US2145721A

US2145721A - Flooded evaporator

Info

Publication number: US2145721A
Application number: US116619A
Authority: US
Inventors: Clarence B Hall
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1936-12-18
Filing date: 1936-12-18
Publication date: 1939-01-31
Anticipated expiration: 1956-01-31

Description

Jan. 31, 1939. c. B. HALL FLOODED EVAPORATOR Filed Dec. 18, 1936 Inventor H, w a H m o B 3m QAQA n e r m c Patented Jan. 31, 1939 V UNITED STATES FLOODED EVAPORATOR Clarence B. Hall, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application December 18, 1936, Serial No. 116,619

9 Claims.

My invention relates to evaporators for refrigerating machines of the type employing a liquefiable refrigerant and a liquid lubricant. v

Refrigerating machines, particularly those of the hermetically sealed type, employing liquefiable refrigerant are commonly provided with a liquid lubricant such as a refined mineral oil which is supplied to the working parts of the mechanism. During the operation of the refrigerant compressor some of the lubricant is unavoidably entrained with the refrigerant and discharged from the compressor so that it is carried in the form of a mist to the condenser where the compressed refrigerant is liquefied. The liquid refrigerant and the lubricant therefor become mixed and the mixture is admitted to the evaporator through the expansion valve. The lubricant and liquid refrigerant may form only a mechanical mixture or they may be partially or wholly soluble and form a solution. If a mixture is formed the lubricant may be separated by gravity and then be withdrawn from the surface of the liquid refrigerant and returned to the compressor When the lubricant and refrigerant form a solution the separation is rendered somewhat more difficult but can be accomplished by withdrawing small amounts of the solution from the evaporator and heating the withdrawn solution to evaporate the refrigerant before the solution can reach the compressor. Whether a mechanical mixture or a solution is formed between the lubricant and liquid refrigerant it is necessary to prevent slugs of liquid from entering the suction line and being drawn into the compressor with possible injury to the mechanism. For this reason an arrangement must be provided for preventing the splashing or surging into the suction line of the liquid in the evaporator. Furthermore, when the liquid refrigerant and lubricant form a mechanical mixture it is desirable to provide a quietzone of liquid in order to facilitate the separation by gravity of the lubricant and the liquid refrigerant. Accordingly, it is an object of my invention to provide a flooded evaporator for refrigerating machines of the type employing a iiquefiable refrigerant and a liquid lubricant, and having an improved arrangement of simp1ified construction for preventing the entrance into the suction line of slugs of liquid regardless of boiling and surging of the liquid refrigerant in the evaporator.

Another object of my invention is to provide a flooded evaporator for refrigerating machines of the type employing a liquefiable refrigerant and a liquid lubricant having an improved baiile constructed of a single plate for facilitating the separation of lubricant from the liquid refrigerant.

Another object of my invention is to provide an improved method for constructing a chamber 6 for facilitating the withdrawal of lubricant or other liquid from the header of an evaporator.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty 10 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 draw- 16 ing in which Fig. 1 is a perspective view of an evaporator embodying my invention; Fig. 2 is an enlarged perspective view of a portion of the evaportor shown in Fig. 1, partly in section, showing the bafile construction; and Fig. 3 is an en- 20 larged sectional view on the line 33 of Fig. 2.

Referring now to the drawing in Fig. l, I have shown a U-shaped evaporator 9 constructed of two sheets of metal [0 and Ii providing a double walled structure. The outer sheet Ii is provided 25 with indentations forming one side ll of a header 8 and a plurality of depending refrigerant circulating U-shaped passages l3 communicating at their upper ends with the header. The sheet I0 is provided with an indentation i4 clearly shown in 30 Fig. 3 which, together with the indentation I2 in the sheet ll, forms a substantially cylindrical header extending across the top of one side of the evaporator. In the bottom of the evaporator is provided a manifold i5 connected by ducts I5 to the lower ends of the passages l3. The refrigerant is supplied to the manifold l5 through a passage i! to which is connected 8. liquid refrigerant supply line [8. Liquid and gaseous refrigerant is, therefore, injected into the passages I3 through the ducts Hi to produce a circulation of refrigerant in the passages. Refrigerant vaporized in the evaporator is withdrawn therefrom through a suction conduit l9 which enters the header 8 through the indentation (2. The liquid refrigerant within the header is normally maintained at a level indicated at 20 in Fig. 3, approximately half filling the header.

The arrangement of the indentations forming the header and circulating passages of the 5g evaporator shown in Fig. 1 is not my invention but is the invention of Christian Steenstrup, and is described and claimed in his copending application, Serial No. 98,456, filed August29, I936, and assigned to the General Electric Company,

the assignee of this present application. I do not, therefore, herein claim anything claimed in the said Steenstrup application which is to be regarded as prior art with respect to this present application.

