US2464766A - Air conditioning apparatus - Google Patents

Description

March l5, 1949. N. A. PENNINGTON 2,464,766

AIR CONDITIONING APPARATUS Filed Jan. 12, 1946 4 Sheets-Sheet 1 INVENToR, NEAL PENN/wrm,

A TTRNEK March 15, 1949. N, A, PENN|NGTQN 2,464,766

AIR CONDITIONING APPARATUS Filed Jan. 12, 1946 4 Sheets-Sheet 2 @l if INVENTOR, NEAL A. PENN/NQTON,

Lax/@www ATTORNEY.

March 15, 1949. N A, pENNlNGTQN 2,464,766

AIR CONDITIONING APPARATUS Filed Jan. 12, 1946 4 Sheets-Sheet 3 PERCENTAQE HumxDlT.

DEW PDNT TEMPERATO RE.

DPH BULB TemPERh-ruaa l PERCENTAGE Hvmmmt. @u

DEW POlNT TE MPERATURE..

DR BULB TEMPEFLTURE INVENTOR,

/VEAL A PENN/NGTON www ATTORNEY.

March l5, 1949. N. A. PENNINGTON 2,464,766

AIR CONDITIONING APPARATUS Filed Jan. 12, 1946 l 4 sheets-sheet 4 Pesacamwsa Hummm?.

DEW Polm- TEMPERATQRE.

DK? BvLBTEMPERATuRE,

INVENTOR, NEAL APENN/rvcavow, BY

ATTORNE Y.

TEN

T OFFICE 2.464.166 Am coNmrromNc APPARATUS Neal A. Pennington, Tucson, Ariz., assignor of one-fifth to Robert-.11. Henley, Tiptonville, Tenn., and one-fourth to Roger Sherman Hoar,

South Milwaukee, Wis.

Application January 12, 1946, Serial No. 640,792

33 Claims. y (01.62-139) .1 2 My invention relates to new and useful imsaid rst variant, taken along the line 2-2 of provements in air-conditioning apparatus, and more particularly to self-contained units for cooling individual rooms, although my invention could equally well be used in a central air-conditioning plant for a building or residence.

The principal object of my invention is to devise a unit for merely cooling the air, without appreciable incidental change in the moisture-content thereof; although by adding appropriate further elements (either conventional or inventive per se) my unit would serve to humidify, dehumidify, or otherwise change the characteristics of the air which is being treated.

Competing units of the prior art involve some refrigerant (such as Freon) cooling-coils, a piped 'circuit for the cooling medium, a compressor, and

a heavy-duty motor to run the compressor. The above-listed apparatus is the chief cause of bulk, of initial expense, of breakdowns and consequent upkeep expense, and of consumption of electric current.

Accordingly it is a further object of my invention to eliminate the above-listed apparatus, and thus provide a unit which is smaller, is less expensive to build, is less expensive to keep in re- In addition to my principal objects, above stati ed, I have worked out a number of novel and useful details, which will be readily evident as the description progresses.

My invention consists in the novel parts and in the combination and arrangement thereof, which are defined in the appended claims, and of which two embodiments are exemplied in the accompanying drawings, which aref hereinafter particularly described and explained.

Throughout the description the same reference number is applied to the same member or to similar members.

Figure 1 is a horizontal section of the apparatus of one variant of my invention, somewhat conventionalized, taken along the line I-I of Figure 2.

Figure 2 is a vertical longitudinal section of ,Figure 1.

Figure 3 is a vertical transverse section of a l'portion of said first variant, taken along the line 3--3 of Figure 2.

Figure 4 is a vertical transverse section of another portion of said first variant, taken along the line 4-4 of Figure 2.

Figure 5 is a horizontal section of the apparatus of a second variant of my invention, taken along the line 5--5 of Figure 6.

Figure 6 is a vertical longitudinal section of said second variant, taken along the line 6--6 of Figure 5.

Figure '7 is a vertical transverse section of said second variant, taken along the line I-l of Figure 6.

Figure 8 is a vertical transverse section of a portion of said second variant, taken along the line 8-8 of Figure 6.

Figure 9 is a vertical transverse section of a portion of said second variant, taken along the .line 9--9 of Figure 6.

Figures 10, 11 and '12 are psychrometric charts, of which Figure 10 shows a'psychrometric circuit of air passing through my iirst variant, Figure 1l shows a psychrometric circuit of air passing -through my first variant under such load conditions as to render said variant relatively impractical, and Figure 12 shows a psychrometric circuit of air passing through my second variant under the same load conditions as Figure 11, thus illustrating the greater practicability of my second variant under such conditions.

Referring now to Figures 1 to 4, We see that II is the main container of the lrst variant of my invention. I2 is an air-inlet from outdoors. I3 is an air-outlet to outdoors, or to the attic space of the building.

In inlet I2, there is a fan I4, the direction of rotation and shape of blades of which is such as Ato impel air to the left in Figure 2, into passage I5, and thence into the room through louvres I6.

