US2286538A - Air conditioning system - Google Patents

Description

June 16, 1942'. G, D,- GULER 2,286,538

AIR CONDITIONING SYSTEM Filed Feb. e, 1937 Patented June 16, i942 AIR CONDITIONING SYSTEM George D. Guler, Philadelphia, Pa., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application February 6, 1937, Serial No. 124,459

(c1. sz- 6) 19 Claims.

` This invention relates in general to the art of air conditioning and is more particularly concerned with the cooling and dehumidication of The primary object of my invention is to provide an air conditioning control system which is relatively simple in operation and which acts to automatically maintain the temperature' and humidity of the air in a space within predetermined limits, such system being also adapted to meet sudden changes in refrigeration load.

In order to reduce excessive temperature or humidity, removal of heat from the air is necessary. Reduction in humidity however, requires a different type of cooling action than does reduction of temperature. In order to reduce the temperature of air it is necessary only to remove sensible heat from the air and to remove part of the superheat of the waterl vapor contained in the air. For reducing humidity however, it is necessary to remove moisture from the air, this requiring rst that the temperature of the air be reduced to the dew-point. Upon removal of heat from the air after the dew-point temperature has been reached, condensation of moisture and consequent dehumidication will occur.

When air is passed over a cooling coil or other type of cooling element both temperature reduction and dehumidication may occur. The

proportion of the refrigeration effect of such coil going towards dehumidication and the proportion of such refrigeration eiect which acts yto cool or reduce temperature will depend upon temperature of the coil and the dew-point temperature of the air. By varying the coil temperature the ratio of cooling to dehumidifying may be varied. For instance, as the coil temperature is 'maintained above the dew-point temperature of the air, the air temperature cannot be reduced below its dew-point. Thus, for this coil condition there will be no dehumidifying action whatsoever and the total refrigeration effect of the coil will go towards temperature reduction or cooling of the air. If, however, the coil temperature is reduced below the dew-point of the air, both a cooling and dehumidifyingI action will occur, the cooling coil acting lirst to reduce the air temperature to the dew-point and then to condense moisture in the air. Inasmuch as the dehumidifying action of the coil increases at a faster rate as the cooling coil temperature is reduced below the dew-point, than the corresponding increase in cooling eiect, the dehumidifying action may be increased without corresponding increase in cooling effect by rein a single conditioning chamber, lthese coils being connected together to a common refrigeration system, each system comprising a battery of compressors. Each cooling coil is provided with a control valve at yits inlet,I these valves acting to prevent or permit ow of refrigerant into their respective evaporators. A temperature control system is employed which acts to pregressively open these valves as the temperature of the air within the space increases above a predetermined value. This temperature control means is arranged also to progressively place the compressors in operation, that is, each time that a valve is opened by the temperature control device, a compressor is likewise placed into operation. By placing these cooling coils in operation as the temperature increases, the cooling area over which the air is passed is increased to meet this increase in cooling load. Due to the fact that a compressor is placed into operation simultaneously with each cooling coil, the temperature of all the cooling coils will remain unchanged regardless of the number of cooling coils in operation. This temperature is selected to cause both a cooling and dehumidifying action on the air. In order to prevent the humidity of the air from falling below a predetermined value, a humidostat is located within the space to be conditioned, this humidostat being arranged to open all of the solenoid valves when the humidity falls below a predetermined value. Due to this opening of all the valves, all of the cooling elements will be placed into operation. As the number of compressors in operation is, .un-

changed, this results (if less than the total number of compressors are in operation) in a rising of pressure within the cooling coils with the consequent rising in temperature of such coils. This causes the temperature of the coils to rise above the dew-point of the air thus stopping all dehumidifying action and causing the entire cooling eiect of the system to go towards sensible heat reduction. This control arrangement therefore forms one object of my invention.

A further object of my invention is to provide an air conditioning system for cooling and dehumidifying air, such system including control devices for varying the temperature and effective area of cooling elements in accordance with temperature and humidity conditions.

A further object of my invention is to provide an air conditioning system having a plurality of cooling elements connected in multiple to a common refrigerant supply means, with control means for sequentially placing said cooling elements into and out of operation and for substantially simultaneously changing the operation of the refrigerant supply means in accordance with a predetermined schedule.

Another object of my invention is the provision of an air conditioning system having a plurality of cooling elements connected to a common refrigerant supply system, with temperature and humidity responsive means for controlling the cooling elements and the refrigerant supply system in a manner to maintain the desired temperature and humidity conditions.

