US2874555A - Evaporator arrangement - Google Patents

Description

Fe 24, 1959 F. A. DISINGER ETAL 2,

EVAPORATOR ARRANGEMENT Filed Dec. 1, 1955 2 Sheets-Sheet 1 A/R FLOW 501/265 Q Q M 1959 F. A. DISINGER ET AL 2,874,

EVAPORATOR ARRANGEMENT 7 Filed Dec. 1, 1955 2 Sheets-Sheet 2 INVENTORS fiazzi Qflzpezg. BY fair: 5 1500 1! ATTORNEY United States Patent 2,874,555 EvAPoRAToR ARRANGEMENT Application December 1, 1955, Serial No. 550,268

2 Claims. (Cl. 62-525).

This invention relates to the field of heat exchangers and more particularly to evaporator arrangements employing cores for conveying heat absorbing mediums.

When a heat exchanger is caused to serve as an evaporator in a refrigeration system, a heat absorbing medium is forced to flow through an expansion valve into the tubes or coils of the evaporator. The resulting transformation of the medium from liquid to the vapor phase within the evaporator requires heat and such heat is drawn from. the-air or other fluid passed incontact with the outside surfaces of the evaporator tubes or core. The transformation does not take place immediately at discharge from the expansion valve as time is required for the requisite heat exchange or heat absorptive action to take place. Accordingly, the tube coils or core portions are at least partially filled with a boiling or agitated liquid and the transformation into the vapor phase takes place within the main body of the evaporator itself. A difiiculty has arisen heretofore in that the agitated liquid, before changing in phase, often rises in one tube or portion of the core to a greater extent than in other portions thereby often entering the compressor which is conventionally used and intended to receive the vapor discharged from the evaporator. Vapor compressors obviously should not be subjected to such treatment. Also, the liquid from one tube or core portion, in possibly spilling 2,874,555 Patented Feb. 24, 1959 an apertured sleeve controlling the liquid level consistent with the direction of flow of the medium contacting the exchanger. Another feature is a metering means in the form of a sleeve associated With an evaporator header and having apertures in the sleeve decreasing in effective flow area considered with relation to evaporator core portions arranged in succeeding order from'the forward side of the evaporator. Still another feature is a heat exchanger in which parallel tube portions communicate with calibrated apertures to equalize the tube work load and in which such portions are arcuately contacted by air centers separated by flanges integral with each air center.

These and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.

- In the drawings:

Fig. l is an elevation view showing the rear side of an evaporator embodying features of the present invention and connected to headers drawn in section;

Fig. 2 is a sectional view taken along the line 2-2 in Fig. 1 and including a diagrammatic representation of a source of heat absorbing medium;

Fig. 3 is a perspective view of an air center as utilized in the structure of Fig. 1;

Fig. 4 is a view similar to that of Fig. 3 but showing a modified form of air center; and

Fig. 5 is a perspective view of still another form of Y air center.

over into an adjacent tube or core portion, interferes with efficient heat absorption by the refrigerant in the evaporator as awhole. This adverse situation is aggravated by the fact thatitheflair or, other fluid which is divesting itself of heat in passing between the evaporator tubes or portions loses most of its divested heat to the first tube or core 'portion withwhich it comes in contact. The temperature differential between the air and the refrigerant decreases as air passes to successive tubes or core portions so that the lasttiibe or" portion contacted by the air is most likely to become full of' liquid refrigerant. lt followsfthat a decreasing" temperature differential along the path of mean heretofore has resulted in an' upwardly; inclined liquid refrigerant level in the evaporator core tending to cause spill-over.

When the evaporator comprises tubes, air centers are employed to further the heat exchange between the mediums employed. A difliculty has heretofore arisen in assembly of the heat exchanger because the air centers are of light gauge metal and spacing of the centers cannot accurately be controlled. It is also noted that in prior devices of this nature the resulting structures of tubes for air centers have left something to be desired as far as structural stability and rigidity are concerned.

An object of the present invention is to provide an improved evaporator arrangement with a controlled liquid level to prevent spill-over. Another object is toprovide an evaporator arrangement or heat exchanger in which parallel tube portions are contacted by air centers giving an improved stable or rigid structure.

A feature of the invention is a heat exchanger combined with a source of fluid heat absorbing medium, the

Fig. 1 shows a rectangular framework 10 defining a rectangular opening 12 through which a heat absorbing medium such as air may be caused to flow. Opposite side portions of the frame 10 are formed in such a way as to present opposing vertical flanges 14' and 16. 'These flanges constitute immediate supporting means for five side-by-side serpentine tubes 18. These tubes have hori zontal portions, the ends of which pass through slots or elongated perforations in the flanges 14 and 16 in a manner well known in the art. An intake manifold 20 is located near the bottom portion of the frame 10 and this header is blocked off at its ends by discs 22 and 24 as best shown in Fig. 2. A conduit 26 servingas a source of supply of refrigerant flowing from a receiver and compressor has one end welded as at 28 to the header 20. The latter is provided with an opening 30 which is placed in registry with an opening 32 formed in a sleeve 34 fitted within the header. The sleeve 34 extends from one end source may be afan or an air guiding duct but it is so placed with relation to the evaporator that the medium flowing from the source 42 will pass through the opening 12 of the frame 10 and then between the parallel portions of the tubes 18. As the sleeve 34 constitutes a metering means for the refrigerant admitted to the tubes 18 from the inlet header 20, it will be understood that the apertures in the sleeve 34 are graduated in size. They decrease in size when considered in the direction of air flow from the source 42 or from the forward side of the evaporator; that is, to the right as viewed in Fig. 2. The first aperture 50 is relatively large. The second aperture 52 may be equally as large in a given situation and depending upon the location of the port 32 as will be understood. The third aperture 54 is slightly smaller. The fourth aperture 56 is still smaller in diameter and the fifth aperture 58 is the smallest aperture of the series. From this, it may be seen that the apertures are in such order as to communicate with rearwardly succeeding portions of the evaporator core and the apertures decreasing in effective flow area or cross-section in that order.