In outlet I3, there is a fan I1, the direction of rotation and shape of blades of which is such as to impel air to the right in Figure 2, sucking exhaust air from the room through louvres I8 ingr: massage I9, and discharging this air into out- Either set of louvres, or both, could be made adjustable. The particular types of fans shown are known as axial-How pressure fans, but other forms of fans or blowers could be substituted, such for example as the type of fan shown hereinafter in my second variant.

'I'he reasons for these optimum speeds will be A explained hereinafter.

21 is a removable dust-mter of any conventional or inventive sort.

Shaft 26 rotates a circular pad 28, which will now be described. Without limitation. but rather merely for convenience in nomenclature, this pad will be referred to as the excelsior pad.

Turning to Figure 4, we see that this excelsior.

pad comprises a hub 28, spokes 80, and a rim 3|.l Each of the sectors, bounded by the spokes and heat-absorbent (l. e. high heat-conductivity, high speciilc heat, and proper surface) such as metal wool, of which I have tried various sorts, including copper wool, but prefer aluminum wool. As in the case of water pad 23, but now for somewhat dierent reasons, the spokes 40 and rim 4l of this aluminum-wool pad 38 are as wide (in a direction parallel to the axis rotation of the pad) as is the pad itself. This helps to hold the stuffing in place, but is primarily for the purpose of preventing air-fiow outwardly radial of the pad, or from passage I9 to passage l5, or vice versa. In this connection, note that bridges 43 are at least deep enough to cover one sector of the pad at each end-of each bridge; thus there will always be at each end of each bridge at least one spoke the rim, is stuffed with excelsior 32, or any other zo place, and also serve` another purpose which will be mentioned hereinafter. If desired a fine-mesh or coarse-mesh screen could be added to each face of the pad, to further help hold the stuihng inA place. Any other sort of water-absorbing rotating pad could be substituted.

This excelsior pad 28 rotates enclosed in a casing 34, each end of which has two circular-segment orifices 38-31. The lower one-quarter (by height) of the pad is immersed in water (or other volatile liquid) in tank 35, which is the lower portion of casing 34. This casing 34 also serves to support the bearings for shaft 2S.

' covered by the bridge, thus effectively sealing oi! the two passages from each other. Bridges 43 also serve to support the bearings for shaft 22. If desired a fine-mesh or coarse-meshscreen could be added to each face of the pad, to further help hold the stufng in place.

The thickness of the aluminum-wool pad will be discussed hereinafter, such discussion being the means of leading up to a statement of the reasons for my second variant.

Any other sort of highly heat-absorbent pad,

l which would permit the free and yet bamed permeation of air parallel to the pads axis of rotation, but not perpendicular thereto, and which does not permit an appreciable conduction of convection of heat by the pad parallel to its axis, could be substituted.

This pad 38 rotates enclosed in a casing 44, each end of which has two sectoral orifices, separated from each other by bridge 43. Upper orifice 48 connects with passage l5. Lower orifice 41 connects with passage I9.

I have found that a rotation of about 30 R. P. M.

is optimum. For the less time that any given por- Both orifices connect with passage I9, there` R. P. M., the radiauy inward gravity now of the water from the soaked upper portion of the periphery of the pad, distributes the water very evenly and at just about lthe right degree of saturation for the best evaporation. The flanges 33 confine this water and prevent it from flowing out of the pad.

Slower rotation would permit too much inward draining, and too much drying out due to evaporation, and so would reduce the total amount of evaporation. Faster rotation would not give time for the desired evenness of distribution, and so would reduce the total amount of evaporation.

Too fast rotation would also result in the entrainment of water particles by the outgoing airstream. Although, of course, we do not care whether or not this stream is thus contaminated, these particles would become carried over into the incoming stream by the aluminum-wool pads, about to be discussed.

Shaft 22 rotates a circular pad 38, which will now be described. Without limitation, but rather merely for convenience in nomenclature, this pad will be referred to as the aluminumwool pad." Turning to Figure 3, we see that this pad comprises a hub 33, spokes 40, and a rim 4|. Each of the sectors, bounded by the spokes and the rim, is stued with some non-hygroscopic air permeable non rusting substance, highly tion of this pad is exposed to each air-stream, the more heat is absorbed from or given oii to the air, due to the greater average temperature-difference between pad and air. And yet, if the pad be rotated too fast, air from one stream is entrained and mixed with the other stream, which is usually undesirable. Still faster rotation would also interfere with the cross-flow of the air through the pad.

On the other hand,l a speeding up of this pad could be employed to partly humidity the incoming air if desired.

Stopping the rotation of the pads will effect simple ventilation.

A water-level gauge 48 serves to inform the occupant of the room whether or not the water is at optimum level. Water can be added or drained through appropriate openings (not shown); and/ or a oat-valve 49 and water supply-pipe 58 could be employed to maintain the water at the desired level.

