US1957036A - Refrigerating coil - Google Patents

Description

y 1, 1934- E. s. H. BAARS ET AL 1,957,036

REFRIGERATING COIL Filed Nov. 2. 1952 2 Sheets-Sheet 1 Ifg'fi.

INVENTOR.

y 1934. E. s. H. BAARS ET AL 1,957,036

REFRIGERATING COIL Filed Nov. 2, 1952 2 Sheets-Sheet 2 I INVENTOR 6. J. 7% @MM/ Z0.%. f. 4 I ma, I ATTORNEY.

@atented i, 1934 BEFBIGEBATING con.

. Ernst S. H. Baars, Milwaukee, Win, and Walter G. E. Bolafl, Kirhwood, Mm; said Bears assignor to The Vilter Manutactnring Company, Milwaukee, Win, a corporation of Wisconsin Application November 2, 19:2, Serial No. 840,762 4 11 Claims. (Cl. 82-126) The present invention relates in general to immovements in the art of refrigeration, and relates more specifically to improvements in-the construction and operation of evaporator coils for refrigerating systems utilizing refrigerants such as methyl chloride and dichlorodifluoromethane, the latter being commonly designated as V In coil type refrigerating systems wherein the 1 refrigerant is circulated by a compressor and in which the flow of refrigerant is controlled by other mechanical parts such as valves requiring lubrication, it is impossible to prevent some of the lubricating oil from with the refrigerant confined within the system. Such mixture of oil with the refrigerant, greatly impairs the eficiency of the system, since it is difficult especially when utilizing refrigerants such as methyl chloride or F12, to cause the oil to gradually advance through the coils with the refrigerant. & a result of this dimculty, the heat er surfaces of the coils soon become coated with oil and oil pockets form in the lower spots,

so that ultimately the evaporators become extremely inefiective and the mechanical parts are insuificiently lubricated.

It is an object of the present invention to provide an improved evaporator coil structure, which will insure eiiective advancement of fixed liquids such as oil, through the coil, together with the volatile refrigerant.

Another object of the invention is lie-provide an improved refrigerating coil especially adapted for use with refrigerants such as methyl chlo ride or Fr -l2, wherein undesirable accumulation or pocketing of oil is automatically and effectivefly prevented.

A further object ofthe invention is to provide an improved multiple tube coil construction wherein basins oi liquid refrigerant of uniform depth are maintained within the heat trans- .ierr'mg portions of the evaporator tubes, while a free passage for gases remains through the entire length oi the coil.

Still another object oi the invention is to provide an improved refrigerating coil structure which is adapted for flexible application to various types oi refrigerating systems, and which may he manufactured at reasonable cost.

A further object of the invention is to provide an improved refrigeration coil end connector or fitting, which will effectively accommodate ex pension and contraction of the coil, and which moreover provides for most efficient operation of the coil structure as a unit.

the invention, and of the mode of constructing re- These and other obiects and advantages will hie apparent from the following detailed descrip- A clear conception or several embodiments of Irigerant evaporator coils in accordance therewith, may be had by referring to the drawings accompanying and forming a part of this specification in which like reference characters designate the same or similar parts in the various views. r

Fig. l is a transverse vertical section through the casing of a forced draft refrigerating unit showing an improved radiator type of coil as semblage and radiating fins, and the section being'taken along the line 1-.l of Fig. 2;

Fig. 2 is a longitudinal section through the unit of Fig. 1, taken along the line 22, and showing an end view of the coil and fittings and crossconnections;

Fig. 3 is a full view or a modified form of refrigerant evaporator coil assemblage especially adapted for room service;

Fig. 4 is an end viewof the improved evapo= rater coil assemblage of- Fig. 3; and

Fig. 5 is an enlarged longitudinal section through the refrigerant delivery end or one of g; coll sections, taken along the line 5-5 of While the present disclosure of the improve-- ment has been restricted to a specific illustration and description of only two types of evaporators of definite capacity, it should be understood that it is not intended to restrict the scope of the invention by such limited disclosure. The invention which primarily involves a new and useful formation of coil end fitting or connector, is obviously applicable to evaporators of various types and capacities. v

Referring specifically to Figs. 11 and 2 or the drawings, the forced draft unit comprises in gen-= eral an outer casingfi having coil supports 9 disposed therein and forming a substantially rectangular sectioned conduit having one end open a fan housing 10 associated with the opposite end of the casing 53 and having therein a fan which is driven by a motor 11, and a coil type ofevaporator consisting of horizontal sections or tubes 12 and end connectors or fittings 13, the coil being supported within the casing 8 by the supports 9. While a ten coil evaporator has been illustrated in Figs. 1 and 2', it should be understood that the actual number of these coils may be varied to suit desired operating conditions.

