US2286605A - Air conditioning system - Google Patents

Description

June 1942 R B. P. CRAWFORD I AIR CONDITIONING-SYSTEM 3 Sheets-Sheet 1 Filed March 3, 1939 inventor Raberi B.P.Crawford Gtfomgg J 1942-. R. B. P. cRA\)v|-oR|: 2,285,695

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9 R. a. P; CRAWFORD AIR CONDITIONING SYSTEM- 7 Filed March 3, 1939 3 Sheets-Sheet 3 n n u n n u ,YI

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U m m w No l n O m n m ..w.. m AM. A a r P E M W, 5 v \2 2 m 01. 3 w i wfi w. z I w Patented June 16, 1942 UNITED STATE s PATENT OFFICE 2,286,605 AIR CONDITIONING SYSTEM Robert B. Crawford, Miami, Fla.

Application March 3, 1939, Serial No. 259,561

14 Claims.

This invention relates to air conditioning systems for maintaining desired air conditions with-- in an enclosure.

An object of this invention is to provide an air conditioning system having two stages of cooling, one primarily for sensible cooling and the other primarily for latent cooling, along with a stage of reheating wherein the heat dissipated by the reheating stage assists the cooling action performed by the latent cooling stage. I

Another object of this invention is to provide a novel cooling tower for dissipating in a more economical manner the heat adsorbed by the cooling apparatus oi an air conditioning system and particularly where the air conditioning system is of the two-stage type with reheat as set forth above. Further objects of this invention reside in the -structure and sequence of operation or the air conditioning system of this invention. Another object of this invention is to provid automatic control systems for the air condition- Figure is a diagrammatic illustration of an other form oi this invention,

Figures 6, 7, -8, and-9 are diagrammatic illus trations of control arrangements utilized in Fig ure 5.

Referring now to Figure 1, an enclosure to be air conditioned is designated at I0. A fan ll draws air through an air conditioning unit generally designated at I! and discharges conditioned air into the enclosure III for air condi tioning purposes. Fresh air, return air, or a mix-. ture oi fresh air and return air enters the air conditioning unit I! and passes progressively over a precooling coil II, an after cooling coil II, and, a reheat coil ll. For purposes of illustration it is assumed that. outside air is utilized for conditioning purposes and under maximum load conditions it is assumed that thisoutside cooling coil 13 is so selected and constructed that it cools, the air to a condition wherein the dry bulb temperature is 65, the wet bulb temperature is 63, and the dew-point temperature is 62. Further it is assumed that the after cooling coil It is so selected that the air leaving this coil assumes a dry bulb temperature of 60. a wetbulb temperature of 57, and a dew-point tempera ture of 55. From the above it is .seen that the precooling coil i3 is utilized primarily for sensible cooling and that the after cooling coil I4 is utilized primarily for latent cooling. The reheat coil I5 is assumed to be associated to be so select- .ed that the condition of the air leaving the same will have a dry bulb temperature of a wet bulb temperature oi,62.5 and a dew-point temperature of 55. In other words, the reheat coil 15 adds sensible heat to the air to prevent the dry bulb temperature oi the air entering the enclosure'from becoming too low.

If 1,000 lbs. per minute of outside air is utilized,-

then the precooling coil l3 removes substantially 17,000 B. t. u. per minute primarily in the form of sensible cooling, the aftercooling ll removes substantially 4,000 B. t. u. per minute primarily in the form of latent cooling and the reheating coil It adds substantially 3,750 B. t. u. per minute in the form of sensible heating. In-other words, the reheat coil l5 adds sensible heat subby the after cooling coil l4.

' Cooling water is supplied to the precooling coil it from a relatively warm evaporator generally designated at It, cooling water is supplied to the after cooling coil II from a relatively cold evaporator generally designated at l1 and reheating water is supplied to the reheat coil Ii from a cooling tower generally designated at 12.

The relatively warm evaporator llmay comprise a chamber 20in which cooled water is collected. This cooled water is withdrawn from -the chamber "through a pipe II by a pump 22 and delivered through a pipe 23 to the precooling coil l3 and for purposes of illustration it is assumed'that the temperature of the water suppliedbythe evaporator I} to the precooling coil 13 is substantially 60. The cooling water is returned from the precooling coil "through a a pipe 24 and a spray II to the evaporator chamsumed that the temperature of 'thisf mter is air has a dry. bulb temperature of 100', a wet bulb temperature 01 802 and a dew-point temperature of 72. It is also assumed that the presubstantially A multi-stage centrifugal compressor 21 shown to be or the three stage type is connected'by apipe 28 to the evaporator, chamber 20 tor reducing the pressure in the stantially equivalent to the latent heat removed ber 20 and for purposes of illustration it is asi chamber and for withdrawing vapor from the chamber 28 whereby some ofthe water sprayed from the spray is evaporated to cool the remainder of the water by evaporation. The multi-stage centrifugal compressor 21 discharges through a pipe 29 into a condenser 38 and for purposes of illustration it is assumed that the centrifugal compressor is so selected and that the condensing temperature in the condenser 30.

is such that the temperature of the water in the evaporator chamber 20 will assume a temperature of substantially, 60. Although a threestage centrifugal compressor has been shown for purposes of illustration it may be a single stage compressor or may have any number of stages and still remain within the contemplation of this invention. The centrifugal compressor 21 is shown to be driven by a multi-stage steam turbine shown as a three-stage steam turbine 3| and here again the three-stage steam turbine may be of the single stage type or may contain any number of stages. "Steam is supplied to the steam turbine 3| through a steam supply line 32 leading from some source of steam (not shown) and the supply of steam to the steam turbine 3| may be controlled by a motorized valve 33 preferably of the proportioning type. The steam turbine 3| discharges through a pipe 34 into a condenser 35. Make up water is supplied'to the evaporator chamber 20 to make up for the water lost through evaporation through a pipe 31 leading from some source of water (not shown) The supply of make up water may be controlled by a valve 38 which in turn is controlled by a float38 responsive to the level of the water in the chamber 28.' The float operated valve 38 therefore maintains the level of the water in the chamber 20 at substantially a constant value at all times.

The relatively'coldevaporator may coma prise a chamber 4| for collecting cold water. This cold water is withdrawn from the chamber 4| through a pipe 42 by a pump 43 and is discharged through a pipe 44 into the after cooling coil I4 and for purposes of illustration it is assumed that the temperature of the water supplied to the after cooling coil |4.is" substantially 50. The cooled water returns from the after cooling coil |4 through a pipe 45 and through a spray 46 to the evaporator chamber 4| and for purposes of illustration it is assumed that the temperature of this water is substantially 60. It is here noted that the'cooling water is supplied to the cooling coils I3 and 4 at the downstream side thereof so that a counter-flow heat exchange between the cooling water and the air being cooled is obtained. This greatly'increases the cooling effect of the cooling coils on the air and increases the spread of the water temperatures.

A multi-stage centrifugal compressor 48 is connected by a pipe 48 to the evaporator chamber 4| for lowering the pressure therein and for exhausting vapor therefrom so that some of the water .emanating from the sprays 46 is evaporated to cool the remaining water. The centrifugal compressor 48 discharges through a pipe 50 into a condenser 5|. For purposes of illustration it is assumed that the temperature of the-condenser 5| and the construction of the centrifugal compressor 48 are such that the water in the evaporator chamber 4| is cooled to a value of substantially 50. The centrifugal compressor 48 is operated by a multistage steam turbine 52 receiving a supply of steam through a steam pipe 53 leading from some source of type regulates the supply of steam to the steam turbine 52. The steam turbine 52 discharges through a pipe 55 into a condenser 56. Here again the centrifugal compressor 48 and the steam-turbine 52 are shown to be three-stage units but as pointed out above, these units may be of the single stage type or may have any number of stages. Make up water is supplied to the evaporator chamber 4| through a water pipe 58 under the control of a valve 59 which in turn is controlled by a float 60 to supply water to the evaporator chamber 4| to make up for water evaporated therein and hence to maintain the level of water in the evaporator chamber 4| at a substantially constant value.