The operation of the just-described first variant of my apparatus is as follows.

Exhaust air, leaving the room through passage I9, passes through the upper portion of excelsior pad 28; wherein, by the evaporation of the water in the excelsior. this air exchanges sensible heat for latent heat in the form of moisture, become nearly saturated (about and its dry-bulb temperature becoming reduced nearly to its wetbulb temperature, which remains substantially unchanged. If this air be drawn from the room, as contemplated, its initial wet-bulb temperature (which is what determines the final dry-bulb temperature of the adiabatic cooling) will be lower than the wet-bulb temperature of the outdo'or air, thus imparting a regenerative eect on the operation; hence this source for the outgoing air is generally preferable.

The thus-cooled outgoing air then passes through the lower portion of aluminum-wool pad 3B, extracting a large portion of the heat therefrom. The waste air then passes out into the outdoors through outlet I3 or into the attic space.

Fresh outdoor air is meanwhile entering at the same rate through inlet I2, and is iiltered by dust-lter 21. It then passes through the upper portion of aluminum-wool pad 38, which has been cooled as already described. This aluminumwool pad extracts a large portion of the sensible heat from the incoming air, without substituting any latent heat in the form of moisture, i. e., without altering the dew-point of .the incoming air.

The thus-cooled, but not humidifled, incoming air then passes on through passage l5 into the room which is being -air-conditioned.

Now, in order for my machine to operate in a steady state, the heat given .to the aluminum- Wool pad by the incoming air stream must equal that given up by this pad to the outgoing air stream. Hence, if the two streams are of the same magnitude, ythe incoming stream will decrease in dry-bulb temperature, within the upper portion of this pad, -by the same amount as the outgoing stream increases in dry-bulb temperature, within the lower portion of this pad.

I have empirically worked out the following rough rule of thumb for determining what thickness of aluminum-wool pad is necessary to accomplish any given desired heat transference: namely that I have found that, at an air veiocity of about 600 feet per minute, and a pad rotation of about revolutions per minute, an anhydrous cooling of about one degree Fahrenheit per inch of -pad thickness yper degree of mean .temperature difference between the pad and each air-stream can be expected. This formula is, however, presented here not so much as a quantitative guide to the designing of machines of the sort invented by me, but rather for purposes of comparison in discussing the Ap-atentable diierences between the two variants herein discussed. This formula is predicated upon the assumption of Ipractically perfect counterow, which is attainable by my invention. The corresponding formula for the thickness of the excelsior pads is rather dierent. The water in one of these pads will acquire and maintain an equilibrium temperature equal to the wet-bulb temperature which the outgoing air has at the pad, and this temperature will be considerably less than the dry-bulb temperature of the air as it enters the pad, and even somewhat less than the dry-bulb temperature of the air as it leaves the pad. The average 4temperature difference between air and water in the pad is the logarithmic mean of these two dierences. Dividing the isowet-bulb cooling in dry-bulb degrees eiected by the pad, by this logarithmic mean, and then multiplying by 0.8, gives us a conservative thickness for the pad. Furthermore, inasmuch as the excelsior pads interpose practically no resistance to the air-stream (as contrasted with the aluminum-wool pads), I build of uniform thickness the excelsior pads of my multipad variant.

To illustrate the application of the aluminumwool pad formula let us consider how to design one of my machines to meet a given situation.

"Let us suppose that we wish .to cool outside air 'of 100 dry-bulb temperature and a '54 dewpoint, so as to bring to a room which (because -of size, leakage and non-insulation) would impose a 5 load on a machine of the rate of airdelivery contemplated. This means that we must cool the incoming air 25, to 75.

This cooling is represented by the line from A to B on Figure 10, the load being represented by the line from B to C.

The outgoing air is represented at C. The excelsior pad cools this air adiabatically (i. e., without change in wet-bulb temperature) to 95% humidity (which is about the practical capacity of such a method of evaporative cooling): i. e., 64.8 dry bulb, represented by D. This air, in then passing through the lower half of the aluminum-wool pad, absorbs exactly the same amount of heat from the ypad as the upper half of the ypad absorbed from the incoming stream, and its dry bulb thus rises anhydrously to 89.8, represented by E.

Let us now apply the formula. The mean temperature difference between the aluminum-wool pad and each air-stream is 5.1 (i. e., DB/2). The temperature change is 25. The thickness of the pad in inches should accordingly be 25 divided by 5.1: i. e., 4.9 inches, thus requiring the air in its complete circuit to traverse a total aluminumwool pad thickness of 9.8 inches. This is a wholly feasible pad-thickness.

But suppose that (due to greater size, and/or leakage, and/'or lack of insulation) the room imposed a load of (say) 12.

We must now cool the incoming air to 68, in order to maintain a temperature of 80 within the room. See Fig. 11. Points A, C, and D are the same, but B' and E are different. temperature diierence is now 1.6, and the temperature change is 32, a total traverse of 40 inches. So the pad has to be 20 inches thick.

This is approaching prohibitive thickness, largely due to the increased resistance to air at the required velocities.

This brings us to my second variant, which although generically the same as my first variant, em-ploys an additional principle which I call temperature cut-back.

Referring now to Figures 5 to 9, we see that 5l is the main container of the second variant of my invention, 52 is an air-inlet from outdoors 53 is an air-outlet to outdoors, but might instead discharge into the attic space of the building.

54 is a divided-impeller squirrel-cage centrifugal fan, one half of which serves to suck air in through inlet 52, and the other half of which serves to drive air out through outlet 53. Two separate fans of this or some other type could be substituted. A motor 55 serves to drive fan 54.

The outgoing air is sucked out through passage 55. The incoming air is driven inthrough passage 5l. 1

Motor 55. through self-contained gear-reduction 58, and sprocket drive 59, drives shaft 50 at the optimum speed of about 30 R. P. M., already discussed. Shaft 60, through sprocket drive SI, drives shaft 62 at the optimum speed of about 3 R. P. M., already discussed.

63 is a removable dust-filter of any conventional or inventive sort.

Shaft 60 rotates two circular pads 64, 65 of the same sort as the aluminum-wool pa described in detail in connection with my first variant. Figure 8 shows an elevation of one of these pads, and illustrates the two air passages 56, 51 through which it rotates.

The mean Shaft 62 rotates two circular pads 6B and 61 of the same sort as the excelsior pad described in detail in connection with my iirst variant. Figure 9 shows an elevation of one of these pads, and illustrates the air passage 56, and tanks 68 and 69 through which it rotates. Inasmuch as the water in each of pads 66 and 61 should acquire and maintain in operation an equilibriumtemperature equal to the wet-bulb temperature which the outgoing air-stream has at the respective pad, and as these two wet-bulb temperatures are seen by Figure 12 to be quite distinct. these tanks should be separate, for the very best results; but this is not imperative.

The operation of my second variant is as follows.

Exhaust air, leaving the room through passage 56, passes through the upper portion of excelsior pad 66; wherein, by the evaporation of the water in the excelsior, this air exchanges sensible heat for latent heat in the form of moisture, becoming about 95%l saturated, and its dry-bulb temperature becoming reduced nearly to its wet-bulb temperature, which remains substantially unchanged.

The thus-cooled outgoing air then passes through the lower portion of aluminum-wool pad 64, extracting a portion of the heat therefrom, and correspondingly having its own drybulb temperature raised thereby, with no appreciable alteration in its own moisture content.

This air now has quite different characteristics from what it had when it left the room, being now of a much higher dewpoint than before, and (usually) of a somewhat higher drybulb temperature, depending on such considerations as the initial temperature of the incoming air, the load, the desired amount of cooling to be effected by the machine, and the relative thickness of the two aluminum pads. All this will be hereinafter discussed.

This exhaust air now passes through the upper portion of excelsior pad 61; wherein, by the evaporation of the water in the excelsior, this air exchanges sensible heat for latent heat in the form of moisture, becoming about 95% saturated, and its dry-bulb temperature becoming reduced to nearly its wet-bulb temperature, which remains substantially unchanged.

The thus-cooled outgoing air then passes through the lower portion of aluminum-wool pad 65, extracting a. portion of the heat therefrom.

The exhaust air is then discharged, by being sucked in through the open left hand (in Figure 7)')end of fan 54, and being thereby blown out through air-outlet 53.

Fresh outdoor air is. meanwhile entering at the-'same rate through air-inlet 52, being sucked in through the open right hand (in Figure 7) end of fan 54, and being thereby blown out into passage 51.

Here it is filtered by passing through dustlter 63. It then passes successively through the upper portion of aluminum pad 65 and through the upper portion of aluminum pad 64, each of which has been cooled as already described. Each pad extracts a portion of the sensible heat from the incoming air, without substituting any latent heat in the form of moisture, i. e. without altering the dew-point of the incoming air. The amount of the dry-bulb cooling of the incoming air by each aluminum-wool pad is exactly the same as the amount of cooling of that pad by the outgoing air.

The thus cooled, but not humidiiied, incoming air then passes on through passage 51 into the room which is being air-conditioned.

If it is desired to partially humidity the incoming air, this can be accomplished by bypassing some of the moist outgoing air from outlet 53 into inlet 52 through cross-conduit 10.

From the fact that my thus described second variant differs essentially from my earlier described rst variant by having two aluminumwool pads instead of one, and two excelsior pads instead of one, it might be erroneously supposed that we have in the second variant a mere duplication of parts or a mere division of parts.

That this is not so structurally is seen by the fact that my second variant does not substitute two aluminum-wool pads in the place where one grew before, nor two excelsior pads in the place where one grew before. Nor is each pad of my first variant divided into two, in place, in my second variant.

But, instead, by alternating the aluminumwool pads with the excelsior pads, I obtain a new i arrangement which is beyond mere duplication or mere division.

In fact two of my type 1 machines hitched together in series would be something quite different again from my type 2 machine, although even this would not constitute a true duplication. True duplication would consist in bitching together two of my type 1 machines in parallel, so as to air-condition twice as large a room.

Furthermore, a psychrometric comparison of my two variants shows that they differ in kind, quite distinctly.

To illustrate this, let us now turn to Figure 12, and see how this second variant of mine solves the problem of Figure 11, namely: outside air at 100 dry bulb, 54 dew point; load 12; desired room temperature 80.

The right-hand aluminum pad anhydrously cools the incoming air from M t0 N, and the lefthand aluminum pad 64 cools it further from N to O. The room load heats it, from O to P. It is then cooled adiabatically by the left-hand excelsior pad 66 from P to Q, and in turn cools the left-hand aluminum pad 64 from Q to R (equal and opposite to NO). It is then cooled adiabatically by the right-hand excelsior pad 61 from R. to S, and in turn cools the right-hand aluminum pad 65 from S to T.

Points M, O, P and Q are fixed by our initial hypotheses. Any given choice of point N fixes points R, S, and T. If we juggle N on a psychrometric chart blank until ON/QO equals NM/SN, then the two pads will be of equal thickness (2 ON/QO each), and their sum will be at the minimum. This fact (mathematically demonstrable), plus considerations of mass production and replaceability of parts, renders it desirable to have the two pads be exact duplicates. My two excelsior pads are similarly made identical.

' From Figure l2 we see that the mean temperature difference in pad 64 is 1.6 and the temperature drop is 8.4". In pad 65, these two gures are 4.5 and 23.6, respectively. So, applying the pad-thickness formula given earlier herein, each pad need be only 5.25 inches thick, a total traverse of 21.0 inches, as compared with 40.0 inches in my rst variant on Figure 11, under identical assumed conditions. Obviously 21.0 inches offers much less resistance to air than 40.0

Surely the obtaining of the same results with two pads involving a total traverse of 21.0 inches as with one pad involving a total traverse of 40.0 inches, the psychrometric circuits being seen at a glance to be quite different for the two typesoi machines, is a proof that we have neither dou.

bled nor split our original single pad.

The use of three aluminum-wool pads and' suggested, or as a basis for a good start of thejuggling, the following approximate formulas are very close.

Let C=tota1 cooling desired, in dry-bulb degrees.

And T=onehalf the dierence between the dry-bulb temperature of the incoming air as it enters the room, and 1 plus the wet-bulb temperature of the outgoing air as it leaves the room.

Then the second cooling in .dry bulb degrees is -3T,

And the thickness of each pad in inches, is that expression divided by T. y

From a study of the charts it may be noted that neither variant of my invention can reduce the dry-bulb of the incoming air to below one degree higher than the wet-bulb which the outgoing air has as it leaves the room. But this limitation does not discredit either type, for it .constitutes merely an indication of as to when a given size of unit is too small for a given job.

It should be noted that, 1n both variants, the

incoming air-stream flows through each aluminum-wool pad in the opposite direction from the flow of the outgoing air-stream, andai; practically identically the same speed. Furthermore, at the optimum speed of pad rotation, and on account of the very small thickness of the individual aluminum filaments, the heat absorbed by the wool in the hot part of the pads cycle of rotation does not have time to travel by conduction longitudinally of the individual ilaments, or from lament to filament, an appreciable distance, before being given up in the cold part of the cycle, and hence remains at substantially the same point in the pad in each of the two airstreams. And the fact that the pad rotates so that each particle thereof is carried in a plane perpendicular to the airflow, prevents any conveying of heat by the pad except perpendicular to the airflow. These factors result in the mean temperature dierence between either air-stream and the wool at any given depth being equal to one half the temperature diil'erence between the two streams at either surface of the pad: i. e., practically ideal counteriiow.

This counterow is indicated, both by practical experience and by theoretical analysis, to be at least highly advisable, and perhaps even absolutely essential.

It should be noted that, in order to attain the advantages which I obtain from counterflow, it is necessary not only to ow my two air-streams in opposite directions, but also to ow them in opposite directions through a means of heat-exchange in which there is no appreciable conduction or convection of heat parallel to the direction of the airiiow.

The importance of such counterflow cannot be overemphasized, for such counterflow enables' each anhydrous heat-exchange between incoming air and adiabatically cooled outgoing air to remove heat from the incoming air to an extent impossible in any system in which there is any averaging of temperature in the heat-exchange means parallel to the direction of iiow of. the air. Such averaging can occur by the use of cool- 10 ing or heating coils, or by the use oi' random flow of non-hygroscopic cooling-heating fluid in pads, or even (although such 110W of uid in pads be strictly perpendicular to the flow of the air therethrough, and hence no averaging takes place within either pad), by commingling the fluid as it passes from pad to pad.

In a thoroughly averaging system, the absolute limit of cooling the incoming air by any one heatexchange is half of the difference between the temperature at which the incoming air enters the heat-exchanger and the temperature at which the adiabatically cooled outgoing air enters the heat-exchanger, and even this theoretic limit is not practically attainable. Even if the averaging of temperature takes place only as the coolingheating fluid passes from pad to pad, the absolute limit is increased merely to two-thirds the abovementioned difference. Whereas in a counterflow system of the sort contemplated by me, the limit is the temperature at which the adiabatically cooled voutgoing air enters the heat-exchanger, and it is quite practical to cool the incoming air to within a very few degrees of this limit.

This full advantage of counterflow cannot be attained in any averaging system, but can be attained in my apparatus.

From the foregoing description it should be clear that either of my two devices will do everything of which the prior art competing devices are capable, and yet takes up less space, and requires less initial cost, less upkeep, and less operating current.

In the claims, when I use the term tank, I intend a tank capable of holding water or other similar volatile liquid, for the purpose described.

In theclaims, I shall refer to the excelsior pad generically as an "air-permeable evaporativeliquid-holding pad; and to the aluminum-wool pad generically as an air-permeable non-hygroscopic pad highly heat absorbent.

Having now described and illustrated two forms of my invention, I wish it to be understood that my invention is not to be limited to the specic forms or arrangements of parts herein described and shown.

For example, if desired, appropriate additional passages and valves could be added, so that optionally part or all of the outgoing air could be drawn from outdoors.

Furthermore, other air-conditioning elements could be added.

My multipad variant is preferable where the cooling load is heavy, and/or in fixed installations. My single-pad variant is preferable where the requirement of a small compact moveable set is paramount.

I claim:

l. In an air-conditioning unit, the combination of: two air-passages; a tank; a pad comprising sectors of air-permeable evaporative-liquid-holding material, this pad being rotatably mounted in such manner as to carry each sector of the pad successively through the tank beneath the liquid level therein and across the rst air-passage; a pad comprising sectors of air-permeable non-hygroscopic highly heat-absorbent material, this pad being rotatably mounted in such manner as to carry each sector successively across each of the two passages; means for rotating the two pa-ds; means for impelling a stream of air in the rst passage, first through the evaporative-liquidholding pad and then through the nonhy-- groscopic pad, whereby this stream of air may be first cooled by evaporation and then may cool` the 'non-hygroscopic pad; and means for impell' ing air in the second passage through the nonhygroscopic pad, whereby this second stream of air may be anhydrously cooled by the non-hygroscopic pad, and may then pass into,the enclosure to be conditioned.

2. An air-conditioning unit, according to claim 1, further characterized by the fact that the evaporative-liquid-holding pad comprises a rim and spokes, all of substantially the same width in an axial direction, and having on each face anges projecting into the sectors bounded thereby.

3. An air-conditioning unit, according to claim 1, further characterized by the fact that the evaporative-liquid-holding pad comprises a rim and spokes, all of substantially the same width in an axial direction, and a packing of excelsior in the sectors between spokes and rim.

4. An air-conditioning unit according to claim 1, wherein the evaporative-liquid-containing pad and the non-hygroscopic pad are so drivably connected to the means for rotating them that, when the former is rotated at approximately 3 R. P. M., the latter is rotated at approximately 30 R. P. M.

5. In an air-conditioning unit, the combination of: two air-passages; means for impelling a separate stream of air through each air-passage; means for adiabatically cooling the air-stream in the rst passage, by the evaporation of water therein; a pad comprising sectors of air-permeable non-hygroscopic highly heat-absorbent material, rotatably mounted in such manner as to carry each sector successively across each of the two passages, this pad lying in the rst passage downstream from the adiabatic cooling means; and means for rotating this pad; whereby the pad may be cooled by the cooled air in the first passage, and in turn may anhydrously cool the air in the second passage.

6. An air-conditioning unit according to claim 5, in which the heat-absorbent material of the rotating pad is metal wool held in rigid formation, and in which there are means to prevent the bypassing of air from passage to passage through or around this pad, and in which each air-stream passes through this pad in a sense opposite to that of the other air-stream.

7. An air-conditioning unit according to claim 5, in which the heat-absorbent material of the rotating pad is aluminum wool held in rigid formation, and in which there are means to prevent the by-passing of air from passage to passage through or around this pad, and in which each air-stream passes through this pad in a sense opposite to that of the other air-stream.

8. An air conditioning unit, according to claim 5, further characterized by the fact that each airstream passes through the non-hygroscopic pad in a direction parallel to its axis of rotation, and in a sense opposite to that of the other air-stream.

9. A rotatable pad for an air-conditioning unit, packed with metal wool, in combination with means for passing two separate and distinct airstreams therethrough, for transfer of heat from one stream to the other.