A still further object is the provision of novel control means for a refrigeration system of the type employing a plurality of cooling elements connected to a common refrigerant supply means, such control means acting to vary both the number of cooling elements in operation and the operation of the refrigerant supply means in a manner to maintain desired temperature and humidity conditions within a conditioned space.

Another object of my invention is the provision of a refrigeration system having a group of cooling coils connected to a group of compressors, such system having a temperature responsive means for sequentially placing said cooling coils and compressors into operation and having a humidity responsive means for dominating part of the action of said temperature responsive means.

Further objects will appear from the following specification and the appended claims.

For a full understanding of my invention, reference is made to the following specification and to the accompanying drawing, the single figure of which illustrates diagrammatically one form which my invention may take.

Reference character I-indicates a conditioning chamber provided with an inlet duct 2 communicating with a space to be conditioned 3. Conditioning chamber I at its opposite or outlet end 4 is connected to a `fan 5 the discharge side of which is connected to the delivery duct 6 which leads to the space 3. Located in conditioning chamber I are a series of cooling coils or elements 1, 6, 9 and I0. These cooling coils are connected by suitable branch pipes to a discharge header II, this header being connected by a suitable conduit I2 to a second header I3. Connected to the header I3 are branch pipes I4, I5, I 6 and I1 which lead to the suction sides of compressors I8, I9, 20 and 2I respectively. In this manner the battery of cooling coils 1, 8, 9 and I is connected as a unit to the battery of compressors I8, I9, and 2I. Connected to the discharge sides of compressors I8, I9, 20 and 2| are branch pipes 22, 23, 24 and 25 these branch pipes leading to a pump discharge header 26. Header 26 is in turn connected to the inlet of a suitable condenser 21, the outlet of this condenser being connected by a pipe '28 to a supply header 29. Supply header 29 is connectedby branch conduits 30, 3l, 32 and 33 to the inlets of cooling elements 1, 8, 9 and I0 respectively. Interposed in each of the branch conduits 30, 3|, 32 and 33 are solenoid flow controlling valves 34, 35, 36 an'l 31. These solenoid valves are prefer-ably of the type which open when energized and which close when deenergized. Also located in the . branch pipes 30, 3|, 32 and 33 are suitable exand 2|,y these compressors discharging into a common condenser from which liquid refrigerant is supplied to the cooling elements.

The operation of the refrigeration system above described is identical with that of an ordinary compression refrigeration system. The compressors reduce the pressure within the cooling coils, thus causing the liquid refrigerant therein to evaporate and absorb heat. This evaporating refrigerant is raised in pressure by the compressors and supplied to the condenser wherein heat is removed causing the refrigerant to condense to the liquid state. This liquid refrigerant is then supplied through the solenoid valves and the expansion valves to the various cooling elements. As the refrigerant passes through the expansion valves its pressure is greatly reduced, this sharp reduction in pressure permitting evaporation of the liquid refrigerantat a low temperature, thus causing heat to be absorbed from the air by the various cooling elements. The evaporated refrigerant is then returned to the compressor and the cycle repeated continuously.

Reference character 45 indicates generally a thermostatic controller. This controller comprises an expansible and contractable bellows 46 which is connected by a capillary tube 41 to a suitable control bulb 48 which may be `located in the return air duct 2. 'I'he bellows 46, tube 41 and bulb 48 are filled with a suitable volatile substance as well known in the art. As the temperature within the return air duct 2 falls, the

vapor pressure of the volatile fill will, decrease, thus causing contraction of the bellows 46. Conversely upon an increase in temperature within the return air duct 2, the vapor pressure within the bulb, tube and bellows will increase, thus causing expansion of the bellows 46. Cooperating with the bellows 46 is a bell-crank lever pivoted at 49 and having an actuating arm 50 and a control arm 5I. bellows 46 and is urged thereagainst by a spring 52 which is connected to a suitable fixed member 53. The control arm 5I cooperates with a control resistance 54 to form a potentiometer. The controller just described is herein illustrated as being so designed and adjusted that when the return air temperature is '75 F., the control arm 5I will just engage the extreme left end of resistance 54. As the return air temperature increases, arm 5I will move to the right, and when the return air temperature increases tov '77 F., the arm 5I will engage the extreme right hand end of control resistance 54. The control arm 5I and the ends of the control resistance 54 are connected to a proportionlng motor generally indicated at 55. This proportioning motor may be of the type illustrated in Patent 1,989,972 issued to Lewis L. Cunningham on February 5, 1935. This type proportioning motor is adapted to rotate a shaft 56 to angular positions corresponding with the position of the control arm 5I on the control resistance 54. In other words, for each position of the control arm 5I on the control resistance 54 there will be a corresponding angular position of the shaft 56.

