US3306591A - Evaporative cooler - Google Patents

Description

Feb. 28, 1967 B. G. VALAZZA 3,306,591

EVAPORATIVE COOLER I Filed Feb. 10, 1964 s Sheets-Sheet 1 INVENTOR BRUNO 6. VALAZZA ATTORNE Vs Feb. 28, 1967 B. G. VALAZZA 3,306,591

EVAPORATIVE- COOLER Filed Feb. 10, 1964 5 Sheets-Sheet 2 INVENTOR. BRO/V0 G. VAM

Feb. 28, 1967 B. G. VALAZZA EVAPORATIVE COOLER Filed Feb. 10, 1964 DECREASE INCREASE AIR TEMPERATURE l 7 5 Sheets-Sheet 5 PAD AREA l 'EITJLILZ] I WATER TEMP I brus PER umT WATER voL. l E 78 -1 74 1: 3:113 1 5 71 WATER CIRCULATED I w i l 7 r; 1 g

M O J 2 WATER EVAPORATED INVENTOR.

BRUNO 4. MM ZZA ATTORN Y United States Patent 3,306,591 EVAPORATIVE COOLER Bruno G. Valazza, 164 W. Central, Coolidge, Ariz. 85228 Filed Feb. 10, 1964, Ser. No. 343,762 1 Claim. (Cl. 261-23) My invention relates to an improved evaporative type cooler. Evaporative coolers have been developed intensively in the relatively arid regions of the southwest, but notwithstanding such development, conventional evaporative coolers have many shortcomings.

Evaporative coolers of the type commonly used for domestic buildings are provided with excelsior pads, frequently formed from aspen wood, and means as provided for pumping water from a sump to a perforated pipe above the evaporative pads with the idea of maintaining them in wet condition. A suitable blower draws the air through the pads, and evaporation of the water on the surface of the excelsior cools the air. The air so cooled is normally delivered directly into the living space being cooled, and as a rule windows or doors are left slightly ajar to permit escape of air from the dwelling.

In an attempt to provide for dilferential cooling action, it has become a common practice to employ a two-speed motor to drive the blower with the objective of obtaining greater cooling action by the movement of a larger amount of air during the hottest portion of the day or season. With existing pads and water supply methods used, a portion of the pads will usually be dry so that some uncooled air mixing with the cooled air reduces the efiiciency of the evaporative unit. When the amount of air passing through the pad is increased, this effect is magnified. Still other problems are associated with the conventional type of evaporative cooler as those familiar with their operation understand.

The principal object of the present invention is the production of an improved evaporative cooler.

Another object is the provision of an evaporative cooler which produces a lower air temperature for a given air input.

Still another object of the invention is the production ofan improved evaporative cooler having less pad area.

Still another object is the provision of an evaporative cooler in which the water temperature in the sump will be lower than in conventional coolers of the prior art, so that this water itself participates in the cooling action on the air.

A further object is to increase the cooling action for a given amount of water circulated.

A still further object is the provision of an evaporative cooler which responds automatically to variation in air temperature, relative humidity, and air flow volume so that the net result is to produce a cooling action generally in accordance with the requirements resulting from ambient weather conditions.

Still a further object is the provision of an evaporative cooler which more positively removes dust, pollen, and noxious odors than conventional coolers of the prior art.

Other specific objects and features of the present invention will be apparent from the following detailed description taken wit-h the accompanying drawings, wherein:

FIG. 1 is a perspective view showing one form of cooler produced in accordance with my present invention, some of the parts being exploded with respect to their normal position to facilitate illustration of novel features;

FIG. 2 is a slightly enlarged transverse sectional view taken on the line 22 of FIG. 1, some of the parts being shown in elevation for purposes of illustration;

FIG. 3 is a sectional view taken along the line 33 of FIG. 2;

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FIG. 4 is a transverse fragmentary view taken on the line 44 of FIG. 3;

FIG. 5 is a sectional view taken on the line 55 of FIG. 2;

FIG. 6 is a composite view in chart form showing fea tures and characteristics of the evaporative cooler of the present invention as contrasted with a conventional evaporative cooler of the prior art having the same general horsepower rating;

FIG. 7 is a graph in which the amount of water evaporated in a given period of time is related to relative humidity;

FIG. 8 is a greatly enlarged perspective view partly in section showing a preferred form of an evaporative pad forming structure;

FIG. 9 is a partially schematic view showing modified form which the invention may take, and

FIG. 10 is a partially schematic view showing a modification in which the speed of the blower driving belt may be adjusted.