The cooling tower generally designated at l8 may comprise a vertical chamber 62 provided with air inlet openings 63 near the bottom thereof. A fan 64 draws air, which may be outside air, through the openings 63 upwardly through the tower and discharges it to atmosphere. The air as it travels upwardly through the tower is contacted by water sprayed from a plurality of sprays for cooling the water and eliminator plates 65 may be provided for preventing moistune from passing into the fan 64. Make up water may besupplied to the'lower portion of the cooling tower through a pipe 66 leading from some source of water (not shown) and the supply of make up water may be controlled by a valve 61 which in turn is controlled by a float 58.' The float valve 61 therefore maintains the level of the water in the lower part of the cooling tower at a substantially constant value.

Water is withdrawn from the bottom of the cooling tower |8 through a pipe 18 by a pump II and is discharged through pipes 12, I3, I4, and I5, a motorized valve 16 preferably of the proportioning or modulating type and a pipe 'I'l to'the reheat coil I5 and for purposes of illustration it is assumed that the temperature of this water is substantially This water gives up heat to the air passing over the reheat coil l5 and in so doing is cooledto a value, illustratively 70, and this 70 water is discharged through a pipe 18 into a coil 18 in the condenser 5|. The condensing temperature in the condenser 5| is therefore substantially '70". which enables the evaporator I! to produce relatively cool water at substantially 50.

Water flows from the coil I9 through a pipe 8| into an ejector 82 and condensed vapor in the condenser 5| is drawn therefrom through a pipe 83 by a pump 84 and is discharged into the ejec tor 82 by a pipe 85. The ejector 82 therefore, mixes water leaving the coil I9 and water leaving the condenser 5| and this water is discharged, illustratively at 1; rough a pipe '88 to one of a plurality of sprays 8 88 and 89 located in the cooling tower l8. Solenoid valves 98, 9|, and 82 determine which spray shall be operated to spray the water into the cooling tower I8 For reasons to be pointed out more fully hereafter, it is desirable to spray the water into the tower at a point where the temperature of the water corresponds substantially to the wet bulb temperature of the airrising upwardly through cooling tower at the point at which it is admitted. For example, if

the temperature of the water is substantially 90' as illustrated and the wet bulb temperature ofthe air just above the spray 89 is substantially 90 then the valve 82 is operated to cause the spray to become operative to'spray water into the cooling tower I8. ,If on the other hand the wet bulb temperature of the air just above the spray 88 should be substantially 90 then the spray 88 would become operative to spray water into the cooling tower. Also if the wet bulb tem-' perature of the air just above the spray 88 should condenser 58 for condensing the steam disbe, say 85, and the temperature of the water returning from the ejector 82 should be substantially 85, then the valve 9I would be operated to cause the spray 88 to spray the 85 water into the cooling tower. The same operation holds true for the spray 81 and the valve 98. Summing up the sprays 81, 88, and 89 are so controlled Y that the water is supplied to the tower at a level dependent upon the temperature of the water andthe wet bulb temperature of the air rising through the tower I8, the arrangement being such that the temperature of the water and the wet bulb temperature of the air substantially coincide at the point of entry of the water into the cooling tower. If under severe load conditions all of the valves 98, 9I, and'92 should be closed charged from the steam turbine 52.. Water flows from the coil I28 through a pipe I21 into an ejector I28 and condensed steam is withdrawn from the condenser 58 through a pipe I29 by a pump I38 and is discharged through a pipe I3I into the ejector I28. The condensed water and the condensed steam are therefore mixed in the ejector I28 and this mixture at illustratively 115 passes through pipes I32 and H4 into one of the sprays II5,- I18, and H1.

In addition to evacuating condensate condensers 38, 35, 5|, and 58 air must also beevacuated therefrom to maintain desired vacuum conditions therein. This may be accomplished in any well known manner either by providing separate air evacuators, not shown, or by constructing thepumps 99, H8, 84, and I38 so that they will remove and vent the air to atmosphere while discharging the condensate to their respective ejectors..

The motorized steam valve 33 which controls the supply of steam to the steam turbine 3| and then the pressure relief valve 93 would open-t0 cause the water to be sprayed into the cooling tower I 8 by the spray 89 or by another spray (not shown) Which preferably wouldibe located above the spray 89.

Water is also delivered by the pump H from the cooling tower I8 at 85 through pipes 12, 13,

and 95 into a coil 98 located inlthe condenser 38. Accordingly the condensing temperature of the condenser 38 is substantially 85 and therefore the evaporator I8 operating at a higher condensing temperature cools the water to only 60 as illustrated. Water is discharged from thecoil 98 through a pipe 91 into an ejector 98 and condensed vapor is withdrawn from the condenser 38 by a pump 99 and is discharged through a pipe I88 into the ejector 98. Accordingly the ejector 98 mixes the water leaving the coil 96 and the condensed vapor leaving the condenser 38 and this water is-disc-harged at illustratively 9.5"

through pipe IN to a spray I82 located in the cooling tower I8 above the sprays 81, 88, and 89.

Water from the cooling tower I8, at 85 is also supplied by the pump 1I through pipes 12 and I85 to a coil I86 located in the condenser-35 and .water is discharged from the coil I88through a pipe I81 into an injector I88. A pump II8 withdraws condensed steam from the condenser .35

through pipe I89 and discharges this steam through a pipe III into the ejector I88. The

condensing water and the condensed'steam are hence which controls the evacuation of the evaporator I8 and the temperature of the water therein may be controlled by a temperature responsive controller I38 responsive to the temperature within the enclosure I8, a temperature responsive controller I31 responsive to the temperature of the air discharged from the precooling coil I3 and by a liquid level controller I38 responsive to the level of the water in the relatively warm evaporator I8. The temperatureresponsive controller I38 operates as the primary control of the steam valve 33 to position modulatingly the same to maintain the temperature within the enclosure between, illustratively, 75 and 85. The temperature responsive controller I31 acts as a secondary or limitcontrol for modulatingly positioning the steam valve 33 to close off the steam valve if the temperature of the air leaving the precooling coil decreases below 65 until such time as the temperature decreases to 68 at which time the valve 33 will. become bulb temperature of the air rising through the cooling tower I8. If load conditions should become extremely severe so that all of the valves I I8, I I9, and I28 should be closed then the water passes through a pressure relief valve -I2I into the upper spray H1 or into an additional spray (not shown) located above the spray II 1.

Water at illustratively 85 is supplied from the cooling tower I8 by pump 1I through pipes 12, 13, 14, and I25 into a coil I28 located in the completely closed." This effectively prevents the temperature of the precooling coll I3 from be coming too low wherebythe precooling coil I3 acts primarily to removesensible heat andnot latent heat. If for some reason the level of the water in the relatively warm evaporator l8 should increase to a high value with the dangerof water entering the centrifugal'compressor 21,

the liquid level controller I38 will close oif the steam valve 33 to'prevent' operation of the water vapor compressor 21., This efl'ectively prevents breakage of the'water vapor compressor 21 which might be caused by water in a liquidstate'entering the same,

The steam valve '54 which controls the supply of steam to the steam turbine 52 and hence which controls the evacuation of the relatively cold evaporator I1 and the temperature of the water therein is controlled by a humidity responsive controller I48 responsive to relative humid- .ity conditions within the' enclosure I8 and is also con olled by a. liquid level controller Ill responsive to the level of the water in the relatively cold evaporator I1, As the relative humidity of the air within the enclosure l8 increases the valve 5| is modulatingly opened and as the relative humidity decreases the valve 84 is modulatingly closed and for purposes of illustration it is assumed. that the humidity controller I maintains the relative humidity within the enclo sure between 45% and 60%. As the valve 84 from the is opened upon an increase in relative humidity to lower the temperature of the after cooling coil I4 the valve. 16 is moved towards an open position a like amount to increase the amount of sensible heat supplied to the air passing over the reheat coil I5. Accordingly as the relative humidity increases the amount of latent cooling and the amount of sensible heating are increased whereby sensible heat is added to replace the latent heat removed. With such an arrangement operation of sprays 81, 88, and 89 are controlled by a temperature responsive controller I43 connected by a capillary tube I44 to a bulb I45 responding to the temperature of the water in the pipe 86. The valves 90, 9|, and 92 are also re spectively controlled by thermostats I46, I41, and I48, responsive to the welt bulb temperatureof the air above the sprays 81, 88, and 89 respectively. The temperature responsive controller I43 and the thermostats I46, I41 and I48 operate to provide the above outlined sequence of operation, namely, admitting water to the cooling tower at a level wherein the temperature of the water corresponds substantially to the wet bulb temperature of the air rising through the cooling tower I8.

