US2244010A - Evaporator - Google Patents

Description

June 3, 194 B. c. JOHNSON ETAL EVAPORA TOR Filed M y 10, 1940 3 Sheets-Sheet l Jul le 3, 1941.

B; C. JOHNSON ETAL,

EVAPORATOR Y Filed 'May 10, 1940 3 Sheets-She et 2 v June 1941- 'B. c. JOHNSON ETAL 2,244,010

EVAPORATOR Filed May 10, 1940 3 Sheets-Sheefi 3 Patented June 3, 1941 UNITED STATES) PATE NT OFFICE.

Evhromrroa 7 Bernard C. Johnson, Libertyville. and Edgard C.

Franco-Ferreira, Chicago, fIll., assignors to- Houdaille-Hershey Corporation, Detroit, Mich,

a corporation of Michigan Application May [10, 1940,;Serial No. 334,306 8 Claims. (cl. 62-41%) This invention relates to sheet metal heat exchangers such as evaporator units for mechanical refrigerators and more specifically relates to wick,

constructions in evaporator units for automatically returning oil entrained in refrigerant in the evaporator unit back to the compressors of the mechanical refrigerating systems.

In refrigerating systems of the compressorcondenserevaporator type, oil from the compressor'finds its way with the refrigerant to the evaporator unit. Many devices have been proposed for trappin this oil in order that the same can be returned to the compressor for performing its lubricating function. Such devices, however, have been expensive and complicated.

The present invention now ,provides a simple,.v

inexpensive wck means for returning oil from evaporator units back to the compressor without short-circuiting the refrigerant flow or in any .way causing the flow of refrigerant back to the compressor before it has completed its heat-absorbing function.

The wick means of the present invention are especially adapted for use in refrigerating systems employing sulphur dioxide as a refrigerant.-

The lubricating oil used in such systems will not dissolve in the sulphur-dioxide to any great extent at the evaporator temperature. According- 1y, it has now been found that the use of a simple wire wick between the evaporator unit headersand the suction line of the mechanical refrigerating system will efliciently return the oil to the compressor without in any way affecting the working conditions of the evaporator.

While the invention will be hereinafter described and illustrated in connection with embossed sheet metal evaporator units, it should be understood that the wire wick means for returning oil to the compressor is adapted for use in other types of evaporator units including the type built up from tubes and headers.

A feature of the invention includes the emfrom the unit without discharging liquid refrigerant therewith.

A specific object of the invention is to provide a device for removing oil from liquid refrigerant by capillary action without loss of refrigerant.

Another object of the invention is to interpose a device between a header and a suction line of an evaporator unit for eifecting transfer of oil from the header to the supply line by capillary action without eifecting removal of liquid refrigerant therewith.

- Other and further objects of th invention will become apparent tothose skilled n the art from the following detailed description of the annexed sheets of drawings which disclose preferred embodiments of the invention.

0n the drawings: Figure 1 is a-diagrammatic elevational'view of a mechanical refrigerating system of the compressor-condenser-evaporator type. including an evaporator unit according to the invention. I Figure 2 is an, enlarged top plan view of the evaporator unit shown in Figure 1 taken along the line II- -II of Figure 1. 'Figure 3 is a side elevational view of the evaporator unit shown in Figure 2 taken along theline IlI-III of Figure 2. I

Figure 4 is an enlarged vertical cross-sectional view, with parts-in elevation, taken along the line IVIV of Figure 2.

Figure 5 is a fragmentary end elevational view" taken along the line V-V of Figure 3.

Figure 6 is a small plan view of a woven mesh material illustrating the manner in which the same is rolled into the wick shown in Figure 4.

Figure 7 is anend elevational view of a modifled form of evaporator unit equipped with a wire wick oil returning means according to this invention.

\ Figure 8 is a fragmentaryplan view, with parts in horizontal section, taken along the line VIII- VIII of Figure 7.

bossing of sheet metal evaporator units to receive the wire wick oil returning means.

It is, then, an object of the invention to provide heat exchangers, .such as evaporator units,-

As shown on the drawings:

In Figure 1 the reference numeral I0 designates a base or support for an electric motor II and a refrigerant compressor l2. The motor drives the compressor l2 through a belt l3.

Compressed refrigerant from the compressor l2 flows through a tube or conduit H into a condenser l5 where it is cooled and condensed into liquid .form. The condensed refrigerant then flows through a tube or conduit it into a receiver tank" from which it is directed, as needed, into a valve I! which injects liquid refrigerant, as needed, through a tube!!! into the shelf tube 2| of an evaporator unit 22. The refrigerant flowing through the shelf tube 2| cools the shelf and is directed through a tube 23 into an embossed header 24011 the bottom of the evaporator unit 22. The header 24 communicates with a plurality of embossed expansion ducts 25 ex tending around the sides and bottom of the evaporator unit and the refrigerant circulates through the ducts 25 into the headers such as 26-on each side of the unit. A suction conduit 21 is embossed on the sides and bottom of the evaporator unit and communicates with the suction line :28 back to the inlet side of thecompressor l2. Ac-

cording to this invention wire wick means such as 29 are interposed between the headers such as 26 and the tops of the suction conduit 21 for removing oil from the liquid refrigerant 'in the headers without removing. liquid refrigerant therewith; The suction line '23 thus receives gasifled refrigerant and oh from the evaporator unit.