The outer casing 8 and supports a may be formed of sheet metal, and the fan or blower 11% which is disposed within the housing 10 may be of any of the well known constructions adapted to force air longitudinally through the conduit formed by the casing 8 and in intimate contact with the tubes 12 and fittings 13. In order to secure improved heat transfer, the horizontal tubes 12 may be provided with radiator fins 14 formed of metal and lying in planes parallel to the direction of flow of the air through the C851 ing 8.

The evaporator consists of a series of ten laterally disposed coils, the upper tube 12 of each of which serves as an inlet for liquid refrigerant, and the lower of each of which constitutes the outlet. A series of cross-connector pipes 15 connect the outlet ends of the coils with the inlet ends of the succeeding coils, and the pipes 15 may be of different internal diameter than the tubes 12. Each bank or nest of coils has a main upper inlet 16 and a final lower outlet 17. and it will beapparent that with the successive coils connected as they are by the cross-connector pipes 15, the refrigerant must flow from the inlet 16 through the succession of coils to the outlet 17.

As previously indicated, the tubes 12 are disposed horizontally or nearly so, and the fittings 13 have their receiving portions curved upwardly to provide dams 18 for establishing elongated basins of liquid within the lower portions of the tubes 12. The reverse curvature of the surfaces of the dams 18, as illustrated in Fig. 5, must be gradual so as to avoid formation of sharp notches or pockets, and the dams 18 must be of less height than the internal diameter of the tubes 12, so that the spaces above the successive liquid basins will remain in open communication with each other. Each. coil therefore has therein a succession of parallel elongated liquid basins of substantially uniform depth, and a continuous free passage extending over the basins and around the bends connecting the basins.

Referring specifically to Figs. 3 and 4 of the drawings, the evaporator comprises in general a series of three laterally adjacent coils each consisting of parallel horizontal U-shaped sections 20; inclined bends or end sections 21 connecting the successive superimposed horizontal sections 20; and cross connectors 22 connecting the outlet ends of the lowermost of each of the horizontal sections 20 with the inlet ends of the uppermost sections 20 of the next coils. This modified evaporator has an upper main inlet 23 and a lower final outlet 24, and the coils may be suitably supported as by braces 25. As in the case of the coils previously described, the end sections 21 form dams 18 which establish elongated liquid basins in the horizontal coil sections 20, while at the same time providing continuous free spaces or passages throughout tlfe length of the coils above the liquid basins and through the end sections 21. Each of the coils of Figs. 3 and 4 may be formed of a single length of pipe, or they may be made sectional as in Figs. 1 and 2, and the cross-connectors 22 may be of the same or of smaller diameter than the sections 20, 21.

' In normal use, both of the evaporators will function substantially the same, so that it will only be necessary to describe the operation of one of these assemblages. During normal operation of the evaporator of Figs. 3, 4 and 5, the fresh supply of liquid refrigerant such as methyl chloride or F-12 together with entrained lubricating oil which is intimately mixed with the liquid refrigerant, is admitted through the inlet 23. The liquid refrigerant and 011 thus admitted forms liquid basins in the successive horizontal U-shaped coil sections 20 while open passages or spaces are maintained above the basins as clearly illustrated in Fig. 5. While some of the liquid refrigerant is being evaporated into these passages and the resultant gas is being drawn off by the compressor in a well-known manner, the excess mixture of oil and liquid refrigerant from each of the basins, is gradually urged up the gradually inclined surfaces of the successive dams 18 and advances in the form of a thin film or layer over the reversely directed surfaces of the dams and through the curved connecting sections 21. When this advancing mixture of excess oil and liquid refrigerant reaches the lowermost horizontal sections 20 of each coil, it is elevated by the suction into the uppermost horizontal section 20 of the next coil, and is eventually returned to the compressor with the gases. This construction therefore makes it possible to maintain a desirable flooded condition in a continuous coil structure, without the use of intervening headers between successive sections of the coil. The gradual approach to the dams l8 insures effective advancement of the oil with the lubricant and prevents pocketing thereof, while the restricted height of these dams provides for the desired open space and passages which permit free withdrawal of the gases.

