US2063646A

US2063646A - Cooling unit

Info

Publication number: US2063646A
Application number: US677870A
Authority: US
Inventors: Harry A Whitesel
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1933-06-27
Filing date: 1933-06-27
Publication date: 1936-12-08
Anticipated expiration: 1953-12-08

Description

. 8, 1936. H. A. wHlrEsr-:AL

COOLING UNIT,`

Fifleduune 27,' 1955 MAM tbovng.

Inventow:

Hamm A Patented Dec. 8, 1936 PATENT oFFicE COOLING UNIT Harry A. Whitesel, Fort Wayne, Ind., ass' or to General Electric Company, a corpora ion of New York Application June 27, 1933, Serial No. 677,870

' 12 claims.

My invention relates to cooling units for refrigerating systems.

It has been found that when meat and other similar perishable food are to be kept in condition for sale and use, such as in meat markets and restaurants, certain narrow ranges of temperature must be maintained in order to preserve the foods satisfactorily for a maximum length of time. It is essential that the temperature throughout the chamber be uniform. Cooling units with forced air circulation are employed in installations of this type and are preferably operated upon the well-known defrosting cycle. It is often diflicult however, to maintain the proper range of temperatures in th'e installations be-i cause the temperature of the cooling units is not Vuniform throughout, so that the air circulated through the cooling unit is not cooled uniformly. This lack of uniformity of the temperature of the surface of the cooling unit is particularly notice--` able when the defrosting cycle is employed, since it is necessary that the entire evaporator should warm up to a temperature above 32 F. in order to completely defrost the evaporator before the operation of the refrigerating machine is started again. When the evaporator is not of a uniform temperature throughout, it is necessary that the control device should operate over a wide rangein order to insure complete defrosting, and it is evident that when such a Wide range ofV temperature is employed there will be a wide range of average temperature in the chamber to be cooled.

This results in variations in temperature inthe cabinet or other chamber to be cooled, which may result in spoilage of food.

Accordingly, it is an object of my invention to provide a cooling unit for refrigerating systems which can readily be maintained at a uniform temperature throughouhand in this way maintain a uniform temperature throughout the chamber to be cooled.

Another object of my invention isl to provide a cooling unit for refrigerating systemsprovided with forced air circulation which is of rugged construction and highly efficient in operation.

Further objects and advantages of my invention will become apparent as the following description proceeds,v and the featuresof novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a partrof, this specification.

For a better understanding of my invention reference may be had to the accompanying drawing in which Fig. 1 is a side elevation of a. refrigerating system provided Awith a. cooling unit embodying my invention; Fig. 2 is a perspective view, partly broken away, of the cooling unit shown in Fig. 1; Fig. 3 is a detailed sectional view of the header and injector constructionj and Fig. 4 is a detailed sectional view of the cooling coil and 5 brine container construction.

Referring to Fig. 1, I have shown a refrigerating system including a housing I0 mounted on a base I I which is a removable top of a refrigerator cabinet or other chamber to be cooled. Within the 10 housing I0 is arranged a motor and compressor casing I2, a refrigerant condenser I3, and a motor I4 having `a fan I5 driven thereby for cooling the casing I2 and the condenser I3. Refrigerant compressed in the casing I2 is liquefied in the con- 15 denser I3 and flows toa ilowLcontrol device or float valve I6 mounted on the top II outside the v housing I0. A cooling unit I1 embodying mylin-, vntion is suspendedon legs I8 from the top'II, .and the liquid refrigerant flows thereto through a 20 conduit I9. The liquid is vaporizedl by absorp- .tion ofheat and is -withdrawn from'the cooling unit I1 through a conduit 20.

The cooling unit as-cdnstructed in accordance with my invention -comprises an evaporator in- 25 cluding a plurality of tubes arranged for-forced circulation of refrigerant therein and surrounded by ilat` containers filled with a negative heat storage substance, such as a glycerine or brine solution. 'I'he evaporator is enclosed in an open- 30 ended casing at one end of which is, detachably secured a fan for circulating air through the casing.

