US2477826A

US2477826A - Method of and apparatus for conditioning air

Info

Publication number: US2477826A
Application number: US722244A
Authority: US
Inventors: Clarence L Ringquist
Original assignee: Trane Co
Current assignee: Trane Co
Priority date: 1947-01-15
Filing date: 1947-01-15
Publication date: 1949-08-02
Anticipated expiration: 1966-08-02

Description

Aug. 2, 1949. c. L. RINGQUIST ,3

METHOD OF AND APPARATUS FOR CONDITIONING AIR Filed Jan. 15, 1947 ,Eig.d

Patented Aug. 2, 1949 UNI TED STATES PATENT *OIFFTCE 2,477,826 TMETHOD or AND APPARATUS'T'GR coNnrrroNme am Glaren'ee -L. Ringquist, La Crosse, Wis.,; as signor to The lrane Company La Crosse, Wis.

amification "January '15, 194i, Se'rial No. 722124; 8 Claims. (01. 62'-6) This invention relates to a'n air conditioning apparatus, or-sysiim, particularly adapted to condition the air 'ih a deem to a l predetermined dew pointand to Jprovide forthe ad'dition .of a predetermined anteater outsideair for'ventilation, with means-for regulalting theamount'of mbisture in the outs'ide air.

"One obj ct of m'y invention is to int'roduce into the roomaipredetermined amount 'o'f outsideair for ventilation purposes and to prevent-the introduction of varying amountsof outside air.

Another object of-myiiriveiition is to treat the outsidehir's'parafew andreuuc'e it t'oa predeterimined :dew rpoint i i e mixing it with recirtcul-ated or room air.

An the :obie' ei my in enti n ri to p ovi e a novel oo ns means erdehumid fy n the a r before-mixingjt with therecirculated air; which will be at a different dew point than theoutside Another object 10f, my invention is to provide means -for conditiening the recirculated air, to provide apredetermined-dewpoint:and to provide means-foreqnditioningthenutsideair-to a differen-t dew point and mixing *thereoircula-ted air and outside air in predetermined amounts to secure a third dewepoint below a predetermined oint i a The above and otherobjects of my invention will be -apparent inthe-following specification and drawings, wherein: n

Fig. -1 shows diagrammatically the apparatus used in my invention. I I r V Fig. 2 'shows an end view -:of the longitudinal heat exchanger.

Fig. 3 showsacross sectional view of the longitudinal heat exchanger.

Referring to Fig. 1,15 represents the room or space "to beeonditibrred,fwherein "outside air is vdrawn int'9 theiiiiletjfiloy'meansiof a 'fan i2 isiqiiijr" gage variet and which draws" the apparatus in a preand "the outside "air is then deterhiiriedamo passed through alongitudinal fin coil 24, acrossseeuon-or'one tr te-e demerits 4s or which is ure-1 e 2.

The app ratusemmed'ajcasmg"compo e of Theta" ii heat exchange mediiii'n to the 2 the pulley iii, belt ljfigp'ull'ey -'2il, attached to Shaft -2 l on which "are mounted fans t2 "and 16.

The recirculated'air is pulled from theroom "25 into the apparatus through the *coil 2 2, "through inlet 34, and'emits irom th'e" coil='22 "into themix- -'-ing chamber l5,wher'e itmikes with the outside air which enters the 0011 2 4 at and 'leaves the coil z l'at 23.

-Referring to Fig. *2 and :Fig. 3 :an --ei'em'ent 48 of the longitudinal fin -coi1 :24 ;is shown as composed of a longitudinal casing 43, with a conduit therein ifljfo'r thence-*0: heat exchange fluid, and between the easing 43am the 'cond'uit hl are interposed heat exehange iins 46 which provide 'air passages '45 htwen 'the easing "43 and the conduit 44.

Theoutside 'ortiitilhtiiig air is drawn: into the 'unit throughtheBphifigQZB, communicating with the outside air, ana'the amount of air 'is controlled by "a damper 21 together with thefan l2 which handles a preueterimneu'amount of air.

The outside air fthefnis passed through the dehumidifyi'ng confluent its into the mixing chamber 15 where it is mixed'fwith the recirculated air "which enters the unit 'itlirough the inlet 36 'a'nd iiajssesthfoug h tlie pdil The coil -22 is supplied iivith heat exchange medium fromth'epipe35, 'ii1whieh'there is interposed a valve 38, -eoritrolli'rig the supply of the doil'ZZ.

