US2109270A - Refrigerating apparatus - Google Patents

Description

Feb. 22, 1938. H. J. KRAcKowlzER A REFRIGERAIIING APPARATUS Fi'ld July 25, 1936 .2 Ad EL m \\M B 7 Patented Febi' 1938 UNITED STATES PATENT ori-"icl:

2,109,270 nEFmGEaA'rmG ArrARA'rUs Hermann J. Krackowizer, Chicago, Ill.

erating systems wherein liquid refrigerant is supplied to a duct or coil of the cooling unit to produce the cooling effect, and has reference more particularly to a method of and facilities for improving the operation `and increasing the efciency of such cooling by trapping liquid refrigerant in the duct or coil.

In refrigerating systems of the prevailing type', l0

er compression into liquid form is introduced through an expansion or control valve into the duct' or coil of a cooling unit in which it is evaporated and converted to gas, thereby lowering the temperature of the cooling unit or coil by the absorption of heat which occurs in the conversion of the liquid into gas. Fromthe cooling unit the gas is withdrawn by the compressor which re-converts the gas into liquid for re-circulation to and evaporation in the cooling unit.

Inasmuch as the eiiiciency of the cooling unit depends largely upon the amount of surface area upon which evaporation is taking place inside the duct or coil, it is important to maintain the largest possible area of wet surface witllin the duct or coil while at the same time allowing ample clearance for passage therethrough of the gas resulting from evaporation. Moreover, in refrigerating systems of this character, it is the practice to operate the compressor intermittently through automatic controls which cause the compressor to discontinue operation when the cooling unit andthe compartment in which'it is located have reached predetermined low temperatures and to resume operation upon a predetermined rise in temperature, and it not only is desirable to maintain a suitable distribution of liquid refrigerant throughout the length of the duct or coil, during operation of the compressor, g so that evaporation and the cooling effect thereof are substantially uniform throughout the length ofthe duct or coil of the cooling unit, but it is also desirable, after the compressor is stopped, to retain in the duct or coil an accumulation of liquid refrigerant which is suitably distributed so that evaporation of liquid takes place uniformly throughout the length of the duct or coil while the compressor is inoperative and when the compressor resumes operation the response in evaporation and cooling effect is similarly prompt and uniform -at all places throughout the duct n or coil.

Heretofore no convenient or satisfactory means has been available to insure maximum wetting of the inside surfaces of the duct or coil of the a refrigerating medium is employed which aft- 193s, serial No. 92,515

(cl. a2-126)' cooling unit orto accumulate liquid refrigerant therein'so that a Isupply remains uniformly distributed throughout the duct or coil either during operation of the compressor or after the operation thereof is discontinued, as the refrigerant, in previous ducts or coils and in the succesf sive reaches thereof drained quite readily therefrom with the result thatproper distribution of liquid refrigerant throughout the duct or coil and thorough wetting ofthe 'inside surfaces thereof was not assured, which in turn not only caused undesirable variations in temperature conditions at different places throughout the duct or coil, but also resulted :in irregular and ineiiicient compressor operation.

The principal objects of my -invention are to insure thorough andouniform wetting of the inside surfaces of the duct or coil of the cooling unit of a refrigerating system; to avoid variations coil which would interfere with or ydiminish the flow of liquid or gaseous refrigerant therethrough; and in general to provide simple, convenient and satisfactory facilities which will insure uniform and maximum wetting of the linside surfaces of the duct or coil of the cooling unit and otherwise increase the eiciency and impro-ve the operation thereof,-these and other objects being accomplished as will be apparentffrom the following description in which refer' 'ence is had to the accompanying drawing, wherein:

Fig. 1 is a side view of a typical cooling unit embodying my improvements;

Fig. v2 is an end view thereof looking at the right hand end of '.Eig.- 1, with parts removed:

Fig. 3 is an enlarged vertical sectional view of a vertical return bend taken on the line 3-3 of Fig. 2; and I Fig. 4 is an enlarged vertical'sectional. view of one of the horizontal return bends taken on the line- 4 4 of Fig, 2 in which these return bends are at the remote end of said Fig. 2 and shown therein in dotted lines. o

Referring to. the drawing, in which I have shown, for purposes of illustration, a preferred embodiment of my-invention, the reference numerati indicates the cooling unit as a whole which, in accordance with prevailing practice,

2' comprises a group of horizontal tubes 6 mounted in parallel relation and supported by Aend plates 'I and 6, said tubes having thereon closely ar-V which may be secured to the respective tubes 6 as at I I in any suitable manner which will insure a leak-proof connection.

At the other end of the cooling unit one of the upper pipes 6 is provided beyond the plate 6 with a fitting I2 by which it is connected with an expension or control valve Il through which liquid refrigerant is supplied from a compressor Il, it being understood, of course, that the usual condenser and receiver areinterposed in the line between the compressor and expansionvalve I3 although not shown since theyform no part of the present invention. One of the lower pipes 6 is provided beyond the plate l with a union I5 by which it is connected with the. pipe I6 which leads to the intake side of the compressor I4, a thermostatic bulb I1 being provided on the pipe I6 adjacent to the cooling unit 6 'as is customary and connected as at I8 with a thermostatic device which regulates the expansion valve I6. The other1 pipe ends beyond the plate 6 are connected in pairs by vertical return bends I6 as best shown in Fig. 2 so that refrigerant entering through the expansion valve I3 passes successively through the two top pipes 6, then through the two pipes immediately therebelow, and so on down to the bottom pipes and from the final one of the latter to the pipe I6 which returns the evaporated refrigerant to the compressor.