During operation of the evaporator the absorption of heat and the consequent vaporization of liquid refrigerant withinthe evaporator results in violent agitation of liquid in the header. In order to prevent slugs of liquid from entering the suction line |9 I provide a baffle plate 2| constituting a barrier between the suction line and the refrigerant circulating passages and forming an elongated chamber about the open end of the suction line within the header. The baiiie plate 2| extends partially below the level of liquid refrigerant and comprises a single plate extending longitudinally of the header for a portion of the length thereof and substantially diametrically across the header at an angle of less than degrees to the horizontal; the bame is provided with integral end pieces 22, which are bent toward the indentation I2 and are provided with arcuate edges 23 conforming to the inner wall of the indentation. The sides of the baffle are provided with upper and lower longitudinal tabs 24 and 25, respectively. The tab 24 is arranged to contact the inner wall of the header throughout its width, while the tab 25 contacts the inner wall over only a portion of its width. It will be noted that the body portion of the baiile 2| is of somewhat lesser width than the diameter of the header and that the tab 25 bridges the space between baiiie and the wall of the header. The purpose of this construction will be explained later. The end pieces 22 do not entirely close the ends of the semi-cylindrical chamber formed by the baffle 2|, but are cut off on a line 25, so that an opening is left at the top of the baffle through which is aflorded free passage of gaseous refrigerant between the chamber and the header. The end plates 22 are further provided with restrictedslots 21 extending above and below the level of liquid refrigerant and affording communication between the header and the chamber defined by the baffle. Tabs 28 may be provided on the end pieces 22 as shown to secure the end pieces to the inner wall of the header; however, these tabs are not essential to the structure.

When constructing the evaporator shown, the sheets of metal l0 and H are stamped to provide indentations forming the header and passages as described above, and the baffle plate 2| is cut and bent to the form illustrated and is then secured to the inner wall of the indentation |2 by welding, brazing or any other suitable manner, so that the tab 24 is securely held in place. The sheets l0 and H are then pressed together so that the complementary indentations l2 and I4 come together to form the header 8 about the baffle 2|. When the sheets l0 and H are thus brought together a longitudinal portion 29 of the tab 25 engages the inner wall of the indentation |4.-

The tab 25 is sprung outward slightly so that when the walls are brought together the baiile is forced into place, the arcuate portions 23 being forced against the inner wall of the indentation l2.

The arrangement of the plate 2| at an angle of less than 90 to the horizontal obviously facilitates this method of assembly since the baffle is thus arranged so that it may transmit force from one side of the header to the other and be held in place thereby. The walls in and II are then secured together and sealed by welding them around the header and between the refrigerant circulating passages, the edges of the sheet l0 being bent around the sheet II, as shown. The sheets are then bent to the U-shaped form of the evaporator as shown in Fig. 1. It will be noted that when the bailie 2| is secured in place by the method just described, the tab 25 is slightly bent or deformed and resiliently holds the baflie against the walls of the header, and the baffle plate, including the and pieces and the longitudinal tabs 24 and 25, conforms substantially throughout its periphery with the inner walls of the header.

During the operation of the evaporator the oil, if separable by gravity from the liquid refrigerant, collects on the surface of the liquid refrigerant within the header l8 and flows through the slots 21 into the quiet zone of liquid within the battle 2|; and when a sufficient amount of oil has col lected it is withdrawn in small amounts with the vaporized refrigerant through the suction conduit l9. If the refrigerant and lubricant form a solution, small amounts of this solution will be withdrawn in a like manner through the conduit l9. Violent agitation and rising and falling of the level of liquid refrigerant within the header, because of boiling and surging of refrigerant within the depending passages of the evaporator, will have little or no effect on the liquid within the baflie 2| and a quiet zone of liquid will be maintained within the chamber defined by the baille regardless of surging or boiling within the header. A suflicient volume of gas or vaporized refrigerant passes through the openingsat the top of the end pieces 2|, so that the pressures are substantially equalized within the header and the chamber within the baffle.

From the foregoing it is apparent that I have provided a simple and eflective arrangement for facilitating the removal of small amounts of lubricant or of a solution of liquid refrigerant and lubricant from the header of a flooded evaporator and for preventing the admission of slugs of liquid to the suction line. It is also apparent that I have provided a greatly simplified method for assembling a bailie within the header of a flooded evaporator.

While I have shown one embodiment of my invention in connection with evaporators for household refrigerating machines, other modifications will occur 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:

l. A flooded evaporator for refrigerating machines of the type employing a liqueflable refrigerant and a liquid lubricant and having an elongated header, means including a suction conduit communicating with said header for removing therefrom gaseous refrigerant and small amounts of liquid, and means including a baiiie plate arranged longitudinally in said header and extending substantially diametrically across said header and partially below the normal level of liquid refrigerant therein for providing a chamber within said header about the end of said suction conduit, said baiiie having an opening therein affording communication between said header and said chamber above and below the level of liquid refrigerant therein.