The valve 38 iseo itr'oll'ed'byla Hry'bulb thermostat 39 throu'ghthe line ifljflsofth'at 'theamount of work performed by the "coil 2f 2 wil1fb1e responsive to the dry 'bulb temperature in "the r'o'o'm "25.

a predetermined temperaturey the thermostat ,39 causesthe valve38*toiepen,' andthe'heat exehange medium from pipe'35 by-passes the coil 22 and leav s'the apparat hrijii'gh 'i' tiifn pipeBB.

The c-eil 2 is s'upp1ied with heat exchange fluid from the pi'pe -'3l. c'oiine'dted' with the pipe 3! is a by-pass pipe 42 whiohconne cts with a pipe 35 which is connected'with'thevalved-Band the pipe 31. Interposed in'the by-pass 42 is a valve 32 which is responsive'toa humidostat 33 situated in the room -25, *whi'ch -'humidostat, through a line M, will control theaoperationof the valve 32 which controlsthe amount of flow of heat exchange fluidthrough'thecoilikbecause when the valve is open'tlie'flow will be through the 'bypass instead ofthrdugNthecoiI; thiis' the amount of work performed by'the'eoil -M'is controlled responsive to the amount or *in'oisture in theroo'm 25. so that' ineffe'ct, the 'coil 24 will remove from the outside air sufilcient moisture so that when mixed with the recirculated air the, latent load requirements will be satisfied.

Assuming that the ventilation requirements of three people in the room are 199.8 lbs. per hour of outside air, and it is desired to maintain the inside air conditioned at 80 dry bulb and 67 Wet bulb, it is apparent that there are required to be removed from the recirculated air the moisture equivalent to the latent load of the people in the room, and that there will also be required to be removed from the outside air a predetermined amount of moisture as to enable the mixture to meet the required moisture requirements.

The former air conditioning systems have been directed to mixing the outside air and the recirculated air and then conditioning the mixture, and due to the variations in the amount of moisture in the outside air, it has been found that this is impractical and the results were unsatisfactory amounts of moisture in the resultant air due to the varying amounts of moisture in the outside air, consequently the apparatus and method disclosed in this invention is directed to conditioning the outside or ventilating air to such a predetermined moisture content as will take care of the assumed latent load in the room and further to condition the recirculated air substantially without the removal of moisture but to remove a sensible heat therefrom so that when the recir- 3510 (grs. per hr. to be removed) 199.8 (amount of outside air) :178 grams per pound of air to be removed to maintain a predetermined moisture content of 78 grains per pound.

78 grs.17.8 grs.=60.2 grs. per pound which corresponds to the moisture content per pound of air with 53 dew point. Thus, the outside air leaving the coil 24, at 23, must have a temperature of 53 saturated. Inasmuch as this leaving temperature of the outside air is lower than the temperature of the recirculated air, it is evident that the outside air will remove a small amount of sensible heat from the recirculated air.

The sensible heat available for cooling below the predetermined dry bulb is then- 199.8 (lbs. of air for ventilation) X024 (specific heat of air) 80 (predetermined D. B. temp.) 53 (leaving temp. of ventilated air) =1280 B. t. u. per hour, subtracting this amount 1280 B. t. u. from 8250 (total B. t. u. sensible load): 6970 B. t. u. per hr. load to be removed by the recirculated air when passing through the recircuculated air is combined with the outside air the lated air coil, and

6970 B. t. u. per hr. to be removed by recirculated air coil 0.24 (specific heat of air) X1730 (lbs. of air to be emitted into room-199.8 lbs. of ventilated air) 19 resultant air will have a predetermined dry bulb. temperature difference, and 80 (predetermined For example: assume a typical office space with dimensions 14 x 16' x 11 high and exposed by two sides and roof, with three occupants, and with the outside air at 95 dry bulb, 78 wet bulb, containing 116 grains of moisture per pound of air and a desired inside air condition of 80 dry bulb, 67 wet bulb and containing 78 grains per pound of air. According to engineering data there would be a sensible heat gain of 6000 B. t. u. due to transmission losses and 2250 B. t. 11. due to internal heat additions from lights and people, or a total of 8250 B. t. u. heat gain. Also, according to engineering data, an internal latent load of 525 B. t. u. due to people.