Located onv the shaftl 56 are a series of cams 51, 58, 59 and 60, the raised portion of these cams being angularly displaced from Aone another. Cooperating with the cams 51, 58, 59 and 66 are Actuating arm 50 abuts against the cam followers 6|, 62, 63 and 64, these cam followers having vmounted thereon mercury switches 65, 66, 61 and 68 respectively. Referring again to the proportioning mator 55, this vmotor is arranged to rotate shaft 56 in a counterclockwise direction as the control arm of controller 45 moves across the control resistance 54 from left to right or in other words upon an increase in return air temperature.

portions and recessed portions. Thev cam 51 is positioned on shaft 56 so that the recessed por-- Thus before the raised portion of cam 58 will engage the cam follower 62, shaft 56 must be rotated further in a counter-clockwise direction, this action occurring only when control arm 5I is moved further across control resistance 54. Similarly the raised portion of cam 59 is angularly displaced in a clockwise direction from that of the cam 58 and the raised portion of cam 66 -is displaced in a clockwise direction from that of the cam 59. It should be apparent therefore, that as the shaft 56 is rotated in a counter-clockwise direction under the control of controller 45 the mercury switch 65 will first be tilted to closed position. Upon further rotation the mercury switch 66 will be tilted toward closed position and upon still further rotation the mercury switch 61 and the mercury switch 68 will be sequentially tilted to closed position. Conversely as the shaft 56 is rotated in a clockwise direction the mercury switches will be tilted to open position in reverse order. It should now be apparent that when the return air is relatively cool, the control arm 5| will engage the extreme lefthand of control resistance 54, thus causing rotation of shaft 56 to a `position to which all of the mercury switches are in open position. As the temperature of the return air increases however, the control arm 5| will move across control resistance 54 from left to right, thus causing counter-clockwise rotation of shaft 56 and tilting of mercury switch 65 to closed position. Upon further increase in temperature shaft 56 will be ro- It will be observed that cams 51, 58, 59 and 66 are provided with raised to the line wire 10. It should thus be apparent that the control boxes 11, 18, 19 and 86 are connected across the line wires 16 and 1| in series with the mercury switches 65, 66, 61 and 68 respectively.

v is connected by wire 88 to one terminal of the solenoid valve 34. In a similar manner electrodes of mercury switches 66, 61 and 68 are connected respectively to the solenoid valves 35, 36 and 31 by wires 89, 96 and 9| respectively. The other terminals of the solenoid valves 34, 35, 36 and 31 are connected together and to line wire 16 by wires 92, 93, 94, 95 andV 96. The control valves 34, 35, 36 and 31 are therefore connected across the line'wires 16 and 1| in series respectively with mercury switches 65, 66, 61 and 68.

. From the foregoing it should be apparent that each of the mercury switches to 68 controls both a solenoid valve and a compressor starter. For instance, when the mercury switch 65 is tilted to closed position the solenoid valve 34 will be energized by a circuit as follows: line wire 1|, wire 12, mercury switch 65, wire 88, solenoid valve 34, wire 92, and wire 93 to line wire 16. Also tl compressor starter 11 for the compressor |8 will be energized as follows: line Awire 1|, wire 12, mercury switch 65, wire 16, compressor starter 11, wire 64, and wire 81 to line wire 16. In a similar manner closure of mercury switch 66 opens solenoid valve 35 and starts the compressors |9, and closure of mercury switches 61 and 68 causes opening of solenoid valves 36 and 31 and starting of the compressors 26 and 2|. It should now be apparent that the number of cooling coils and compressors placed in operation is dependent upon return air temperature. In other words, when the return air temperature is below apredetermined value, for instance degrees, the control arm 4| of the temperature controller 45 will engage the extreme left-hand portion of control resistance 54, this causing the proportioning motor 55 to rotate shaft 56 to a position in which all of the mercury switches are in open position. As the temperature of the return air increases the proportioning motor will rotate shaft 56 in a manner hereinbefore described to tilt mercury switch 65 to closed position, this causing opening of solenoid valve 34 and startingof the compressor I8. As the temperature continues to rise shaft 56 will `be rotated further, this causing tilting of the mercury switch 66, this in turn causing openingA of the solenoid tated further in a counter-clockwise direction nected by wire 16 to one terminal of the control box 11 for the compressor I8. In a similar manner the mercury switches 66, 61, and 68 are connected to the compressor control boxes 18, 19 and 86 by wires 8|, 82 and 83 respectively. The other terminals of control boxes 11, 18, 19 and 86 are connected by means of wires 84, 86 and 81 `valve 35 and starting of the compressor I9.` In

a similar manner as the return air temperature increases further, the. mercuryswitches 61 and 68 will be sequentially moved to closed position, this causing sequential opening of solenoid valve 36 and starting of compressor 26 and opening of solenoid valve 31 and starting of compressor 2|. number'of cooling elements and compressors in operation is sequentially increased.

