US3524331A - Refrigeration apparatus including condenser and evaporator in a housing - Google Patents

Description

3,524,331 REFRIGERATION APPARATUS INCLUDING CONDENSER AND Aug. 18, 1970 w. T. OSBORNE EVAPORATOR IN A HOUSING 2 Sheets-Sheet 1 Filed Dec. 50, 1968 INVENTOR. WiLLlAM T. OSBORNE.

. ATTORNEY.

W. T. OSBORNE REFRIGERATION APPARATUS INCLUDING CONDENSER AND Aug. 18, 1970 EVAPORATQR IN A HOUSING 2 Sheets-Sheet 2 Filed Dec. 30, 1968 INVENTOR. WILLIAM T. OSBORNE.

ATTORNEY.

United States Patent O REFRIGERATION APPARATUS INCLUDING CON- DENSER AND EVAPORATOR IN A HOUSING William T. Osborne, East Syracuse, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Dec. 30, 1968, Ser. No. 787,887 Int. Cl. F25b 1/00 US. Cl. 62498 3 Claims ABSTRACT OF THE DISCLOSURE The present invention is directed to refrigeration apparatus comprised of a compressor, condenser and evaporator, the condenser and evaporator being housed within a generally cylindrical shell having a relatively large opening therein to permit ease of installation of components within the shell, the condenser being partially surrounded by a semi-elliptical casing welded or otherwise secured to the shell and mounting a cover member attached by welding or like techniques to the shell and casing. Such an arrangement minimizes bending moments or stresses at the points of attachment of the shell, casing and cover member, as are occasioned by a pressure difference between the condenser and evaporator compartments, and permits utilization of high pressure refrigerants with a minimum increase in the thickness of the shell and casing walls.

BACKGROUND OF THE INVENTION It is known in the art to which this invention pertains to provide as a part of a refrigeration machine a Shell member which is normally generally cylindrical, and by means of an arcuate partition, to divide the interior of the shell into condensing and evaporator compartments. The condensing chamber is under substantial pressure determined by the discharge pressure of the compressor employed, while the evaporator compartment is under reduced pressure, being in communication with the suction of the compressor.

Under these circumstances, it will be appreciated that the partition is under stress acting in a direction to cause disengagement of the partition from the interior walls of the shell. One solution to this problem has been to weld the partition to the tube support sheets in the condenser compartment and also to weld the sheets to the shell member.

With the advent of high pressure refrigerants, such as R-12 and R-SOO, it is even more necessary to minimize stresses, and if in any shell member greater access to the interior of the shell can be provided, an additional important advantage is achieved.

SUMMARY OF THE INVENTION The present invention is particularly directed to refrigeration apparatus which incorporates therein a generally cylindrical shell member in which interiorly thereof the condenser is partially encased by a semi-elliptically shaped divider member which mates with a generally arcuately shaped cover member secured to the divider member and shell member to produce when assembled a complete ellipse.

When a significant pressure difference exists between the condenser and evaporator compartments, the divider member, whether it be of arcuate shape as in the prior art, or of semi-elliptical configuration as by this invention, tends to bow inwardly and apply stresses to the shell. In the instant arrangement this is effectively avoided by imparting greater structural integrity to the divider or casing, and by reducing bending moments at the points of attachment of the divider to the shell and to the cover member by making the curvature of the latter common to the shell and condenser casing or divider. Additionally, and as will later be pointed out in further detail, the shell construction of this invention provides maximum access to the shell interior during the assembly operation, greatly facilitating location and welding of the internal components. This markedly facilitates assembly and results in increased production.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a machine constructed in accordance with this invention;

FIG. 2 is a view in section taken substantially along line II-II of FIG. 1 to better illustrate the novel shell member of this invention;

FIG. 3 is a sectional view of the shell prior to beginning of the assembly operation; and

FIG. 4 is also a sectional view of the shell member showing the divider member in place and the cover member about to be placed thereon.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings for an illustration of a machine incorporating the teachings of this invention, there is shown a centrifugal refrigeration machine 10 incorporating a centrifugal compressor 12 for the purpose of extracting gaseous refrigerant from the evaporator and forwarding it under increased pressure to the condenser.

A particular feature of this invention is the construction of the heat transfer unit associated with the refrigeration machine. Normally, it is conventional that two separate heat transfer units be provided to accomplish the normal condensing and evaporating functions in the machine of the type under consideration. This invention includes the provision of a cylindrical shell member 14 in which there is provided a semi-elliptical casing dividing the interior of the shell into a condensing compartment 18 and evaporator compartment 20. Further details of the casing and shell will be brought out hereinafter.

It is to be seen from FIG. 2 that housed by the casing 16 and disposed within the condenser compartment 18 are a plurality of support sheets 22 which mount tubular members 24. The evaporator compartment 20 also includes a plurality of tubular members 26 supported by a plurality of tube sheets 28. Conventional water boxes 30 and 32 are provided for the purpose of directing cooling water through the tubular members 24 and 26.

Within the casing 16 there is located a plate member 34 having a passage 36 therein leading to a subcooler 38 provided with a plurality of tubular members 40. Condensed refrigerant from the condenser compartment 18 drains through the passage 36 into the subcooler 38 in heat transfer relationship with cooled water passing through the tubes 40. The su'bcooler communicates with conduit means 42 for directing the subcooled refrigerant under control of float valve means 44 through conduit means 46 to the evaporator chamber 20. As is appreciated, a refrigerant vessel or economizer may be interposed between the conduit means 42 and 46, and that the subcooler 38 can be positioned at other locations than that shown, or may even be eliminated in certain applications.

The refrigeration machine 10 of this invention further includes a pair of spaced perforate plate members 48 and 50 which function to assure even distribution of the refrigerant throughout the length of the tube bundle in the evaporator compartment. Also forming a part of the machine disclosed is a compressor discharge conduit 52 leading to the condenser compartment 18 and a compressor suction conduit 54 leading from the evaporator compare ment 20'.

High pressure refrigerants, exemplified by R-l2 and R-SOO which, respectively, boil at atmospheric pressures at about 21.6 F. and 28.3 F., produce across the baffle or divider member separating the condenser and evaporator compartments a substantial pressure differential. For example, in certain applications this may be of the order of 125 p.s.i. This obviously imposes substantial stresses upon the divider or baffle.

In the case of an arcuate bafile welded at its opposite ends to the shell, pressures of this magnitude would in all likelihood impose suflicient stresses or bending moments on the weld joints to fracture the same. Naturally, the vessel thickness could be increased, however, this is generally not considered to be economically feasible. The baffle type arrangement was designed for use with low temperature refrigerants, such as R l1, which create a pressure difierence across the 'bafile of a maximum of about 20 p.s.i, and the arcuate baffle has been very effective under these conditions.

Referring now to FIGS. 2 and 4, a casing or divider member particularly designed for high pressure applications and embracing the novel concepts of this invention is of semi-elliptical shape, the distance between the spaced ends being about 50 to 90, by way of example, so that when cover member 56, the shell member 14, which has an opening 58 spanning an arc preferably of about 65, and the casing are assembled and welded together in a manner later to be described, portions of the spaced ends of the casing underlie the spaced ends of the arcuately shaped cover and the circumferentially spaced ends of the shell to assure tight weld joints between the parts mentioned, which is of particular importance under the high pressure conditions encountered. These weld joints are designated at W-l and W-2 in FIG. 2.

Under normal operation of the refrigeration machine disclosed, the complete cycle of which will shortly be described, the refrigerant in the condenser compartment 18 is at a temperature of about 102 F. and a pressure of approximately 120 p.s.i.g., while the refrigerant in the evaporator chamber 20 is at a temperature of about 35 F. and a pressure of the order of 32.5 p.s.i.g. when using R-l2, all figures given being merely by way of example. These pressures are exerted normal to the lines of curvature of the shell 14 and casing 16, and relatively speaking, the pressure forces on the casing walls are quite substantial.

The semi-elliptical configuration of the condenser casing 16 and its angular position within the shell member 14, as is shown in FIG. 2, not only provides a desirable geometric shape in which to arrange the required condenser components, but also provides an abundance of flow space in the evaporator section to insure a liquidfree flow of gas from the boiling refrigerant in the evaporator tube bundle 26 to the suction line 54.

As with any non-circular vessel, fluctuating pressures within the vessel, brought about by varying operating conditions and changing cooling water temperatures, will produce deflections of the vessel 16, sometimes referred to as breathing. As opposed to the arcuate baflle known to vthe art, the semi-elliptical divider 16 of substantially equal material thickness with reverse bend ends and tangential attachment to the cooler shell is more capable of deflecting to contain a much greater internal pressure while transmitting significantly less bending moments to the cooler shell at the points of attachment, earlier designated in FIG. 2 by the lengends W-l and W-2.

Prior to describing a preferred mode of assembly of the heat exchanger of this invention, a brief review of the operation of the refrigeration machine disclosed will now be made. Compressor 12 is operated so as to create a predetermined pressure in the evaporator compartment 20 of the shell 14 through conduit 54- connecting with the evaporator and the suction of the compressor. Liquid refrigerant present in the evaporator evaporates as it extracts heat from the cooling fluid flowing through the tubular members 26 forming the tube bundle in the evaporator compartment 20.

The vaporized refrigerant is compressed and forwarded through discharge line 52 to the condenser compartment 18 where it is liquefied as heat is extracted therefrom by the cooling medium flowing through the tubes 24 located in the condenser. The liquid refrigerant drains through opening 36 in the plate member 34 into the subcooler 38 and is further cooled as it passes over the tubular members 40.