The solenoid valves H8, H9, and I20 are controlled by a temperature responsive controller I50 which is connected by a capillary tube I5I to a bulb I52 containing a volatile fluid and responsive to the temperature of the water in the pipe H4. The valves H8, H9, and I20 are also respectively controlled by thermostats I53, I54, and I55 responsive to the wet bulb temperature of the air above the sprays H5, H6, and H1, respectively. The temperature responsive controller I50 and the thermostats I53, I54, and I55 operate to cause the water to be admitted to the cooling tower I8 at a point wherein the temperature of the water and the wet bulb temperature of the air rising through the cooling tower I8 are substantially the same.

It is here noted that the temperature of the precooling coil I3 is maintained at a relatively high value so that it will perform substantially only sensible cooling, and this is brought about by using relatively warm condensing water in the condenser 30. The temperature 'of the after cooling coil I4 is lower than the temperature of the precooling coil I3 so that the after cooling coil I4 performs primarily latent cooling and this is brought about by using relatively cool condensing water in the condenser 5|. In other words, colder water is supplied to the condenser for obtaining lower temperatures in the relatively cold evaporator |1 without the expendl ture of additional energy. This system, therefore, provides a most economical mode of operation for obtaining desired dry bulb and relative humidity conditions within the enclosure I0.

responds substantially to the wet bulb temperature of the air, the efiiciency of the cooling tower Figure 2 is a diagrammatic illustration of the manner in which the temperature responsive controllers I36 and I31 and the liquid level responsive controller I38 control the operation of the motorized stem valve 33. The motor of the f.

motorized steam valve 33'may be of the type shown and described in Patent No. 2,028,110 granted to D. G. Taylor on January 14, 1936. Power is supplied to the proportioning motor by line wires I and I6I leading from some source 5| than is supplied to the condenser 30 and Y of power (not shown) and the proportioning motor is provided with control terminals I62, I63, and I 64. The oppositelyacting relay coils and the balancing potentiometer contained with the proportioning motor are connected across the control terminals I62 and I84 and the junction of the oppositely acting relay coils are connected to the control terminal I63, all as illustrated in the above referred to D. G. Taylor patent. When the external resistance across the terminals I62 and I63 becomes less than the external resistance across the terminals I63 and I64 the valve 33 is moved towards an open position and when the external resistance across the terminals I63 and I64 becomes less than the external resistance across the control terminals I62 and I63 the valve 33 is moved towards a closed position.

The temperature responsivecontroller I36 may comprise a bellows I66 charged with a volatile fluid for operating a lever I61 against the action of an adjustable tension spring I68. The lever I61 in turn operates a slider I 9 with respect to a resistance element I10 and for purposes of illustration it is assumed that when the temperature is '75", the slider I69 assumes an extreme right hand position and as the temperature increases to the slider I69 is progressively moved to the leftuntil it assumes an extreme left hand position.

The temperature responsive controller I31 responsive to the temperature of the air leaving the precooling coil I3 may comprise a bellows I12 charged with a volatile fluid for operating a lever I13 against the action of an adjustable tension spring I14. The lever I13 operates a slider I15 with respect to a resistance element I16 and for purposes of illustration it is assumed that the slider I15 assumes an extreme left hand position when the temperature is substantially 65 and is moved progressively to the right as the temperature decreases to .a value or 60 '2,2se,eo s' whereupon the slider I15 assumes an extreme right hand position.

The liquid level controller I38 may comprise a pivoted lever I18 operated by a float I19. The

lever in turn operates a mercury switch I88 provided with electrodes I8I, I82, I83, and I84. vwhen the level of the water in the evaporator chamber 28 is normal the electrodes I83 and I84 ,are bridged but if the level of the water should become abnormally high then the electrodes I8I and I82 are bridged. s

The control terminal I62 is connected by wires I86 and I81 to the left end of the resistance element I18 and the controlterminal I64 is cone nectedby wires I88, I98, and I9I to the right end of the resistance element I18. The control terminal I64-is also connected by wires I88 and l89-to the right end of the resistance element 916, The control terminal I63,is connected by a wire I92 to the electrodes I82 and I83-and the electrode I84 is connected by wires I93 and I94 to the slider I15. The left end of the resistance a lever 281 against the action of an adjustable ized valve 33 to stop operation of the water vae por compressor 48 whereby damage tothe compressor is effectively prevented.

Figure 3 illustrates the manner in which the humidity responsive controller I48 and the liquid level responsive controller I controls the operation of the motorized .steamvalve 54 and the motorized valve 16. Here again the motor of the motorized steam valve 54. may be of-the type shown and described in the above referred to D. G. Taylor patent and it is supplied with power from line wires- 288 and 28I leading from some I source of power (not shown). The proportioning motor 54 is provided with control terminals 282, 283, and 284 for controlling the direction 'and extent of movement of the motorized valve.

The humidity responsive controller I48 may comprise a hygroscopic element 286 for operating tension spring 288. The lever 281 in turn operates a slider 289 with respect to a resistance element.2I8 and for purposes of illustration it'is element I16 is connected by a wire I95 to the slider I69. A resistance element I96 is connected betweenwires I86 and I93 to counteract the effect of the resistance I16. when the slider I15 is in the extreme left-hand position as shown in Figure 2. The electrode I8I of the'mercury switch I88 is connected by wires I91; I98, and

I88 to the control terminal I64. 1

With the parts in the positions shown it is seen that the resistance, element I18 of the temperature responsive controller I36 is connected across the terminals I62 and I64 andthat the ..slider I69 is connected directly to the control terminal I63. Hence the-motorized valve 33is under the control of the temperature responsive controller.l36 and since the'slider jI69 thereofis in amid-position the motorized valve 33 is likewise in a mid-position. As the temperature increases the slider I69 is moved'towards the left to move the motorized valve 33 towards an open position and as the temperature decreases the slider M9 is moved towards theright to move the valve 33 towards a closed position. :Accorde ingly the motorized valve 33 is modulatingly.

positioned between an openand closed position as the temperature within the enclosure I8 varies. between/15 and 88 to maintain desired dry bulb temperature conditions within the enclosure I8.-

If now the temperature of the air leaving the precooling coil I3 should decrease below 65 the slider I15 of .thetemperature responsive controller I31 moves toward the right and in so doing it does two things, it gradually decreases the .external resistance across the control terminals I83 and I64 t move the motorized valve 33 toseries with the slider I69 of the temperature responsive controller I36 to decreasethe sensitivity thereof. Accordingly as the temperature leaving the precooling coil I3 decreases from 65 to 68 the motorized valve 33 is graduatingly positioned towards a closed position; In this manner low'-- ering of the' temperature of the precooling coil I3 to a value which would cause latent cooling is effectively prevented. If the level of the water in the evaporator chamber 28 should become abnormally high a substantially complete short circuit across the controlterminals I63 and I64 is completed and-'this circuit may be traced from the control terminal I63 through wire I92,

' electrodes I82 -and I8I andwires I91, I 98, and I88 back to the other control terminal I64. This causes complete closing movement of themotor- 1 assumed that when the relative humidity is 68% the slider 289 assumes an extreme left hand position and as the relative humidity decreases from to 45% the slider 289 is progressively moved to the right across the resistance element The liquid level responsive controller I may comprise a pivoted lever 2I2 operated by a float 2I3 for operating a mercury switch 2I4 having electrodes 2I5,'2I6, 2", and 2I8. When the level of the water in the evaporator chamber 24! is normal the electrodes'2l5 and 2I6 are bridged. The control terminal 282 is connected by a wire 228 to the left end of'the resistance element 2I8 and the control terminal 284 is connected by wires 22I and 222 to the right end of the resistance element 2I8. The control terminal 283 is connected by'wire- 223, electrodes 2I1 and 2I8 and wire 224 to the slider 289. The electrode 2I5 of the mercury switch 2 I4 is connected by wires 225 and MI to the control terminal 284.

