US2118637A - Evaporator for refrigerating machines - Google Patents

Description

May 24, 1938. 1.. w; ATCHISON EVAPORATOR FOR REFRIGERATING MACHINES Filed March 5, 1956 n o :m 9 r e 3% 13m ew m vd 2 W O my 9 b Patented May 24, 193% ear curios EVAPORATOR FOR EEFEIGERATING MACHINES 1 Leonard W. Atchison, Schenectady, N. Y., assignor to General Electric il'iompany, a corporation of New York Application March 5,

t Claims.

My invention relates to evaporators oi the flooded type for refrigerating machines.

Evaporators of the flooded type for refrigerating machines are commonly provided with a header in which the liquid and gaseous refrigerant are separated and from which the gaseous refrigerant is withdrawn. Some or the lubricant which is utilized to lubricate the working parts of the refrigerant compressor is unavoidably carried with the refrigerant into the evaporator. It is necessary to provide some arrangement for returning the lubricant to the compressor in order to prevent a large accumulation of lubricant in the evaporator which would interfere with its operation by reducing vaporization of refrigerant and deplete the supply of lubricant available for lubricating the working parts.

When the lubricant and liquid refrigerant form an intimate mixture not separable by gravity, it

is necessary to withdraw small amounts of the mixture from the header of the evaporator and heat this portion of the mixture to evaporate the refrigerant and separate it from the lubricant. When the lubricant andliquid refrigerant are separable by gravity they may be separated within the evaporator by providing an undisturbed zone of liquid therein from the top of which the lubricant may be withdrawn with the aseous refrigerant; this prevents slugs of liquid refrigerant from entering the compressor with possible damage to the parts thereof; v

It is an object of my invention to provide a flooded evaporator for refrigerating machines having an improved arrangement for separating liquid refrigerant and lubricant, and for withdrawing the lubricant irom the evaporator.

Another object of my invention is to provide a flooded evaporator for refrigerating machines which is constructed of sheets of metal secured together and having indentations formed therein to provide a header, refrigerant circulating passages communicating with the header and a lubricant separating device between the header and. the suction line.

A further object of my invention is to provide a flooded evaporator for refrigerating machines including a header and refrigerant circulating passages and having an arrangement for separating liquid refrigerant and lubricant which is operable whether the liquid refrigerant and lu-' 1936, @erial No. W269 which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention reference may be had to the accompanying drawing, in which Fig. l is a front elevation of a household refrigerating machine provided with an evaporator embodying my invention; Fig. 2 is an enlarged perspective rear view of the evaporator showh in Fig. l; and Fig. 3 is an enlarged side elevation, partly in section, of a portion of the evaporator shown in Fig. 2.

Referring now to Fig. l, l have shown a household refrigerating machine including a thermally insulated cabinet it having a door it and provided with a thermally insulated top l2 on which is mounted a refrigerating machine. The refrigerating machine includes a closed casing IS in which is arranged a motor and a compressor, an air cooled condenser I4 surrounding the cas ing It and having a condenser conduit it formed therein, a liquid receiver or float valve chamber l6 and a U-shaped flooded evaporator II supported from the top l2 within the cabinet l0.

cabinet ill and the vaporized refrigerant is withdrawn through a suction line i9 and returned to the compressor within the casing l3.- Within the casing I3 is provided a body of a liquid lubricant, such as highly refined mineral oil, which is circulated about the working parts of the motor and the compressor to lubricate them. Some of this lubricant is unavoidably entrained in the refrigerant discharged in the compressor and finds its way through the, condenser and float chamber to the evaporator H. In order to prevent the accumulation of the lubricant within the evaporator II, it is necessary to provide some arrangement for separating the lubricant and refrigerant and for returning the lubricant to the compressor casing. The evaporator I1, is, therefore, provided with a lubricant separating chamber in which the lubricant and refrigerant are permitted to separate either by, gravity or by heating and which is so arranged that the lubricant alone will flow toward the suction line and will be withdrawn from the evaporator with the gaseous refrigerant, the liquid refrigerant in the separating chamber being evaporated before it can reach the suction line.

The construction of the evaporator and lubricant separating chamber is clearly shown in Figs. 2 and 3. The evaporator I1 is constructed of inner and outer metal sheets 20 and 2|, respectively, secured together about their edges by welding or in any other suitable manner, the edge of the sheet 20 being bent around the edge of the sheet 2|, as indicated at 22. The sheets 20 and 2! are bent in U-shaped form to provide the side and bottom walls of a freezing chamber. Therefrigerant passageways of the evaporator are formed by indentations in the sheets 20 and 2 I, and the sheets 20 and 2| are secured together by welding, brazing, or in any other suitable manner between the indentations in order to provide further strength. The two sides of the evaporator are of identical construction, each side being provided with a header 23 partially filled with liquid refrigerant wherein liquid and gaseous refrigerant are separated, and a plurality of refrigerant circulating conduits 24 are provided to connect the headers 23 and permit the circulation of liquid refrigerant about the walls of the evaporator.

