US2536081A - Method and means of air conditioning - Google Patents

Description

1951 N. A; PENNINGTON 2,536,081

METHOD AND MEANS OF AIR CONDITIONING Filed 051.. 12, 1943 s Sheets-Sheet 1 INVENTOR iVeaZ H Pennington BY ATTORNEYS Jan. 2, 1951 N. A. PENNINGTON 2,536,031

METHOD AND MEANS OF AIR connxnonmc Filed Oct. 12, 1943 5 Sheets-Sheet 2 j INVENTOR JV'eaZ ziPennz'hgion ATTORNEYS Jan. 2, 1951 N. A. PENNINGTON METHOD AND MEANS OF AIR CONDITIONING 5 Sheets-Sheet 15 Filed Oct. 12, 1945 Jan. 2, 1951 N. A. PENNINGTON METHOD AND MEANS OF AIR CONDITIONING 5 Sheets-Sheet 4 Filed Oct. 12, 1943 INVENTOR Me I H. Pennington ATTORNEYS 1.951 N. A. PE NNINGTON 2,536,081 METHOD AND MEANS OF AIR CQNDITIONING Filed Oct. 12, 1943 5 Sheets-Sheet 5 m r. s Q W m p A 7 WP a M Z M a F m \WIQ u v w .6 M M Patented Jim. 2, I951 METHOD AND MEANS or AIR CONDITIONING Neal A. Pennington, Tucson, Ariz. Application October 12, 1943, Serial No. 505,924

8 Claims.

' This invention relates generally to the art of air conditioning. Specifically the invention is dirooted to the cooling and humidifying of warm, and relatively dry, outside air and directing it into the space which it is wished to air condition, suchas rooms of homes, theatres, auditoriums, business places and the like.

The primary object of the invention is to provide an economical, compactair conditioning unit which will avoid the use of mechanical refrigcrating units, outside water towers, or metallic heat exchange coils of any kind.

Another object of the invention is to produce a method and means of cooling and humidifying air wherein a preliminary contact cooling is provided by bringing the air into direct surface contact with a continuously exposed non-hygroscopic cooling medium without intervening metallic walls such as coils, plates or the like, and then further subjecting the air to evaporative cooling and humidifying by passing it through a continuously exposed film of water or the like; maintaining, in the meantime, desirable relations between the various factors determining a comfortable state of the air, viz: its dry bulb temperature, its wet bulb temperature, and its relative humidity, all determined solely by outside weather conditions and without the use of mechanical controls such as thermostats humidistats, and the like.

The advantages of the present invention will be most conspicuous in those geographic areas where the air to be conditioned generally possesses a lower humidity than is desirable. In such areas my improved method preliminarily cools the air without adding moisture (latent heat) and then, while still further cooling it adds to its moisture content in just the desired amount to produce the proper relative humidity, this being all accomplished at a minimum cost and with a minimum of moving parts.

The accomplishment of my objectives involves a two-stage operation. The first stage exists to cool the cooling medium to. near the wet bulb temperature of the air to be conditioned prior to its surface exposure to such' air; and the second stage exists to utilize such cooling medium, plus a water stream to properly treat the air to be conditioned, all in a manner and with the results as will full appear by a perusal of the following detailed specification. The two stages are preferably incorporated in one compact unit or may be placed at separate points, where that practice might be found desirable.

In the drawings similar characters of reference refer to like parts in the several views:

Figure 1 is a diagrammatic outside elevation of a compact unification of the two stages of my improved apparatus I I Figure 2 is a vertical sectionof the same.

Figures 3, 4, 5, and 6 are crosssectional views of the unit taken respectively on the lines 8-4, 4-4, 5--5, and 6-6 of Fig. 2.

Figure 7 shows a modified form or the invention.

Figure 8 is a sectional view taken on a line 8-8 of Fig. 7. I

Mechanism Referring now more particularly to the characters of reference on the drawings, the numeral l designates a storage tank for the non-hygroscopic oil or other non-hygroscopic liquid, described more in detail under the description of operation contained later in this specification.

The liquid is adapted to be withdrawn from the tank I throughapipe 2 by a pump 3 and is forced by said pump through apipe 4 to two branches 5 and 6. I

The branch 6 leads to and is adapted to discharge into a circular distributing trough I in the bottom of which are provided a plurality of holes 8.