Referring now particularly to Fig. 2, as an example of one manner of carrying out my inven- 35 tion, I have shown a cooling unit including an evaporator comprising an upper header 2| connected by a vertical conduit 22 to a lower header 23, and a plurality of looped tubes or refrigerantcirculating members 24 connected between the 40 upper and lower headers. In order to produce circulation of refrigerant within the evaporator, I provide an injector system for causing the refrigerant to flow upward through. t-he looped tubes 24 to the upper header 2| and to return 45 through the vertical conduit 22 to the lower header. This injector system includes a conduit 25 entering the lower header and extending therethrough past the openings of the tubes 24 and branch conduits or injector tubes 26 which 50- looped tubes to the headers. As can be seen,

tance into the lower end of the looped tubes 24, and when a mixture of gaseous and liquid refrigerant formed when liquid refrigerant passes through the oat valve is forced out through the injector tubes, it will cause a ow of the refrigerant within the tube 24 toward the upper header and promote vaporization of liquid refrigerant in the tubes. The header 2l is maintained partially lled with liquid refrigerant and to a level indicated at 2Ia above the upper openings of the tubes 24 and the conduit 22. Any refrigerant which is vaporized due to the absorption of heat will be carried along by the ow in the tubes 24 and will collect in the upper header, from which it is withdrawn through a suction connection 21 by the compressor. The rapid circulation of liquid refrigerant which carries the vaporized refrigerant quickly to the upper header insures a uniform temperature and heat-absorbing Acapacity throughout all of the tubes of the evaporator, since pockets of vapor cannot remain within the liquid for anysubstantial time to act as insulating layers to prevent uniform absorption of heat, and since the agitation due to circulation and the presence of vapor injected into the looped tubes prevents any superheating 'of theliquid refrigerant which would also vary the rate of absorption of heat. As is evident from Fig. l, the tubes 24 slope upwardly at all points and,

since the liquid level in the header is maintained above the upper ends of the tubes 24 and the opening of the conduit 22," natural circulation of the liquid refrigerant through the evaporator will continue during the inactive part of the operating cycle during which refrigerant is not being injected into the evaporator. This circulation, as is well understood in the art, is produced by the upward movement of vaporized gas within the evaporator. Since more vapor will be formed in the tubes 24 by the absorption of heat than in the conduit 22, there will be a-tendency for the refrigerant to circulateupward through the tubes 24 and downward through the conduit 22.

On either side of each looped tube 24 I provide sheets 28 joined thereto, which extend the eective heat-absorbing surface of the tubes 24, In the preferred embodiment illustrated and clearly shown in Fig. 4, I fold the edges of one 'of the sheets 28 about the other and join them,

as indicated at 29, to form a sealed container or tank 3B. I prefer to seal the 'joints 29 at the edges of the sheets 28 and attach the tubes 24 to these sheets by brazing, but this may be done in any other suitable manner. This container is filled with a negative heat storage substance 30a such as a glycerine or brine solution,

or any other suitable liquid, which will be frozen during the operation of the refrigerating mechanism and will be melted during the idle periods of the mechanism by the absorption of heat from the chamber to be cooled. The use of such a solution provides an additional storage capacity or fly wheel efect, since suiicient heat must be absorbed to melt the frozen solution before the temperature of the evaporator can be appreciably raised. In order to still further increase the eifective heat-absorbing surface of the evaporator units comprising the looped tubes 24 and the surrounding containers 30, I weld sheets of metal, stamped to form zig-zag ns 3l on both sides of each container, the fins 3| extending horizontally. This arrangement of the tubes within the containers and of the ns secured .to

aoeae the-injector tubes 26extend a substantialdisfrom the fins directly through the containers toY the refrigerant within the tubes, which avoids the delay in the transmission of heat occurring when the brine solution or other fluid completely surrounds tlie refrigerant tubes. These fins are arranged in staggered relation so that the attached portion 32 on one side of each tank will be opposite the raised portions 33 of the zig-zag iins on the other sideof the tank and I arrange the fins on the adjoining tanks so that the raised portions 33 on one tank will be opposite the attached portions 32 on the other tank. This effects a more uniformdistribution of the heatabsorbing areas between the tanks. All of the iins 3| are parallel and extend horizontally along the tanks. The evaporator is enclosed in a casing 34 which constitutes an air duct and which includes an upper plate 35, a lower plate 3B, and side plates 31, which are joined together at their edges. The upper header extends above the upper plate 35 and beyond both sides of the casing 34. Each evaporator unit is securely held in place between the upper and lower plates. This is accomplished by forming indentations 38 in the upper and lower plates transversely of and extending toward the evaporator units. Each container is provided with a rib 39 extending around the periphery thereof and formed when the sides.

