US2779170A

US2779170A - Evaporator circuit

Info

Publication number: US2779170A
Application number: US437252A
Authority: US
Inventors: Jr Douglas A Solley; Frank A Schumacher
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1954-06-16
Filing date: 1954-06-16
Publication date: 1957-01-29
Anticipated expiration: 1974-01-29

Description

Jan. 29, 1957 D. A. SOLLEY, JR., ET AL 2,779,170

EVAPORATOR CIRCUIT Filed June 16, 1954 FIG.4

INVENTOR. DOUGLAS A. SOLLEY, JR.

' FRANK A. SCHUMACHER THEIR ATTORNEY United States Patent EVAPORATOR CIRCUIT Douglas A. Solley, Jr. and Frank A. Schumacher, Erie,

Pa., assignors to General Electric Company, a corporation of New York Application June 16, 1954, Serial No. 437,252

1 Claim. (Cl. 62-126) This invention relates to evaporator construction and, more particularly, to a refrigerant system for household refrigerators.

Household refrigerators should operate satisfactorily in widely varying ambient temperatures. Thus, a refrigerator may be disposed on the exterior of a house, such as a back porch, where it will be located in an average ambient temperature during the winter considerably lower than if it were disposed inside of the house; and the reverse, of course, would be true during summer. It is necessary to design the refrigerating system of a household refrigerator to meet these varying conditions of operation; more particularly, the charge of the refrigerating medium in a refrigerating system must be sufiicient to circulate properly in the refrigerator evaporator in low ambient temperatures and, similarly, the charge must not be too great as to cause liquid refrigerant to excessively flood past the evaporator in high ambient temperatures.

The present invention provides an inexpensive and efiicient arrangement for the refrigerating system of a household refrigerator that will allow for a large varying ambient temperature without the entire evaporator becoming loaded with liquid refrigerant to such an extent that the liquid refrigerant will be flooding past the evaporator for an excessive length of time whenever the system is operating.

A primary object of the present invention is to provide a vertical header for the refrigerant circuit of an evaporator that will permit the refrigerant charge to be operated under extreme load conditions with the result that only the liquid level of the refrigerant in the header varies as the load conditions vary.

An object of this invention is to provide an improved refrigerant circuit for an evaporator.

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

In accordance with this invention, an evaporator is provided which is defined by a series of walls. A refrigerant circuit is disposed about certain of these walls. This circuit includes a vertical header into which one end of the circuit extends. An outlet conduit is connected with the header, these two parts being so arranged that in the operation of the system, refrigerant vapor is withdrawn by the refrigerant compressor from the header through the outlet; and so that any liquid refrigerant in the vapor is separated in the header before the vapor is withdrawn. In the usual way this vapor is converted to liquid by the operation of the compressor and associated condenser and restrictor system, and the liquid is returned to the evaporator circuit at a low point therein remote from the header. The refrigerant is thus circulated through the refrigerant circuit, the header functioning to separate the liquid from the vapor, and the level of liquid in the header at any time depending automatically upon the cooling load im- 2,779,170 Patented Jan. 29, 1957 posed on the evaporator, and hence upon the ambient temperature.

'For a better understanding of this invention reference may be had to the accompanying drawing, in which:

Fig. 1 is a plan view of the refrigerant circuit of an evaporator embodying the present invention;

Fig. 2 is an enlarged fragmentary sectional view of a portion of the evaporator taken along the line 2-2 of Fig. 3;

Fig. 3 is a side elevational view of the evaporator; and

Fig. 4 is a diagrammatic view of the refrigerant system.

Referring to the drawing and particularly Fig. 1, this invention has been shown in one form as applied to a refrigerator having an evaporator 1 including a top wall 2, a back or rear wall 3, a bottom wall 4, and side walls 5. In order to form the usual open fronted box type of evaporator, it will be understood that the portions of the evaporator are folded along the dotted lines 6. The walls of the evaporator are then joined together by suitable means such as welding to form the unitary structure.

The refrigerant circuit includes a continuous tube 7 that is disposed about the top wall 2 (Fig. 2), back wall 3, and bottom wall 4. The ends of this tube are connected to a chamber 8, which is relatively elongated in the vertical direction and has a considerably larger diameter than the tube 7. One end of the tube 7 is connected to the upper end of the chamber 8 and the other end of the tube 7' is connected to the lower end of the chamber 8 (see Fig. 2). While the tube 7 and chamber 8 are shown disposed about the top wall 2, back wall 3, and bottom wall 4, it will be understood that the tube 7 and the chamber 8 could be embedded into the walls of the evaporator, if desired. The end 9 of the tube 7 extends downwardly into the upper end of the chamber 8 for a predetermined distance.

A suction conduit 10 is connected to the chamber 8 above the end 9 of the tube 7 as shown in Figs. 2 and 3. The conduit 10 carries the vaporous refrigerant from the chamber 8 to the compressor 17 of the well-known refrigerating system; and since its entrance opening in the chamber 8 is above the upper end 9 of tube 7 liquid refrigerant is prevented from being carried out through the conduit 10 so that the compressor will not be damaged due to liquid passing therethrough. It will be understood and as shown diagrammatically in Fig. 4 the liquid refrigerant returned to the system by the compressor 17 will be fed thereto at a point located at a low level in the system, such as the opening 11. Thus vaporous refrigerant is withdrawn from the chamber 8 through suction conduit 10, is converted to liquid by the compressor 17 and the associated condenser 18 and restrictor 19 and is returned to the system as liquid at the opening 11. The refrigerant fiows through the system in a clockwise direction (as viewed in Fig. 4).