With the parts in the positions shown in Figure 3 the control potentiometer formed by the slider 289 and the resistance element 2I8 is con-.

I nected directly to the control terminals 282, 283,

wards a closed position and it adds resistance in and 284 and since the slider 289 is in a midposition the motorized valve 54 is in a mid-position. As the relative humidity increases the slider 289 is moved to the left to graduatingly open the motorized valve 54 and as the relativehumidity decreases the slider 289 is moved toward the right to graduatingly close the motorized valve 54. Accordingly the valve 54 is modulatingly positioned in accordance with variations in relative humidity within the enclosure I8 to maintain the relative humidity within the en-' closure I8 within predetermined limits, illustratnected tocontrol terminals 228, "Sand 338 of I the motorized valve 16 which may also be of the type shown and described in the above're; ferred to D. G. Taylor patent. Power is supplied to the proportioning motor 16 by means of line wires 23I and'232 leading from some source of power (not shown). The connections are so arranged that as themotorized valve 54 is graduatinglyopened and closed the motorized valve 16 is also graduatingly opened and closed in like amounts. Hence as the relative humidity increases the valve 54 is opened to increase the evacuation of the relatively cold evaporator I1 and the valve 16 is opened to increase the amount of reheat performed by the reheat coil .I5 whereby the amount of dehumidification is increased without materially afiecting the dry bulb temperature within the enclosure I9.

Referring now to Figure 4 the temperature responsive controller I43 which responds to the temperature of the water in the pipe 86 may comprise a' bellows 235 connected by the capillary tube I44 to the bulb I45 for operating a switch arm 236 against the action of an adjustable tension spring 231. The switch arm 236 is adapted to progressively move across contacts 238, 249, and 249 and for purposes of illustration it is assumed that the switch arm 236 engages the contact 238 when the temperature of the water is substantially 90, that it engages the contact 239 when the temperature of the water is substantially 85", and that it engages the contact 240 when the temperature of the water is substantially 80.

The thermostat I46 may comprise a bellows 242 charged with a volatile fluid for operating a switch arm 243 against the action of an adjustable tension spring 244. The switch arm 243 is adapted to engage contacts 245, 246, and 241 and for purposes of illustration it is assumed that the switch arm 243 engages the contact 245 at substantially"80, that it engages the contact 246 at substantially 85, and that it engages the contact 241 at substantially 90. The structure of the thermostats I41 and I48 is exactly the same as that of the thermostat I46 and therefore like reference characters for like parts have been utilized.

' Power is supplied to the control system by means of line wires 250 and 25I leading from some source of powerinot shown), the line wire 250 connecting to the switch arm 236 of the temperature responsive controller I43 and the line wire 25! connecting by wires 252 to the solenoid valves 90, 9|, and 92. The switch arms 243 of the thermostats I46, I41, and I48 are connected to their associated solenoid valves 90, 9I, and 92 respectively, by wires 253. The contacts 238, 239, and 240 of the temperature responsive controller I43 are connected to busses 254, 255, and 256, respectively, and these busses are in turn respectively connected to the contacts 241, 246, and 245 of the thermostats I46, I41, and I48.

With the parts in the position shown in Figure 4 the temperature of the water in the pipe 86 is substantially 90 and the wet bulb temperature of the air rising through the tower I8 is substantially 90 at a point adjacent the thermostat I 48. A circuit is thereupon completed from the line wir'e 250 through switch arm 236,

, contact 238, buss 254, contact 241 andswitch arm 243 of the thermostat I48, wire 253, solenoid valve 92, and wire 252 back to the other line wire 25I. Accordingly the solenoid valve 92 is opened and the 90 water in the pipe 86 is discharged through the spray 89 in contact with air which has a wet bulb temperature of substantially"90. The other solenoid valves 90 and 9| are closed. If the wet bulb temperature 01 the air'rising throughthe cooling tower should be 90 adjacent the thermostat I41, then the solenoid valve 9| would open and the solenoid valve 92 would close to cause the spray 88 to introduce the 90 water into the tower, at a level wherein the wet bulb temperature is substantially 90. Likewise, if the wet bulb temperature adjacent the thermostat I48 should be 90, then the solenoid valve 90 would open and the sole noid valve 9| would close to render the spray 81 operative. If now due to a decrease in cooling load the temperature of the water in the pipe 85 should decrease to 85 and the temperature adjacent the thermostat I 41 should be 85", then the valve 9| would open whereby the spray'88 would operate to admit the 85 water at that point in the cooling tower where the wet bulb temperature of the air rising through the cooling tower is substantially 85. If under these reduced load conditions the wet bulb temperature adjacent the thermostat I48 should be 85, then the spray 89 would be operated to spray the 85 water into the tower I8 or if the temperature adjacent the thermostat I46 should be 85 then the spray 81 would be operated to spray 85 water into the tower I8. The same sequence of operation holds true if the temperature of the water in the pipe 86 should be From'the above it is seen that the control system of Figure 4 operates at all times to cause the water flowing through the pipe 86 to be admitted into the cooling tower at a level wherein the temperature of the water is substantially the same as thewet bulb temperature of the air rising through the tower. This is an extremely important feature of this invention since it al-- lows'the air rising through the tower to perform the maximum amount of cooling at all times. To illustrate this point assume that the temperature of the water in the pipe 86 is and that the wet bulb temperature, of the air adjacent the spray 88 is 85. As the air rises through the tower it picks up heat from the water emanating from the sprays and accordingly the wet bulb temperature of the air progressively increases as the air rises. The wet bulb temperature of the air adjacent the spray 89 will therefore be above 85 and the wet bulb temperature of the air adjacent the spra 81 will therefore be below 85. The water falling from the sprays I02 and H5, H6 or II1 is being cooled by the air and will assume values substantially corresponding to the wet bulb temperatures of the air at the various levels in the tower. If now the 85 water flowing through the pipe 86 should be admitted to the tower through the spray 89, it will be cooler than the wet bulb temperature of the air at this level.

This water will therefore absorb heat from the air and accordingly it will be heated up which is just the opposite action to that desired. Further, by admitting the 85 water to the tower at this point the air rising through the tower will have less chance to cool the water falling from the upper sprays I02and II5, II6 or II1 to as great an extent than if this water was not so admitted,

since the air will not contact the falling water for as long a period of time. In other words, admitting the 85 water at this level cuts short the cooling action of the rising air on the water falling from the sprays I82. and H5, H6 or 1.

sired minimum,

.the cooling tower is greatly increased by this method of operation and smaller cooling towers with a smaller flow of air therethrough may be utilized for accomplishing a predetermined amount of cooling.

The wiring of the control system of Figure 4' may also be utilized for controlling-the solenoid valves H8, H9 and I inthe upper part of the 1 tower to admit water to the upper part of the tower at levels wherein the temperature of the water corresponds to the wet bulb temperature of the air. Of course difierent temperature settings of the thermostats I53, I54 and I55 and the temperature responsive controller I50 will be utilized but the sequence of operation will be substantially the same and therefore a further description of. the operation is not considered necessary. It is found that someof the water admitted to the .tower by the sprays is carried upwardly within the air in the form of a mist to the eliminator plates and then drops down through the air in the form of relatively heavy drops. A .double cooling action by the air is therefore provided namely cooling the mist and cooling the drops. Accordingly, when the sprays H5; H6 and H1 are controlled in the manner pointed out above this "double cooling action becomes more pronounced as the level at which the water is admitted is lowered. This sequence of operation therefore affords still greater economies in the operation of the tower.

Summing up, by spraying water into the tower at levels corresponding to the temperature of the water, that is by spraying the warmer water into tower at the upper portion thereof and the cooler water into the tower at the lower portion thereof, a counterflow heat exchange takes place-between the water and the rising air which increases the efliciency of operation of the cooling tower. By

admitting the water into the tower at levels wherein the temperature of the water corresponds to the wet bulb temperature of the rising air, the efliciency of operation of the tower is further increased. Accordingly, with the tower'arrangement of this invention a maximum amount ignated at 268. Here as in the previous modifications, a counterflow heat exchange is afforded between the air being conditioned and the water in the coils 263, 264, and 265 whereby the efliciencyof the system'is increased.

