US2840352A - Evaporative condenser - Google Patents

Description

I June'24, 1958 M. L. GHAI ETAL EVAPORATIVE CONDENSER 2 Sheets-Sheet 1 Filed Sept. 1, 1955 INVENTORS Mccdan I. Qfwu',

m m w BM m ATTORNEYS June 1958 M. L. GHAI ET AL EVAPORATIVE CONDENSER 2 Sheets-Sheet 2 I Filed Sept. 1, 1955 INVIENTORS Mada-n .ZT.

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ATTORNEY}? United States Patent EVAPORAT IV E CONDENSER Madan L. Ghai, Manchester, and Cecil Boling, West Hartford, Conn., assignors, by mesue assignments, to Dunham-Bush, Inc., West Hartford, Conn, a corporation of Connecticut Application September 1, 1955, Serial No. 532,053

4 Claims. (Cl. 257 -37) This invention relates to evaporative cooling, and more in particular to an evaporative condenser for a refrigeration system.

An object of this invention is to provide an improved evaporative condenser and an improved methodof operation for the same. A further object is to-provide an improved method and apparatus for passingwater in counterflow relationship with air through a fin assembly. A further object is to provide improvedgas and liquid contact apparatus. A still further object is to provide an improved evaporative condenser unit. A further object is to provide for the above with structure which is inexpensive to manufacture and maintain, and which is light in weight, sturdy, and free of the difliculties which have been encountered with similar structure in the past.

These and other objects will be in part obvious, and in part pointed out below.

In the drawings:

Figure 1 is a showing of one embodiment of the invention, with the associated refrigeration circuit shown schematically;

Figure 2 is an enlarged fragmentary perspective of a portion of the evaporative condenser of Figure 1;

Figure 3 is an enlarged sectional view on the line 3 -3 of Figure 2;

Figure 4 is a view of the condenser assembly on the line 44 of Figure 1; and,

Figure 5 is a plan view of the unit of Figure 4.

Evaporative condensers have been provided wherein the refrigerant is condensed within the tubes of a coil having external fins. Water is supplied to miantain the external surfaces of the coil in wet condition, and air flows through the coil to evaporate the water, thereby to carry away the heat of condensation of the refrigerant.

Difiiculties have been encountered with this type of equipment, particularly in that the water and air do not flow over the coil surfaces evenly. That is, some surfaces do not remain wet, and therefore are not effective as evaporative cooling surfaces. With some such structures, the air passageways tend to become filled with water so that no air flows through them, and the surfaces of such passageways are rendered ineffective as evaporative cooling surfaces.

It is an object of the present invention to overcome the difiiculties which have been encountered with apparatus of the above character, and to provide structures which are efiicient and dependable in use at all times. g

In the illustrative embodiment of the invention, a coil structure is provided having horizontal tubes with fins thereon which are so shaped as to form closed air, channels extending from one face of the coil to the other. The coil is positioned at an angle to therhorizontal, and water is distributed with the aid of gravity over the face of the coil which is exposed upwardly. The water flows through the channels and is evenly distributed so that all of the surfaces of all of the fins and the tubes are maintained in wet condition. The air enters the coil at the face which is exposed downwardly, and flows through the coil countercurrent to the water flow. The volume of Water in pairs.

flow is such with respect to the size of the channels that no channel is blocked by water, and a substantial stream of air flows through each channel. The water flows from the downwardly exposed surface of the coil into a sump tank, and it is recirculated.

Referring to Figure 1 of the drawings, a unit 2 has a casing 4 with the sump tank 6 on the bottom thereof, side walls 5, and a top wall 7. Casing 4 is closed except for a rectangular air'inlet opening at the right, and a circular air outlet opening 10 at the left. Air is drawn through the unit by a fan 12 positioned in the outlet opening 10 and driven by a motor 14. Mounted within casing 4 upon the side walls 5 thereof is a condenser.coil.16 which is formed by a plurality of interconnected horizontal tubes having refrigerant gas inlet and liquid refrigerant outlet headers. Positioned upon these coils is a fin assembly 17 to be. described more fully below. Directly above condenser coil 16, and substantially overlying the upwardly exposed face 18 of the coil isa rectangular water distributor pan 20 which has openings in its bottomwall so that small streams of water flow from the pan in an evenly distributed flow pattern throughout the zone above the coil. Positioned beneath pan 20 and adapted to intercept water flowing from the pan, is a water distributor screen 22 which breaks the streams and droplets of water by impact, and causes a fine spray of the water to be distributed very evenly throughout the face 18 of coil 16. The water then flows through the coil, and that which is not evaporated drops down into the sump tank.