In theV drawing, I have illustrated v'the coml pressors as being of equal size, and the cooling coils 1, 8, 9 and I6 as progressively increasing in size. The reason for this variationdn size of thev cooling coils is that the temperature difference between the air being cooled and the cooling Under arising temperature, therefore, the

the compressors are of equal size, and the cooling eilect of each coil is equal, it will be apparent that when an additional coil and compressor are placed in operation in the manner. above described, the increase in load caused by the additional cooling ccil will be just carried by the additional compressor, and hence the pressure in the coolingcoils in operation will not be affected. While I have shown the coils of being of varying size and the compressors as being of equal size, it will be apparent that if desired, the coils may be made of equal size and the compressor capacities varied correspondingly. The important feature is that the capacities of the compressors be approximately equal to the cooling ellect of their corresponding cooling coils. It will be apparent however that my invention is not limited to this feature. i

Located in the conditioned space 3 is a humidity controller generally indicated at |00. This controller comprises a mercury switch carrier which is pivoted at one end and which carries a mercury switch |02. To the free end of `element |0| is connected a spring |03 which is in turn connected to a suitable fixed member |04. Also connected to the free end of element |0| is a humidity responsive device, this device comprising of a plurality of strands of moisture responsive material, these strands being secured to clamping members |06 and |01, the clamping member |06 being secured to the switch carrier |0| and the clamping member |01 being secured to a suitable fixed support. As the humidity within the space increases, the strands |05 will increase in length thereby permitting the spring |03 to tilt the switch carrier |0| in a clockwise direction, thereby tilting mercury switch |02 to open position. When the humidity decreases however, the strands |05 will decrease in length thus rotating switch carrier |0| in a counter-clockwise direction against the action of spring |03. When the humidity falls to a predetermined value such as 50% the shrinking of strands |05 will be sufficient to cause the mercury switch |02 to be tilted to closed position.

Reference character ||0 indicates generally a relay controlled by the humidostat |00. This relay comprises a plurality of switch arms III,

- ||2, ||3 and ||4 arranged to cooperate with contacts ||5, ||6, ||1 and ||6 respectively.

These switch arms are connected to a suitable p plunger located within the magnetic iield of relay coil H9. When relay coil ||9 is energized the plunger is moved to the right thereby moving switch arms ||2, ||3 and ||4 into vengagement with their respective contacts. When, however, the relay coil ||9 is deenergized, the switch arms are moved away from their contacts by means of gravity or springs (not shown). The switch arms to ||4 are connected by wires |20 and |2| to the line wire 1|. The contacts ||5, 6, ||1 and |8 are connected respectively by wires |22, |23, |24 and |25 to the wires 88, 89, 90 and 9| and in this manner are connected to the solenoid valves 34, 35, 36 and 31 respectively. One end of the relay coil ||9 is connected to line wire 1| by means of wire |2|, and the other end of coil ||9 is connected by wire |26 to the mercury switch |02 of the humidity controller |00, the other electrode of said mercury switch |02 being connected by wire |21 to the line wire 10.

The function of the humidity controller |00 and the relay ||0 is to cause opening of all of the solenoid valves whenever the humidity within the conditioned space falls below a predetermined value. So long as the humidity within the space 3 is above such predetermined value the mercury switch |02 will be tilted to open position thereby deenergizing the coil ||9 of relay ||0. Upon falling of the humidity to the predetermined value, the mercury switch |02 will be tilted to closed position this energizing' relay coil 9 by a circuit as follows: line wire 10,

wire |21, mercury switch |02, wire |26, relay coil ||9 and wire |2| to line wire 1|. Energization of relay coil ||9 will cause the switch arms to ||4 to engage their respective contacts H5 to ||8. Engagement of switch arm with the contact ||5 will energize the solenoid valve 34 by a circuit as follows: line wire 1|, wire |2|, wire |20, switch arm contact ||5, wire |22, wire 88, solenoid valve 34, wire 92, and wire 93 to line wire 10. In a similar manner engagement of switch arm ||2 with contact ||6 will energize the solenoid valve 35, and engagement of switch arms ||3 and ||4 with their respective contacts, ||1 and ||8, will cause energization of the respective solenoid Valves 36 and 31. It should therefore be seen that when the humidity within the space 3 is below a predetermined value, the solenoid valves 34, 35, 36 and 31 will be opened independently of the action of the mercury switches 65, 66, 61 and 68. The energization of relay ||0 while causing opening of all the solenoid valves however has no effect upon the number of compressors in operation. In other words, the number of compressors placed in operation is controlled entirely by the temperature controller 45, while the number of cooling coils placed in operation is controlled by the temperature controller so long as the humidity within the space is above a predetermined value. When, however, the humidity falls below such value, all of the solenoid valves will be opened regardless of the action of the temperature controller.

Operation In practicing my invention the capacities of the compressors Will be made suiciently high to enable one compressor to reduce the temperature of one coil below the dew-point of the air passing thereover. The capacities however are preferably not great enough to enable one compressor to reduce the temperature of more than one coil substantially below the dewpoint of the air. Therefore, with one compresser and one coil in operation, the temperature of the coil will be below the dew-point of the air thereby causing the coil to have both a dehumidifying and a cooling action. Similarly if two compressors and two coils are in operation the temperature of both coils will be below the dew-point of the air and as long as the same number of compressors and coils are in operation, the temperature of the coils will remain below the dew-point. If, however, all of the coils are placed in operation, and b'ut part of the compressors are operating, the temperature of the coils will be above the dew-point, thereby causing the coils to have only a cooling action.

With the parts in the position shown the return air temperature is about 76 degrees as indicated by the control arm 5| of temperature controller 45 engaging the mid portion of control resistance 54. Under this temperature condition the proportioning motor has rotated the shaft 56 to the position shown in which the aasasse fore will cause the humidity within the space to gradually decrease, this action causing. the

mercury switchv |02 to be tilted towards closed.

position. When the humidity falls to a predetermined value, for instance 50%, the mercury switch |02 will be tilted suiliciently to cause closure thereof, this in the manner previously l described, causing vopening of all of the solenoid plished entirely by the temperature controller.

As the number of cooling coils and compressors in operation are equal, the temperature of the two cooling coils in operation is below the dewpoint and therefore both reduction in temperature and reduction in humidity is being effected.

Should the `return air temperature fall, the control arm 5| of the temperature controller will be rotated in a` counter-clockwise direction; this causing rotation of the proportioning motor shaft 56 in a clockwise direction which will ultimately result in tilting of the mercury switch 66 to open position, this in turn causing closing of the solenoid valve .35 and stopping of its corresponding compressor Alil. Should the temperature continue to fall the proportioning motor shaft 56 will be further rotated in a clockwise direction this tilting mercury switch 65 to vopen position causing closing of solenoid valve 34 and stopping of compressor I8. Therefore, whenthe temperature is lowered to a predetermined value (in this case '75 FJ, all of the cooling coils and all of the compressors will be placed out of operation thus preventing. further reduction in temperature regardless of what the prevailing humidity may be.

If, however, the temperature of the return air should increase, the proportioning motor shaft will be rotated in the opposite direction, this causing sequential opening of the mercury switches 65, 66,. 61 and 60. In other words, as j the return air-temperature increases first one cooling coil and one compressor will be placed in operation. As the return air temperature increases further, a second cooling coil and a second compressor will be placed in operation.

Similarly upon further increase in temperature l a third cooling coil and compressor and a fourth cooling coil and compressor will sequentially be placed in operation.V As the number of compressors in operation will under this mode of control remain equal to the number of cooling coils in operation, regardless of what the air temperature may be, the temperature of whatever number of cooling coils is placed in operation will remain below the dew-point of the air this causing the cooling coils to both removesensible heat from the airand dehumidify the air. In other words, so long as the humidity remains above the number of cooling coils placed in operation will be dependent only upon valves. If now, less than the total number of cooling coils and compressors had been placed in operation by the temperature controller, the opening of all solenoid valves will have the effect of placing a greater refrigeration load upon the compressors then in operation. The result of this increase in load upon the compressors will be a rise in pressure within the evaporators, this causing the temperature of the evaporators to risecorrespondingly.` As hereinbefore mentioned this rise in temperature will be suilicient to cause the temperature of the cooling coils to be above'the dew-point of the air. Due to this rise in temperature of the cooling coils there will be no further dehumidifying action, and the entire refrigerating action of the coils will go towards reducing only the temperature of the air being conditioned. At this time it will be vnoted all of the cooling coils are in operation and hence the cooling surface is at a maximum. The effect of the humidity controller |00, therefore, is to increase thecooling area and to incr'ease the temperature of the cooling coils whenever the humidity falls below a predetermined value, this resulting shifting of the cooling eect of the coils to cause a maximum of sensible heat removal and a minimum of latent heat removal.