Referring now to the drawings, the embodiment of the invention shown in the drawings employs a frame 11 suitably formed of rolled shapes such as angles and welded together to support sumps 12 and a blower housing 13, the sumps and blower housing suitably being formed of sheet metal and tied together to produce a structure in which all of the air entering at ends of the device is delivered out through a discharge opening 14 for delivery into a suitabje duct system (not shown). The cooler of FIG. 1 would normally be placed on the roof or in any suitable location outside of the building to permit delivery of adiabatically cooled air to the duct system directly and with minimum exposure to the sun and ambient air temperatures.

The frame 11 has a generally rectangular extension 16 at opposite sides of the blower housing and this rectangular extension of the frame supports an evaporator drum indicated generally by the reference character 17. As noted particularly in FIGS. 1 and 2, the frame extension 16 is provided with a pair of top surface notches 18 supporting uncircular ends of an axial shaft 19 on which the evaporator drum is rotatably mounted. The evaporator drum 17 has an end frame of which spokes 21 form a part, a suitable frictionless bearing 22 being disposed between such end suppont and the shaft 19. Because of this construction the evaporator drum 17 rotates very freely on its shaft 19.

The evaporator drum includes a honeycomb shaped absorbent fibre structure 23 which is supported between the tubular coated wire members such as shown in the drawings. The tubular wire members engage the end frames and may be of any suitable type such as for example one-half inch hardware cloth. The honeycomb structure is formed by slightly overlapping a plurality ofapertured sheets of fibrous material to form a very porous pad with a low percentage of large voids. Water is entrained within the interstices of this material, rather than on the surface as is the case with excelsior pads of conventional evaporative coolers.

Before describing further the functioning of the evaporator drums, reference will be made .to the blower which in the present case is of conventional drum type. The blower indicated generally by the reference character 26 has a frame including a pair of spiders 27 at its ends supporting the frame on a blower shaft 28. The blower has the usual plates 29 on its periphery so that when it is rotated at relatively high speed it draws air through its ends between the spokes 31 of the spider 27 and discharges the air from its periphery for delivery through the opening 14. To drive the blower a conventional electric motor 32 carries a driving sheave 33 on its shaft which in turn drives a belt 34 engaging a driven pulley 36 mounted on the shaft 28.

Referring now further to the drawings the sump 12 is provided with an upturned radial portion 37 which lies close to the end of the evaporator drum 17. A radial projection 38 spaced from the projection 37 at the opposite side of the evaporator drum forms a water trough for maintaining water at a suitable level as will be explained and as shown in FIG. 3. The housing is situated in such a manner that a semi-circular housing cap 39 is supported over the sump 12 at each end. An end projection 41 generally identical with the projection 37 also lies close to the end of the evaporator drum 17. The structure is such that air is caused to enter through an end opening 42 and thence to enter the interior of the evaporator drum 17. The end frame 43 of the evaporator drum facing the blower is closed so that air entering the evaporator drum must pass through the circular pad-like portion 23 before it can escape out into the space 44 surrounding the evaporator drum and enter the blower housing through an end opening 46. Thus all of the air entering the blower through the evaporator drum 17 must of necessity pass through the evaporative layer 23 before it can enter the blower.

