US2319565A - Evaporative cooler - Google Patents

Description

May 18, 194-3 R. s. STRATTON EVAPORA'IIVE COOLER Filed Au 1,4942- 2 Sheets-Sheet;

Patented May 18, 1943 UNITED STATES PATENT OFFICE EVAPORATIVE COOLER Robert S. Stratton, Phoenix, Ariz.

Application August 1, 1942, Serial No. 453,171

2' Claims.

This invention relates to evaporative coolers of the type that has recently come into extensive use in the southwest semi-arid portions of the United States and wherein outside air is drawn through a porous evaporative medium moistened with water and forced into the room to be cooled under pressure sufficient to maintain a draft therethrough, and thereby prevent the accumulation of excess humidity.

It has been found byuse that this type of cooler depends for its efiiciency'upon the rapid evapora tion of water in the porous pad throughout the entire area of the pad which must be uniformly moistened. While various substances have been used in the evaporative pads of these coolers the substance best suited and almost universally used is excelsior. Apparently its evaporative action is derived not only from the evaporation on the surface of the fibers which compose the pad but also on the capillary action of the fibers themselves in drawing the moistening water from parts of the pad more heavily supplied to those less heavily supplied with water.

While excelsior can be carded and worked so as to form a uniformly composed matrix it is, even so, impossible to compose the substance so that water will distribute itself evenly throughout the entire area of the pad when it is moistened by the usual methods heretofore employed. 7 These methods have included, for the most part, a water supply pipe positioned along the top edge of the pad and provided with a plurality of downwardly opening holes spaced as close together as is consistent with the supply of water and the size of the spray desired. V

It is further found that the pad works best when it is moistened but not wet to the extent of being wringing wet, i. e., flooded with water. In the latter case the air is blocked' off so that it does not flow freely through the matrix of the pad and, further, it can only obtain the temperature of the supply water since when the pad is flooded there is not suffisient evaporative action to reduce the surface of the fibers that contact the'air flow down to the lowest possible temperav ture produced by evaporation. Further, flooding the pad with excess water is obviously wasteful.

To maintain the pad in the desired moistened condition various means have been resorted to,

including specially built pads wherein the excelsior matrix is composed by various mechanical means, all of which are designed to prevent coursing. This is a condition wherein the Water descending through the pad from the small perforations in the supply pipe will follow and f courses entirely dry. Since the entire are of the pad is subject to the same air pressure and since there is less resistance through the dry portions of the pad, due to the absence of water film between the fibers, the greater portion of the air is drawn through the dry portions of the pad and does not receive the proper moistening or cooling effect by evaporation that it should.

It is obvious that to obtain the best efiiciency from these types of coolers the entire pad should be uniformly moistened so that there will be no fair holes or dry spots in the pad to draw hot air through the pad and to mingle with the moistened, cooled air which is drawn through the properly moistened portions.

In view of the foregoing, one of the objects of the invention is to provide a method and mechanism of moistening the pad of this type of evaporative cooler. in amore uniform and efficient manner than heretofore used. p

A second object is to provide a type of pad in combination with a new and novel type of moistener which has a more efficient moistening action than that heretofore used, with the result that the pad is uniformly moistened and coursing is prevented and dry spots in the pad eliminated.

A third object is to provide a device as above described which is simple to construct and economical to operate and that may be easily regulated to accommodate itself to the varying atmospheric conditions under which it may be used.

A fourth object is to provide such a device with mechanism whereby evaporative water may be recirculated over the evaporative pad to secure both economy in the use of the water and to take advantage of the drop in the temperature of the recirculated water and to provide in conjunction with the recirculating mechanism an automatic dumping means so that water in which salts and dissolved substances have been concentrate by evaporation will be periodically dumped and removed from the apparatus at predetermined periods, thereby preventing the pores of the fibers of the pad from filling up with concentrated salt and lime solutions.

Other objects will appear hereinafter.

I attain the foregoing objects by means of the devices shown in the accompanying. drawings, in ,which-- Figure 1 is a front elevation of a device containing my improvement with a portion of the pad broken away to show the interior construction;

Figure 2 is a plan view thereof;

Figure 3 is a vertical sectional view of the water distribution turret;

Figure 4 is a plan view of the turret with certain portions brokenaway to show interior construction;

Figure 5 is a transverse sectional elevation of one of my devices provided with a Water circulating mechanism combined with an automatic dumping mechanism as well as a float feed valve with the evaporative pad removed to show the interior construction; and

Figure 6 is a plan'view thereof.

Similar numerals refer to similar objects in the several views.