The relatively warm evaporator 266 may comprise a chamber 210 in which cool water is collected and this cool water is drawn from the chamber 210 through a pipe 2 by a pump 212 and is discharged through a pipe 213, a motorized valve 214, and a pipe 215 to the precooiing coil 263. For purposes of illustrationit is assumed that the temperature of the water supplied to the precooiing coil 263 is substantially 60. Water is withdrawn from the precooling coil 263 at, illustratively, 85 through a pipe 216 and is discharged through a spray 211 into the evaporator chamber 210. Part of the water thus sprayed is evaporated to cool the remainder of the water to substantially 60. The evaporator chamber 210 is connected by a conduit 218 to a nozzle chamber 219 of a steam jet ejector 280. Steam is supplied to the nozzles of the steam ejector by.

'a steam pipe 28l leading from some source of steam (not shown) and the supply oi steam is regulated by a motorized valve 282. The steam jet ejector 280 discharges into a nozzle box 283 of a second ejector 284. Water is supplied to the nozzles of the second ejector by'a pipe 265 and the water mixed with the steam and air ejected from-"the ejector 280 is collected in a hot well 1286. For purposes of illustration it is assumed of cooling-with a smaller tower and less air flow is made possible.

Figure 5 illustrates an arrangement wherein steam jet eiectors are utilized for cooling purposes instead of. the steam drivencentrifugal compressors as in Figure 1 and also in Figure 5 a different control arrangement is illustrated.

The enclosure to be air conditioned is designated at 260 and a fan 26l draws air through an air conditioning unit262 and discharges conditigned airinto the enclosure 2 60. Either .fresh airfreturn air, or a mixture of fresh air and return air passes over a precooiing coil 263, an

after'cooling coil 264, and a reheat coil 265 all located in the air conditioningiunit 262. Cool water is supplied to the precooling 'coil 263 by a relatively warm evaporator 266, cold water is supplied to the after cooling coil 264 by a relatively cold evaporator 261 and water is supplied to the reheat coil 265 by a coolingtowerflgenerally desthat the temperature of the water entering the nozzles through thepipe 285 is substantialiy 85 to that the temperature of the water obtained in the evaporator chamber 210 is substantially 60. Make up water is supplied to the evaporator chamber 210 by means .of a water pipe 281 leading from some source of water (not shown) and the supply of water is icontrolled by a valve 288v which in turn is controlled by a float 289 to maintain the level of the water in the evaporator chamber 210 substantially constant.

The relatively cold evaporator 261 may comprise an evaporator chamber 290 in which wateris cooled and collected. A pump 292 withdrawscoid water from the evaporator chamber 290 through a pipe 29l and discharges this cold water through a pipe 293 to the after cooling coil 264. For purposes of illustration it is assumed that the temperature of this water is substantially Water is discharged from the after cooling coil 264 through a pipe 294, illustratively, at into a spray 295 located in the evaporator chamber 290. Part .of the water sprayed out of the spray 295 evaporates to cool the remainder of the water. A conduit 296 connects. the evaporator chamber 29 0 to a nozzle box 291 of a steam jet ejector 298. Steam is supplied to the nozzles in the nozzle 'box 291 through a steam pipe 299 leading from some source of steam (not shown) and the supply of steam is regulated by a motorized valve 380. The steam jet ejector 298 discharges into a nozzle box 30l of a second ejector 302 and water, illustratively, at.70 is supplied to the nozzles through a pipe 303. By reason of this 10" supplyoi make up water is controlled by a valve such is within the contemplation of this invention.

The cooling tower 268 may comprisea vertical chamber 2l8 provided adjacent its lower end with openings 3! i. A fan 3l2 draws air through the troller in controlling the motorized valve 282 maintains the temperature of the air leaving the precooling coil 263 between60 and 64. As the temperature increases the valve 282 is moved towards an open position and as the temperature decreases the valve 282- is moved towards a closed position. The motorized steam valve is also controlled by a temperature responsive controller 458 connected by a capillary tube 45l to a bulb 452 charged with a volatile fluid and responsive to the temperature of the water in the pipe 213. When the temperature of the water in the Pipe 213 is openings 3 and upwardly through the cooling tower t.) be discharged to atmosphere. The air in passing upwardly through the cooling tower contacts water sprayed from a plurality of sprays for cooling the water and moisture is prevented from entering the fan 3I2 by means of eliminator plates 3l3. Make up water is supplied to the cooling tower 268 through a water pipe 3|4 leading from some source of water (not shown) and the supply of make up water is-regulated by a valve 3l5 which in turn is operated by a float 3l6 to maintain the level of the water in the bottom of the cooling tower 268 substantially constant.

For purposes of illustration it is assumed that the water in the cooling tower is cooled to substantially 85 and this 85 water is withdrawn from the cooling tower 268 through a pipe 320 by a pump 32! and is discharged through pipes 322 and 285 into the nozzle box 283 of the ejector of the relatively warm evaporator. By reason of this 85 water the temperature maintained in the evaporator 266 is cooled to, illustratively, 60.

, Water is withdrawn from the hot well 286 heat coil 265 at, illustratively, 70 through pipe 338, motorized valve 33l, and pipe 383 into the nozzle box 3! of the ejector of the relatively cold evaporator 261. Water is withdrawn from the hot well 384 through a pipe 333 by a pump 334 and is discharged through a pipe 335 into one of a plurality of sprays 336, 331, and 338 located in the cooling tower 268. For purposes of illustration it is assumed that the temperature of this water is substantially 95, The operation of the sprays 336, 331, and 338 is controlled by solenoid valves 339, 348, and 34!, respectively, and the purpose of these valves is, as set out above, to admit the water at a level in the cooling tower 268 wherein the water temperature corresponds to the wet bulb temperature of the air' rising through the cooling tower 268. If under severe load conditions when all three solenoid valves 338, 348, and 3 should be closed, then the pressure relief valve 342 opens to admit the water to the upper spray 3 38 or to spray 326 located above the spray 338.

The motorized steam valve 282 is controlled by a temperature responsivecontroller 344 responsive to the temperature of the air leaving the precooling coil 263 and for purposes of illustration it above 59, the temperature responsive controller 344 controls the valve 282 but when the temperature of the water decreases below 59 the valve 282 is closed. I

The motorized valve 308 controlling the operation of the relatively cold evaporator 261 is controlled by a temperature responsive controller 345 responsive to the temperature of the air leaving the after cooling coil 264 and this temperature responsive controller operates to maintain the temperature of the air at that point between substantially 59 and 62. As the temperature increases the valve 388 is moved towards an open position to decrease the temperature of the Water in the after cooling coil 264.and as the temperature decreases the valve 308 is moved towards a closed position to increase the temperature of the water in the after cooling coil. The temperature responsive controller 344 in addition to controlling the operation of the steam valve 282 also controls the operation of the steam valve 300 to close the steam valve 308 when the temperature of the air leaving the precooling coil 263 decreases to substantially 60. When the temperature of the air leaving the precooling coil 263 decreases to 60 there is really no need for further cooling this air and therefore the relatively cold evaporator 261 and the after cooling coil 264 is rendered inoperative.

The motorized valve 214 which regulates the rate of fiow of cooling water through the precooling coil 263 is controlled by a temperature responsive controller 346 responsive to the dry bulb temperature within the enclosure 268. As the temperature increases the valve 214 is moved towards an open position to increase the rate of flow whereby the air is cooled to a further extent by the precooling coil. As the temperature within the enclosure decreases the valve 214 is moved towards a closed position to throttle the flow of water through the precooling coil 263 whereby the air is cooled a lesser extent. For purposes of illustration it is assumed that the temperature responsive controller 346 operates to maintain the dry bulb temperature within the enclosure 260 between and The motorized valve 328 which regulates the. flow of water through the reheating coil 265 is controlled by a humidity responsive controller 341 responsive to the relative humidity within the enclosure 260. Upon an increase in relative humidity the valve 328 is moved towards an open position to increase the amount of reheating accomplished by the reheat coil 265 and as the rel- I ative humidity decreases the valve 328 is moved is assumed that this temperature responsive con- 75 towards a closed position to decrease the amount. of heating by reheat coil 265. By increasing the amount of reheating the relative humidity 01' the air discharged into the enclosure 268 is decreased and therefore desired relative humidity condi I tions are maintained within the enclosure .280. For purposes of illustration it is assumed that the aasaeot humidity responsive controller 341 operates to to the temperature of the water in the pipe 333.