A water supply tank 47 is disposed immediately below the blower and supported on the frame 11, but for convenience in FIG. 2 is shown separated from the frame. Water 48 in this supply tank is maintained at a suitable level by any conventional means such as a float valve (not shown). A pump 49 operated by an electric motor 51 delivers Water through a vertical pipe 52 to a supply line 53, the ends of the supply line terminating in a pair of transverse apertured water supply pipes 54. The apertures 56 are made relatively large to avoid clogging, but the supply pipe 54 and apertures 56 are so positioned as shown in FIG. 3 that water is deposited in relatively large amount at one side of the evaporator drum 17. The water weights the drum so as to cause it to rotate in the direction of the arrow (FIGS. 1 and 3) in a manner which will be explained more in detail hereinbelow. The excess water drops into the sump and a level is maintained by the provision of an overflow rim 57 as shown in FIG. 2. A portion of the blower housing and the projection 38 form a water overflow receptacle 58 drained by a pipe system 59 and delivered back to the water supply tank 47.

The overflow rim 57 causes a water level to be maintained to a point indicated by the letter A in FIG. 3 so that as the evaporator drum 17 rotates, the entire thickness of the evaporative pad 23 will be covered by the water in the sump. This allows time for the circular evaporative pad 23 to become completely saturated. As air passage causes water evaporation from drum 17, the left side (FIG. 3) will be lighter because there is no replacement of water between the points B and C. This is not quite a 180 arc, and its extremes may be varied by shape in water depth and location of pipes 54. The right side of the drum is heavier because of the replacement of water through the pipe 54, although water is continually evaporated from the entire exposed surface of the drum above the water line. Since the cylindrical evaporator pad 23 is fully saturated with water as it leaves the sump and water is again added through the pipe 54, there is no possibility of the pad at any time becoming sufficiently dry to permit uncooled air to pass through it. The arrangement therefore is such that there is always ample water available for evaporation regardless of how fast the drum turns. Depending on several factors, the drum may rotate between about one and ten revolutions per minute, but rotations at between about one and one-half to two complete revolutions per minute is usually adequate. The speed of rotation of course depends on many factors including engineering design and relative humidity so that the invention is not limited to any particular speed of rotation.

The embodiment of the invention shown in FIGS. 1-8 produces good results, but the principles involved can result in many different forms of structure without departing from the features and scope of the invention. Illustratively the drums 17 are open at one end but they may be open at both ends to receive ambient air, or in the system shown in FIG. 1 a single evaporator drum unit may be employed instead of two as indicated. Capacity is one factor which will determine the size of the unit and the number of drums employed, but capacity is not merely a function of the number of drums employed.

In FIG. 8 I employ a single drum housing 61 within which a single relatively long evaporator drum 62 is rotatably supported. Openings 63 for ambient air are provided at each end of the housing, and the single evaporator drum 62 extends entirely across the drum housing and has its open ends in communication with the openings 63. A blower housing 64 is offset from the drum housing and carries a blower 66 adapted to be driven by a suitable source of power, air being drawn into the ends of the blower through passageway 67 communicating with the evaporator drum housing to draw air from the exterior peripheral surface of such drum and discharged by the blower through a discharge opening 68 communicating with a space to be cooled. The features of construction of the drum, blower, and water control system may be identical with those shown in the first embodiment, proportioned however to fit the somewhat modified structure of the FIG. 8 design.

A feature of the present invention is the ease of maintenance. Conventional stationary evaporative pads have a tendency to lime up in spots so that after a period of use the pads are no longer uniformly absorptive and air passes differentially through the body of the pad. In addition, when the conventional pad has been in use for some time, there is a tendency for the excelsior to shift and develop openings through which air can pass with practically no cooling action at all. The large amount of water employed causes not only the pads but other parts to be fouled by the hardness in the water, an effect commonly called liming. The result is that when pads are changed the procedure is a lengthly one and frequently involves immediate cleaning of many parts of the evaporative cooler.