The ventilation requirements for three people at the rate of 15 C. F. M. per person would be 45 C. F. M., which is equal to 199.8 pounds of air per hour. A further assumption is the dry bulbtemperature of the mixed air entering the room should not be lower than 60.

8250 (sensible load in B. t. u.)

which is the total amount of sensible cooling performed by the mixed outside and recirculated air. The other equation referred to the latent load is:

525 B. T. U. (latent load) X 1050 (latent heat of water) 7000 (gr. per lb.)=3510 grs. per hr.

to be removed from the water on account of the latent load, and

dry bulb air temperature)-19==61 air leaving recirculated air coil, thus, 199.8 lbs. of ventilated air is mixed with 1529.2 lbs. recirculated air to obtain 1730 lbs. of air emitting from the unit into the room.

Mixing 1529.2 lbs. of recirculated air at 61 dry bulb and having moisture content of 78 grains per pound, with 199.8 lbs. of outside dehumidified air at 53 dry bulb temperature and with a moisture content of 60.2 grains per pound, produces a final condition of the mixture of 60.1 dry bulb temperature and a moisture content of 75.95 grains per pound, which will maintain in the room, conditioned air of 80 dry bulb and with a moisture content of 78 grains per pound.

Under the present type of units where the outside air and recirculated air are mixed before conditioning, mixing 199.8 lbs. of 95 dry bulb and 116 grains of moisture per pound outside air with 1529.2 pounds of 80 dry bulb and 78 grains of 1730 pounds of air per hour moisture per pound results in a mixture of 81.4" dry bulb and 82.3 grains of moisture per pound, and from the coil curve this could be conditioned to 61 dry bulb with a moisture content of 75.95 grains of moisture per pound, which is the desired condition.

However, assume the outside conditions to vary so that the outside air drops to dry bulb with 117 grains of moisture per lb. and the inside conditions to be maintained at 80 and 78 grains of moisture per pound as previously. The required dry bulb temperature of the mixed air to maintain 80 would be 69.8, and the air mixture would be 199.8 pounds of 35 dry bulb air with 117 grains of moisture per pound and 152912 pounds of 80 dry bulb air with 78 grains of moisture per pound, resulting in a condition of 808 dry bulb with 82 am ss grains of moisture per pound; In order toreduce this. mixture to the desired moisture'content of 75.95 grains per pound, it would be necessary to reduce the dry bulb temperature to 64 accord ing to thecoil curve, WhiCh'lS 5.8 below the dry bulb temperature necessary to maintain the desired temperature and wouldresult in undercooling the room. Also, if the dry bulb temperature of the mixed air wasreducedonly to 69.8 then the moisture content, would be 77 grains per pound, which would not be enough to absorb the latent load in the room and the humidity would be too high. L

Assume the same conditions with the outside air taking care of the latent load as disclosed herein:

I-Ieat' gains are: I 2000 Transmission taccording 2250 Internal Sensible heat engineering 525 latent data The required dry bulb leavingtemperature of the mixed air is 69.8 .from the following equation 4250 (sensible load B. t. u.) 1730 (lbs. of air, mixed) X 0.24 specific heat of air and 80--10.2=69.8

The desired moisture content is 78 grains per pound of air as before and to maintain this condition the mixed air must have a moisture content of 75.95 grains per pound, which is 2.05 grains per pound (the latent load) less than the desired moisture content of the room air.

The outside air is reduced to 53 saturated as before, resulting in a moisture content of the conditioned outside air of 60.2 grains per pound.

The sensible heat available for removal by outside air is 1280 B. t. u. The total sensible heat load of 4250 B. t. u. is therefore reduced by 1280 B. t. u. which leaves 2970 B. t. u. sensible heat to be removed by the recirculating coil. The temperature of the air leaving the recirculating coil would be 71.85 dry bulb as shown by the following equation:

-808.15=71.85 dry bulb, which will produce a mixture of 697 dry bulb with a moisture content of 75.95 grains per pound, which is the desired condition. It is obvious from the foregoing example that the method of having the outside or ventilating air take care of the latent load and the recirculated air regulating the dry bulb temperature, possesses distinct advantages over the method of mixing the outside air and recirculated air to a mixture which is then conditioned.

