosed within a metal housing 3D, the lower part of the housing being flush with the fan (not shown), in order to eliminate any projection below the housing 30. In this form also suitable baiiles a and 30h are provided to direct the flow of the air downwardly. The iiow of the air in this modiiied form is similar to the form previously described and illustrated in Figure 5.

The cooling conduits I3 constitute a part of a conventional refrigerating unit schematically illustrated in Figure 4. The expanded gaseous refrigerant from the conduits I3 is returned to a compressor 3| which forces it through a suitable conduit 32 into a condenser 33 from which it passes into a suitable receiver 34. From the receiver 34 the compressed and liquied refrigerant passes to the expansion valve 3l through the conduit 36. The thermostat 29, controls the expansion valve 3l to maintain the appropriate temperature conditions desired in accordance with conventional mechanism for adjusting the thermostat. It will also be understood that the motor for operating the compressor may be controlled by suitable conventional automaticr controls. Since this forms no part of the invention, no further description is necessary.

From the above description it will be readily apparent that this invention provides a system for cooling the air inside a storage room or cabinet in such a manner that dehumidication of the items stored in the cabinet will be kept to a minimum and the formation of frost on the cooling conduits will be prevented. Also the construction reduces to a minimum the turbulent air conditions or localized drafts of high velocity air. The cooling of the entire Volume of the air in the cabinet or room is effected by the proper correlation between the temperature of the cooling conduit and the volume and velocity of the air circulated over the cooling conduits so that the temperature of the air is reduced by a series of steps rather than by sharp reduction of the temperature of the air immediately surrounding the cooling conduits. Also the construction provides a very compact unit in which the cooling is effected by producing an insulating curtain of air which extends from the ceiling of the cabinet to the bottom thereof whereby certain portions of the air will leave the curtain as it absorbs heat and will gravitate toward the center where it will be carried by the induction from the fan across the cooling conduits. This is to be distinguished from some of the prior devices Where the air is sharply chilled as it passes over the refrigerating coils down to the bottom of the cabinet from where all of the air rises gradually upwardly resulting in stratification of the air. In the present device the Ycoolest air comes from the place where the warmer air normally tends to migrate and for that reason there will be a much more uniform temperature throughout the volume of the air in the room or cabinet.

There is a certain temperature gradient due to conduction through the air from the cooling unit II. This temperature gradient is represented in Figure 5 by the broken line trapezoid 40. The temperature gradient due to gravity is represented by the solid line trapezoid 4 I. In both instances the lengths of the top and bottom sides of the trapezoids are intended to `represent theA general relative values of temperature. No attempt is made to represent the exact temperature at any point, it being understood that there is a state of continuous motion and that Figure 5 is merely shown for the purpose of attempting to visualize the conditions existing inside the cabi` net or room which causes a more uniform temperature distribution. The arrangement of the cooling unit entirely throughout the ceiling of the room or cabinet tends to neutralize stratification of the air due to the action of gravity.

Although the invention has been described in considerable detail, it will be apparent to those skilled in the art that many variations are possible without departing from the inventive concept. It is therefore desired that the invention not be limited except insofar as is made necessary by the prior art and by the appended claims.

Having thus described the invention, what is -claimed is:

1. In a refrigerator or air cooler including a cabinet er room, air cooling means arranged immediately adjacent the ceiling of said cabinet or room, said air cooling means being limited to a relatively small depth of the top of the space of said cabinet and the effective cooling area of said means being distributed to a uniform depth horizontally throughout the width of said cabinet or room, means supplementing the action of gravity for circulating air over said cooling means in heat exchange relation therewith, enclosure means having a central aperture and spaced lateral discharge outlets for isolating said cooling means from the body of air in said cabinet or room, except at said aperture which serves as the inlet for the flow of air to said cooling means and at the discharge outlets at the ends of said enclosure means adjacent the opposite walls of said cabinet or room, whereby a curtain of cooled air will be discharged adjacent the walls of said cabinet or room and air from said curtains of air will be free to drift under the combined action of gravity and said circulating means toward the center of said cabinet or room in accordance with its temperature rise, the ilow of air producing a temperature gradient in the body of air which tends to offset the temperature gradient due to the-action of gravity, thereby producing a gradual drift of air from adjacent the side walls of said cabinet or room toward the center of said cabinet or room and toward the induction draft produced by said circulating means.

2. In a refrigerator or cold storage unit including a cabinet or room having a main storage area, a partition arranged adjacent the ceiling of said cabinet or room and with said ceiling forming a restricted area and air conduit, extending transversely of said cabinet or room, said partition having an aperture intermediate its ends and the ends' of said partition terminating just short of the opposite sides of said cabinet or room forming discharge outlets adjacent said opposite sides, cooling means in said restricted area or air conduit, means for inducing a draft of air upwardly and inwardly through said aperture in said partition and outwardly through said restricted area in heat exchange relation with said cooling means and out of said discharge outlets adjacent the opposite side walls of said cabinet or room in relatively thin curtains of air where the cooled air is permitted to fall under the action of gravity and to drift toward the Acenter of said main storage area progressively from the top to the bottom of said main storage REFERENCES CITED area under the combined influence of gravity 1 and the heat absorbed from said main storage lThf fowm? rllferens are of record m the area, whereby the progressive drift toward the e 1S pane center of said main storage area tends to offset 5 UNITED STATES PATENTS the natural temperature gradient and stratifca- 7 tion of air due to gravity, the gradual drift of- Ll'hlgzz e 11115958193 4 the air in the curtains causing all of the air to 211621-52- Wune june 13 1939 move progressively toward said aperture at low 2212748* Parker Aug 27 1940 velocity and Without turbulence where it must 10 2241558 Read Max', 13 1941 circulate over said cooling means and thereby 2-320525 Krtze June-1 1943 elimi ate any dead air spots in said main storage l area. 2,433,655 Dinoppola Dec. 30, 1947 VIRGIL P. WARREN, II.

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