From the foregoing it should be apparent that I have disclosed an air conditioning control system which acts to maintain the temperature and humidity of the air below desired values, this system acting to vincrease the cooling coil surface as the temperature within the conditioned space increases thereby increasing the cooling etlect as needed to maintain the space temperature within the desired limits. It should further be apparent that the temperature controller will place the same number of compressors in operation as the number of cooling coils, this causing both the temperature of the return air, the number of cooling coils being progressively increased as the return air temperature increases and being decreased as the return air tcmprogressively l Due to the fact that the perature decreases.

' nmnber of compressors in operation is varied simultaneously with the number of cooling coils,

the temperature of the cooling coils in operation Iwill remain substantially constant.

So long as the humidity of the space 3 is above the predetermined value, the cooling coils in operation will act to both cool and dehumidify the air. The operation of the coolingcoils therethe cooling and dehumidifying action to be increased as the space temperature increases, this action occurring so long as the humidity within the space isabove a predetermined value. When, however, the humidity falls below such predetermined value, all of the cooling coils are placed in operation,'thus causing increase in temperature oi' the cooling coils thus decreasing the dehumidifying action of such coils while increasing' the temperature reducing or cooling action.

While for purposes of description I have assumed certain values of temperature and humidity as the control points of the temperature and humidity controllers, it will be obvious that these values may be varied as desired. Also, while I prefer to proportion the cooling coil and compressor capacities so that the temperature of the cooling coils will be above the dew-point of the air when less compressors are in operation than cooling coils, I do not wish to be limited to this as it will be apparent that even though thecooling coil temperature is below the dew-pointv` of the air under this condition, there would be less dehumidifying action than would occur were the number of coils and compressors in operation equal. Furthermore, While I prefer to obtain a variable refrigeration action by employing a plul rality of compressors and varying the number of l connected as a group to a group of said cooling gest themselves to those skilledin the art. I

therefore desire to be limited only by the scope of the appended claims and the prior art.

I claim as my invention:

l. In an air conditioning system, in ,combination, a conditioning chamber, means connecting said conditioning chamber with a space to be conditioned, cooling means in said chamber, means for supplying cooling uid to said cooling means, control means for graduatingly varying the flow of cooling fluid through said cooling means, control means for graduatingly varying the operation of said cooling fluid supplying means, and temperature and humidity responsive means for controlling said control means,l one of said responsive means being arranged to control graduatingly `bothof said control means, and the other of said responsive means being arranged to cooperate in controlling one only of said control means.

2. In an air conditioning system, in combination, a. conditioning chamber, means connecting said conditioning chamber with .a space to be conditioned, -a plurality of cooling -devices in said chamber, common means for supplying cooling fluid to said devices, sequential control means for sequentially placing said cooling devices into or out of operative relationship with said cooling :duid supplying means substantially simultaneously with varying said `cooling uid .supplying means, temperature responsive means for actuating said sequential control means, and humidity responsive means or placing said cooling devices into operative relationship with said cooling iluid supplying means independently of said sequential control means.

3. In an air conditioning system, in combination, a conditioning chamber, means connecting said conditioning. chamber with a space to be conditioned, a plurality of cooling elements in' said chamber, common'means for supplying cooling uid to said elements, ilow. control means for controlling the flow of cooling iiuid into said elements, supply control means for said cooling iluid supply, a controller for actuating said ilow control means in a manner to sequentially .place said cooling elements into'tor out of operation, said controller being also arranged to control said supply control means'to change the cooling uid supply substantially simultaneously with changing the number of cooling elements in operation, and temperature and humidity responsive means, one of said responsive means being' arranged to actuate said controllenand the other of said responsive means being arranged to cooperate with said controller in controlling one onli7 of said control means.