It is apparent from the foregoing that I have invented a new and novel means of conditioning the air in a room, set forth in the following claims, in which I claim:

1. A method of air conditioning a space com prising moving apredetermined amount of outside air in parallel fluid flow heat exchange relationship with a heat exchange fluid, moving air from said space into heat exchange relationship with a heat exchange fluid, then mixing said outside air and said air from the space, and moving the mixed air into the space.

2. A method of air conditioning a space comprising moving a heat exchange fluid through a first heat exchanger and then through a second heat exchanger, moving outside air into parallel fluid flow heat exchange relationship with the heat exchange fluid in said first heat exchanger, moving air from said space into heat exchange relationship with the heat exchange fluid in said second heat exchanger, then mixing said outside air and said air from said space and then moving the mixed air into the space.

3. Apparatus for air conditioning a space comprising means for moving a predetermined amount of outside air in parallel fllllld flow heat exchange relationship'with a heat exchange fluid, means for moving air from said space into heat exchange relationship with a heat exchange fluid, means for mixing said outside air and said air from said space and means for moving the mixed air into the space. I 4. Apparatus for air conditioning a space comprising a first heat exchanger having means for conducting heat exchange fluid and means for conducting air in heat exchange relationship with said means for conducting heat exchange'fluid, said means for conducting heat exchange fluid and said means for conducting air'being substantially parallel with each other, means for moving outside air through said means for conducting air, a second heat exchanger, means for moving air from said space through said second heat exchanger, means for mixing said outside air leaving the first heat exchanger with said air from said space leaving said second heat ex= changer and means for moving the mixed air into the space.

5. Apparatus for air conditioning a space comprising a plurality of conduits for conducting a heat exchange fluid, a plurality of ducts with each duct surrounding one of said conduits and being of such a size as to provide a passageway for air between said duct and said conduit, heat transfer fins in said passageway, said fins extending longitudinally of the conduit and the duct, means for moving outside air through said ducts, a heat exchanger, means for moving air from said space through said heat exchanger, means for mixing said outside air leaving said ducts and said air from said space leaving said heat exchanger and means for moving the mixed air into the space.

6. Apparatus for air conditioning a space comprising a first heat exchanger having liquid conduits with a supply and a discharge opening and conduits for conducting air, said liquid conduits and said air conduits being constructed and arranged for parallel flow of liquid and air, a second heat exchanger, a conduit connected at one end to the discharge opening of the conduit of said first heat exchanger and at the other end to said second heat exchanger for conducting liquid discharged from said first heat exchanger to said second heat exchanger, means for movin outside air through said first heat exchanger, means for moving air from said space through said second heat exchanger, means for mixing said outside air leaving said first heat exchanger and said air from said space leaving said second heat exchanger and means for moving the mixed air into said space.

7. Apparatus for air conditioning a space comprising a first heat exchanger, a second heat exchanger, means for conducting a heat exchange fluid first through said first heat exchanger and then through said second heat exchanger, a first by-passing means for conducting the heat exchange fluid around said first heat exchanger, humidity responsive means in said space for controlling the operation of said first by-passing am ss means, a second Icy-passing means for conducting. the heat exchange fluid around said second heat exchanger, a temperature responsive means in said space for controlling the operation of said second by-passing means, means for moving outside air through said first heat exchanger, means for moving air from said space through said secand heat exchanger, means for mixing the air from said first heat exchanger with the air from said second heat exchanger and means for moving the mixed air into said space. a

8. Apparatus for air conditioning a space comprising a casing having a first inlet opening for admitting outside air, a second inlet opening for admitting air from said. space, a mixing chamher, and an outlet opening in the casing for discharging air from the mixing chamber into said space, a first heat/exchanger having air ducts arranged to discharge air into said mixing chamber, a conduit leading from said first inlet opening to said first heat exchanger, a fan in said conduit for moving air in said conduit, a fan mounted in said mixing chamber at the outlet 8. opening, for, discharging; air from, said mixing chamber into said space, means mounting said fansona common axis of rotation, a second heat exchanger atthe second inlet opening, the second heat exchanger having air ducts arranged in a direction normal to the air ducts of said first heat exchangertdd-ischargeair in'a direction normal to, the. direction of ,the air stream from said first heat exchanger;

CLARENCEL. RINGQUIST.

REFERENCES CITED The following refererrces are of record in the file of this patent: