US2680492A - Air dehydration unit - Google Patents

Description

June 8, 1954 R. s. KOPP 2,680,492

AIR DEHYDRATION UNIT Filed June 22, 1951 REACTIVATING 7 Sheets-Sheet l AT INLET REACTIVA I 'l] 'l HEAT 0U T L; E T

CONDITIONED AIR OUTLET I AIR TO BE CONDITIONED INLET CONDITIONED AIR OUTLET 5 35 46 7O 'Hh f! hh E I T F g.2 I: Y {I l l l 5.523%??? k 134 ift I :1: I f I I 11% r" 69 i ll 1 J 3nnent0r R. 3 KO PP (Ittorneg June 8, 1954 R. s. KOPP 2,680,492

AIR DEHYDRATI ON UNIT Filed June 22, 1951 7 Sheets-Sheet 2 coumnouao AIR ou'rLET I6 FI I. 3 4 I I 70 I I I T I 42 I I I I I I I I2 I l 4,3 --1'---IIIII I I III J I I I :OIIIJDIIDI'CIDONBEED I'--H I H INLET III I I-I I I I I 69 I I I I I l I I I I I 72 LJ L 70 6 CONDITIONED AIR OUTLET Fig. 4 I 4 REACTIVATING 42 I To BE R. S. KOPP 6 WQI,

Gttomeg June 8, 1954 R. s. KOPP 2,680,492 AIR DEHYDRATION UNIT Filed June 22, 1951 7 Sheets-Sheet 3 CONDITIONED AIR OUTLET R E ACT IVATING HEAT INLET CONDITIONED AIR OUTLET AIR T0 as coNm INLET Zinnentor 36 9 RS. KOPP attorney June 8, 1954 R S, KOPP 2,680,492

AIR DEHYDRATI ON UNIT Filed June 22, 1951 '7 Sheets-Sheet 4 CONDITIONED AIR OUTLET Fly. '7

REACTIVATING- 46/ HEAT INLET 60 CONDITIONED AIR OUTLET 3nventor R. S. KOPP Gttorneg June 8, 1954 R. s. KOPP 2,680,492 AIR DEHYDRATION UNIT Filed June 22, 1951 7 Sheets-$heet 5 3nnentor R. 's. KOP P (Ittorneg June 8, 1954 R. s. KOPP 2,680,492

AIR DEHYDRATION UNIT Filed June 22, 1951 7 Sheets-Sheet 6 "Fig. IO

3maentor R. S. KOPP attorney June 8, 1954 R. s. KOPP AIR DEHYDRATION UNIT 7 Sheets-Sheet 7 Filed June 22, 1951 Zhwentor R. S. K O P P Q2 attorney Patented June 8, 1954 UNITED STATES PATENT OFFICE 2,680,492 AIR DEHYDRATION UNIT Roger S. Kopp, Arlington, Va. Application June 22, 1951, Serial No. 232,990 Claims. (01. 183-4.6) This invention relates to air conditioning units A still further object of the invention is to proof the type adapted to be used in air conditioning vide an improved method of air conditioning and cooling systems of rooms, buildings, and the which comprises causing the air to be treated to like for the purpose of maintaining relative huflow in contact with a compressed fibrous matemidity of any desired degree therein. rial having a hygroscopic salt uniformly distrib- An object of the invention is to provide an imuted therethrough, successively exposing dry composed absorption plates, wh ch wheel 1s so aiabsorption of mo1sture by the material and subranged within a casing that the air to be COIldI- In quently exposing the wet material for contact tioned flows through the wheel in such a man with heated air having a predetermined temperher that the moisture in the air is absorbed by e in a y g C a r w y h m t ia the heel, is dried a predetermined amount so that a con- Another object of the invention is to provide an stant relative humidity of any desired degree can improved air conditioning unit comprising a be maintain d in the treated air by the degrees wheel rotatable solely by gravity and composed of proportionate temperature u e n the drying of a plurality of radially disposed absorption hambe plates, and having a casing enclosing the wheel Wi h the foregoing and other objects and adand formed with a. series of plenum chambers so vantages in view, the invention consists in the flows through th h 1 only my a dlrectmn bseveral parts which will be hereinafter more fully stantially parallel to the axis of rotation of the described and claimed. wheel. In the accompanying drawings:

Another object of the invention is to provide Fig. 1 is a top plan View of on ir'o d an improved air conditioning unit comprising unit embodying the Present ve t n; means for causing the 'air to fiow in contact with 2 is an elevation of e unit Shown in an absorption material adapted to absorb moislooking at the reaotivatihg eat inlet side I ture from the air, means for exposing the wet thereof;

material for contact with heated air having a pre- 3 is an elevation looking at he e pp site to the side shown in Fig. 2;

Fig. 4 is an elevation looking at the rear of the sequently exposing the dried material to the air unit;

to be conditioned whereby a, constant relative f' 5 is an elevation ng at he front of the humidity of any desired degree can be maintained fi g i i in the treated air by the degrees of proportionate a 6 is a vertical section en along he line temperature used in drying the wet material of Another Object of the invention is to provide an Fig. 7 is a vertical section taken along the line improved air conditioning unit comprising means of 6; for causing th air t flow in t t t an Fig. 8 is a vertical section taken along the line absorption material adapted to convertthe latent of heat of the air into sensible heat and to increase 9 is a Vertical Section taken along the l ne the sensible temperature of the air proportional of to the quantity of moisture absorbed, and means 10 is n nlar ed section of the hub of the for reducing the sensible temperature of the de- Wheel taken along the line l9|0 f 6; humidified air. Fig. 11 is an enlarged section of the rim of the Another object of the invention is to provide Wheel taken along the line l of and an improved method of dehumidifying air which 121's an enlarged Section o the hub porti n comprises causing the air to flow in contact with of the Wheel Shown in a compressed fibrous material having a hygro- Referring t the d w s, and especially to scopic salt uniformly distributed therethrough, Fig. 6, the improved air conditioning unit comabsorption of moisture by the material, and subfully described. sequently exposing the wet material for contact The wheel H has a shaft l3 of suitable length, with heated air to remove the moisture therefrom. and a bearing I4 is mounted on the shaft near each end thereof so that the shaft and the wheel thereon are free to rotate in the manner to be hereinafter referred to. Each bearing [4 is supported by a standard i5, as shown best in Figs.

6 and 12.

The wheel i i has a pair of spaced hubs i6 fixed to the shaft I3 by means of set screws or other suitable fastening means, indicated at M, Fig. 12. Each hub is formed with a plurality of radial bores i8 which extend inwardly from the outer periphery of the hu the inner portion of each bore it being formed with screw threads iii.

A rod 20, having an inner end threaded portion 2|, is mounted in each bore it, the screw threads of the portion 2i of the rod engaging the screw threads is of the bore 18 so that the rod is tightly secured to the hub I6.

In the present instance, each hub 1'8 is shown as being provided with six rods 28. understood, however, that any suitable number of rods 2% may be employed, depending upon the size of the wheel and other structural character istics which might enter into the design and construction of the invention.

Encirclingthe outer ends of the rods 28 carried by each hub it, is an annular band 22 which is secured to each rod bymeans of a screw or other suitable fastening element, as indicated at 23, Fig. 11'. Each band 22 is located in substantially the sameplane as is each hub I5 of the wheel,

and said bands constitute the rims or fellies of the wheel, as shown in Fig. 6. The rods are the spokes of the wheel.

Disposed between the hubs l6 and the rims or bands 22, is a plurality of plates 25. These plates 25are preferably formed from rectangular sheets of suitable material, and all of said plates should preferably beef equal size and weight, so that when the plates are assembled in the wheel, the

wheel will be balanced and free to turn on its axis. In order to provide means for retaining the plates 25 in position an inner retainer 25 is fastened to the hubs lt'yand an outer retainer 2'1 is fastened to each band or rim 22.

As shown in Fig. 10, the inner retainer 26 may be in the forrnof a tube of corrugated sheet metal, which tube encircles the hubs 1 S and enclosesthe portion of the shaft i3 between said hubs. (see alsoFigs. 6 and 12.). This tube with the corrugations formed lengthwise. thereof, providesa series of radiall-y disposed slotsor grooves 28, into each of which is inserted an edge portion of a plate 25-.

In order-toprevent shiftingmovement of the plates lengthwise of the retainer 25, a plate 29- is mounted on the outer face of each hub 15. The

plate 29 is formed with a central opening 30 some what larger in diameter than the diameter of the shaft it, so that when it is desired to remove or insert a plate'ib, the plate29 can be detached from the hub i5 and then shifted to dispose the outer periphery thereof inwardly with respect to the outer periphery of the hub IS. The plates 25 may be detachably secured to the hubs it by screws or. other suitable fastening means, as indicated at 3|, Fig. 12.

As shown in Fig. 11, the outer retainer 2'! may be in the form of a strip of corrugated sheet metal which is secured in any suitable manner to the inner face of each band 22. The metal strips 2'! provide a series of slots or grooves 32 into each of which is inserted an edge portion of a plate 25.

Since the plates 25 are arranged radially of the wheel, the grooves 28 are disposed close together, andthe grooves 32 are disposed somewhat farther. apartwith respectto the spacing of the It Will be.

the submerged plates to-become grooves 28. In actual practice the wheels I i have been constructed with approximately plates. In this way the plates were spaced apart an angle of approximately 2 degrees.

In Fig. 9 a typical arrangement of the plates 25 between two of the spokes or rods as has been shown. It will be understood that in both Fig. 9 and Fig. 10, the plates extend entirely around the hub of the wheel, said plates being uniformly spaced apart.

The plates 25 are preferably formed of inert, fibrous, light-weight material'with a high factor of absorption. One material suitable for use in constructing. the plates is rock wool, or as is commonly Known, asbestos, since such material can be molded or formed into boards or sheets of different thicknesses, and it is also adapted to various degrees of density and rigidity which, in consequence, permits its use over such a range as to meet the conditions which may be imposed upon it by differences in mechanical design.

In addition 'to asbestos fibres, other suitable materials for the base of the-plates 25 are balsam wool, kapok, eel grass, rock cork, sugar cane fibre, cotton linters, wood pulp and the like textile fibres, and, in fact, any otherknown inert fibrous material.

Since the plates 25 should be treated so as to render them highly absorbent to moisture in air flowing through the unit,.any method may be used to prepare the inert fibrous materials foruseas dehydrating materials. 7

By one method I have used wool or asbestos boards or sheets as produced by manufacturers of asbestos products. These sheets are saturated in a solution of hygroscopic salt, such as calcium chloride (CaClz), or any other hygroscopic salt. In some cases compounds ofseveral of the hygroscopic salts have been used.

In order to properly saturate the plates 25, the latter are submerged in a salt solution until the fibres of the plates are thoroughly wet. Usually it-requires approximately one hour for urated. Of course, theamount plates should be submerged in the salt solution depends upon thekind of material and the density thereof, but ordinarily after the plates have been submerged in the salt solution for anhour they. are thoroughly saturated; plates are then dried to remove therefronn. In drying the plates, they may be placed. in a continuousdryer under a counter flow ofair heated to a temperature of 180 F. to 220 F. Usually the plates must remainin the dryer for approximately one hour before the moisture is entirely removed therefrom. When the plates. are. thus prepared, the hygroscopic salt or salts will. be evenly distributed throughout the inert basematerialin fixation inits dry state.

In addition to calcium chloride referred to above, lithium chloride (IiCl) lithium bromide (LiBr), calcium bromide (CaBrz), and other hygroscopic salts-having in their normal state low vapor pressures may also be used for treating the plates for use in the apparatus of the present invention.

When exposed to air or gases having a higher vapor pressure than the hygroscopic salt; the salt absorbs vapor saturation occurs. Namely, saturation occurs when the vapor pressureof. the

the standard rock thoroughly sat-.

.of ,time the The saturated the moisture from the air or gases until hygroscopic solution is raised by absorbing so much-moisture andrection parallel to the shaft I3.

diluting the hygroscopic solution to that point where absorption ceases and equilibrium occurs.

The upper portion of the and 3B are arranged close to the outer periphery of the wheel I l, the clearance between said walls and the wheel being sufficient to permit free rotation of the wheel.

Since the walls 35 and 36 enclose the periphery of the wheel II, chambers are formed in the casing l2 at each Each end of the wheel H is spaced a suitable distance from the end At the front of the the At the rear of the device and located between and the rear wall 42, there is a tubular member 44.

The ends of the tubes 43 The front tending peripheral flange 45 which overlaps the laps the rear edge of the wall 35.

The front end portion of the device is pro- If so desired, an L-shaped wall the walls 41 and 48.

. The rear end portion of the device is provided with four partitions or walls GI, 62, 63 and 64 may connect which extend flange 4'6 and a plurality of 68. The chamber 65 is connected to an air to be conditioned inlet by flanged openings 89, I0, manner.

The air to be conditioned entering the chamber 65 through the inlet 69 passes chamber 57 substantially between the top and bottom of the chamber, as shown in Fig. 8.

From the upper portion of the chamber 5'! the The radiator 16 has an inlet connection 19 and an outlet connection 80. The direction in which the cooling fluid flows through said radiator is indicated by arrows in Fig. 7.

The purpose of the radiator 36 is identical with the purpose of radiator 15, but the radiator 76 in consequence a greater pressure becomes sorption of moisture by the The plates 25 difference of vapor plates. of the wheel will absorb up to rotate (see my Patent No. 2,115,226). in the section of the wheel between .51 and 65 are The plates chambers wetter than the plates between available for more efiicient abaes roaz the-chambers 51: and 166:, chambers 58 and .66' are and the plates between drier. than the: plates: of

the. wheel disposed .betweencharnbers 51. and .66..

Thecounterflow of air through the: wheelabovereferred .to' is; important. The plates between 61 being. wetter,.have a higher the air, making its first pas.-

therefore, permits the moist plates of the wheel toabsorb quantities of moisture 1 from .the: moistair.-

The second passageof air through the-wheel is of that air which has been partially dried, and this drying process will reduce the vapor pressure of the air, butthe section of the wheel disposed between chambers 51 and fifiwhich is comprised of drier plates, also because of its relatively greater lower vapor pressure, will extract additional moisture from the practically dry air which has passed through the wheel between chambers 65 and 51.

The heated reactivating air enters the separate plenum chamber 51;: Fig. .7, and flows through the wheel in the same manner as the air to be: conditioned flows through the wheel into chamber 59, Fig.8, and counterflows through the wheel and into chamber 68, Fig. 7, from whichit is exhausted through the outlet 12, Fig. 4. This passage of heated air through the wettest part of the wheel dries the moisture from the plates, thereby permitting the wheel to turn in its normal cycle as it accumulates more moisture from the air being conditionedin the manner above referred to.

It should be noted that the plates 25 of the wheel I! which are disposed between the chambers. 5S. and ii!- are drier than the plates disposed between the chambers 59 and 68.

The temperature of the air supplied to the re activating heat inlet I'l whichis used to dry the plates of the wheel. ll need not exceed 150 F. under normal operating conditions. The entering reactivating heated air in passing over the drier section of the wheel, first picks up a quantity of moisture, and in so doing, the sensible heat of the drying. air is reduced. This-iscaused by the absorption of moisture by the drying air. This sensible temperature of the then. further reduced as the air absorbs more moisture from the wetter plates in its second pas- I sage through the wheel between chambers 59 and 68. Consequently, effective drying is obtained: at relatively low temperatures, which in turn permits accurate control through the heat exchange that occurs on the adiabatic line, as all drying temperatures are within this definite range.

This adiabatic range also' permits application of the quantity and volume of heat so that any degree of dryness of the plates within basic chemical limits maybe appliedwhich in turn is the through which any desired vapor pressure means difierence within chemical limits can be obtained through which the ante be conditioned is subjected.

From the foregoing it'will be noted that I have provided a new method of dehumidiiying air which comprises passing the air in contact with a compressed fibrous. material having a hygro-.

scopic salt uniformly distributed therethrcugh. This action converts the latent'heator the air into sensibleheat and consequently increases the sensible temperature of. the-air in proportion to the wheel disposed.

heated: air is through the radiators 15 the quantity: of. moistureabsorbed. Since the wheel I I becomes overbalancedasitcollects moisture in the section thereof defined by the. plenum chambers 51.. and 65,.the wheel slowly rotates so that iresh material is. successively exposed :for contact with the air at the rate of absorptionof moisture; The method further includes reducing ture of the air by passing the air successively and 15. Finally,- the wet absorption material of the wheelis exposed for contact with the heated air'admitted' through the inlet ll, and thus. the moisture is-removed therefrom before this portion of the wheel moves into alignment with. the upper plenum chamber 58.

The laws governing water vapor absorption from. air by calcium chloride. solutions have-been determined in experimental and full-size units. Itis found that the amount of water absorbedin unit. time on unit area of absorbent is directly proportionalto the difference in vapor pressure ofwater in the air and in the absorbing solution, and. to the 0.8 power of the velocity of the-air past that area.

Thisrelationship isexpressed thus:

=0.030l pW- -Agms/hn. ==O.462 pl! A grains/hr.

where For a velocity or 100045. RM; over the absorb-. ing surface, V- =approximately 252. and

10:7.59' p A gins/hr. =117 1) A grains/hr.

This;

formula. agreesaccurately with those which. can be. calculated from heat transfer-coefficients and. the relationbetween heat transfer and water vapor difiusion. They are independent of temperature.

The same. formula in reverse applies onthe drying. side.- .ofthe wheel.

Without the application of heat to the drying side. the wheel will turn andthe plates absorb until the wheel attains equilibrium. However,- when drying is started or occurs on thereacti vating side: of the wheel, the-moisture deleted thereby provides absorption capacity equal to the amount dried. The more completely the plates are. dried in reactivation, the greater is the amount which they can absorb on the conditionineside- In like manner the lower the temperature of the. drying air the more water or moisture is left in the plates and the lower is theability of the plates to absorb. It is accurately proportional and equal to the mean temperature difference.