10. In an air-conditioning unit, the combination of two air-passages; liquid-containing means; a plurality of pads each comprising sectors of air-permeable evaporative-liquid-holding material, each pad being rotatably mounted in such manner as to carry each sector of the pad successively through the liquid-containing means beneath the liquid level therein and across the iirst air-passage; a plurality of pads each comprising sectors of air-permeable non-hygroscopi'c highly heat-absorbent material, each pad being rotatably mounted in such manner as to carry each sector successively across each of the two passages; means for rotating all the pads; means for impelling air in the first passage, first through one evaporative-liquid-holding pad, then through one non-hygroscopic pad, and so on alternately, whereby this stream of air is alternately cooled by evaporation and then cools a non-hygroscopic pad; and means for impelling air in the second passage through the non-hygroscopic pads successively, whereby this stream of air is an-` hydrously cooled by the non-hygroscopic pads, and then passes into the enclosure to be conditioned.

11. An air-conditioning unit according to claim 10, wherein the non-hygroscopic pads are all of substantially the same thickness.

12. An air-conditioning unit, according to claim 10, further characterized by the fact that each air-stream passes through each non-hygroscopic pad in a direction parallel to its axis of rotation.

13. An air-conditioning unit, according to claim l0, further characterized by the fact that each air-stream passes through each non-hygroscopic pad in a direction parallel to its axis of rotation, and in a sense opposite to that of the other airstream, and that each air-stream passes through. the non-hygroscopic pads in an order opposite to that of the other air-stream.

14. An air-conditioning unit according to claim 10, wherein the liquid-containing means for each evaporative-liquid-holding pad is distinct.

15. An air-conditioning unit, according to claim 10, further characterized by the fact that each air-stream passes through each non-hygroscopic pad in a direction parallel to its axis of rotation, and in a sense opposite to that of the other air-stream, and that each air-stream passes through the non-hygroscopic pads in an order opposite to that of the other air-stream, each non-hygroscopic pad being characterized' by being incapable of appreciable conduction or convection of heat thereby in a direction parallel to the axis of rotation of the pad,'and by being incapable of appreciable airow therethrough in a plane perpendicular to its axis of rotation.

16. An air-conditioning unit according to claim" 5, in which the heat-absorbent material of the rotating pad is of such structure that no appreciable conduction or convection of heat thereby' parallel to the direction of airflow therethroughl will take place during one rotation of the pad, and in which there are means to prevent the by passing of air from passage to passage through or around this pad, or radially outwardly from this pad, and in which each air-stream passes through this pad in a sense opposite to that of the other air-stream.

17. -An air-conditioning unit according to claim 10, in which the evaporative-liquid-holding means is water-holding means, and the liquid-containing means is water-containing means.

18. In an air-conditioning unit, the combination of two air-passages; a plurality of evaporative air-cooling elements, located in the first air-passage; a plurality of pads each comprising sectors of air-permeable non-hygroscopic highly heat-absorbent material, alternating with the' cooling elements; each pad being rotatably mounted in such manner as to carry each sectori successively across each of the two passagesy means for rotating the pads; means for impelling a stream of air in the first passage, iirst throughl onecooling element, then through one non-hygroscopic pad, and so on alternately, whereby this first stream of air may be alternately cooled by evaporation and then may cool a non-hygroscopic pad; and means for impelling air in the second passage through the non-hygroscopic pads successively, whereby this stream of air may be anhydrously cooled by the non-hygroscopic pads, and then may pass into the enclosure to be conditioned.

19. The process of conditioning outdoors air for use in an enclosure, by heat but not moisture exchange with air extracted from the enclosure, which comprises: impelling a stream of air into a, passage; therein anhydrously reducing the drybulb temperature of said air a given amount, by a heat-exchange with the outgoing air; and then passing the thus-cooled air into the enclosure; extracting a stream of air from the enclosure into a second passage; adiabatically reducing the dry-bulb temperature of said stream of outgoing air by evaporating a liquid therein, to below the dry-bulb temperature which the incoming air had when anhydrously cooled as above; and nally anhydrously increasing the dry-bulb temperature of said outgoing air, by heat-exchange with the incoming air, an amount equal to the reduction of dry-bulb temperature of the incoming air effected by that same exchange, the range of dry-bulb change of the incoming air effected by this exchange overlapping the range of dry-bulb change of the outgoing air more than one half.