Located immediately below the trough I and concentric therewith is a circularpad 9 made up of excelsior or other fibrous, spongy or foraminous material of sufficient porosit to readily allow the passage of air therethrough.

from said trough ma pass through the holes 1 and seep by gravity down through the pad 9 in a manner to cover the wall structure of the pad and keep the liquid in substantial surface extrough I2 is another circular pad ll similar to the pad 9 sothat liquid seeping through the holes l3 will flow by gravity through the pad and be held in continuous surfaceexposure toany air passing through such pad.

The pad I rests in a collecting trough Ii which Being posiltioned immediately below the trough I, liquid 3 has bottom holes it which will discharge liquid from the trough l5 into the reservoir I.

I1 is a water reservoir tank from which a pump l8 forces water through a pipe l9 to two branches and 2|. The branch 2| leads to a circular spray head 22, somewhat larger in diameter than, and arranged concentrically around, the upper distributing trough I. A valve 2: controls the flow of liquid through the branch 2|.

A circular pad 23 of similar composition to that of the pad 9 is disposed concentrically around the latter and beneath the water spray head 22 so that water discharging from the spray head will flow by gravity through the pad 23 and be held in continuous surface exposure to any air passing therethrough.

The bottom of the pad 23 rests in a water collecting trough 24, which ha a plurality of discharge openings 25 which lead and discharge into a circular water distributing trough 26 arranged concentrically inside the inner periphery of the trough i2 and having a plurality of distributing holes 21. The branch 20 of the water pipe leads to a distributing head 28 disposed immediately below the trough 26.

A circular pad 29 of similar composition to that of the pad 23 is arranged concentrically inside of the pad [4 and immediately below the trough 26 and spray head 28 so that liquid discharged from either of these will flow by gravity through the pad 29 and be held therein in continuou surface exposure to any air passing through said pad.

The bottom of the pad 29 rests in a pan 30 from which openings 3| lead to a discharge trough 32.

Make-up water may be admitted to the tank H by a pipe Ila, the proper level in the tank being automatically controlled by a float valve llb.

Both of the tanks i and I1 may be provided with suitable drains la and 110, respectively, for cleaning purposes.

Within the air-well A formed by the concentrically arranged pads 9 and 29, I provide a series of deflecting plates 33.

Preferably supported on the frame work of the unit is an air blower fan 34 driven by any suitable means, such as a belt 35 from a motor 36, which motor also drives the pump 3 through the medium of belt 31.

An air duct 38 leads from the fan 34 and completely surrounds and encloses the upper end of the well A so that air driven from the fan through the duct will be forced into said well. A part of this air will be deflected by the plates 33 to pass through the porous pads 9 and 23, and another part will be deflected to pass through the porous pads 29 and i4.

Surrounding the pads 9 and 23 is an enclosed casing 39 having a divider partition 40 on one side, and on the opposite side is provided an outlet duct 4| having divider plates 4la, the duct 41 leading to the space to be air conditioned.

Operation variant, now being described), or (as in my sec- 0nd variant, to be described hereinafter) may be due to having the same vapor pressure as the air being treated although inherently hygroscopic. Preferably, although not necessarily so. this fluid would be a light grade of white mineral oil, particularly an oil refined from a naphthenic base oil found in some of the Western crudes in the United States. An example of such an oil is White Oil No. 3 U. S. P. or Standard CT-70 oil, both produced by the Standard Oil Company of California. This oil, particularly the CT-70, is inexpensive, has a. low viscosity (about 30 centipoises as 65 F.), a good thermal conductivity, a

good specific heat, and practically zero vapor pressure at the temperatures employed. It has a specific gravity a little less than water, and a very good penetration of wood and other fibers. It is odorless and non-toxic, highly resists oxidation and will not spoil or acquire an odor upon long exposure to air. Lastl and of great importance, it is almost one hundred per cent nonhygroscopic, which is very essential to the successful carrying out of my improved method of air conditioning. The part that such a nonhygroscopic buid plays in my novel method will appear as this description of operation is proceeded with.

This non-hygroscopic oil or other fluid is pumped from the tank I through the pipe 2 by the pump 3 and forced through pipe 4 to branches 5 and 6. That passing through the branch 6 is discharged into the distributing trough 1 and flows through the holes 8 into the pad 9. It then flows by gravity through such pad 9, and due to the composition of the latter is held in a state of very considerable surface exposure.