The wheel permits motion only ifsufficient absorption occurs to over-balance it. The rate at whichthe wheel rotates about its axis and thecapacity of the wheel within the formula is the direct reciprocal of the drying: of the plates. For

thesereasonsthe device can maintaina constanta rate. proportional to- .thesensible temperaof radially disposed flat absaid absorption plates being uniapart whereby the wheel is norsorption plates, formly spaced chambers formed in the casing at each end of said wheel, means for conducting moist air into said plenum chambers axially through a segment of said wheel to permit absorption of moisture by the plates then in said segment, and means for conducting heated ing with the loss of moisture by the plates in the angularly offset segment of the wheel to unbalance and effect rotation of the wheel.

4. Apparatus according to claim 3, including cooling means associated with said casing in the path of the moist air being conditioned.

5. An air conditioning unit comprising a wheel including a plurality of radially disposed flat absorption plates, said absorption plates being uniformly spaced apart whereby the w .eel is normally balanced, means for supporting said wheel casing and by means of said plenum chambers axially through a segment of said wheel to permit absorption of moisture by the plates then in said segment, and means for conducting heated air into said casing and by means of other plenum chambers axially through an angularly offset segment of said wheel in a plurality of successive back and forth passes to permit absorption of of the wheel opermoisture by the plates in the angularly offset segment of the wheel to unbalance and effect rotation of the wheel.

6. An air conditioning unit comprising a wheel including a, plurality of wheel, means for conducting moist air into said casing and by means of said plenum chambers axially through forth passes to permit absorption of moisture by said heated air from the plates then in said oiiset segment, the absorption of moisture by the plates in one segment of the wheel operating with the rotation of the wheel.

7. An air conditioning unit comprising a wheel including a plurality of radially disposed flat absorption plates, said absorption plates being uniincluding plural coohng means associated with said casing in the path of the moist air being conditioned to cool said air between successive passes through the wheel.

9. An air conditioning unit comprising a wheel including a plurality of radially disposed flat ab sorption plates, said absorption plates being uniformly spaced apart whereby the wheel is normally balanced, means for supporting said wheel for free rotation about a horizontal axis, a casing enclosing said wheel, a plurality of plenum chambers formed in the casing at each end of said wheel, means for conducting moist air into said axially through a segment of said wheel to permit absorption of moisture by the plates then in said segment, means for conducting heated air into one side of said casing and by means of other plenum chambers axially through an angularly oiTset segment of said wheel in successive back and forth passesto-permit absorption of moisture by said heated air fromthe-plates then .in said offset segment, the'final heated air pass :being through alower portion oisaid ofiset segment and below the first heated air pass, and an outlet for conducting heated airout of said casingtadjae cent the bottom thereof, the absorption'of moisture -by the plates in one segmentofxthe wheel operating with the loss of moisture bytheplates in the. angularly off-set segment of the wheel to unbalance and effect-rotation ofthewheelr 10.- An air conditioning unit comprising. a wheel including a plurality of radiallydisposed flat absorption plates, said-absorption plates being uniformlyspaoedapart'whereby the wheel is normally-balanced, means forsupporting said wheel for free rotation about a horizontalaxiaa casing enclosing said wheel, aplurality of plenum .chambers formed in the-easing ateach end oijsaid wheel-,- means for conducting moist airyinto-zone side of said casing adj'acent the ebottomthereof and, .by-: means of said plenumcham-bers :axiallythrough a segment of said whee in three succes sive back and forth passes to permit absorption of moisture. by theplates then in said-: segment; each successive pass being through a higher portion ofsaid segment, anoutlet for conducting conditioned-air out'of the oppositeside of said.

casingadjacent ,the .top thereof, meansefor scondueting heated air into. one side: of said casing and by means of other plenum: :chambers axially through an angnlarly offset segment oi said wheel in successive back and; forth passes to permit-absorption: of moisture by said heated air from the plates then in said offset segment, the final heated air, passbeing through a lower portion ofsaid offsetsegment and below the first heated air pass,- andaan outlet for conducting heated air out of said casingtadjacent the bottomtthereof, the absorption ofmoistu-re by the-platesr-in one-segment of the wheel operating with the loss of moisture by the platesin, the angularly offsetsegment of the a wheel to 1 unbalance and .efiect rotation :of-the wheel.

Referenees, Cited in. .thenfileiof this. patent UNITED. STATES PATENTS.

Images