4. In an air conditioning system, in combination, a conditioning chamber, means connecting said conditioning chamber with a space to be conditioned, a plurality of cooling elements in said chamber, a plurality of cooling' duid circulating devices, said circulating devices being elements, now-control means for controllingv the o'w of cooling fluid into said elements, control means for said cooling fluid circulating devices, acontroller for actuating said flow control means in a manner to sequentially place said coolingv elements into or out of operation, said controller being also arranged` to actuate said circulating .ate said controller, and the other of said respon'- sive means being arranged to cooperate with said controller in controlling one only of said control means. f v

5. In an air conditioning system, in combination, a conditioning chamber,v means connecting said.A conditioning chamber with a space to be conditioned, direct expansion cooling means inv said chamber, means for supplying refrigerant to said cooling means, a back pressure reducing means connected to said cooling means, control means forgraduatingly'varying the ilow of refrigerant to said cooling means substantially simultaneously with graduatingly changing the operation of said back pressure reducing means; temperature responsive means in control of said control means, and humidity responsivity means ducing means, and temperature and humidity responsive means for controlling said controly means, one of said responsive means-being arranged to control graduatingly both of said control means and the other of said responsive means being arranged to cooperate in controlling one only .of said control means. .f i

7. In an air conditioning system, in combination, a' conditioning chamber, means connecting said conditioning chamber with a space to be conditioned, a plurality of direct expansion cooling devices in said chamber, means forsupplying refrigerant to said cooling devices, ,common back pressure reducing means for saidrcooling devices, control means for sequentially preventing or permitting now of refrigerant4 into said coolingdevices, control means for graduatingly controlling said back pressure reducing means, and, temperature and humidity responsive means for controlling said control means, one of said responsive means being arranged to control both of said control means andl the other of said responsive means beinglvar'ranged to cooperate in controlling one only of`- said control means.

8. In an air conditioningv system, in combination, a conditioning chamber, means connecting be conditioned, cooling means in vices, control means for graduatingly controlling said back pressure reducing means, temperature responsive means for controlling both of said f control means, and humidity responsive means arranged to cooperate with said temperature responsive means in controlling the ow of refrigerant into said cooling devices only.

9. In a system of the class described, in combination, a cooling means, means for supplying cooling fluid to said cooling means, control means for graduatingly controlling the flow of cooling iluid, control means for graduatingly controlling the operation 'of said cooling fluid supplying means, a controller for graduatingly actuating both of said control means, and a second controller for actuating one only of said control means.

10.' In an air conditioning system, in combination, a conditioning chamber, means connecting said conditioning chamber with a -space to said chamber,

space, said cooling means consisting of a plurality'of separate' cooling devices, means foi-.con-` ducting cooling iiui'd to said cooling means, means for reducing the temperature of the cooling fluid comprising means for varying the volumetric output of the cooling duid temperature reducing means, separate valve means for controlling the variable capacity means for supplying cooling fluid to said cooling means, flow control means for varying the flow of cooling uid through said cooling means, control means for varying the capacity of said cooling uidsupplying means, thermostatic meansv for controlling both in a manner to -substanofsaid control means tially simultaneously vary the flow of cooling medium and the 'capacity of said cooling fluid supplying means, and humidity responsive .means flow of cooling fluid into said cooling devices,

temperature responsive means for controlling said temperature reducing means and s'aid valve means to correspondingly vary Vboth 'the volumetric output of said temperature reducing means and the number of cooling devices in operation upon variation in temperature, in a manner to maintain the temperature of the cooling uid substantially constant irrespective of demand upon the ltemperature reducing means -caused by variation in ilow, and humidity re' -sponsive means f or increasing the flow of cooling uid admitted to said cooling means upon a defor cooperating. with said thermostatic means in controlling the flow control means only.

11. In an air conditioning system, the combination comprising, cooling means for cooling a crease in humidity Without correspondingly varying-the volumetric output of said cooling fluid temperature reducing means.

lll. Inl an air conditioning system, the combi,-

nation comprising, cooling means for cooling'a space, means for conducting cooling iluid to said cooling means, means for reducing the temperature of the cooling uid comprising means for varyingthe volumetric output of the-said cooling uid temperature reducing means, means for controlling the ow of cooling fluid into said cool'- ing means, temperature responsive means for controlling said temperature reducing means and. said flow control means to correspondingly vary both thevolumetric output of Said temperature reducing means and the flow of cooling fluid admitted to the said cooling means upon variation in temperature, in a manner to maintain the temperature of the cooling fluid substantially constant irrespective of demand. upon the temperature reducing means caused by'variation in now,A

and humidity responsive means for increasing ow of cooling uid admitted to said cooling means upon a decrease in humidity without correspondingly varying the volumetric output of the said cooling fluid temperature reducing means.