In order to trap liquid refrigerant in each pipe, the horizontal 'return bends yIII are offset upwardly as indicated at 20 and shown in Figs. 1, 2, and 4 and the top portion of each vertical return bend I6 is offset upwardly as indicated at 2I and shown in Figs. 1, 2, "and 3, preferably to such an extent that the bottom oi' the passageway at the highest part of the rise or offset 20 or 2| of the respective return bend I0 or I9 is at the level of the top of the passageway of the tube 6 from which that return bend leads, asis clearly shown in Figs. 3 and 4 by the dotted line 22. To accomplish the same trapping eilect in the last pipe 6 which leads through the union I 5 and the return pipe I6 tothe compressor, the end of said pipe 6 may be turned up as shown at 2l and the adjoining portion of the pipe I6 may be formed to provide a suitable bend 26 to afford with the bend 24 a rise corresponding to that of the offsets 2I of the return bends I9 so that the outflow from the last pipe 6 is controlled in like manner and to the same extent as from the other pipes 6.

Thus in the absence of some vcause such as release of gas yand flow thereof through the tubes 6., each tube 6 individually may accumulate therein a quantity of liquid to a sufficient level to completely illl the tube since the level at which each tube overflows substantially coincides with the top of the passageway through the tube. However, the amount of liquid refrigerant that will occupy each tube at a given time -will depend upon the relative rate of fiow of the liquid refrigerant through the expansion valve and evaporation thereof in the coil, and, moreover, as evaporation occurs in the tubes, the released gas will lower the level ofthe liquid to provide space for accumulation and outflow of gas, and this effect will be cumulative in successive tubes in the respect that the liquid level in each succeeding tube will be such as to accommodate the gas released therein and also that released in and passing therethrough from the preceding tubes. this trapping effect of the rises 20, 2I and 24-26, however, being such, and the .supply of liquid refrigerant being preferably regulated so as to maintain aquantity of liquid in all of the tubes 6.

'I'hus in each tube a substantial area of the tube surface is below the level of the liquid refrigerant trapped therein and, moreover, the turbulence of the liquid that occurs as evaporation ltakes place causes a wetting of' the tube surface above the liquid level and substantially the entire inside surface of each tube is thus maintained in a wet condition so that .evaporation takes place in like manner over the entire inside surface of each tube and maximum heat absorption, as well as uniform temperature condition of all the tubes, is thus assured. Moreover, upon interrupting theoperation of the compresser, since liquid refrigerant has been accumulated in all the tubes, each tube not onlyhas a prolonged cooling effect, due to the presence of a quantity of cold liquid refrigerant therein, but the evaporation that occurs after the com,- pressor has stopped is participated in by the liquid in all the tubes so that uniform heat absorp'tion conditions prevail throughout all the tubes and there is accordingly no variation of tube temperature such as occurs during the oif' cycle with other cooling units in which the liquid refrigerant at that time drains to and evaporates in the low'er tubes, thereby imparting to these lower tubes a lower temperature than that vof the upper tubes and causing a pocketing of the warmer gases in the upper tubes. Furthermore, with my individually trapped tube arrangement, when the compressor resumes operation and pressure in the coil is thereby reduced, the trapped ,refrigerantin each tube immediately and uniformly responds to the reduction of pressure and all the tubes are accordingly uniformly and siy multaneously cooled.

Various means may be employed to accomplish the trapping effect of the distorted return bends that are shown herein, as, for example, plain return bends may be employed instead of the oil'set return bends I0 in-which case the offsetsin the return bends I9 will serve to accumulate liquid refrigerant in each pair of pipes that are at the same level, or each tube 6 may slope upwardly to its outlet end so as to trap liquid therein, or offsets may be provided in the tubes 6 instead of at the return bends,l or other fonns of return bends lmay be employed, or any other -means may be provided to step up the duct or coil at suitable places or intervals to trap liquid in selected vparts of the duct or coil. Also other types of cooling -units-or arrangements of coils or tubes may be employed, such for example as cast coils and either with or without ns as desired.

c Therefore, while I have shown and described my invention in a preferred form, I am aware vthat various changes and modifications may be made without departing from the principles of my invention, the scope of which is to be determined by the appended claims.

I claim as my invention:

1. A cooling unit having a pair of horizontal, laterally spaced tubes at the same elevation, and la. return bend connecting corresponding ends of the tubes and having a passageway therethrough from one tube to the other, said passageway being elevated substantially midway be' tween the tubes to form a dam obstructive to flow of liquid from either tube to the other.`

2. A cooling unit having a pair of horizontal, laterally spaced tubes at the same elevation, and a return bend connecting corresponding ends of the tubes and having a passageway therethrough from one tube to the other, said passageway being elevated substantially midway between the tubes to the level of the top'of the tube openings to forni a dam obstructive to ow of liquid from either tube to the other.

3. A cooling unit of the class described, comprising an upright group of tubes divided into pairs of substantially parallel' tubes, the members of each pair of tubes being in a substantially horizontal plane, a bend connecting the.

outlet end of the inlet tube of each pair of tubes to the inlet end of the discharge tube of the same pair of tubes and provided with an upwardly directed oiset, and an upright bend connecting the outlet end of each discharge tube of each pair of tubes to the inlet end of the inlet tube of the next adjacent lower pair of tubes and provided with an uprightly directed offset, the offset in the respective bends constituting dams obstructive to the ilow of liquid.

4. A cooling unit comprising an upright group of tubes divided into substantially horizontal pairs wherein the tubes of each pair are at the same elevation, return bends connecting tubes of each pair at one end of the unit,each return Y bend being provided with an upwardly extending offset forming a dam obstructive to ow of liquid between said tubes, and upright return -bends connecting tubes at diierent elevations at the opposite end of the umt and provided with upwardly extending offsets to form dams obstructive to ow of liquid from the higher tube to the lower tube.

' HERMANN J. KRACKOWIZER.

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