US2953906A - Refrigerant flow control apparatus - Google Patents

Description

Sept. 27, 1960 L. K. QUICK 2,953,906

REFRIGERANT FLOW CONTROL APPARATUS Filed May 9, 1955 p i f5 FXPANS/ON z I V41. v5 1 EVHPORA TOR /Z CONDENSER 4 COMP/965501? 3 45 44 38 55 I 3 5 34 INVENTOR. ZESTER K QU/CK ATTOR Yf 1/ 5 :nomical in construction, l dent in operation.

' device of adapting United rates Patent- 2,953,906 REFRIGERANT FLow CONTROL APPARATUS Lester K. Quick, 1416 W. 7th Ave., Eugene, Oreg.

Filed May 9, 1955, Ser. No. 506,784

I '8 Claims. or. 6281) This invention relates to refrigerating apparatus and more particularly to improvements in the manner of retturriing gaseous and liquid refrigerant to the compressor inf :such apparatus during hot gas defrosting operations. application is a continuation-in-part of the applicanon, Serial "No. 436,784, filed by me in the United States Patent Office on or about June 15, 1954, and now abandoned.

The apparatus of the invention is particular useful in connection with refrigerating systems which employ hot gas defrosting. In such systems, portions of the hot gases passing through the evaporator or refrigerating coil are condensed to form slugs of liquid refrigerant which, if permitted to pass to the compressor, result in damage to the apparatus and possible injury to persons who may be near at hand.

The principal object of the present invention is the provision of apparatus which will eliminate the possibility of damage to refrigerating systems by slugs of liquid refrigerant discharged from the evaporator or refrigerating coil.

A further object of the invention is the provision of apparatus of the indicated type which will permit the unrestricted return of gaseous refrigerant from the evaporator to the compressor and a controlled return of liquid refrigerant.

A still further object of the invention is the provision of apparatus of the indicated type which, during hot gas defrosting, will effect a controlled rate of reevaporation of the liquid refrigerant flowing back from the evaporator to the compressor.

Another object of this invention is to provide in a refrigeration system, means which will return liquid refrigerant to the compressor at a controlled rate when the refrigerating system is being utilized for the defrosting of the evaporator thereof through the delivery of hot refrig- .,erant from the compressor to the evaporator.

Still another object of the invention is the provision of a d vice of the indicated type which is simple and ecoeasy to install, and highly efli' A further object of the invention is the provision of a the indicated type which is compact, thereby it for close installations and which is further r-characterized by the complete absence of any moving :par-ts thereby adapting it for continuous operation over (extended periods of time without servicing of any kind.

These and other objects and advantages of the invention will become more apparent from the following detailed description, taken with the accompanying drawings, -wherein:

Figure 1 is a diagrammatic view of a refrigerating sys- :tem embodying the apparatus of the present invention.

Figure 2 is a vertical cross-sectional view of one form 40f apparatus in accordance with the invention.

Figure 3 is a vertical cross-sectional view of a modiffied form of apparatus in accordance with the invention.

In the preferredembodiment of my invention I have diagrammatically illustrated a refrigeration system in which I have incorporated diagrammatically the factors embodying my invention and wherein the hot gas from the compressor may be delivered directly to the coiling or conduits of the evaporator when desired to effect defrosting of the coil or surfaces of the evaporator. During this operation the evaporator functions in a manner similar to the condenser in the normal refrigeration cycle so that the gaseous refrigerant used to elfect the defrosting is condensed, or at least a portion thereof may be condensed, depending upon the quantum of heat 'required to raise the temperature of the evaporator surface sufl iciently to eifect the defrosting operation. This condensed refrigerant is, in accordance with my invention, metered, i.e., returned at a controlled rate to the compressor and at such rate as may be handled by the compressor without damage thereto, avoiding the passing to the compressor of a slug of refrigerant which would be extremely detrimental thereto. As illustrated in Figure 1, the evaporator is designated by the numeral 10 and this evaporator may be of any of the conventional forms, either tube or plate, as desired.

The evaporator is normally supplied with liquid refrigerant from the condenser 14 through the expansion valve 15. The compressor 11 supplies gaseous refrigerant under compression through the condenser through a line 12. The refrigerant after evaporation in the evaporator is returned to the compressor 11 through a return or low pressure line 13.

In accordance with my invention, when frost has accumulated on the surface of the evaporator, the hot gas from the compressor ll is lay-passed around the condenser 14 and expansion valve 15 through a by-passed defrost line 16. This lay-passing may be controlled by means of a simple valve 17. The hot gas entering the evaporator gives up its heat to the surface thereof with the result that the surface is raised above the freezing point of water and the ice melts upon the surface and is eliminated therefrom. A portion of the hot gas which has given up heat may be condensed to a liquid as it is under the compressor pressure. The evaporator 10 during this defrosting operation functions similarly to the condenser 14 during normal refrigeration cycling. The refrigerant including that portion which has been condensed passes through the refrigerant return line .13 and if allowed to return to the compressor, would deliver to the compressor the slug or slugs of liquid refrigerant container 60 may have any desired shape, for example,

circular, rectangular or the like, and is formed of a ma terial having the requisite strength, as well as resistance to corrosion by the refrigerant. The closure 19 may, if desired, be formed as a removable cap secured to the container in any suitable manner, as by nuts and bolts. A fluid-tight joint will, of course, be provided.