During operation, air is drawn in at the right through the air inlet opening, and it.passes through the coil countercurrent to the water flow, and is discharged at the left by fan 12. At the right of fan 12 there is an eliminator screen 24 which intercepts particles of water in the air stream and directs them downwardly to the sump tank. Water is withdrawnfrom the sump tank by a pump 26, and passes through a pipe. 28 to the water distributor pan 20 at the top of the unit. A predetermined water level is maintained in the sump tank by a float valve 30 which controls the admission of feed water from a line 32. An

overflow pipe 34 discharges excess water to waste.

As. shown best in Figure 4, the condenser coil 16 has horizontal tubes 36 interconnected at their ends by U- bends to form a number of separate refrigerant circuits. Each of tubes 36 has an annular radially deformable internal finassembly 41 which is held against the inner surface of the tube by an inner tube which has been expanded after assembly. In this embodiment, there are seven such circuits of six tubes each, and the tubes are two deep in the coil (see Figure 5) s'o that the tubes are Each of these circuits is connected at oneend to a hot gas refrigerant inlet header 38, and. at the other end to a liquid refrigerant outlet header 40. The liquid header 40 has a refrigerant connection 39 at'its lower end,

and the liquid refrigerant line is connectedv through. a" horizontal extension 44. Similarly, an extension 42 is provided for the gas line. The refrigerant headers and connections (see Figure 1) are alongthe downwardly exposed face 19 of the condenser coil, and extensions 42 and 44 are horizontal. V I 1 I 7,

It has been indicated above that the condenser coil has a fin assembly17 on its tubes. This fin assembly. is formed by a number of individual fins 46 (Figures 2 and 3) positioned in side-by-side relationship upon the tubes between the tube plates or channels 47, and each fin extends from the top to the bottom of the coil and the full depth of the coil, that is, from face 18 to the opposite face 19. The structure of the fins, and the relationship between the fins and the tubes, are shown in Figures 2 and 3 which show a section a group offins associated wtih four of the horizontal tubes.

Each fin is provided witha number of square channels 48 positioned,respectively:between 'the various pairs of tubes. Eachopening 49through, thefins for a tube is provided with a fl ange portion 50 drawn from the body of: the fin andzhaving six contact prongs-52 having con tact feetl54. During assembly, the finsare placed onto the tubes, and they arepushedtoward each other so that each of the collars 50 contacts the next fin, thus to pro videaccurate spacing'between fins. ,Thi spacing is also insuredby channels 48 which are shaped as shown, so that the outer surface of the bottomtof each of the channels rests against and somewhat into the top of the channel in the next adjacent fin In this way, each channel is closed to form a passageway/ 56 which is square in cross section, and these passageways extend from one face of the coil to the other. There are also passageways 57 in which the tubes are positioned. Each collar 50 readily and efficiently transmits heat from its tube section to the adjacent portion of its fin, and thence to the air and water.

,-In this embodiment, the condenser coil is so-positioned that its faces 18 and19 are at an angle of 60 to the horizontal Hence, thepassageways between these faces provide for the flow of water through them by the action of gravity, and yet the air flows through the coil in a generally horizontal direction. This provides uniform flow and countercurrent relationship between the water and air, with minimum resistance to air flow. The gas refrigerant from the compressor is delivered to the gas header 38, and the liquid refrigerant, flows from the liquid header 40 through the U-tube 39. The refrigeration system is represented schematically in Figure 1, and includes a compressor 60, a receiver 62, and an evaporator 64. f

During operation, faulZ (Figure 1) draws air through the casing, the air entering at 8 and being exhausted at 10. Simultaneously, pump 26 withdraws water from the sump 6 and delivers it to the distributor pan 20.. The water falls from the distributor pan and is dispersed by the distributor screen'22so that it falls evenly over the face18 of condenser coil 16. The water throughly wets thesurfaces of the fins and the tubes, andflows through the passageways countercurrent to theairflowr The passageways 56 are of sutlicient cross-sectional dimensions to prevent the blocking of the passageways by water. The rapid flow of air tends to cause water to cling to the fins at face 18, and water is thus accumulated. Thisaccumulated water is constantly added to by the water from the spray, and there is a constant surface flow therefrom along each fin surface from face 18 to face 19. It has been found that this substantially increases the effective air and: water heat transfer surface and the evaporation of water. r

The :water drops from the lower face 19 towardthe sump, but some of the 'water is entrained in the flowing stream ofair and drawn baclrinto the condenser coil 16. The water whichis not entrained in that manner falls intothe sump and may be recirculated.