The subcooled refrigerant then passes through the conduit 42 and is delivered to the evaporator compartment 20 through the action of the float valve 4-4 in control of liquid flow through the conduit 46. Liquid refrigerant passes through the spaced perforate plate members 48 and 50 which, as was noted previously, assure even distribution of the refrigerant throughout the length of the tube bundle in the evaporator compartment. The refrigeration cycle is now complete.

It was earlier pointed out that one of the additional important aspects of this invention is the provision of'a shell which provides ease of accessibility to the interior thereof for location and securement of the internal com ponents. A current practice is to employ two substantially cylindrical solid wall shells to make up the condenser and evaporator sections of the heat exchanger. The shells are supported upon stationary fixtures and it is required that a workman crawl into the shell in order to weld the tube support sheets and the other necessary components. The space within the shell is rather confining and effecting the necessary welds is somewhat time consuming.

By utilization of the shell structure of this invention, which is located during assembly of the heat exchanger upon a fixture capable of being rotated to various fixed positions during location and welding of the internal components, the assembly operation is greatly facilitated. The workman or welder can, if he so desires, thereby make essentially all of the welds while standing on the work floor without the necessity of completely entering the 'shell.

Referring now to FIGS. 3 and 4, it is to be seen that the shell 14 has an arcuate portion removed therefrom between the points x and y of an extent approximating an arc of 65 In a typical assembly operation, a first step would be to weld the perforate plate members 48 and 50 to the bottom of the shell 14, and then weld to the shell in spaced relation therealong the desired number of the tube support sheets 28.

While a different sequence of steps may be followed, one approach would be to then locate within the shell 14, either individually or as a subassembly, the casing 16, the subcooler 38, plate member 34, tube support sheets 22 and the conduit 42. Obviously, other components are located within the shell to make up a complete heat exchanger.

When all components are suitably secured within the shell, the cover member 56 is properly positioned upon the spaced ends of the casing 16, which previously had been tack welded to the shell at the locations shown, the tube sheets in an earlier step having been Welded to the casing. After the member 56, which as shown supports the conduit 52, is positioned in place, it is butt welded to the casing and to the circumferentially spaced ends of the shell 14. In this regard, a longitudinal extending fillet weld is normally made along the casing and shell between the tack welds at opposite ends of the shell prior to the butt welding operation.

It can be seen from the foregoing description that provision of a relatively large opening in the shell 14 greatly facilitates the assembly operation, permits completion of the welding at one station, and results in production economies.

While there has been described a preferred embodiment of the invention, and a preferred method of assembly of the heat exchanger, it will be understood that the invention is not limited thereto but may be otherwise embodied within the scope of the following claims.

I claim:

1. A refrigeration machine including a refrigerant compressor, heat transfer means comprising a shell member of substantially cylindrical configuration having a relatively Wide opening on the circumference thereof to permit ease of access to the interior of said shell member during assembly of said heat transfer means, a generally semi-elliptical casing dividing said shell member into a condenser compartment and an evaporator compartment, a cover member of substantially arcuate shape closing the opening in said shell member and being secured to said shell member and to said casing, means forming a connection between the compressor discharge and said condenser compartment, and means forming a connection between said compressor suction and said evaporator compartment.

2. A refrigeration machine of the character defined in claim 1, in which the opening in the shell member has an arcuate length of between about 50 and 90, the space between the ends of the semi-elliptical casing is less than between 50 and 90, and the arcuate length of the cover member approaches the arcuate length of the shell opening, the'opposite ends of the shell ends defining the opening and the opposed ends of the cover member being in close face-to-face relation and overlying the opposed ends of the casing, whereby when said shell, casing and cover member are secured one to the other, bending moments at the points of securement are minimized and separation of the secured parts is essentially entirely eliminated during flexing of the casing occasioned by variations in the pressure differential on the opposite sides thereof.

3. A method of assembling a heat transfer assembly for use in a refrigeration machine, which comprises forming a generally cylindrical shell member with a relatively wide opening on the circumference thereof to permit ease of access to the interior of said shell member for placement and securement of the requisite components therein, locating within said shell member means for performing refrigerant evaporative functions, positioning in close adjacency to the opening in said shell member a semielliptical 'casing housing refrigerant condensing means therein, completing the circumference of said shell member by locating upon said casing in abutting relation to the ends of said shell member means closing the opening therein, and effecting a high pressure resistant joint between said shell member, casing and closure means, whereby during pressure variations across said casing fracture of the joints is avoided.

References Cited UNITED STATES PATENTS 3,118,290 1/1964 Weller 62506 3,315,485 4/1967 Clark 62-504 3,440,835 4/1969 McGrath 62-505 MEYER PERLIN, Primary Examiner US. Cl. X.R.

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