The closure 19 has associated therewith an inlet con duit 20, connected to the return line from the evaporator,

and an outlet conduit 21 connected to the return line to the compressor. The inlet conduit 20 extends downwardly through the closure 19 and'preferably' has its discharge end 22 positioned in the upper portion of the casing, as shown.

The outlet conduit 21 likewise extends downwardly through the closure 19 and is formed within the container with a reversely bentportion 23 consisting of leg portions 24 and 25 connected at their lower ends by a curved or bight portion 26. The intake end 27 of the outlet conduit is disposed in the upper portion of the container so as normally to be above the level of any liquid therein, and is alsopreferably disposed somewhat above the discharge end 22- .of the inlet conduit 29. The curved or bight portion 26 is disposed in the lower portion of the container and is provided with an opening 26' fora purpose to be described.

During the defrosting operation, gaseous and liqujd refrigerant from the evaporator returnthrough the line 13 and inlet conduit 20 into the container 60. The gaseous refrigerant thenpasses into the intake 27 of the outlet conduit 21 and the liquid refrigerant collects in the container. In the arrangement described, it will be apparent that the passage of gaseous refrigerant through the container is substantially unrestricted.

As the liquid refrigerant accumulates in the container it is withdrawn therefrom at a controlled rate and returned to the compressor, along with the gaseous refrigerant, by a novel arrangement now to be described. Secured within the opening 26, in any suitable manner, is a capillary tube 28 having an intake end 29 and a discharge end 30. The intake end 29 of the capillary tube is disposed exteriorly of the outlet conduit 21 and is preferably enclosed with a screen 31 of a fineness such as to prevent the entry of particles having a tendency to clog the capillary tube. The discharge end 30 extends into the outlet conduit into the path of gaseous refrigerant flowing therethrough and has its open end disposed in the direction of such flow. The discharge end 30 is preferably disposed at one side of the curved or bight portion 26.

During operation of the device, the flowof gaseous refrigerant around and past the discharge end 30 sets up a suction in the capillary tube which is communicated to the intake end 29. Thus, when the level of liquid in the container is up to, or above, the intake end 29, liquid is aspirated through the tube in controlled amounts. The liquid refrigerant discharged from the tube is, for the most part, evaporated and any portion not evaporated, along with any oil, is in such small amountsas to have no tendency whatsoever to damage the compressor.

In the modified form of the invention shown in Figure 3, the numeral 60 designates a container having a bottom closure 32 and a top closure 33 which may, as before, be removable. In this form of the invention, the inlet and outlet conduits 34 and 35 preferably pass through the side wall 36 of the container and, as shown, are oppositely disposed. The discharge end 37 of the inlet conduit 34 is turned downwardly and, as before, extends somewhat below the intake end 38 of the outlet conduit 35. As in the previously described embodiment, gaseous refrigerant passes through the container substantially free and unrestricted while liquid refrigerant collects therein and is fed therefrom at a controlled rate by the capillary tube 39.

The tube 39 may be secured in the container 36 in any suitable manner as by the brackets 40. The intake end 41 of the tube 39 is enclosed with a screen 42 and while shown at the bottom of'the container can obviously be located at any desired point below the intake 38 of the outlet conduit 35. The discharge end 43 of the tube.39 extends into the outlet conduit 35 through the intake 38 thereof and has its open end disposed in the direction of flow of gaseous refrigerant therethrough. As before, the flow of gaseous refrigerant through the outlet conduit 35 past and around the end of the capillary tube 39 will set up a suction in the tube 39 so that a controlled amount of liquid will be aspirated therethrough for discharge'into the gaseous refrigerant blowing through the outlet conduit. Also, as before, most of the liquid refrigerant discharged from the capillary tube into the flowing gaseous refrigerant passing through the outlet conduit will be reevaporated and returned to the compressor in gaseous form.

To further increase the suction effect at the discharge end 38 of the capillary, the outlet conduit 35 may be provided with a Venturi type constriction 44 surrounding the open end of the tube, as shown. As is well known, the increase in velocity of the flowing stream of gaseous refrigerant as it passes through the constricted portion 44 produces a corresponding reduction in pressure at this point which, as indicated, further increases the suction already existing in the outlet conduit.

It will thus be seen that the present invention provides simple, economical and highly effective apparatus for the intended purpose. In both embodiments of the invention, gaseous refrigerant is returned to the compressor at substantially the same rate it is discharged from the evaporator while the liquid refrigerant is trapped and returned to the compressor at a controlled rate and under conditions such that there is no damage to the compressor. The rate of return of liquid refrigerant will depend, of course, on the size and length of the capillary tube and the degree of suction exerted thereon. By proper control of these factors the rate of return of liquid may be regulated, as desired.

In a preferred embodiment the intake ends of the capillary tubes are disposed adjacent the bottoms of the containers. It will be appreciated, however, that these may be disposed at any desired point in the container below the intakes of the outlet conduits.