The refrigerant in the condenser coil 16 is cooled efficiently and in a dependable manner. The desired ratio of water flow to air flow is maintained, and the heat is dissipated in a minimumspace, The static pressure drop is maintained at an acceptable low value. The use of the corrugated channel fins makes it possible to have hori-' zontal air flow and vertical water flow, and still there is full counterfiow actionbetween the air and water. This permits the use of gravity flow for the, water, and yet the air flowsfreely. f

Itshould be noted (see Fig.3 that the passageways 57 have minimum cross sections which are substantially the same as the cross sections of passageways 56, but thatfat thesides of the tubes passageways 57 are of substantially greater width than passageways 56. This ar- 4 rangement tends to maintain a proper distribution of water between the passageways, even if there is some improper water distribution from distributor screen 22. This fin arrangement also tends to insure a proper distribution of air between the various passageways, and there is a counter-flow of water and air through each passageway. Within each passageway, a film of water flows along the fin surfaces, and if the film becomes excessive, droplets appear and the excess water is carried back up by the air stream to the upper side of the coil (left-hand side in Fig. 1). This excess Water is thereby delivered to the water inlet side of the coil and flows through other passageways which are not supplied with excess water. In each of the passageways 57, the air tends to produce somewhat of a jet action at the air outlet side of the zone or zones of minimum dimension. This aids in producing the desirable results discussed above.

' As many possible embodiments may be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to be understood that all matter hereinabove set forth, or shown in the accompanying drawings is to be interpreted as illustrative and not in the limiting sense.

We claim:

1. In a refrigeration system, an evaporative condenser assembly comprising, a casing having air inlet and outlet openings to permit transverse air flow, an evaporative condenser coil positioned within said casing and extending at an angle to the horizontal and across the path of said air flow, water distributing means overlying the upper inclined face of the-evaporative condenser coil to distribute water uniformly over said face, a fan in the casing to cause air to flow through said casing and said evaporative condenser coil, said coil comprising a plurality of tubes interconnected to provide a plurality of individual fluid circuits, a pair of headers connected, respectively, to said individual fluid circuits to supply fluid thereto and withdraw fluid extending from the upper to the lower inclined faces of the coil and enclosing at least one row of tubes, and the Walls of said channels forming said passages dividing the upperface of the evaporative condenser coil into a plurality of adjacent openings to uniformly roportion the water supplied to each unit of area on the upper face of the coil which thereafter is confined to a passage as it flows through the condenser coil whereby to cause the same quantity'of water to pass through corresponding areas of the coil throughout its entire area.

2. An evaporative condenser assembly comprising, a casing having air inlet and outlet openings to permit transverse air flow, an evaporative condenser coil positioned within said casing and extending at the angle to the horizontalwith vupper and lower inclined forces and across the path of 'said air flow, water distributing means overlying the upper inclined face of the coil to distribute water uniformly over said face, a fan in said casing to cause air to flow through said casing and coil, said evaporative condenser coil comprising a plurality of fins arranged in spaced vertical planes and having rows of aligned openings, tubes extending through the openings transversely of the fins, each fin having channels projecting laterally from one side thereof between adjacent tubes of a row, said channels on each fin engaging the corresponding channel on the next adjacent fin to provide separate passageways around each tube of the row which passageway extend through the coil from one face to the other, and the ends of the walls forming said channels dividing the upper face of the coil into a plurality of adjacent openings to uniformly proportion the water supplied to each unit of area on the upper face of the coil which is confined to and flows through a passageway independently of the flow through other passageway to cause the same quantity of water to pass through all portions of the evaporative condenser assembly throughout its entire area. 1

3. An evaporative condenser assembly in accordance with claim 2 wherein said channels projecting laterally from said fins form passageways which are substantially square in cross-section and, wherein alternate passageways are formed between adjacent channels which are rectangular in cross-section.

4. An evaporative condenser assembly in accordance a with claim 2 wherein each of said tubes includes an internal fin structure, comprising, a'plurality of radial fins engaging the interior wall of the tube, and means holding said. internal finassembly radially against the inner surface of the tube.

References Cited in the file of this patent UNITED STATES PATENTS

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