of the tank are joined at 29 by folding the edges of the plates 28 over each other. These ribs are fitted into slots 40 cut in the indentations 38 and are welded or otherwise secured to the upper and lower plates around these slots, as indicated at 4I. This method of construction provides a rigid unit which will withstand large stresses. Any moisture which is condensed on the evaporator and ows to the bottom plate 36, will be drained from the bottom plate through a pipe 42 provided at therear thereof.

In order to provide a circulation of air through the cooling unit longitudinally of the heat-absorbing ns, I provide a motor-driven fan 43 mounted on an end plate 44 of the casing 34, Whichvimpels the air from the fan through the cooling unit to the opposite open end thereof. 'I'he fan 43 and a driving motor 45 for driving the fan are secured to the end plate 44 on radial struts 46, the end plate being provided with a cylindrical fan housing 41 having perforations 48 to permit passage of air therethrough. The end plate 44 is provided with side anges 49 engaging the side plates 31 of the casing on the outer sides thereof, and the end plate rests on the bottom plate 36 adjacent an upturned iiange 50 which prevents the end plate from sliding off the bottom plate. An inturned iiange 5I at the upper edge of the end plate 44 rests against the upper header 2l and closes the casing along the upper edge thereof. The side flanges 49 are detachably secured to the side plates 31 by thumb screws 52 which may quickly be released to vpermit removal of the end plate from the cooling unit. By this In the operation of the refrigerating system shown in Fig. 1, refrigerant compressed by the compressor within the casing I 2 flows to the condenser |3 where it is liquefied and then collects in the oat chamber IC. When a sufficient quantity of liquid refrigerant has collected, the float valve operates to allow the refrigerant to enter the conduit I9. 'I'he liquid refrigerant is partially vaporized in passing through lthe valve and the mixture of liquid and vapor refrigerant ows through the conduit I9' and is injected through the tubes 26 into the tubes 2l and induces circulation of refrigerant through the looped tubes to the upper header' and back to the lower header. The vaporzed refrigerantintroduced through the injector tubes together with the circulation produced thereby prevents any superheating of the liquid refrigerant in the evaporator since a liquid refrigerant boils readily in the presence of its vapor. The rapid circulation together with the absence of lsuperheating of the liquid refrigerant assures a uniform temperature throughout the evaporator. The evaporator is maintained on what is commonly known as a defrosting cycle, the temperature of the l y coils being maintained by a suitable thermostatic frost is formed on the evaporator.

control device alternately above and below the freezing point of water. When this methodl of operation is utilized, no appreciable amount of It will be evident that the mean evaporator temperature is considerably higher than when a conventional or non-defrosting cycle below freezing is employed. However, since the fan' continuously circulates the air through the cooling unit and consequently throughout the chamber to be cooled, the temperatures in all parts of the chamber to be cooled are maintained substantially uniform,l

and the temperature difference between the warmest part of the chamber to be cooled and the cooling unit, is relatively small. Since the evaporator units are all maintained at a substantially uniform temperature throughout, all of the air passing through the casing 34 is uniformly cooled. If in the operation of this system a sudden increase in load is imposed, as by placing warm articles in the space to be cooled, the air circulated through the casing 34 will transfer heat through the fins 3l and the sheets 28 to the refrigerant circulated in the tubes 24 and also to the negative heat storage substance or solution in the containers 30, which vprovides for simultaneous cooling by the refrigerant and negative heat storage substance. In this way a high momentary peak capacity is obtained with a minimum capacity of the refrigerating system.

While I have shown and described my invention in connection with a compression refrigerating system, it will be understood that it is applicable to other types of refrigerating systems, and I do not desire my invention to be limited to the specific construction shown and described, and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A flooded evaporator for refrigerating/ systems comprising an upper header and a lower header, looped tubes connecting said headers,'

maintaining said upper header partially` filled with. liquid refrigerant, and means for withdrawing gaseous refrigerant from said upper header.