Upon an increase in temperature of the water in the pipe 333 the valve 33| is moved towards a closed position and upon a decrease in tempera ture it is moved towards an open position. If the temperature of the water should increase, the condensing action of the ejector for the relatively cold evaporator would decrease and hence the temperature of the water cooled by the relatively cold evaporator would increase. In. response to this increase in temperature of the water in the pipe 333 the valve 33! is moved towards the closed position to slow down the rate of circulation in the water through the reheat coil 263 which maintains the condensing vtemperature at a relatively low value. For purposes of illustration, it is assumed that the temperature responsivecontroller 343 maintains the temperature of the water in the pipe 333 between 60 and 70 so that water in the relatively cold evaporator 231 may be cooled to substantially 50; Valve 33! in effect acts as a limit control for valve 328 to prevent fluctuation in enclosure relative humidity upon wide changes in enclosure drybulb temperature. r

Figure 6 illustrates the manner in which the motorized valves 282 and 363 are controlled by the temperature responsive controllers 344 and 345. The motorized valve 232 may be operated by a proportioning motor which may be of the type shown and described in the above referred to D G. Taylor patent. Power is supplied to the motorized valve 232 by means of line wires 355 and 356 leading fromsome source of power (not shown) and the motorized valve 232 may be provided with control terminals 351, 333, and 353.

The temperature responsive controller 344 may comprise a bellows 366 charged with a volatile fluid for operating a lever 36! against the action of an adjustable tension spring 332. The lever 33| operates a slider 363 with respect to a resistance element 364. The lever 36l may be provided with an extension 333 for operating a V mercury switch 363 having electrodes 331, 363,

363, and 313. For purposes of illustration it is assumed that when the temperature of the air leaving the precooling' coil 263 is at 6 1 the slider 363 is in the extreme right hand position and as the temperature progressively decreases, the- 43."). The leverinturnoperates a mercury switch 456 having electrodes 431133, 453, and463. For purposes of illustration it is that the electrodes 433' and 463m bridged when the water temperature :is' above 53andthat the elec-] i whereupon the water is cooled to a greater extent v 9 trodes 431 and .433 are bridged when the water temperature'falls below 53.

The control terminal 331 is connected by wires 312 and 432 to the left end of the resistance element 334, the'control terminal 333 is connected by a wire 313 to the right end of the resistance element .3 34, and the control terminal 333 is connected by a wire 314 to the electrodes 433 and 433. The electrode 433 is connected by a wire 463 to the slider 333 and the electrode 431 isconnected by wires 434 and 312 to the control terminal 331. With the parts in the position shown in Figure 6 the slider 333 is in the extreme right hand position and the motorized valve 232 is wide open. As the temperature decreases to move the slider 333' towards the left the motorized valve .232 is progressively moved towards a closed position. Accordingly the motorized valve 232 is positioned in accordance with the temperature of the air leaving the precooling coil 233. If the temperature or the water in the pipe. 213 should fall below 59, then the connection between the control terminal 333 and the slider 363 is broken and the control terminal 333 is connected through the electrodes 453 and 431 to the control terminal 331. This closes the steam valve 232 to prevent the production of too cold water by the temperature responsive controller 344 if the thermostat 343 has throttled the valve 214 to a relatively great extent. v

The motorized valve 333 may also be operated by a proportioning motor of the type shown and describedin the above referred to D. G. Taylor patent. Power is-supplied to the motorized valve by means of line wires 313 and 311 leading from some source of power (not shown) and the motorized valve may be provided with control terminals 313, 313, and 333 for. controlling the difluid for operating 'a lever 333 against the action of. an adjustable tension spring 334. The lever .333 operates a slider 333 with respect to a resistance element 336 and for purposes of illustration' it is assumed that when the temperature oi the air leaving the after cooling coil 234 is 62 the slider 333 is in-the extreme right hand position asshown and as the temperature decreases the slider 333 is moved progressively to the left until such time as the temperature decreases to 59 whereupon the slider 333assumes an extreme left hand position. I c

The control terminal 313 is connected by wires 333 and 333 to the left end of the resistance ele-' ment 336 and the control terminal 333 is connected-by a wire 333 to the right end of the resistance element 333; The control terminal 313 is connected by a wire 33l to the electrodes 333 and 333 of the mercury switch 363, the el. trode 313 being connected-by a wire 332 to the slider 333 and the electrode 313 being connected by v wires 333 and 333 to the control terminal 313. With the parts in the positions shown in Figure 6 controller 436 may the slider 333 is in an extreme right'hand position and the motorized valve 333 is wide open.

As the temperature gradually decreases to move the slider 333 toward the left the motorized valve 330 is graduatingly positioned towards a closed position. Accord y the motorized'valve 333 is positioned in accordance with the position of the slider 333 as determined by the temperature of the air leaving the after cooling coil 234. If now the temperature leaving the'precooling coil 263 should decrease to 60 the electrodes 313 and 333 are unbridged, and the electrodes 333 and 313 are bridged which completes a substantially short circuit; across the terminals 313 and 313 to move ture responsive controller 343. Here again the motorized valve may be operated by a proportioning motor of the type shown and described in the above referred to D. G. Taylor patent and power is supplied to this motor by means of line wires 403 and 4M leading from some source of power (not shown). The motor is also provided with control terminals 402, 403, and 404. The'temperature responsive controller 343 may comprise a bellows 403 charged with a volatile fluid for operating a lever 433 against the action of madjustable tension spring 401. The lever 403 opcrates a slider 403 with respect to a resistance element 433 and for purposes of illustration it is assumed that the slider 403 sweeps progressively from left to right across the resistance element 433 as the temperature of the enclosure 230 increases from 75 to 80.

The control terminal 432 is connected by wire 4i3to the left end of the resistance element 403 and the control terminal 404 is connected by wire 4| I to the right end of the resistance element 403. The control terminal 403 is connected by wire 2 to the slider 403 whereby the potentiometer formed by the resistance element 433 and the slider 433 is connected across the terminals 402, 433. and 404. Upon an increase in temperature the slider 403 moves, to the right to move the valve 214 towards an open position and upon a decrease in temperature the slider 403 moves towards the left to move the valve 214 towards a closed position. Accordingly the valve 214 is modulatingly positioned in accordance with the temperature within the enclosure 233 to regulate the cooling effect of the precooling coil 233 which maintains desired temperature conditions within the enclosure 233.

Figure 8 illustrates the manner in which the motorized valve 323 is graduatingly positioned by the relative humidity responsive controller 341 responsive to the relative humidity within the enclosure 233.- The motorized valve 323 may be operated by a proportioning motor also of the type shown and described in the above referred to D. G. Taylor patent and power is supplied to this proportioning motor by means or line wires 3 and 4i3.leading from some source of power (not shown). The proportioning motor is also. provided with control terminals 4H, 3, and 3. The relative humidity responsive controller 341 may comprise a hygroscopic element 423 for operating a lever 422 against the action of an adjustable tension spring 42L The lever 422 operates a slider 423 with respect to a resistance element 424 and for purposes of illustration it is assumed that asthe relative humidity within the enclosure 233 increases from 45% to 60% the slider 423 is progressively moved from an extreme left position to an extreme right position The control terminal 4ll is connected by wire 423 to the left end of the resistance element 424 and the control terminal 4l3 is connected by a wire 423 to the right end of the resistance element 424. The control terminal '3 is connected by wire 42'! to the slider 423. With the'parts in the position shown the slider 423 is in a midposition and hence the motorized valve 323 is in a mid-position. As the relative humidity increases the motorized valve 323 is graduatingly positioned towards an open position and as the relative humidity decreases the motorized valve is graduatingly positioned towards a closed position. Accordingly the relative humidity controller 341 modulatingly positions the motorized valve 323 to regulate the flow of water through the reheat coil 233 to maintain the relative humidity in the enclosure 233 between 45% and 60%.