After the oil leaves the pad 9 it flows into the collecting trough ill from which it flows through openings ll into the second distributing trough I2 and passes through holes I3 into the pad l4. It then flows through this pad by gravity and is thus again held in a state of substantial surface exposure. As it leaves the pad l4 it is collected in the trough l5 and flows through the opening l6 back into the tank l ready to repeat the circuit just described. That portion of the oil allowed to flow through the branch 5, if any, is discharged directly into the trough l2 and there joins the flow of the oil from the pad 9.

The water from the tank I! is forced by the pump l8 into the pipe l9 and thence to the branches 20 and 2|. That portion flowing through the branch 2| reaches the spray head 22 and flows therefrom by gravity through the pad 23 where it is held in very substantial surface exposure. As it leaves the pad 23 the water collects in the trough 24 and discharges from there through the holes 25 into trough 26 and thence through holes 21 into pad 29. It flows through this pad by gravity and is again spread out into a state of substantial surface exposure. It leaves the pad 29 to coQlect in the pan '30, flowing thence through openings 3| to drain 32, whence it is carried to tank IT. Water from the branch 20 flows through sprinkler head 28 and joins with the water coming from pad 23 to flow through pad 29.

Air is forced by fan 34 through duct 38 into well A, where it is broken into two streams, one passing through pads 9 and 29 and thence to the space to be air conditioned; and the other through pads 29 and I4 to the atmosphere.

The pads are inclined toward the air streams in the ratio of about one inch per foot of height, or other suitable ratio, in order to overcome the tendency of the air to blow the liquid toward the The flowing streams of non-hygroscopic oil and of water function to cool and humidity the air stream which flows to the space to be ditioned, as follows:

This air stream originates from the outside atmosphere, which is warm and relatively dry, and is forced by pressure of fan II to blow first through the pad I, then through the pad II, into the casing II, and finally through duct Ii to the space to be conditioned.

The non-hygroscopic oil flowing through the pad I has been cooled in the manner described later. Therefore, as the air stream is diffused through Dad I it comes into intimate heat but not moisture exchange relationship with such non-hygroscopic liquid. -This causes the air to give up some of its sensible heat to the liquid, but without acquiring any additional moisture or latent heat in the process, and accordingly without having its dew point changed. Hence, in passing through the pad I this streamof air to be conditioned has'its dry bulb temperature and wet bulb temperature lowered and. loses aportion of its total heat.

ThisairasitleavesthepadIpassestoand through the pad II where the water is flowing in a state of surface exposure. Here the air is brought into both heat and moisture exchange relationship with the water and is hence further cooled, evaporatively, and humidified, its wet con . r 8 stitute a departure from the essential portions of my invention to have two separate water circuits.

The :air stream passing through the pad II in contact with the water therein is cooled by mp oration of such water to or near the wet bulb temperature of the outside atmosphere.

This air then passes across to and through the pad II through which the non-hygroscopic liquid from the pad I is flowing. Here this cool and saturated air picks up heat from the liquid which the latter had acquired from the stream of air passing through pad I.

It will be evident. therefore, that as the second stream of air passes through pad II it has its sensible heat greatly reduced, 1. e. its dry bulb temperature is reduced to near its original wet bulb temperature.

bulb temperature remaining essentially constant. c

The air thus cooled and humidified moves through casing II and duct Ii to the space to be air conditioned.

The portion of the water passing through needle valve lid and pipe 2| to final passage through pad II is usually only a small portion of the total water circu.ated through the system and can be controlled to fit conditions by operation of such needle valve 2 in.

As this water seeps down through the humidifv s pad II and hence comesinto contact with the air flowing through such pad, it has its temperature quickly lowered to, or very near, the wet bulb temperature of such air. This air has a lower wet bulb temperature than that of the warm dry outside air because it has just passed through the non-hygroscopic liquidin pad I and given up some of its sensible heat. It follows therefore that the water passing through pad II very quickly assumes a temperature lower than the wet bulb temperature of said outside air.

This cooled water then Joins and mixes with the portion of water not passed through valve II at a point Justabove the pad II, as previously described. This mixture atfirst has a temperature slightly lower than the temperature olthe water coming directly from tank il. However.

ture desired in the air to be cooled. All these because of its exposure to the warm dry outside 1 air being pushed through the pad II by the fan II, the water moving through such pad II very quickly assumes a temperature at or near the wet bulb temperature of such warm dry outside air, surrounding the whole apparatus, and at substantially the same temperature as the water in tank ll. Thus, it will be noted that the use oi one divided and then rejoining water circuit, rather than two separate water circuits, results in not wasting the coolness which the water acquires in the upper pad II. Also I save the cost of two water pumps. It would not, however, conthrough such pad. The air is then in heat but not moisture exchange relation with said liquid, and hencesuch air reduces the temperature of the non-hygroscopic liquid to near the original wet bulb temperature of the air to be treated, so.

that this fluid will function in removing heat from the first stream or air when the cycle of movement of the liquid again carries it through the pad I. It should benotad, as already mentioned, that the first stream of air is further cooled by the evaporatio of water in pad II.