The upper ends of the tubes 18 communicate in a conventional manner with an outlet header 60 which is adapted to convey vapor emerging from the evaporator for a short distance on its way to the compressor of a refrigeration system.

The horizontal or parallel portions of the tubes 18 are flanges 66 of each air center contacting the adjacent air center. Conveniently and advantageously, but not necessarily, the air centers 62 are assembled upon reinforcement rods or tubes 74 which may or may not be fixed to the supporting flanges 14 and 16. The tubes 18, frame 10 and air centers 62, as well as the reinforcing rods 74, may be made of aluminum and these component parts are all joined together by brazing to form a rigid mechanically stable and unitary structure.

Fig. 4 shows an air center 80 similar in all respects to the air center 62 except that along the central portion thereof and alternating with the reinforcement flanges 70 are perforations 82 provided to agitate and vary the air flow and thereby increase the heat exchange characteristics of the unit in which the air center is to be built.

Each perforation 82 is defined by two oppositely offset portions 86 and 88 formed from the single piece of metal utilized in making the air center 80.

Fig. 5 depicts an air center 90 which is also similar to the air center 62 in all respects including the flanges 70, but in this case ridges 92 are provided which extend in the same direction from the main body of the center as do the flanges 66 and 70. These ridges promote a slightly different agitation of the heat absorbing medium passing through an exchanger in which the air centers are utilized.

In operation, refrigerant such as Freon is introduced from the conduit 26 to the chamber defined by the sleeve 34. This liquid refrigerant under low pressure is distributed to the various tubes 18 by way of the metering apertures 0r orifices 50, 52, 54, 56 and 58. As the orifice 58 is the smallest of the series, the least amount of refrigerant will be distributed to the rearmost tube 18 (extreme right-hand tube in Fig. 2) and each of the forward tubes 18 will be supplied with a greater amount of liquid refrigerant. As the pressure differential between the air and the refrigerant is the greatest at the forward side of the evaporator, vaporization will occur more readily in the forward tubes. As a consequence, the liquid within the evaporator core constituting the tubes as a whole will be more nearly horizontal than would be 4 the case if equal amounts of refrigerant were metered to all the tubes. As a consequence, the likihood of spillover to the compressor or from one tube to the other is reduced to a mimimum.

It will be appreciated that the order of succession assumed by the apertures of decreasing size is related to the forward side of the evaporator or to the direction of air flow between the tubes. It is not essential that the inlet header and its sleeve 34 lie in the direction of air flow as is the case in the arrangement illustrated. The sleeve 34 could extend at any angle with respect to the direction of air flow but the smallest aperture 58 should be in communication and govern the flow with respect to the rearmost portion or tube of the evaporator core.

We claim:

1. An evaporator arrangement comprising a source of fluid heat absorbing medium, a heat exchanger with a forward side in the path of said medium and having an inlet header and an outlet header connected by a core for the conducting of a refrigerent fluid, said inlet header being lower than said outlet header, metering means as- 'sociated with said inlet header and comprising a sleeve inside the header with apertures in the wall of said sleeve in such order as to communicate with rearwardly succeding portions of said core, and said apertures decreasing in effective flow area in said order to introduce more of said refrigerant fluid to portions of said core near said inlet header and less to portions of said core more remote from said inlet header.

2. An arrangement comprising a source of air flow and an evaporator located in the path of said air flow, said evaporator including an upper outlet header and a Y lower inlet header, a series of tubes arranged in parallel relation and connecting said headers, the planes of said tubes being spaced and transverse to said path, metering means associated with said lower inlet header to control the flow of refrigerant fluid to said tubes, metering apertures defined by said metering means, each of said apertures leading to one of said tubes, and the effective flow areas of said apertures decreasing in successive order from the said source of air flow whereby distribution of said refrigerant fluid to said tubes is not equalized and the liquid levels inthe tubes are caused to approach a common horizontal plane.

References Cited in the file of this patent UNITED STATES PATENTS 1,846,608 Phelps Feb. 23, 1932 1,854,278 Smith Apr. 19, 1932 1,890,205 Andresen Dec. 6, 1932 2,023,739 Mason Dec. 10, 1935 2,099,186 Anderegg Nov. 16, 1937 2,138,777 Zellhoefer Nov. 29, 1938 2,163,591 Deverall June 27, 1939 2,237,239 Smith Apr. 1, 1941 2,336,077 Eberhart Dec. 7, 1943 2,707,868 Goodman May 10, 1955

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