The oil is thus returned to the compressor for performing its lubricating function while the gasifled refrigerant is compressed by the compressor form horizontal flanges' 30 adapted for attach- 23 communicating with the header .24.

sired, the tube 2| can include and be a part of stop for articles mounted on the bottom wall of the unit. Upturned flanges 33c are also provided at the rear end of the shelf 33 to act as stops for ice trays or other articles mounted on top of the shelf.

In order to cool the shelf 33 the inlet tube from the valve l9 described in Figure 1 communicates with a tube 2| secured to the underof the tube as shown in Figure 2 is suflicient.

The tube 2| discharges into a connecting tube If dethe tube 23 as shown. Liquid refrigerant thus flows from-the valve l9 through the tube under the shelf and thence into the header conduit 24 inent to the roof of a refrigerator cabinet so as to suspend the unit in the top of the cabinet.

Th outer sheet of the unit 22 is embossed to form the header duct 24 extending longitudinal- Both at the bottom of the unit, from which it is distributed through the expansion ducts 25 into the headers 26. Any oil entrapped with the refrigerant will float on top of the same in the headers 26. As the liquid refrigerant boils off in the header, the gas or vapors therefrom are .dis-

duct 21 and back to the compressor.

The liquid refrigerant is preferably kept at a level in the evaporator headers 26 beneath-the tops thereof. i

According to this invention woven wire mesh material such as a copper screen 35 (Figure 6) is rolled into a tight roll 36 toi'orm a capillary activ wick. Copper wire of about 80-mesh is highly efllcient but it should be understood that other metal wicks can be used in place of woven wire. Fabric wicks are also operable but, since the evaporator unit is formed by a brazing oper-,

to form elongated cylindrical headers 26 extending longitudinally along the tops of the side walls of the unit and communicating with the tops of the expansion ducts 25. The expansion ducts 25 terminate in the bottoms of the headers 26.

c The suction duct or discharge duct 21 of the evaporator unit is embossed in the outer sheet of the unit and extends from the tops of the side walls around the sides and bottom of the unit' to an embossed dome-like portion 3| on the inside sheet of the unit. The suction duct 21 does not communicate with the header 24. as illustrated in Figure 5 but discharges into the dome portion 3| which receives'th suction line 28 communicating with the inlet side of the compressor l2 as explained above.

In this form of evaporator unit,- therefore, the suction or return duct is embossed in th unit and extends around the sides and bottom of the unit so that it can be exhausted through a single tube leading to the compressor unit. The ern-J bossed suction duct 21 receives gasifled refrigerant from the tops of both headers 26 through embossed ducts 32 on the inner sheet of the unit.

' Each of these ducts joins the top of a header26 flanges 33a which are riveted as at 34 to the side walls of the unit. The shelf also has a dependent flange 33b at the rear end thereof to act as a 75 bossed cylindrical headers 43 in the. top of the material should be capable of resisting the brazing temperature.

if desired.

The tightly rolled wire mesh wicks 29 are insertedthrough-U-shaped tubes 31 and project tom portion of the headers 26 and also extends into the top portion of the suction tubel'l. Oil floating on top of the liquid refrigerant in the header passes up the wick 29 by capillary action, through the tube 31 and into the suction tube 21 where it is removed along with the gasifled refrigerant. The refrigerant does not flow up the wick by capillary action and, as a result,

only the oil is pwsed through the tubes 31.

If desired apassageway can be embossed on either or both of the metal sheets forming the evaporator unit in place of the tubes 31. The wick 29 can be laid between the sheets in the embossed passageway provided therefor when tion.

In th modification disclosed in Figures 7 and 8, a U-shaped evaporator unit ill composed'of brazed-together metal sheets bent in the shape of a U has the outer sheetthereof embossed witha plurality of ducts such as expansion ducts 4| extending around the sides and bottom of the unit and communicating with an embossed header 42 in the bottom of the unit and with the em- Asbestos wicks might be used assembled for the brazing operaunit. The side walls of the'unit are provided with outturned flanges 40a. for suspending the unit from the ceiling of a refrigerator cabinet. In place of the embossed suction duct '21 the headers are connected through a .suction tube V bridging the top portion of the unit. The suction tube. 44 communicates with the :top portion of each header near one end thereof. The mlddl of the tube 44 is connected with the tube or duct 28 leading to the compressor of the refrigerating system.