The above described ycles of operation, with the desired resultants. made possible by the fact that in both th ds I and II the liquid employed is non-hygr opic, i. c. it neither gives up or absorbs moisture from the air which comes in contact with it, but is in merely heat exchange relationship with the air, thus allowing the twophase or dual operation whereby the same liquid moving in a continuous circuit or cycle is utilized to first cool the air to be conditioned and then, reversely, is itself cooled to condition it for functioning to again cool air to be conditioned. I have found that the most satisfactory results may be obtained from this dual or two-phase operation by so setting up the apparatus that the second or cooling stream of air is greater than the first stream to be cooled. Just how much greater depends upon the mean summer wet bulb depression prevailing in the climate in the area in which it is intended to operate it, and upon the amount of lowering of the wet bulb temperafactors can readily be calculated and applied to give the desired results.

The evaporative' cooling. 1. any, and the humidifyihg of the air tobe conditioned occurs solely in the pad II, and these factorscan be controlled by the setting of the needle valve Ila,

which determines the amount of water allowed to pass through such pad II. This is usually only a small portion of the total water circulated through the system.

While the stage of the apparatus for cooling and humidiiying the air to be conditioned, and that of cooling the non-hygroscopic fluid, are here disclosed as united into one compact unit, it is obvious that they may be located at separate points if that should beiound desirable.

The form of the unit here shown is circular. It could, however, be square or such other shape as may be selected without in any way affecting the mode of operation set forth.

Inl'iga'landIIshowamodifledformof contact at that particular instant.

conditioned-. 1

The concentration of solution is not constant. At any time it merely has, or tends to have, that particular concentration which-will give it a vapor pressure equal to the vapor pressure of the atmospheric air with which it is in When the amount of moisture in the air changes and hence the vapor pressure of the air changes (as it will from day to day or even from hour to hour, under normal weather conditions), the concentration of the hygroscopic solution also automatically changes in such a way that its vapor pressure tends to assume a value equal to the current vapor pressure of said air. This has to be the case because it the atmospheric air becomes more moist, then the solution will no longer be bal-' anced with it but will have a lower vapor pressure than that of said air, and hence will absorb v moisture from it until the vapor pressures of the two are again equal. On the other hand, if the air changes in such a way as to become drier then the vapor pressure of the solution will be greater than that of the air. Hence water will evaporate from the solution into the air until the equilibrium of vapor pressure is restored. Thus, it can be said that at that time the solution is, in a sense, non-hygroscopic. and useful as a cooling agent for the purposes of my invention. It will never be necessary toadd water to the solution, except perhaps when flrst placing the solution in the apparatus, as the concentration thereof. which is variable, is constantly maintained at the proper value by the vapor pressure of the atmospheric air.

I will now describe in detail the modified structure used when a solution of the character described is employed in carrying out my improved method of cooling air;

Mechanism The numeral 42 designates the solution tank in which is maintained a supply of hygroscopic liquid of such concentration that when cooled and brought into contact with the air to be conditioned it will be in heat but not moisture exchange relation with the latter.

From the tank 42 a pipe 49 leads to a pump 44 driven by any suitable means, such as a belt 45 from a motor 46. A pipe 41 leads from the pump 44 to a coil 48, the convolutions of which are embedded in a pad 49 of a structure such as that oi. the pad l4.

From the top of the coil 49 a pipe 59 leads to an annular trough in the bottom ofwhich is provided a pattern of holes 52.

Immediately below the trough ii and arranged so that the holes 52 register therewith is a Dad 53 01 a construction similar to that of the pad 9. The bottom of the pad 53 rests in an annular pan 54 which has an outlet pipe 55 leading to and discharging into the tank 42.

The numeral 56 designates a water supply tank having a supply pipe 51, the supply being controlled by a float valve 59.

