US2274967A - Evaporator for refrigerating systems - Google Patents

Description

March 3, 1942. v R s; NELSON HAL 2,274,967

EVAPORATOR FOR REFRIGERATING SYSTEMS Original Filed Aug. 8, 1936 Patented Mar. 3, 1 942- UNITED STATES PATENT .OFFICE 2,274,967

avaroaa'roa ron maronasrmc assignors to The ten, Ohio, a cor- No. 94,941 V 3 Claims. .(Cl. 62-126) Thisinvention relates to an evaporator construction for use in an absorption refrigeration system of the type employing an inert gas and operating at high'internal pressures such as are necessitated when, for example, ammonia is used as the refrigerant medium, ,water as the absorbent, and hydrogen, nitrogen or other similar gas as the inert pressure equalizing medium.

The problem of constructing an evaporator for an absorption refrigeration system of the type described above is quite different from that encountered in making an evaporator for a com pression type refrigerator. For instance, com- I pression machine evaporators fall into two general classifications, namely, the flooded and the dry types. In neither of these two types is it necessary to circulate the liquid refrigerant through the evaporator in any particular manner. Nor is it necessary to provide for the circulation of an inert gas through the evaporator, or to make the evaporator passages sufllciently large to convey a large volume of inert gas, and a relatively small volume of liquid refrigerant. And of course, since inert gas is not present, it is unnecessary to so construct the evaporator that liquid refrigerant will not seal the passages and prevent the flow of inert gas.

Since compression refrigerators operate under low internal pressures as compared to three fluid absorption apparatuses using ammonia as a refrigerant, the problem of selecting a material of suiiicient strength to stand high pressures and yet which is easily workable is not present.

Heretofore, absorption refrigerator evaporators, when made from conduit, have been fabrisated from a plurality of pro-fanned sections of conduit welded or otherwise joined together. Such conduits have been arranged relatively close together and in. substantially vertical planes at the sides of a sharp freezing or ice tray chamber.

This mode of construction has many disadvantages. For example, the very cold evaporator conduits are in direct heat exchange relation to the food compartment air of a refrigerator, and in indirect heat exchange relation to the water in the ice trays within the sharp freezing chamber. Consequently, the air is cooled to an undesirably low temperature and the wateris frozen too slowly or not at all. Furthermore, the moisture in the box air condenses on the evaporator conduits in the form of frost and reduces the evaporator efliciency very greatly. Frequent defrosting by discontinuing the operation of the refrigerator, and the spoilage of foodstuffs by dehydration is therefore unavoidable.

The present invention provides an evaporator construction which entirely overcomes the disadvantages of constructions heretofore proposed. It is accordingly an object of this invention to provide an evaporator for refrigerator which is simple, economical to fabricate and which has none of the undesirable characteristics or disadvantages of prior known structures.

More specifically, it is an object of the invention to provide an evaporator made from a continuous, jolntless conduit bent in-such fashion that at least some of the conduit sections are located in close heat exchange relationship to a chamber to be maintained at a low temperature, but in remote heat exchange relationship to a chamber to be maintained at a relatively higher temperature.

Another object of the invention is to provide an evaporator of the type described in which the evaporator conduits 'are positioned beneath the ice tray supporting shelves and which thus serve to support said shelves.

A'further object of the invention is to form an evaporator for a three fluid absorption refrigeration apparatus from a continuous conduit bent to provide a plurality of superimposed, horizontally positioned banks each of which banks comprises a plurality of conduit sections spaced apart laterally to support an object to be cooled.

A still further object of the invention is to provide an evaporator construction in which the normal flow of liquid refrigerant therethrough will not prevent or seriously interfere with the circulation of the inert gas.

Other objects and advantages reside in certain novel features of the arrangement and construction of parts as will be apparent from the following description taken in connection with the accompanying drawing in which Figure 1 is a view in perspective of an evaporater assembly in which the present invention is incorporated and illustrating one embodiment thereof.

Figure 2 is a View in perspective of another embodiment of the invention.

Referring to the drawing in detail and first to the structure shown in Figure 1, it will be seen that the evaporator there shown includes a rectangular, metallic box or housing, open at the front and back, the box having side walls It and l2, 9. top l3 and a bottom I. The box may have one or more central horizontal partitions l5 therein so as to provide a structure adapted to receive ice cube pans or the like for quick freezing the contents thereof.-

For transferring heat from the box to some cooling fluid, each of the horizontal surfaces I3, I l and I5 have a reversely bent pipe secured to the under side thereof.

Thus, in the arrangement of Figure 1 a single pipe is bent to form a number of horizontal conduits below each of the surfaces I3, I and I5 and to provide connections therebetween. The

a three fluid absorption other.

parallel portions of the pipe beneath the top l3 of the box are designated l5 and it will be seen that they are joined alternately at the front and the back by reverse bends. Similar parallel portions of pipe, similarly connected, are shown at H beneath the partition IS in the box, while similar parallel portions B8 are located beneath the bottom it of the box.