Figure 9 illustrates the manner in which the motorized valve 33i may also be operated by a proportioning motor which may be of the type shown and described in the above referred to D. G. Taylor patent and power is supplied to the proportioning motor by means of wires 433 and 431 leading from some source of power (not shown); The proportioning motor may also be provided with control terminals 432, 433, and

434 for controlling the direction and extent of movement of the motorized valve. The temperature responsive controller '343 may comprise a bellows 433 connected by the capillary tube 343 to the bulb 333 for operating a lever 433 against the action of an adjustable tension spring 431.

The lever 433 operates a slider 433 with respect to a resistance element 433 and for purposes of illustration it is assumedxthat as the temperature of the water in the pipe .333 increases from to the slider 433 is moved progressively from an extreme left hand position to an extreme right hand position.

The control terminal 432 is connected by a wire 443 to the left end of the resistance element 433 and the controlterminal 434 is connected by a wire 44! to the right end of the resistance element 433. The control terminal 433 is connected by a wire 442 to the slider 433. with the parts in the position shown in Figure 9 the slider 433 is in a mid-position and hence the motorized valve 33! is in a mid-position. As the temperature of the water increases the slider 433 is moved to the right to move the valve 33l towards a closed position and as the temperature decreases the slider 433 is moved towards the left to move the motorized valve 33! towards an open position. Accordingly the motorized valve 33l is positioned in accordance with the position of the slider 433 which in turn is positioned in accordance with the temperature of the water in the pipe 333. The temperature responsive controller 343 therefore maintains the temperature of the water in the pipe 333 between 60 and 70 so that relatively cold water may be produced in the relatively cold evaporator 231.

Figure 4 illustrates also the manner in which the solenoid valves 333, 343, and 3 of the cooling tower 233 may be controlled to admit water to'the cooling tower at a level wherein the temperature of the water corresponds to the wet bulb temperature of the air rising through-the cooling tower 233. As explained above, this greatly increases the efllciency of operation of the cooling tower 233 so that the coldest possible water is at all times produced thereby.

From the above it is seen that the modification shown by Figure 5 accomplishes generally substantially the same results as are accomplished by the modification shown in Figure 1.

It is obvious that the control arrangement of Fi re 5 may be appliedto the modification of Figure l and likewise the control arrangement of Figure 1 may be applied to the modification of Figure 5. For purposes of illustration in this application, various temperature values have been assumed'but it is obvious that these values may be varied to suit difierent types of installations.

Although for purposes of illustration two forms of this invention have been disclosed other forms thereof may become apparent to those skilled in the art upon reference to this disclosure and therefore this invention is to be limited only by the scope of the appended claims and prior art.

I claim as my invention: 7 1. In an air conditioning system for conditioning the air of an enclosure, the combination of,

I cooling means and reheating means for conditioning the air, a refrigerating apparatus for supplying a cooling fluid to the cooling means for cooling the air and'including a condenser for dissipating the heat absorbed, a cooling tower, means for supplying a reheating fluid Y from the cooling tower to the reheating means to dissipate heat to the air whereby the air is reheated and the reheating fluid is cooled, means for supplying the cooled reheating fluid from the reheating means to the condenser of the refrigerating apparatus to increase the heat dis-,- sipating effect of the condenser, and means for returning the reheating fluid from the condenser to the cooling tower to be cooledthereby.

2. In an air conditioning system for conditioning the air' of an enclosure, the combination of,

cooling means and reheating means for conditioning the air, a refrigerating apparatus for supplying a cooling fluid to the cooling means for cooling the air and including an evaporator for cooling the cooling fluid by evaporation, evacuating means for withdrawing vapor from the evaporator and a condenser for condensing the vapor withdrawn, a cooling tower, means for supplying a reheating fluid from the cooling to the air whereby the air is reheated and the reheating fluid is cooled, means for supplying the cooled reheating fluid from the reheating vaporwithdrawn, a cooling tower including a chamber, a fan-for circulating air through the chamber, sprays adapted to spray a fluid into the chamber in contact with the air circulating therethrough-whereby the fluid is cooled therein and means for collecting the cooled'fluid, means for supplying-cooled fluid from the cooling tower to the reheating means to dissipate heat to the air whereby the air is reheated and the fluid is cooled further, means for supplying the cooled fluid from the reheating means to the condenser of the refrigerating apparatus for condensing the vapor to increase the cooling effect of the refrigerating apparatus, and means for supplying the condensed ,vapor and the fluid from the condenser to the sprays of the" cooling tower at a point therein wherein the temperature of the fluid corresponds to the wet bulb temperature of the air circulating therethrough. 1

tower' to the reheating means to dissipate heat means to the condenser of the refrigerating apparatus for condensing the vapor to increase the cooling effect of the refrigerating apparatus, and means for introducing the condensed vapor and the reheating fluid from the condenser to the cooling tower to be cooled thereby. a

3. In an air conditioning system for conditioning the air of an enclosure, the combination of,- cooling means and reheating means for conditioning the air, a refrigerating apparatus for supplying a cooling fluid to the cooling means for cooling the air and including 'acondenser for dissipating the heat absorbed, a cooling tower including a chamber. a fan for circulating air through the chamber, sprays adapted to spray a fluid into the chamber in contact with the air circulating therethrough whereby the fluid is cooled therein and means for collecting the 'cooled fluid, means for supplying cooled fluid from the cooling tower to the reheating means to dissipate heat to the air whereby the air is reheated and the cooled fluid is cooled further,

of the cooling tower at a point thereinwherei'n 5. In an air conditioning system for conditioning the air of an enclosure, the combination of, sensible cooling means, latent cooling means and reheating means for conditioning the air, a first refrigerating apparatus for supplying a cooling fluid to the sensible cooling means for cooling the air and including a condenser for dissipating the heat absorbed, a second refrigerating apparatus for supplying cooling fluid to the latent cooling means for cooling the air and including a condenser for dissipating the heat absorbed, a source of fluid, means for supplying fluid from said source to the condenser of the flrst refrigerating apparatus to increase the heat dissipating effect of that condenser, means for supplying fluid from said source to the reheating. means to dissipate heat to the air whereby the air is reheated and the fluid is cooled, and means for supplying the cooled fluid from the reheating means to the condenser of the second refrigerating apparatus to increase the heat dissipating effect of that condenser.

6. In an air conditioning system for-conditioning the air of an enclosure, the combination of, sensible cooling means, latent cooling means and reheating means for conditioning the air, a first refrigerating apparatus for supplying a cooling fluid to the sensible cooling means for cooling the air and including an evaporator for cooling the cooling fluid by evaporation, evacuating means for withdrawing vapor from the evaporator and a condenser for condensing the vapor withdrawn, a second refrigerating apparatus for supplying cooling fluid to the latent cooling means for cooling the air. and including an. evaporator for cooling the cooling fluid by evaporation, evacuating means for withdrawing vapor from the evapo rator and a condenser for condensing the vapor withdrawn, a source of fluid, means for supplying fluid from said source to the condenser of the first refrigerating apparatus for condensing the vapor to increase the cooling effect of the first refrigerating apparatus, means for supplying fluid from said source to the reheating means to dissicrease the cooling effect of the second refrigerating apparatus.

7. In an air conditioning system for conditioning the air of an enclosure, the combination of,

sensible cooling means, latent cooling means and reheating means for conditioning the air, a first refrigerating apparatus for supplying a cooling fluid to the sensible cooling means for cooling the air and including a condenser for dissipating the heat absorbed, a second refrigerating apparatus for supplying cooling fluid to the latent cooling means for cooling the air and including a condenser for dissipating the heat absorbed, a cooling tower including a vertical chamber, a fan for circulating air upwardly through the cham ber, upper and lower sprays adapted to spray fluid into the chamber in contact with the air circulating therethrough whereby the fluid is cooled and the air is heated and means-for collecting the cooled fluid, means for supplying cooled fluid from the'cooling tower to the condenser of the first refrigerating apparatus to increase the heat dissipating effect of that condenser, means for supplying cooled fluid from the cooling tower to the reheating means to dissipate heat to the air whereby the air is reheated and the fluid is cooled further, means for supplying the cooled fluid from the reheating means to'the condenser of the secondrefrigerating apparatus to increase the heat dissipating effect of that condenser, 'means for supplying the fluid from the condenser of the first refrigerating apparatus to the upper sprays of the cooling tower to contact the fluid with the warmer air in the cooling tower, and means for supplying the fluid from the condenser of the second refrigerating apparatus to the lower sprays of the cooling tower to contact the fluid with the cooler air in the cooling tower.