The conduits 24 extend below the level of liquid refrigerant in the headers 23, so that the conduits are flooded with liquid refrigerant. Above the headers 23 are provided passages or chambers 25 communicating at one end with the headers 23 through an upright connection 26 and at their other ends remote from the header connection with a cross connection 21 to which the suction line I9 is connected. The passages 25 are inclined from the connection 26 toward the cross connection 21 and are provided on their lower sides with a plurality of pockets 28, which are arranged to trap liquid refrigerant and lubricant at successively lower levels along the passage between the header and suction line, as clearly shown in Fig. 3.

trapped in the pockets 28 at the bottom of the passage 25. The pockets 28 at the end of the passage 25 near the. connection 26 are deeper than those at the other end and the pockets are so arranged that each one will overflow into the adjacent pocket nearer the suction line and, consequently, the liquid will move toward thesuction line as more liquid is added to the pockets 23' near the connection 26. If the mixture of liquid refrigerant and lubricant'in the pockets 2! is separable by gravity the lubricant will settle out on top of the refrigerant in the pockets and, consequently, the lubricant tends to overflow from one pocket to the next while the refrigerant remains in the pockets at the bottom where it is vaporized by the absorption of heat from the walls of the evaporator and is then withdrawn through During the operation of the evaporator l| liquid refrigerant and lubricant are admitted the suction line IS with the gaseous refrigerant. Liquid refrigerant, therefore, will not reach the last pocket 28 and only lubricant will be withdrawn through the suction line. If the mixture of liquid refrigerant and lubricant is not separable by gravity there results, nevertheless, a

separation of the refrigerant and lubricant in the pockets 28 since the pockets 28 hold the mixture so that it can absorb heat from the walls of the evaporator and, consequently, refrigerant is continuously vaporized from the mixture; the mixture in the succeeding pockets as it flows toward the suction line contains less and less liquid refrigerant. By providing a sufficient length of the passage 25. and a sufficient number of the pockets 28 the separation of liquid refrigerant and lubricant may be "accomplished within the pockets so that lubricant alone reaches the last pocket and is withdrawn through the suction line. a

It is readily apparent from the foregoing that I have provided a flooded evaporator for refrigerating machines having arranged therein a simple and effective device for separating liquid refrigerant and lubricant whether the mixture of liquid refrigerant and lubricant be separable by gravity or not.

While I have shown and described my invention in connection with a flooded evaporator for household refrigerating machines, other applications will readily be apparent to those skilled in the art. I do not, therefore, desire my invention to be limited to the particular construction shown and described and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A flooded evaporator for refrigerating machines including sheets of metal secured together and having a header formed therebetween for separating liquid and gaseous refrigerant, a refrigerant circulating conduit formed between said sheets and communicating with said header, means for admitting liquid refrigerant and lubricant to said conduit, means including a suction line for withdrawing gaseous refrigerant from said evaporator, and means including a passage formed between said sheets above said header for providing communication between said header and said suction line, said last-mentioned means including a plurality of pockets communicating with. said passage for facilitating the separation of liquid refrigerant and lubricant to prevent the withdrawal 'of slugs of liquid refrigerant through said suction line.,,.

2. A flooded evaporator for refrigerating machines including sheets of metal secured together and having a header formed therebetween for separating liquid and gaseous refrigerant, a plurality of refrigerant circulating conduits formed between said sheets and communicating with said header, means for admitting to said conduits liquid refrigerant and lubricant, means including a suction line for withdrawing gaseous refrigerant from said evaporator, means including a passage formed between said sheets and communicating-at one end with said header and at the other end with said suction line for removing gaseous refrigerant and lubricant from said header, and means including a plurality of pockets formed between said sheets in said passage for trapping liquid refrigerant and lubricant and for facilitating the separation of the liquid refrigerant and lubricant to prevent the withdrawal 2,118,687 7 of slugs of liquid refrigerant through said suction line.

3. A flooded evaporator for refrigerating machines including sheets of metal secured together and having a header formed therebetween for separating liquid and gaseous refrigerant, a plurality of refrigerant circulating conduits formed between said sheets and communicating with said header, means for admitting to said conduits liquid refrigerant and lubricant, means including a suction line for withdrawing refrigerant from said evaporator, means including a passage formed between said sheets and communicating atone end with said header and at the other end with said suction line for removing gaseous refrigerant and lubricant from said header, and means including a plurality of pockets formed between said sheets and arranged to trap liquid at successively lower levels in said passage between said header and said suction line and to cause the liquid in said pockets to overflow from one pocket to another toward said suction line for facilitating the separation of liquid refrigerant and lubricant.

l. An evaporator oi the flooded type for refrigerating machines including complementary U-shaped sheet metal portions forming a plural-- ity of walls of a freezing chamber, a header formed between said sheet metal portions in each leg of said evaporator, a plurality of refrigerant circulating conduits formed between said sheet metal portions and connecting said headers, means for admitting liquid refrigerant and lubricant to said conduits, means including a passage formed between said sheet metal portions in each of the legs of, said evaporator and extending substantially parallel to and above said headers for removing gaseous refrigerant and lubricant from said headers, means including a suction line connecting said passages remote from said headers for removing gaseous refrigerant and lubricant from said evaporator, and means including a plurality of pockets arranged in said passages for trapping liquid refrigerant and lubricant and for facilitating the separation oi the liquid refrigerant and lubricant to prevent the withdrawal of slugs of liquid refrigerant through said suction line. 7

LEONARD W. ATCI'HSON.

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