The right hand one of the parallel conduits l6 below the top 43 of the box may extend out to the rear thereof as shown at is and provide means for either the entrance or the exit of the inert gas. A conduit 20 which may supply liquid refrigerant to the evaporator may be connected to this conduit 19 at that point. Likewise the conduit H3 at the extreme left and bottom of the evaporator may extend to the rear thereof as shown at 2! to provide either the entrance or the exit for the inert gas to the evaporator and. a liquid conduit 22 may be connected to the bottom thereof to provide a drain for the evaporator. The rear of the conduit It at the left hand upper corner of the evaporator may be connected to the left hand conduit H at the rear of the evaporator by means of a connecting.

portion 23 and likewise the right hand parallel portion I! may be connected to the right hand parallel pipe i8 by means of the connecting portion 24 at the rear of the evaporator. Thus one continuous jointless pipe is provided with a number of bends sufficient to provide a stack of three parallel banks of passageways one above the In Figure l, the connections between banks are shown located at the rear of the evaporator structure. The system could of course be constructed to provide any desired number of parallel banks of coils within the stack.

Any liquid supplied to the upper end of the continuous coil will flow by gravity downwardly therethrough without forming a pocket or seal which would prevent the flow of the inert gas. The coil of pipe provides means for transferring heat directly from the interior of the evaporator box structure to the fluids in the coil, and the box itself constitutes means adapted to receive and conduct heat indirectly from the surrounding air to the fluids within the coil. The ex- -terior of the box or housing may be provided with fins or the like for aiding in this heat transfer if desired.

parallel conduits 35. In each case the conduits are below the horizontal portion of the box structure which they-cool. The return bends in the parallel conduits Stand 35 at the rear left-hand corner of the casing extend rearwardly beyond the shelf 25 and the bottom plate 26 to accommodate respectively the depressed portions thereof;

In the arrangement shown in Figure 2, the lower portion of the evaporator is at the forward and left hand side thereof and a drain conduit 22 may be connected thereto to drain any liquid which does not evaporate in the evaporator. From the point of connection of the conduit 22, the cooling coil extends upwardly along the left hand wall of the box structure and then to the rear to form the exit or entrance for inert gas as shown at 2!.

While only two embodiments of the inven tion have been shown and described herein it is obvious that many changes may be made without departing from the spirit of the invention or the scope of the annexed claims.

We claim:

1. An evaporator adapted for use in an absorption refrigerating system using inert gas, said evaporator comprising a continuous, jointless conduit for conducting inert gas and a. refrigerant and bent to provide sets of interconnected parallel portions in spaced parallel horizontal planes, a sheet metal box associated with said conduit and having horizontal ice tray support ing shelves, one above and in heat exchange relation with each set' of said horizontal portions, the

Figure 2 shows an embodiment of the invention similar to that of Figure 1 except that the The central shelf 25 of the box and the lower helf 26 are provided with offset or vertically gxtending portions 21 and 28 respectively so that he distance between the upper and lower portions of the box is slightly less at the right half thereof than at the left, as viewed in Figure 2. The shelves thus provided at the right portion of the box structuremay be used to support ice cube pans of shallow depth, as for example, those shown at 29 and 30 while the left hand part of the evaporator may support relatively deep pans for freezing ice cream or the like as shown at 3| and 32.

The top of the box structure may be cooled by parallel portions 33 similar to the parallel portions l5 of Figure 1, the central partition 25 of arrangement being such that said horizontal conduit portions underlie said shelves, means for conducting inert gas to said conduit and means for conducting liquid refrigerant thereto.

2. An evaporator adapted for use in an absorption refrigerating system using inert gas, said evaporator comprising a continuous pipe for circulating inert gas and a refrigerant and bent to provide sets of interconnected parallel portions in spaced parallel horizontal planes, a sheet metal box associated with said pipe and having horizontal shelves, one above and in heat exchange relation with each set of said horizontal portions, means for conducting inert gas to said pipe and means for conducting liquid refrigerant thereto, said box being deeper on one sidethan the other to provide an arrangement having large chambers on one side and small chambers on the other side.

3. An evaporator for an absorption refrigerating system using an inert gas and a refrigerant liquid, said evaporator comprising a continuous,

culating the inert gas and refrigerant, said eonduit being bent to provide a plurality of horizontal banks of tubing, each bank having a plurality of straight horizontal lengths of conduit interconnected byat least two return bends and said banks being superimposed one over another and spaced from each other, said continuous conduit between the spaced adjacent banks maintaining said banks in said spaced relation to form supports for shelves, shelves of heat conducting material secured to the upper sides of all of said straight lengths of conduit in each bank, means for conducting inert gas to said conduit, and means for conducting a refrigerant thereto.

RUDOLPH S. NELSON. ARNOLD D. SIEDLE.

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