A suitable water pump 59 is provided, and leading from this pump is a pipe 99 having two branches 6i and 62, there being a control valve 99 in the branch I. The branch ll connects 8 with a spray coil 84 disposed atop the pad 4| and adapted to discharge onto the top of said pad so that the water may seep through the pad.

The branch 62 leads to and connects with a spray coil disposed atop an annular pad ll of a structure similar to the pad 23. This pad is concentric with the pad 53 and rests on the bottom of a housing 61 in the bottom of which are holes 69 which are immediately above the pad 49 so that water passing through the pad 6! will discharge through these holes 68 onto the pad 49. The pad 49 rests in a trough 58a having a drain 9912 so that the water from pad 49 is col lected in trough 58a and discharges through drain 56b into the tank 58.

The housing 51 forms an air chamber around the pads 59 and 66. It has a divider partition 89 on one side and an outlet duct ill on the other side leading to the space to be air conditioned. Divider plates II are within the housing adjacent the duct 19. A portion 66a of the pad 69 is blanked oi! so that air will not pass directly from the pad into the duct 10 at that point. Pad 23 could be similarly blanked.

An air blower fan 12 is driven by a belt 13 from motor 46, and a duct 14 leads from the fan to the well W formed between the pads 51 and 49.

Operation The operation of the pump 44 draws the liquid from the tank 42 and forces it through the coils 48 where it is cooled in the manner hereinafter described. The cooled liquid then passes through pipe 59 into trough ii, passes through holes 52 and seeps by gravity through pad 53. At the same time water from tank 56 is pumped through pipe 80 and branches 6i and 62 to spray heads 64 and 65 to flow by gravity through pads 66 and 49 in the manner previously described, and thence through trough 56a and drain 58b into tank 59.

The air to be conditioned is drawn from the atmosphere by the fan 12 and forced through the duct 14 into the well W. Here deflecting plates 15 divert a portion of the same to cause it to pass through the pad 53. Here it comes into direct contact with the liquid flowing through the pad. Although this liquid is hygroscopic in character it is, as stated, held at such a degree of concentration as to render it substantially nonhygroscopic. It is therefore maintained in heat but not moisture exchange relationship with the air passing through the pad 53. This causes the air to give up some of its sensible heat to the liquid, but without acquiring any additional moisture or latent heat in the process and without having its dew point changed. Hence, in passing through the pad 53 this stream of air to be conditioned has its wet bulb temperature lowered and loses a portion of its total heat.

As this air leaves the pad 53 it passes to and through the pad 66 through which the water is flowing in a state of substantial surface exposure. At this point the air is brought into both heat and moisture exchange relationship with the water and is hence further cooled, evaporatively, and humidified, its wet bulb temperature remaining essentially constant.

An even flow of the air through the pads 53 and 69 is eflected by the deflectors 89 and H and the conditioned air passes into the housing 61 and hence through the duct 19 to the space to be conditioned.

The water passing through the pads 46 and 49 will be cooled in substantially the same manner as that passing through the pads 23 and 29 of the other has i the invention previously de- 7 scribed: Since the coil 48 is embedded within the pad I this cooling of the wateraround this coil operates to lower the temperature of the solution inside the coil to near the wet bulb temperature 'of the air to-be treated prior to'the solution reaching and flowing through the pad 53 so that at that point it is effective to lower the temperature'ofthe air in the manner described.

The specific order of the steps of the method,

and the apparatus selected and herein illustrated as preferred embodiments of my invention have been clearly set forth in connection with the foregoing detailed description of the invention. To those skilled in the art modifications of the specific structures and their application in carrying out the method of the invention will be evident from the detailed description of the specification. It is to be understood that the words which have been used are words of description rather than of limitation and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of the invention in all of its aspects.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

1. Apparatus for the conditioning of air commeans to flow water through one of said last named pads, means to flow said non-hygroscopic liquid through the other of said last named pads and thence to the first mentioned means, and means to flow air first through the water-containing pad and then through the pad containing the non-hygroscopic liquid.