In the present invention the rotation of the pad results in even and uniform distribution of such deposits as may occur, with no development of open spaces through which air may tunnel without cooling. When there is an indication that the pads should be changed, all that is necessary is to lift the upper housing portion 39 as shown in FIG. 1, bodily lift the drum assembly 17 including its shaft and bearings (see FIG. 1), and replace it with a new or repaired drum having the functional characteristics of a new drum. This system lends itself to so-called repairexchange maintenance in which the serviceman provides a like-new drum assembly at a relatively low price in exchange for the old drum assembly which he then cleans, inspects and repairs with simultaneous replacement of the pad and any other non-functioning parts.

The advantages of the evaporative cooler of my invention will be made clear by reference to FIGS. 6 and 7 where a comparison is made between an evaporative unit corresponding to FIG. 1, and a conventional stationary pad unit of the same rated capacity. In all instances in the charts the indicated characteristic of the conventional evaporative cooler is shown in solid lines and the corresponding performance characteristics of the embodiment of my invention used shown in broken lines. The improved performance of my invention is particularly si-gnificant because the total pad surface is much less in my drum than in the conventional structure using three or four pads, each with an area of about seven and onehalf square feet.

Looking first at FIG. 6 the chart shows that there is a marked decrease in air temperature in spite of the fact that the pad area is less. This comparison is shown by the two 'bar graphs indicated by the reference characters 71 and 72. At 73 it will be noted that the water temperature is also reduced in the case of the device of the present invention while at 74 the two bar graphs show an increase in the number of B.t.u.s per unit volume of water circulated. In the case of my invention also the amount of water circulated is also decreased as shown at 76.

In FIG. 7 the amount of water evaporated and therefore the cooling action obtained is plotted against relative humidity of the ambient air. Where the X and Y axes cross, there is a condition of 100% relative humidity with no water evaporation, some water may be entrained in a rapidly moving column of air. The solid line 77 shows the effect of decrease of relative humidity in the conventional evaporative cooler while the broken line 78 shows the manner in which the evaporation is increased when the evaporative cooler of my present invention is employed. It should be understood that the figures given in the graphs, while approximately correct, are primarily intended for comparison, because actual values depend upon a number of factors which are not always possible of control in a commercial unit.

An important characteristic which partially explains FIG. 7 is that a decrease in the relative air humidity causes faster water evaporation and a greater weight differential on opposite sides of the evaporator drum 17. The resulting imbalancing of the drum causes it to rotate faster. As the drum is rotated more rapidly, more water is picked up from the pan into which the drum dips, so that still greater evaporative action occurs. As a result there is an automatic proportioning of the amount of water delivered to the path of the air when the relative humidity of the air is decreased, a result which normally occurs as ambient air temperature increases. Higher air temperature also causes more rapid water evaporation and a faster drum rotation even if the relative humidity should remain constant. This automatic response will also occur, moreover, even if only the amount of air passing through the pad is increased. Thus as shown in FIG. 10 both the sheave 133 and blower 136 may have portions of different diameters so that the belt 134 can be shifted to vary the speed of the blower and the amount of air moved. This is illustrative, as change in blower speed is more conventionally accomplished by more sophisticated means, one common practice being to equip the blower with a two-speed motor. When a two-speed motor is used with conventional evaporative coolers, doubling of the air flow for example will come nowhere near doubling the cooling effect. When employing an evaporative cooler produced in accordance with the present invention however there will be an increase in cooling action over and above that indicated by the increased amount of air, keeping in mind that operations must be at all times within the limits of a particular design.

Supplying actual test figures to support the showing in FIGS. 6 and 7, I found that when employing my present invention the temperature of the water in the system will be at least about 5 lower than the temperature of the water in the usual conventional evaporative cooler sump. In the cooler of my invention there is also less water circulated, because in the present case the circulated water is employed only to weight the drum to rotate the same, while the water which is actually evaporated for the most part is that removed from the pan into which the bottom of the drum extends.