2. A flooded evaporator for refrigerating machines of the type employing a liqueflable rea iii frigerant and a liquid lubricant and having an elongated header, means including a suction conduit communicating with said header for removing therefrom gaseous refrigerant and small amounts of liquid, and means including a baffle plate arranged longitudinally in said header and extending substantially diametrically across said header at an angle of less than 90 to the horizontal and partially below the normal level of liquid refrigerant therein for providing a chamber within said header about the end of said suction conduit, said baffle having an opening therein affording communication between said header and said chamber above and below the level of liquid I refrigerant therein.

3. A flooded evaporator for refrigerating machines of the type employing a liqueflable refrigerant and a liquid lubricant and having a substantially cylindrical header, means including a suction conduit communicating with said header for removing therefrom gaseous refrigerant and small amounts of liquid, and means including a baffle plate arranged within said header and cooperating with the walls thereof to form a semi-cylindrical chamber within said header partially below the normal level of liquid refrigerant therein for providing a quiet zone of liquid about the end of said suction conduit, said baflie having an opening therein affording communication between said chamber and said header above and below the level of liquid refrigerant therein.

4. A flooded evaporator for refrigerating machines of the type employing a liqueflable refrigerant and a liquid lubricant and having an elongated header, means including a suction conduit communicating with said header for removing therefrom gaseous refrigerant and small amounts of liquid, and means including a baffle plate arranged longitudinally in said header and extending substantially diametrically across said header and partially below the normal level of liquid refrigerant therein for providing a chamber within said header about the end of said suction conduit, said baiileplate having end pieces extending therefrom to the side walls of said header to enclose said chamber, at least one of said end pieces being provided with a restricted slot affording communication with said header above and below the level of liquid refrigerant therein.

5. A flooded evaporator for refrigerating machines of the type employing a liqueflable refrigerant and a liquid lubricant and having an elongated header, means including a suction conduit communicating with said header for removing therefrom gaseous refrigerant and small amounts of liquid, means including a baffle plate arranged longitudinally in said header and extending substantially, diametrically across said header and partially'below the normal level of liquid refrigerant therein for providing a chamber within said header about the end of said suction conduit, said baflle having an opening therein affording communication between said header and said chamber above and) below the level of liquid refrigerant therein, and means including longitudinal tabs formed on said baffle plate for securing said plate within said header.

6. A flooded evaporator for refrigerating machines of the type employing a liqueflable refrigerant and a liquid lubricant and having an elongated header, means including a suction conduit communicating with said header for removing therefrom gaseous refrigerant and small amounts longitudinally in said header and extending substantially diametrically across said header and partially below the normal level of liquid refrigerant therein for providing a chamber within said header about the end of said suction conduit, said baflie plate being of slightly lesser width than said header, and means including a longitudinal tab formed on said plate for extending said plate to the walls of said header and for resiliently maintaining said plate in position within said header, said baflle having an opening therein affording communication between said header and said chamber above and below the level of liquid refrigerant therein.

7. A flooded evaporator for refrigerating machines of the type employing a liqueflable refrigerant and a liquid lubricant and including a header, means for providing a plurality of refrigerant circulating passages communicating with said header below the level of liquid refrigerant therein and depending therefrom, means including a suction conduit entering said header for removing gaseous refrigerant and lubricant therefrom, and means including a baflle plate arranged within said header partially below the level of liquid refrigerant therein and having portions contacting the interior walls of said header and cooperating with the walls of said header for providing a chamber within said header about the end of said suction conduit, said plate constituting a barrier between said suction conduit and said refrigerant circulating passages, a portion of said plate having a restricted opening therein extending above and below the normal level of liquid refrigerant and affording communication between said header and said chamber.

8. In an evaporator of the flooded type constructed of sheet metal providing complementary portions ofa double wall structure and having a header formed by at least one indentation in said sheet metal, the method of providing a separating chamber within said header, which comprises forming a baille plate of resilient material to conform over a portion of its periphery to the shape of the inner walls of said header, securing a portion of said baflle to one inner wall of said header prior to assembly of said header, pressing said bafile into place by pressing together said complementary portions of said double wall structure to deform a portion ofsaid bailie and resiliently press said portion of said periphery in place against said wall, and thereafter securing together and sealing said sheet metal portions.

9. In an evaporator of the flooded type constructed of sheet metal providing complementary portions of a double wall structure and having a substantially cylindrical header formed by at.

;by the other one of said tabs forces said baflie into position and is deformed to maintain it resiliently in place, and thereafter securing togather and sealing said sheet metal portions. of liquid,meansincluding a baffle plate arranged r CLARENCE B.