2. Air conditioning apparatus comprising a first stage and a second stage, the flrststage including two foraminous pads. means to flow a stream of water through one of said pads, means to flow a warm non-hygroscopic liquid through the other had. means to pass air through the water-containing pad to evaporatively cool said air to a temperature lower than the non-hygroscopic liquid, means to then pass said cooled air through the other pad in contact with said nonhygroscopic liquid whereby to eflect heat exchange relationship between the two and reduce the temperature of the liquid; the second stage comprising two foraminous pads, means to flow said cooled liquid through one of said pads in direct contact with the surface area thereof, means to flow a stream of water through the other pad in direct contact with the surface area thereof, means to flow a stream of air through the first pad of said second stage and in direct surface contact with the cooled liquid thereof and in heat exchange relationship therewith,

whereby to reduce the temperature of said air, means to then pass said air through the second pad of said second stage and in direct contact with the water flowing through the latter whereby to effect further cooling of such air and to humidify the same, and means to then pass said air to the space to be air conditioned. 3. An air conditioning apparatus comprising a stage and a second stage. the first stage in- 10 eluding a foraminous pad, means to flow a liquid through said pad out of direct contact with the surface area thereof, means to flow a stream of water through the pad indirect contact with the surface area thereof, means to flow astream of air throughthe padin direct contact with the water whereby to evaporatively cool the water and effect the lowering of the temperature of said liquid; the second stage comprising two foraminous pads, means to flow said cooled liquid.

in, direct contact with the water flowing through the latter whereby to effect further cooling of such air and to humidify the same, and'means to then pass said air to the space to be .air conditioned.

4. An air conditioning apparatus comprising two stages, each stage including two concentrically arranged foraminous pads, means to pass a non-hygroscopic liquid through the inner pad of the second'stage and from there to the outer pad of the first stage and in direct contact with the surface area of both pads. means to pass a stream of water through the outer pad of the second stage and the inner pad of the first stage and in direct contact with the surface area of both pads, means to pass a stream of air first through the inner pad of the second stage and then through the outer pad of such stage, and in direct contact with the liquid and water respectively, and thence to the space to be air .Gdlidi-yp tioned, and means to pass a stream of air first through the inner pad of the first stage and then through the outer pad of such stage in. direct contact with the water and liquid respectively,

and thence to the atmosphere.

5. That method of conditioning air which comprises establishing a zone of liquid which is inherently hygroscopic but is rendered efi'ectively non-hygroscopic by being of such a concentration as to cause its vapor pressure to automatically come into equilibrium with the vapor pressure of the air with which it comes into contact, and which liquid is maintained at a temperature lower than that of the air to be conditioned and is held in a state of substantial surface exposure, passing the air to be conditioned into heat but not moisture exchange relationship with such liquid, and supplying such air to the space to be condit'oned.

. 6. A method of conditioning warm dry air, which comprises: cooling a stream of air (of characteristics similar to those of the air to be treated) by bringing it into direct contact with a flowing stream of water; cooling a continuously circulating stream of non-hygroscopic liquid by bringing it into direct contact with said stream of air; bringing the air to be treated into direct contact with the thus cooled liquid; then increasing the moisture content of said last-men- 7. In an apparatusforthe conditioningof'air,the

combination of a heat exchanging but not moisture exchanging cooler, which cooler comprises x a foraminous pad and a stream of non-hygroscopic liquid circulating through the pad, such liquid being of lower temperature than the temperature of the air to be conditioned; a humidiiler comprising a foraminous pad and a stream of water circulating through said last named pad; the liquid circuit and the water circuit being wholly distinct, and means to force the air to be conditioned first through the cooler and then through the humidifier.

8. In an apparatus for the conditioning of air, the combination of: a heat exchanging but not moisture exchanging cooler, which cooler comprises a foraminous pad and a stream of nonhygroscopic liquid circulating through the pad, such liquid being of'lower temperature than the temperature of the air tobe conditioned; a humidifler comprising a foraminous pad and a stream of water circulatng through said last named pad; the liquid circuit and the water circuit being wholly distinct; means to force the air to be conditioned first through the cooler and then through the humidifier; a casing enclosing said pads; and a duct leading from the v The following references are of record in the file 01' this patent:

UNITED STATES PATENTS Number Name Date 1,486,367 Dunlap Mar. 11, 1924 1,681,926 Bell Aug. 28, 1928 1,743,974 Mallet Jan. 14, 1930 1,894,229 Weber Jan. 10, 1933 1,909,823 Forrest et a1. May 16, 1933 1,961,308 Thompson June 5, 1934 1,962,572 Richardson June 12, 1934 2,017,027 Forrest Oct. 8, 1935 2,090,287 Cornelius Aug. 17, 1937 2,108,248 Bichowsky Feb. 15, 1938 2,114,787 Smith Apr. 19, 1938 2,127,993 Crawford 1 Aug. 23, 1938 2,211,886 Dudley Aug. 20, 1940

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