12. In an air conditioning system,

connecting said conditioning chamber with a space to be conditioned, cooling means in said chamber for removing heat from passes through said chamber, means for conducting cooling fluid to said cooling means, means for reducing the temperature of thecooling fluid comprising means having a plurality of stages of volumetric output of the saidcooling fluid, means for controlling the flow of cooling fluid into said cooling means, temperature responsive means'in control of said temperature reducing4 means and said flow controlling means, said temperature responsive means being arranged to increase the now ofl cooling fluid into said cooling means and to 'correspondingly vary the voluthe the air as itv the combination comprising, a conditioning chamber, means space, means for conducting cooling fluid to said coolingmeans, means for reducing the tempera I ture of the cooling fluid comprising means for varying the volumetric'output ofsaid cooling fluid temperature reducing means, means vfor controlling the tlow of cooling uid intovsaid cooling means,` a rst control means for controlling, said temperature reducing means and said iiow -controllmeans to correspondingly vary both the volumetric output'of said temperature reducing means and theow of cooling fluid admitted to said cooling means, in a manner to maintain the temperature of the cooling uid substantially constant irrespective of demand upon the temperature reducing means caused by variation in flow, and a second control means for increasing the ilow of cooling'iluid admitted to said cooling means without correspondingly varying the volumetric output of said cooling fluid temperature reducing means.

15. In an air conditioning system, the combination comprising, cooling means for cooling' a space, means for conducting cooling uid to said cooling means, means for reducing the temperatune of the cooling uid comprising means for Vvarying' the volumetric output of said cooling duid temperature reducing means, means vfor controlling the ow of cooling iluidinto said metric output of the said'cooling fluid tempera- 75 cooling means, a rst control means for controlling said temperature reducing means and said now control means to correspondingly vary both the volumetric output-.of said temperature reducing means andthe flow of cooling fluid admitted to said cooling means, in -a'manner to maintain the temperature of the cooling fluid substantially constant Airrespective of demand upon the temperature reducing means caused by variation in now, a second control means for increasing theilow of coolinguld admitted to said cooling means without correspondingly varying the volumetric output of said cooling fluid temsaid evaporator means, variable capacity .com-

presser means, means operable automatically to `initiate and terminate operation of 'the compressor in response to increase above and decrease below a predetermined temperature of air, means for automatically increasing and decreasing both the portion of the evaporator means containing liquid refrigerant and the rate of uid translation (by volume) of saidcompressor means in response to increaseland decrease, respectively, in temperature of air, and means operating automatically to increase-and decrease the ratio of the rate of fluid translation (by volume) to the liquid containing portion of the evaporator means in response to increase 'and decrease, respectively, in humidity of air.

17. In air cooling and dehumidifying apparatus, the combination of evaporator means, variable capacity compressor means and a condenser connected in` a refrigerant circuit, means oper,- able in response to increase intemperature of air above a first predetermined value for effecting operation of the apparatus with a reduced portion of the evaporator means containing liquid refrigerant and the compressor operating at reduced rate vof .iiuid translation (by volume), means operable in response to increase in humidity of air for increasing the ratio of the rate of :duid translation (by volume) of said compressor means to the liquid containing portion of the evaporator means, and means operable in response to increase in temperature of `air above a second and higher predetermined value for in- 4 c-reasing the liquid containing portion of the evaporator means independently of humidity.

18. In an air conditioning system, a refrigerating system including compressor means and a plurality of evaporators for removing sensible and latent heat from the air to be conditioned,

means for circulating air in heat exchanging relation with said evaporators and through a space to be conditioned, a valve associated with each' evaporator for controlling the flow of refrigerant into said evaporator, a thermostatic controller responsive to the temperature in a space being conditioned and movable between different controlling positions, means responsive to the humidity in said space and means operatively connecting said thermostatic controller and said humidity responsive means to said valves and operative to cause vopening of the valves to all of said evaporators when the thermostatic controller is in a predetermined high temperature position, and to cause opening of less` than all 4of said valves when *the space humidity rises to a predetermined value and the thermostatic means assumes a lower temperature position than said predetermined high temperature position. 19. In an air conditioning system, a refrigerating system including compressor means and a plurality of evaporators for removing sensible and latent heat from the air to be conditioned, means for circulating air in heat exchanging relation with said evaporators and through a space to be conditioned, a valve associated with each evaporator for controlling the iiow of refrigerant into said evaporator, a thermostatic'controller responsive to the temperature in a space being conditioned and movabley between different controlling positions, means responsive to the humidity in said space and means operatively connecting said thermostatic controller and said humidity responsive means tosaid valves and operative to cause closure of the valves to all of said Ievaporators when said space temperature and said humidity are both low, to cause opening of the valves to all of said evaporators when the thermostatic controller is in a predetermined high temperature position, and to cause opening humidity rises to a predetermined value and the thermostatic means assumes a lower temperature position than said predetermined high temperature position.

GEORGE D. GULER.

of less than all of said valves when the spacev

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