While preferred embodiments of the invention have been illustrated and described herein, the invention is not to be construed as limited to the specific details disclosed except as included in the following claims.

I claim:

1. A method of operating and defrosting refrigerating apparatus comprising, the steps of; compressinga gaseous refrigerant, passing said compressed refrigerant gas through an evaporator to defrost the same, withdrawing gas and condensed liquid from said evaporator, collecting said condensed liquid in a body, establishing a stream of said withdrawn gas and directing said stream to flow away from said body of liquid from a point thereabove, metering liquid from said body into said stream flowing away from said body at a predetermined rate, and Without substantial re-evaporation of the said liquid and recompressing said stream of gas and liquid to repeat said cycle.

2. In a refrigerating system providing hot gas defrosting and employing a compressor, a condenser, an expansion valve, and an evaporator, said system having a conduit from said compressor to said evaporator for bypassing the condenser and expansion valve during the defrosting cycle: an accumulator trap positioned in the return line from the evaporator to the compressor comprising a closed container; an inlet conduit for the container adapted to deliver gaseous and/ or liquid refrigerant from the evaporator thercinto; an outlet conduit for delivering refrigerant from said container to the compressor, said outlet conduit having a reversely-bent substantially U-shaped portion disposed in the container and having an intake for gaseous refrigerant disposed in the container above the normal level of liquid therein whereby the gaseous refrigerant passes directly through the container while the liquid refrigerant collects therein; and means in the said U-shaped portion adjacent the lower section thereof below the level of liquid refrigerant in said container for admitting liquid therethrough for discharge into said outlet conduit at a uniformly slow rate.

3. In a refrigerating apparatus, a compressor, a condenser for condensing compressed gas to a liquid, an evaporator connected to said condenser through an expansion means, a bypass means for selectively conducting compressed gas from said compressor to said evaporator for defrosting the same, a return line from said evaporator to said compressor, a trap in said return line and comprising a closed chamber, said return line having an inlet leg and an outlet leg communicating with said chamber, at least said outlet leg having an open end in said chamber above the level of any liquid therein, means defining a metering passageway for conducting liquid refrigerant from adjacent the bottom of said chamber into said outlet, the liquid refrigerant in said chamber being metered into said outlet leg at a controlled rate to return normally as a stream of gas and liquid to said compressor without substantial re-evaporation of said liquid.

4. In a refrigerating apparatus, a compressor, a condenser for condensing compressed gas to a liquid, an evaporator connected to said condenser through expansion means, a by-pass means for selectively conducting compressed gas from said compressor to said evaporator for defrosting the same, a return line from said evaporator to said compressor, a trap in said return line and comprising a closed chamber, said return line having an inlet leg and an outlet leg in said chamber, each of said legs having an open end in said chamber above the bottom thereof, a metering conduit in said chamber having one end thereof adjacent the bottom of said chamber and extending upwardly therefrom with its other end extending into said outlet leg and facing in the direction of gas flow therein whereby any liquid refrigerant in the bottom of said chamber is aspirated into said outlet leg at a controlled rate.

5. Apparatus as defined in claim 4 wherein said metering conduit comprises a capillary tube.

6. Apparatus as defined in claim 4 wherein said outlet leg is provided with a 'Venturi restriction therein surrounding said other end of said metering conduit.

7. A method of operating and defrosting refrigerating apparatus comprising, the steps of; compressing a gaseous refrigerant, passing said compressed refrigerant gas through an evaporator to defrost the same, withdrawing gas and condensed liquid from said evaporator, collecting said condensed liquid in a body, establishing a stream of said withdrawn gas and directing said stream to flow adjacent and above said body of liquid, and causing flow of said gas in said stream to aspirate liquid upwardly from said body into said stream at a predetermined rate and then without substantial re-evaporation of said liquid recompressing said stream of gas and liquid.

8. In a refrigerating apparatus, a compressor, a condenser for condensing compressed gas to a liquid, an evaporator connected to said condenser through expansion means, a by-pass means for selectively conducting compressed gas from said compressor to said evaporator for defrosting the same, a return line from said evaporator to said compressor, a trap in said return line and comprising a closed chamber, said return line having an inlet leg and an outlet leg communicating with said chamber, each of said legs having an open end in said chamber above the level of any liquid within the chamber, a metering conduit in said chamber having one end thereof adjacent the bottom of said chamber and extending upwardly therefrom with its other end extending into said outlet leg and arranged therein whereby liquid refrigerant in the bottom of said chamber is aspirated into said outlet leg at a controlled rate to return normally as a stream of gas and liquid to said compressor without substantial re-evaporation of said liquid.

References Cited in the file of this patent UNITED STATES PATENTS 2,530,440 Nussbaum Nov. 21, 1950 2,534,032 Kollsman Dec. 12, 1950 2,589,855 Pabst Mar. 18, 1952 2,614,402 Swart Oct. 21, 1952 2,641,908 La Porte June 16, 1953 2,701,455 Kleist Feb. 8, 1955 2,787,135 Smith Apr. 2, 1957

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