20. The process of conditioning outdoors air for use in an enclosure, by heat but not moisture exchange with air extracted from the enclosure, which comprises: impelling a stream of air into a passage; therein anhydrously reducing the drybulb-temperature of said air a given amount, by a rst and a second heat-exchange with the outgoing air; and then passing the thus-cooled air into the enclosure; extracting a stream of air from the enclosure into a second passage; adiabaticaily reducing the dry-bulb temperature o said stream of outgoing air, by evaporating a liquid therein, to below the dry-bulb temperature which the incoming air had when cooled by the second of the two cooling steps mentioned above; anhydrously increasing the dry-bulb temperature of said outgoing air, by the second heat-exchange with the incoming air, an amount equal to the reduction of dry-bulb temperature of the incoming air effected by that same exchange, the range of dry-bulb change of the two streams effected by this exchange overlapping each other more than one half; adiabatically reducing the drybulb temperature of said stream of outgoing air, by evaporating a liquid therein, to below the drybulb temperature which the incoming air had when cooled by the iirst of the two cooling steps mentioned above; and finally anhydrously increasing the dry-bulb temperature of said outgoing air, by the rst heat-exchange with the incoming air, an amount equal to the reduction of dry-bulb temperature of the incoming air efected by that same exchange, the range of drybulb change of the incoming air elected by this exchange overlapping the range of dry-bulb change of the outgoing air more than one half.

21. In a heat-exchanger for an air conditioning unit, the combination of I two parallel air-passages; means for impelling air in' one direction through one of these two passages; means for impelling air in the opposite direction through the other of these two passages; a pad comprising 14 sectors of air-permeable non-hygroscopic highly heat-absorbent material, this pad being rotatably mounted in such manner as to carry each sector of the pad successively across each of the two 1 passages, the material being such and so packed that there can be no appreciable conduction of heat by the pa-.i axially thereof in the time of one rotation; means to prevent appreciable leakage of air radially from the pad; means to prevent appreciable leakage of air from one passage to the other angularly through the pad; and means to prevent appreciable leakage of air from one passage to the other by by-passing the pad.

22. Apparatus according to claim 9, further characterized by the fact that the two air-streams pass through the pad in parallel and opposite directions.

23. In an air-conditioning unit, the combination of two air-passages; an air-permeable evaporative-liquid-holding pad, extending across the first passage; means to continuously supply evaporating liquid throughout this pad; a pad comprising sectors of air-permeable non-hygroscopic highly heat-absorbent material, this pad being rotatably mounted in such manner as to carry each sector successively across each of the two passages; means for rotating this latter pad; means for impelling a stream of air in the rst passage, rst through the evaporativeliquid-holding pad and then through the nonhygroscopic pad, whereby this stream of air may be first cooled by evaporation and then may cool the non-hygroscopic pad; and means for impelling air in the second passage through the nonhygroscopic pad, whereby this second stream of air may be anhydrously cooled by the non-hygroscopic pad, and may then pass into the enclosure to be conditioned.

24. An air-conditioning unit, according to claim 23, further characterized by the fact that the evaporative-liquid-holding pad comprises rigid elements to hold rigid the form of the pad, and.

water-absorbent air-permeable material supported thereby.

25. An air-conditioning unit, according to claim 23, further characterized by the fact that the evaporative-liquid-holding pad comprises rigid elements to hold rigid the form of the pad, and a packing of excelsior supported thereby.

26. An air-conditioning unit, according to claim 23, further characterized by the fact that the nonhygroscopic pad comprises rigid elements to hold rigid the form of the wheel, and non-hygroscopic air-permeable material highly heat-absorbent supported thereby. i

27. An air-conditioning unit, according to claim 23, further characterized by the fact that the nonhygroscopic pad comprises a rim and spokes, all of substantially the same width in an axial direction, and a packing of non-hygroscopi airpermeable material highly heat-absorbent in the sectors between spokes and rim, the packing being held axially immovable with respect to the rim and spokes.

28. An air-conditioning unit, according to claim 23, further characterized by the fact that the non-hygroscopic pad comprises rigid elements to hold rigid the form of the wheel, and metal wool rigidly supported thereby.

29. An air-conditioning unit, according to claim 23, further characterized by the fact that the non-hygroscopic pad comprises rigid elements to hold rigid the form of the wheel, and aluminum wool rigidly supported thereby.

30. An air-conditioning unit according to claim 28, in which the air passages and impelling means each stream of air will pass through said pad at 5 and spokes, and by having adjacent each face of 15 this pad a ixed transverse bridge between the two air-passages, each half of this bridge having a shape and area at least equal to the shape and area of one sector of the pad.

32. An air-conditioning unit, according to claim 2o Number 23, further characterized by the fact that each air-stream passes through the non-hygroscopic pad in a direction parallel to its axis of rotation.

33. An air-conditioning unit, according to claim 23, further characterized by the fact that each 25 16 air-stream passes through the non-hygroscopic pad in a direction parallel to its axis of rotation, and in a sense opposite to that of the other alrstream.

NEAL A. PENNINGTON.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,510,340 Pauls Sept. 30, 1924 1,762,320 Wood June 10, 1930 2,075,036 Hollis Mar. 30, 1937 2,083,436 Bothezat June 8, 1937 2,361,692 Karlsson et al Oct. 31, 1944 FOREIGN PATENTS Country Date 134,256 Great Britain Oct. 27, 1919 387,517 Great Britain Feb. 9, 1933 548,400 France Oct. 20, 1922 148,763 Germany Mar. 10, 1903

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