According to the invention 9. rolled wire mesh screen forming a wick 45 is inserted .in the tube 44 with the ends 450 thereof extending into the headers 43 and terminating near the bottom bottom of the unit connecting the tops of the headers, and wick devices bridging the headers and the tops of the passageway for removing oil from the headers into the passageway.

2. A sheet metal evaporator unit comprising a pair of secured-together contiguous metal sheets defining the side walls and "bottom-of a sharp freezing chamber, said sheets being embossed to define a header on each side wall, atv least one thereof. An intermediate portion 45b of the wick is inserted into the suction tube 28.

- In the unit 40 refrigerant is fed into the inlet duct or header 42, passes upwardly through the expansion ducts 4| into the headers 43 from which it boils oil or gasifles and the vapors pass through the suction duct 44 into the suction tube 28. However, oil entrained with therefrigerant will float on top of the liquid refrigerant in the headers 43 and will travel upward, by capillary action, through the wick 45 into the suction line a 28 where it can be removed together gasifled refrigerant.

The evaporator unit 40 can be equipped with a sheet metal shelf 46 having downturned side flanges 46a riveted to the side walls of the unit by means of rivets such as 41. 'The rear end of the shelf can have a downturned central flange portion 46b acting as a stop for articles mounted on the bottom wall of the unit under :the shelf. The rear of the. shelf can also have an upturned flange 460 on each side of the downturned flange to act as stops for ice trays mounted on the shelf.

From the above descriptions it should be understood that the invention now provides simple,

with the inexpensive wick means for removing oil or other lubricant from heat exchangers such as evapo- 'rator units. The invention specifically provides sheet metal evaporator units equipped 'with wick means between the headers and the suction lines for removing oil from the headers without removing refrigerant before the refrigerant has been completely spent.

a In one form of the invention the sheet metal evaporator unit is provided with an embossed v suction duct andembossed headers together with a capillary path between the headers and the suction duct. In another form of the invention a stamped sheet metal evaporator unit has the headers thereof joined by a bridging suction pipe for gasifled refrigerant and this pipe contains a wick extending into the bottoms of the headers for effecting a flow of oil into the suction line.

It will, oi course, be understood that various 'details of construction maybe varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

We claim as our invention: I 1. A sheet metal evaporator unit comprising secured-together contiguous metal sheets deflning the side walls and bottom of a sharp freezing chamber, at least one of said sheets being embossed to deflne a header on each side wall, at

least one of said sheets being further embossed to define a passageway along the side walls and 7 'of said sheets being further embossed to deflne a passageway Joining the tops of each header, a

single exhaust communicating with said passageway, means defining additional passageways joining the tops of each header with the tops of said first mentionedpassageway, and metal wick members extending through said additional passageways and projecting into said headers and said first mentioned passageway for removing oil from the headers by capillary action.

3. In an evaporator unit composed .of inner and outer contiguous secured-together metal sheets defining refrigerant circulation ducts and headers communicating withthe ducts together with an embossed flute on one sheet connecting the tops of the headers, the improvement which comprises wick. means interposed between the headers and said flute for conveying oil from the headers into the flute.

4. A U-shaped evaporator unit having header chambers in each side wall thereof and a suction tube bridging the side walls and communicating tube and pipe having the ends thereof extending into the bottom portions of said headers and having an intermediate part thereof inserted into said tube.

6. A sheet metal evaporator unit comprising secured-together inner and outer contiguous metal sheets enclosing a sharp freezing chamber and being embossed to provide refrigerant circulating passageways around the chamber, said sheets being further embossed to provide headers at the top ends of said passageways and communicating with the passageways, said outer -sheet being further embossed to provide a discharge flute around the sides and bottom of the unit, saidinner sheet being embossed to provide a passageway joining the tops of the headers with the tops of said flute, U-shaped metal tubes connecting the tops of the headers with the tops of the flute, and wick means in said U-shaped tubes projecting into the headers and flute for conveying oil out of the headers.

- '7. In an evaporator unit including means deflning a header chamber and means deflnlng a I suction line in laterally spaced relation from said header chamber for discharging refrigerant out of the header chamber, the improvement which comprises a U-shaped tube bridging the space between the header chamber and the suction line and having the legs thereof in communication with the header and the suction line, and a tightly rolled wire mesh rod in said tube having the ends thereof projecting. from said legs of the tube into the liquid-receiving portion of the header chamber and into the suction line respectively.

8. A sheet metal evaporator unit composed of U-shaped inner and outer metal sheets secured together in contiguous relation and embossed to .5

provide a header chamber in the top portion of each leg 01' the U together with refrigerant circulating ducts extending from the header chambers around the sides and bottom of the U,.the

BERNARD C. JOHNSON. EDGARD C. FRANCO-FERREIRA.

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