The evaporative pad 2 is made cylindrical with arcuate notched portion cut out at 3 to conform to the fan housing 4. This pad is vertically positioned and the bottom rests in a circular bottom pan 5 which has a rim 6 suiiicient to retain any water spilling down the outside of the pad, thereby forming an annular trough, the inside edge of which opens into a centrally positioned sump 1. The pad fits tightly around the fan housing 4 which is provided with flanges 8 on the outside and flange 9 on the inside. The top of the pad is closed by a conically shaped lid Iii having a rim ll sufficient to extend down the top edge of the pad, forming a seal. The top and bottom flanges are held together by spring clamps [2. The pad is made with an inside cylinder of hardware cloth or expanded metal M and a concentrically positioned outer sheath [5 of the same material with a space between these elements filled with excelsior E6. The top and bottom edges are laced or held together with heavy twine or wire hooks so as to form a compact unit which will, in turn, rest in the bottom pan and support the top cover.

Referring to Figure 1, an electric motor carrying a fan 2! is positioned within the interior of the body or housing formed by the pad and the top and bottom closing element with the axis of its shaft in line with th center of the circular housing 4 and positioned just within the interior face of the housing so that the fan will direct a draft of air out through the housing space causing a suction through the pad. Supports 22 are attached to the base tray 5 to maintain it in this position. Water is introduced into the cooler through the supply pipe 25 which leads through a control valve 26 with its handle conveniently positioned on the face of the housing structure. The supply pipe thence leads upward through the center of the cooler body and ends in a threaded thimble 2"! (see Figure 5) which is aligned with the axis of the cylindrical pad body and positioned just below the inside of the cover Ill.

After the cover is secured in place the turret 3!! is attached. This consists of a stationary portion which having a nipple 3!, a thread adapted to screw into the thimble 2'! and thereby secure support. A force pipe 32 extends radially from a closing cap 23 on top of nipple 3| and ends in a tangentially positioned nozzle 33. A supporting spindle 3 5 extends vertically and axially upward from cap 23 and bears in the apex of the turning portion of the turret.

The movable portion of the turret includes a combined rotor 35 which is made in the form of an annular trough having inwardly extending fins 3% throughout its inner circumference and an annular trough 3'! throughout its lower portion. This is supported at the top by the conical Car pointed top bearing of spindle 34 which journals cover Hi. It will be noted that the main portion of the cover is conically shaped and that the rim 44 extends above the outer periphery of this cover sufficiently to form an annular trough around the edge. A series of perforations 45 are made around this annular trough and are equally spaced and positioned above the upper edge of the pad 2 which is positioned just beneath. Preferably these perforations are near the outer periphery of pad rather than near its center.

A switch 16 may be positioned on the front face of the fan housing to control operation of motor 2i).

Operation of this form of my invention is as follows:

Supply pipe 25 being connected with a source of water under pressure, valve 26 is opened and water allowed to flow through force pipe 32. Whereupo-n it issues with suficient force from nozzle 33 to turn the turret 33. Water quickly fills the trough portion 3'! and is discharged through the sweep 42 from which it issues principally under the force of gravity with only a slight centrifugal throw. The size of pipe 42 is proportioned so that water flows solely from it under no considerable pressure. Whereas, water flows out of nozzle 33 with sufficient pressure to cause the turret to rotate, not at any considerable speed but at about one turn every second.

While this speed is not critical the best results are secured where the flow of water is suflicient to provide a gravity flow through the sweep pipe such that the pad is doused or drowned by the sweep pipe as it turns and the size and number of holes 45 is sufficient so that water discharged by the sweep will immediately flow on into the pad, and will not accumulate in the annular channel within rim H.

To those familiar with the art it will be seen that since the water flows from the sweep in a volume suificient to douse the upper portion of the pad over which it may be momentarily positioned, the pad is thereby moistened sufficiently so that its upper edge is drowned; that is,

' there is suflic ent water immediately supplied to it so that coursing is prevented; the entire upper rim of the pad is thus uniformly drowned or wetted when the sweep rotates. The water thus supplied is not only evenly distributed by the rotary motion of the sweep but is supplied in such volume at any one point that coursing is impossible. It is known that coursing of. wetted channels through the pad occurs because a small volume of water is squirted from the necessarily small openings in the supply pipes of the ordinary type of cooler.

These openings can not be made large enough to supply a suflicient volume of water to flush the top of the pad in the area of the discharge hole to prevent coursing as this would use, an excessive amount of water. The small discharge trickles down the pad following the course of least resistance, forming wet streaks of courses with dry areas adjacent. However, by the use of a movable supply nozzle such as the rotary sweep here disclosed, an adequate supply of water is furnished momentarily to each portion of the upper rim of the pad to drown out the courses. While the upper rim of the pad is thus supplied with a sufiicient amount of water to prevent coursing the total amount is not in excess, considering the depth of the pad. The supply of water is regulated by valve 26 so that the pad is adequately wetted throughout its entire area. The speed with which the sweep turns is regulated accordingly and, as before stated, is not particularly critical so long as it maintains distribution of the Water without throwing it. The water seeps down through the pad and the unevaporated portion collects in sump 1 from which it is removed by drain 29.