From the foregoing description, it will be apparent that the present invention provides simple, compact and highly efficient means for advancing a mixture of liquid refrigerant and other liquid such as oil, through a refrigerating coil, merely by proper formation of the coil end sections. Because of the fact that lubricating oil tends to mix intimately with refrigerants such as methyl chloride and F-12, the improved coil construction is especially well adapted for such refrigerants, although it may also be used to advantage with other refrigerants. The coils may be readily constructed either of one piece of pipe or in sections, and while providing ample capacity for liquid refrigerant, the dams 18 at the coil ends, do not interfere with but in fact augment free circulation of the liquid and gas through the system. By virtue of the fact that the dams 18 may all be made either of the same or of different predetermined height, perfect distribution of the liquid throughout the coil strucelongated liquid basin, and a dam at the delivery end of said basin having a gradually inclined surface of approach, said dam being or less height than the basin forming section.

2. In 'a refrigeration coil, superimposed suban "a l and stantially horizontal tubular sections, and a curved end section connecting adjacent ends of said horizontal sections, said end section having reversely curved portions forming a dam of less vertical height than the internal diameter of said tubular sections at said end of the upper of f tion, said end section forming a dam at said upper section delivery end and also providing a gradually curved constantly open passage for gases connecting the crest of said dam with the upper inner portion of said upper tubular section.

4. In a'refrigeration coil, upper and lower substantially horizontal tubular sections, and an end section connecting the delivery end of said upper section with the receiving end of said lower section, said end section forming a dam of less height than the internal diameter of said upper section at said upper section delivery end and also providing a gradually curved open passage from the crest of said dam to said lower section receiving end.

5. In a refrigeration coil, upper and lower substantially horizontal tubular sections having adjacent delivery and receiving ends out of vertical alinement, and a gradually curved inclined end section connecting said ends, said end section having a bottom portion thereof extended above the bottom but disposed below the top of the adjoining upper section delivery end.

6. In a refrigeration coil, upper and lower U- shaped substantially horizontal tubular sections having adjacent delivery and receiving ends out of vertical alincment, and an inclined end section connecting said upper and lower section ends and forming a dam extending above the bottom of said upper section.

7. In a refrigeration coil, upper and lower U- shaped substantially horizontal tubular sections having adjacent delivery and receiving ends out of vertical alinement, and an inclined end section connecting said upper and lower section ends and forming a dam extending above the bottom of but below the top of said upper section.

8. In a refrigeration coil, upper and lower substantially horizontal tubular sections having adjacent superimposed delivery and receiving ends, and a reversely curved end fitting connecting said ends and forming a dam of less height than the diameter of said upper tubular section at said delivery end.

9. In a refrigeration evaporator, a laterally adjacent series of coils each comprising a plurality of superimposed horizontal sections connected by reversely curved end sections, and conduit means connecting the lowermost section of one coil with the uppermost section of a succeeding coil.

10. In a refrigeration evaporator, a laterally adjacent series of coils each comprising a plurality of superimposed horizontal sections connected by reversely curved end sections, and conduit means connecting the lowermost section of one coil with theuppermost section of a succeeding coil, said end sections providing a dam at the delivery end of each of said horizontal sections.

11. In a refrigeration evaporator, a laterally adjacent series of coils each comprising a plural-v ity of superimposed horizontal sections connected by reversely curved end sections, and conduit means connecting the lowermost section of one coil with the uppermost section of a succeeding coil, said end sections providing a dam of less height than the diameter of saidtubular sections at the delivery end of each of said horizontal sections.

ERNST S. H. BAARS.

WALTER G. E. ROLAFF.

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