Giving further figures, tests have shown that for each forty pounds of water circulated per minute an average increase of 200 additional B.t.u.s of cooling is obtained, expressing the factor conversely, or in other words 200 additional B.t.u.s of heat are removed from the air and water. For a given horsepower also the .pad area of the present cooler may be decreased an average of about 25% to 30%. An unexpected advantage of my invention is the almost complete elimination of dust, pollen, and chemical substances causing noxious odors. Theoretically much of this material should be filtered out by the usual evaporative pad, but imperfections in the usual pad of the type described leave a great deal to be desired from the standpoint of the removal of dust, pollen, and other materials from the air. Since the pad of my present invention will not acquire open spots and shifting of excelsior, and since also the pad is at all times amply wetted with water, there ispractically a complete removal of air borne particles. These particles of course are flushed from the pad and find their way into the water and to the bottom of the supply tank 47. A drain pipe 81 controlled by valve 82 permits the removal of solid air borne substances from time to time as well as the removal of particles deposited from the water such as insoluble inorganic substances. In the case of my invention the materials of the type commonly referred to as hardness when applied to water seem to deposit out as a loose flack to a considerable extent, rather than being deposited entirely on surfaces into which feed water comes in contact.

In the drawings and in the description of the specific embodiment of the invention shown the heavy side of the drum is loaded with excess water to bias it in a direction to cause rotation of the drum around its axis. The axis preferably comprises a fixed shaft with friction reducing bearings such as ball bearings between the drum and drum shaft. The water introduced to weight one side of the drum provides make-up water for the pan into which the bottom of the drum dips. It should be understood that my invention is not limited to a combination in which this specific relationship exists. It is obvious that any liquid heavier than water but preferably a liquid which is immiscible therewith can be utilized to impart greater weight and therefore faster rotation to the drum. Such a relatively heavy immiscible liquid will fall to the bottom of the drum housing pan as a separate layer and is readily removed without removing water. Make-up water can be introduced either directly to the pan or by means of an apertured pipe as shown, the heavy liquid either being introduced with the water or separately in accordance with a pre-conceived design. Still other means for biasing the drum in a direction to cause its rotation may be employed and it should be noted that regardless of how the drum would be weighted, the automatic increase or decrease of the drums speed of rotation in response to change in temperature or relative humidity or amount of air passing through the pad will still be obtained.

I have described my invention in detail so that those skilled in the art may understand the manner of practicing the same, but the scope of the invention is limited by the claim.

I claim:

Air and water cooling apparatus for air conditioning of living space comprising (a) aframe,

(b) a blower housing supported on said frame with an air outlet opening adapted to deliver air to said living space,

(c) a power driven blower in said blower housing,

(d) a pair of generally tubular drum housings having a fixed bottom portion and separable top portion, each such drum housing communicating with said blower housing and having a generally circular end opening communicating with ambient atmosphere,

(e) a frame portion in each drum housing having a top non-circular recess,

(f) a drum shaft supported on said frame with a noncircular portion engaging in said top recess,

(g) a drum in each drum housing with one closed end and one open end facing said circular opening,

(h) a friction reducing bearing means between said drum and shaft,

(i) a tubular peripheral evaporative pad carried by each drum,

(j) a water pan in each drum housing with an overflow to maintain a constant level, said drum extending into said pan,

(k) a water supply tank, and

(1) means for delivering water from said tank to one side of said drums, said water falling into said pan as make-up water therefor,

(in) means for delivering said overflow water from said pans to said supply tank,

(n) said pan water wetting said pad as the drum rotates and air is passed through said pad for cooling and an upside of the drum being thereby lightened,

(0) said water delivered to a downside of the drum to weight the same and cause the drum to rotate (p) whereby any factor causing an increased rate of evaporation of water from the pad causes faster rota tion of the drum and delivery of a larger amount of evaporative water into the path of incoming air.

References Cited by the Examiner UNITED STATES PATENTS Furbush 308-29 Kirby 26183 X Larsen 261-92 X Robic 261-92 X Bock 261-29 Kenny 26192 Osburn et al. 26192 McGrath.

Norris 26l92 X Leister 308-29 X Alguire 26183 X HARRY B. THORNTON, Primary Examiner.

T. R. MILES, Assistant Examiner.

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