2. Avilooded evaporator for refrigerating systems having a header and a plurality of looped refrigerant circulating tubes connected to said header, means for maintaining said header partially lled with liquid refrigerant, a containerv surrounding each of said tubes and having walls securedthereto, said container having a negative heat storage substance therein, a plurality of parallel heat-absorbing ns secured on said container, and means for directing circulating air longitudinally along said fins.

3.A flooded evaporator for refrigerating systems having an upper header and n a lower header, a plurality of looped tubes connecting said headers, means injecting refrigerant into the lower ends of said tubes' for inducing aow of liquid refrigerant from said lower Vheader to said upper header, means for returning liquid `said upper header, means forreturning liquid refrigerant from said upper header to said lower header, a container surrounding each of said looped tubes, said container having walls in contact with both sides of said tubes and having a negative heat storage substance therein; means for withdrawing Vaporized refrigerant from said upper header, a casing surrounding said containers, and means for circulating air through said casing over the surface of said containers.

5. A flooded evaporator for refrigerating systems having an upper header and a lower header, a plurality of looped refrigerant-circulating tubes connecting said headers, means including a conduit entering said lower header and injecting refrigerant into the lower ends of said tubes for inducing a flow of liquid refrigerant from said lower header to said upper header, means for returning liquid refrigerant from said upper header to said lower header, means for withdrawing vaporized refrigerant from said upper header, a container surrounding each of said looped tubes and having side walls secured in contact with said tubes, saidycontainer having a negative heat storage substance.

therein, parallel zig-zag heat-absorbing fins secured to said containers, a casing surrounding said containers, andmeans for circulating lair longitudinally of said fins through said casing over the surfaces of said containers. I

6. A cooling unit for refrigerating systems including a casing constituting an air duct, an

evaporator including a plurality of refrigerantcirculating members having plates arranged within said casing, means including a wall of said casing having slots therein for supporting said plates, the edges of said plates entering said slots 'in said wall and being secured to said walls around said slots, and means for impelling air through said air duct and between said members.

'7. An evaporator for refrigerating systems comprising a header and a plurality of depending looped refrigerant-circulating tubes, flat containers surrounding said tubes and having a neg-r ative heat storage substance therein, a rib on the edge of each of said containers, and a casing surrounding said containers, said casing including upper and lower plates havingelongated indentations therein transverse to said containers, said ribs and said plates being welded together at the indentations in said plates.

8. An evaporator for refrigerating systems having a plurality of refrigerant-circulating conduits, a casing surrounding said conduits, a ange v on said casing, a removable end plate having a cylindrical housing thereon and resting on said casing against said flange, means for removably securing said plate t0 said casing, and means including a fan and a motor` secured to said end plate for forcing circulating air through said casing.

9. A cooling unit for refrigerating systems including a casing having top, bottom, and side plates, an evaporator comprising a header and a plurality of refrigerant-circulating tubes ar- Y ranged Within said casing, an upwardly extending means including a second set of tubes arranged in the lower ends of said looped tubes for admitting liquid refrigerant to said unit and vfor inducing a ow of liquid refrigerant through said looped tubes from said lower header to said upper 11. A ooded evaporator for refrigerating systems comprising an upper horizontal header and -I a lower horizontal header, looped tubes connecting said headers, means including a second set of tubes arranged in the lower ends of said looped tubes for admitting liquid refrigerant to said unit and for inducing a flow of liquid refrigerant through said looped tubes from said lower header to said upper header, means including a conduit connecting said headers for returning liquid refrigerant from said upper header to said lower header, means for maintaining said upper header partially filled with liquid refrigerant, and means for withdrawing gaseous refrigerant from said upper header.

12. A flooded evaporator for refrigerating systems having a header and a plurality of looped refrigerant circulating tubes connected to said header, means for maintaining said header partially filled with liquid refrigerant, containers surrounding each of said tubes and. having walls secured thereto, said containers having a negative heat storage substance therein, a plurality of parallel heat absorbing ns secured on said containers, a casing surrounding said containers, and means for directing circulating air through said casing longitudinally along said fins.

HARRY A. WHITESEL.