The tube 7, as shown in Fig. 2, is bent at the portion 12 to provide a trap that serves to prevent bubbles in the liquid refrigerant from flowing in a reverse direction to the desired flow. Thus, if the liquid refrigerant in the chamber 8 has suflicient elevation to provide rapid flow through the evaporator tube whereby the bubbles are unable to flow in a reverse direction, then a trap is not nec essary. The elevation of the liquid refrigerant in the chamber 8 is dependent on the height of the chamber and the weight of gas charge.

The location of the connection of the conduit 10 to the chamber 8 also permits oil that might ordinarily be trapped in the evaporator tube to be carried back to the compressor by a surge or two of liquid refrigerant at the beginning of an on cycle; that is, during the off cycle the oil collects at the top of the liquid refrigerant in the chamber 8 and is mixed therewith. When the compressor is started, refrigerant vapor is removed from the chamber 8 by the conduit resulting .in a sudden pressure. reduction in the chamber 8. This results in violent boiling of the refrigerant and the confining of the boiling refrigerant in a vertical column like the chamber 8 causes a slug of the liquid refrigerant to move rapidly upwardly. A portion of this slug, which is oil rich, is drawn into conduit 10 where the liquid refrigerant vaporizes. This results in a return to the compressor of oil that might be trapped in the evaporator. This phenomenon subsides after the initial burst. The amount of oil returned through the conduit 10 by this reaction is dependent upon the distance between the end 9 of tube 7 and the center line of conduit 10 and the diameter and. length of the chamber 8. These factors may be varied for the particular evaporator circuit.

A drier 14 is disposed in the lower portion of the chamher 8 to remove any water that may have collected in the liquid refrigerant before the liquid refrigerant is returned to the refrigerant circuit through the tube 7.

Considering the operation of the present invention, liq

uid refrigerant is supplied from the compressor 17 by means of the condenser 18 and restrictor 19 to the tube 7 through the opening 11. The liquid refrigerant supplied through the opening 11 to the tube 7 passes through the tube in the direction of the arrows (Fig. llikewise in Fig. 4) to the chamber or vertical header 8 disposed about the back wall 3. The refrigerant entering the chamber or header 8 through the tube 7 consists of both liquid and vaporous refrigerant, depending on the load on the refrigerating system. Since the outlet end 9 of the tube 7 is disposed beneath the point where the conduit 10 enters the chamber 8, it will be observed that the liquid refrigerant and vaporous refrigerant mixture is discharged downwardly away from the inlet to the suction conduit 18 so that the liquid and vapor will. separate before the vaporous refrigerant enters the conduit 10 to pass to the compressor.

Liquid refrigerant will collect in the chamber 8 with the level of the liquid refrigerant depending on the load on the refrigerating system. Thus, if a heavy load is imposed on the refrigerating system, gas bubble formation in the chamber 8 is rapid so that the level of liquid refrigerant in the chamber 8 will be high whereas if the load is low, the level of the liquid refrigerant will be low due to a reduction in the formation of gas bubbles. The drier 14 serves to remove any water that may have collected in the liquidrefrigerant.

It will be observed that the conduit 10 isbeveled so that its lower edge extends into the chamber 8 for a greater distance than its upper edge 16. This beveled end of the conduit It) prevents splashes of liquid from being carried over with the vapor into the conduit 10 and then to the compressor 17. While the conduit 10 has been shown as terminating at the back wall 3, it will be understood that the conduit 10 could extend into one of the side walls 5, if desired. While the refrigerant tube 7 has not been shown as applied to either of the side walls 5, it will be understood that portions of the tube 7 could be placed about or in either or both of the side walls 5, if desired. It .alsowill beunderstood that the side walls 50f the evaporator as well as the top wall 2 and bottom wall 4 could be eliminated, if desired.

This invention has the advantage of insuring that only dry vapor is returned to the compressor. This invention also has the advantage that a varied charge of refrigerant will operate the evaporator properly, and that a fixed charge will operate at extremely different load conditions with only the liquid level in the header varying.

Another advantage of this invention is that the diameter and length of the chamber 8 and the distance between the end 9 of the tube 7 and the center line of the conduit 10 may be adjusted for any particular evaporator circuit so that the oil, which might ordinarily be trapped in an evaporator, is carried back to the compressor by a surge or two of liquid refrigerant for a short period of time at the beginning of an on cycle.

While the present invention has been described by reference to a particular embodiment thereof, it will be understood that modifications may be made by those skilled inthe art without actually departing from the invention. Therefore, the appended claims are intended to cover all such variations as come within the true spirit and scope of the invention.

We claim:

Anevaporator construction including at least top, back and bottom walls, a refrigerant circuit including a vertically arranged chamber on the back wall and a continuous tube disposed about said top, back and bottom walls in cooling relation therewith, the ends of said tube being connected to the upper and lower ends of said chamber to provide a continuous refrigerant circuit, an opening in the portion of the tube disposed about the bottom wall through which liquid refrigerant is supplied to the circuit, a suction conduit connected to the upper part of said chamber for withdrawing vaporous refrigerant from said chamber, said chamber being of a greater diameter than said tube, the lower end of said tube being connected to said chamber below the level of liquid refrigerant therein, the upper end of said tube being connected to the upper end of said chamber and extending downwardly into the upper portion of said chamber below the suction conduit connection to discharge liquid and vaporous refrigerant into said chamber in a downward direction away from said suction conduit connection so that liquid entrained in the vaporous refrigerant is separated therefrom in said chamber priorto the withdrawal of the vaporous refrigerant' through said suction conduit.

References Cited in the file of this patent UNITED STATES PATENTS 2,172,129 Philipp Sept. 5, 1939 2,658,359 Money Nov. 10, 1953 2,665,566 Grimshaw Jan. 12, 1954 2,665,567 King Jan. 12, 1954 2,687,023 Herndon Aug. 24, 1954