Where it is desired to secure the beneficial results and economy by recirculating the evaporating water, the mechanism shown particularly in Figures 5 and 6 is included in the evaporator body in addition to that shown in Figures 1 and 2.

Here 50 indicates a small circulating pump, having its intake 5| positioned near the bottom of sump I, driven by a small motor 52 and delivering water through a pipe 53 to the top of a storage tank 54 centrally positioned within the case above the top of a pivotally mounted drain trip tank 55.

Water is discharged from the tank 54 upward through pipe 56 which corresponds to pipe 25 shown in Figure l, and terminates in the fitting 21. A bypass or return valve 58 is positioned above the fluid level in the sump so that the proper amount of water may be fed through pipe 56 to operate the turret and the balance returned to the sump. Water is supplied to the sump through pipe 60 and maintained at a predetermined level by a float valve 6 I.

When pump 50 is started tank 54 is filled and is maintained filled during the operation. This tank is provided with petcock discharge 63 positioned so as to discharge a predetermined small amount of water into the trip tank 55. This latter is supported on a transverse shaft 64 and provided with balancing weights 65 so that normally it rests in the position shown in solid lines, Figure 5, and is maintained in position by stop 51.

Supporting shaft 64 turns with this tank, carries a sheave wheel 65 over which a chain 67 is run and is connected at its lower end to a lug 68 attached at the free end of flexible drain syphon tube 69 which leads through a suitable elbow fitting 10 to the discharge pipe II set into the bottom of sump I.

When at rest and in normal inoperative posie tion the intake end of this flexible discharge tube is raised so that the elbow fitting 12 at its inner open end is above the water level in the sump and no water can be discharged. As the tripping tank 55 fills with water frompetcock 63 it becomes over balanced and turns clockwise to the position indicated by dotted outlines 5511.

A baffle I4 is provided in the top open end of this tank and retains the water contained when it is in the tripped position permitting it to discharge only through a small orifice 15. Due to the position of the support shaft 64 and balancing of the tank when it is moved to the horizontal position it is retained inthis position by the weight of the water until substantially all the water has run out through the opening 15. It will be noticed that bafile 14 does not entirely close the top of this tank and, therefore, water is free to enter through the unclosed slot 16.

After tank 55 is emptied balance weights 65 return it to the vertical position. Regulation of cock 63 will time the operation of tank 55 to any desired cycle, this depending on the solids dissolved in the water used. Movement of this tripping tank from the vertical position indicated by solid lines to the horizontal or tripping position lowers supporting chain 61 and flexible tube 69 so that the fitting i2 is immersed beneath the surface of water in sump l and the tube 69 assumes the position indicated by dotted outlines 69a. In this position the tube with its fittings acts as a siphon and draws substantially all of the water out of sump 1 into the discharge 7 pipe 1|. Orifice I5 is made of a size so that water will not drain from tank 55 until the predetermined amount of water in sump i has had time to fully siphon out.

This group of mechanisms includes the storage tank 54, trip tank 55, balanced as stated and connected to the flexible siphon discharge tube 69 may be termed an intermittent automatic sump drain. It will be noticed that since the supply pipe 53 enters the top of tank 55 the tank will remain filled with water after motor 52 has been stopped and this water will continue to slowly flow through petcock 63 until all the water in tank 54 has been drained out. The capacity of storage tank 54 is made slightly greater than that of tank 55 so that after the operation of the entire cooling unit is stopped, including the operation of pump 52, the water remaining in sump I will be automatically drained and discharged without any attention being required from the user of the device.

Aside from this automatic intermittent dumping action the operation of this form of the device is the same as that of the device shown in Figure 1. The position of the pad is indicated by dotted outlines 11.

Having now described my invention and explained its use, I wish to be limited only by the following claims.

I claim:

1. An evaporative air cooler having a body consisting of an evaporative pad positioned around its perimeter, a bottom portion forming a closure, and having a sump, a top lid forming a closure for the top thereof, and having an annular trough around its perimeter, the bottom thereof being perforated with a plurality of equally spaced holes positioned above the top rim of said pad, a circulating fan positioned within said body portion and adapted to direct air outward through a vent,

a vent opening formed in the side of said pad, a

Water supply pipe adapted to deliver water under pressure to a turret nozzle positioned above said top, a water distributing turret including an annular turbine chamber, positioned above an annular trough provided with a supporting bearing above said discharge nozzle and adapted to turn in a horizontal plane and carrying a water distributing sweep pipe, said pipe extending radially therefrom to the annular trough formed around the outer rim of said top, a means for regulating the flow of water through said supply pipe.

2, An evaporative cooler having a case including a circular evaporative pad, a top cover therefor provided with an annular trough above the top of said pad, a plurality of perforations along the bottom of said trough and above the top of said pad, a rotating sweep pipe adapted to distribute water to said trough, a bottom pan closure including a drain, a fan housing positioned in the side of said pad, and a fan adapted to draw air through said pad and force it out through said housing.

' ROBERT S. STRATTON.

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