8. In an air conditioning system for conditioning the air of an enclosure, the combination of, sensible cooling means, latent cooling means and reheating means for conditioning the air, a first refrigerating apparatus for supplying a cooling fiuid to the sensible cooling means for cooling the air and including an evaporator for cooling the cooling fluid by evaporation, evacuating means for withdrawing vapor from the evaporasupplying cooling fluid to the latent cooling means condenser of the second refrigerating apparatus for condensing the vapor to increase the cooling effect of the 'second. refrigerating apparatus, means for supplying the fluid from the condenser of the first refrigerating apparatus to the upper sprays of the cooling tower to contact the fluid with the warmer air in the cooling tower, and means for supplying the fluid from the condenser of the second refrigerating apparatus to the lower sprays of the cooling tower to contact the fluid with the cooler air in the cooling tower.

9. In an air conditioning system for conditioning the air of an enclosure, the combination of, sensible cooling means, latent cooling means and-reheating means for conditioning the air, a first refrigerating apparatus for supplying a cooling fluid to the. sensible cooling means for cooling the air and including a condenser for dissipating the heat absorbed, a second refrigerating apparatus for supplying cooling fluid to the latent cooling means for cooling the air and including a condenser for dissipating the heat for cooling the air and including an evaporator for cooling the cooling fluid by evaporation,

- evacuating means for withdrawing vapor from the evaporator and a condenser for condensin the vapor withdrawn, a cooling tower including a vertical chamber, a fan for circulating air upwardly through the chamber, upper and lower sprays adapted to spray fluid into the chamber in contact with the air circulating therethrough whereby the fluid is cooled and the air is heated and means for collecting the cooled fluid, means for supplying cooled fluid from the cooling tower to the condenser of the first refrigerating apparatus for condensing the vapor to increase the cooling effect of the first refrigerating apparatus,

means for supplying cooled fluid from the cooling tower to the reheating means to dissipate heat to the air whereby the air is reheated and the fluid is cooled further, means for supplying absorbed, a cooling tower including a vertical chamber, a fan for circulating air upwardly through the chamber, upper and lower sprays adapted to spray fluid into the chamber in contact with the air circulating therethrough whereby the fluid is cooled and the air is heated and means for collecting the cooled fluid, means for supplying cooled fluid from the cooling tower to the condenser of the first refrigerating apparatus to increase the heat dissipating effect of that condenser, means for supplying cooled fluid from the cooling tower to the reheating means to dissipate heat to the air whereby the air is reheated and the fluid is cooled further, means for supplying the cooled fluid from the reheating means to the condenser of the second refrigerating apparatus to increase the heat dissipating effect of that condenser. means for supplying the fluid from the condenser of the flrst refrigerating apparatus to the upper sprays of the cooling tower to contact the fluid with the warmer air in the cooling tower, and means for supplying the fluid from the condenser of the second refrigerating apparatus to the lower sprays of the cooling tower at a level wherein the temperature of the fluid corresponds substantially to the wet bulb temperature of the air. I

10. In an air conditioning system for conditioning the air of an enclosure, the combination of, sensible cooling means, latent cooling means and reheating means for conditioning the air, a first refrigerating apparatus for supplying a cooling fluid'to the sensible cooling means for cooling the air and including an evaporator for Y cooling the cooling fluid by evaporation, evacuating means for withdrawing vapor from the evaporator and a condenser for" condensing the vapor withdrawn, a second refrigerating apparatus for supplying cooling fluid to the latent cooling means'for cooling the air and including an evaporator for cooling the cooling fluid by evaporation, evacuating means for withdrawing vapor from the evaporator and 'a condenser for condensing the vapor withdrawn, a cooling tower including a vertical chamber, a fan for circulating air upwardly through the chamber, upper and lower sprays adapted to spray fluid with the chamber in contact with the air circulating therethrough whereby the fluid isv cooled and the air is heated and means for collecting the cooled fluid, means for supplying cooled fluid from the cooling tower to the condenser of the first refrigerating apparatus for condensing the vapor to increase the cooling effect of the first refrigerating apparatus, means for supplying cooled fluid fromthe cooling tower to the reheating means to dissipate heat to the air whereby the air is reheated and the fluid is cooled further, means for supplying cooled fluid from the. re-

heating means to the condenser of the second' refrigerating apparatus for condensing the vapor to increase the cooling effect of the second re-.

frigerating apparatus, means for supplying the fluid from the condenser of the first refrigerat-.

supplying a cooling fluid to the cooling means for cooling the air and including a condenser for dissipating the heat absorbed, means for supplying a reheating fluid to the reheating means to dissipate heat to the air whereby the air is reheated and the reheating fluid is cooled. means for supplying the cooled reheating fluid from the reheating means to the condenser of the refrigerating apparatus to increase the heat dissipating eflect of the condenser, means responsive to the temperature of the air leaving the cooling means for controlling the operation of the refrigerating apparatus, and means responsive to psychrometric conditions of the air in the enclosure for controlling the reheating effect of the reheating means.

12. In an air conditioning system for conditioning the-air of an enclosure, the combination of, sensible cooling means, latent cooling means and reheating means for conditioning the air, a first refrigerating apparatus for supplying a cooling fluid to the sensiblecooling means for cooling the air and including a condenser for dissipating-the heat absorbed, a second refrigerating apparatus for suppLving cooling fluid to .the latent cooling means for cooling the air and including a condenser for dissipating the heat absorbed, a source of fluid, means for supplying fluid from said source to the condenser 01 the first refrigerating apparatus to increase the heat dissipating efiect of that condenser, means for supplying fluid from said source to the reheating means to dissipate heat to the air whereby the air is reheated and the fluid is cooled, means for supplying the cooled fluid from the reheating means to the condenser of the second refrigerating apparatus to increase the heat dissipating effect of that condenser, means responsive to the temperature of the air in the enclosure for controlling the operation of the first refrigerating apparatus, and means responsive to the moisture content of the air in the enclosure for controlling the operation of the second refrigerating apparatus and the reheating eiiect of the reheating means.

13. In an air conditioning system for conditioning the air of an enclosure, the combination of, sensible cooling means, latent cooling means and reheating means for conditioning the air, a first refrigerating apparatus for supplying a cooling fluid to the sensible cooling means for cooling the air and including a condenser for dissipating the heat absorbed, a second refrigerating apparatus for supplying cooling fluid to the latent cooling means for cooling the air and including a condenser for dissipating the heat absorbed, a source of fluid, means for supplying fluid from said source to the condenser of the first refrigcrating apparatus to increase the heat dissipating efiect of that condenser, means for supplying fluid from said source to the reheating means to dissipate heat to the air whereby the air is reheated and the fluid is cooled, means for supplying-the cooled fluid from the reheating means to the condenser of the second refrigerating apparatus to increase the heat dissipating efiect of that condenser, means responsive, to the cooling efiect of the sensible cooling means for controlling the operation of the first refrigerating apparatus, and means responsive to the cooling effect of the latent cooling means for controlling the operation of the second refrigerating apparatus.

14. In an air conditioning system for conditioning the air of an enclosure, the combination of, sensible cooling means, latent cooling means and reheating means for conditioning the air, a first refrigerating apparatus for supplying a cooling fluid to the sensible cooling means for cooling the air and including a. condenser for dissipating the heat absorbed, a second refrigerating apparatus for supplying cooling fluid to the latent cooling means for cooling the air and including a condenser for dissipating the heat absorbed, a source of fluid, means for supplying fluid from said source to the condenser of that first refrigerating apparatus to increase the heat dissipating effect of that condenser, means for supplying fluid from said source to the reheating means to dissipate heat to the air whereby the air is reheated and the fluid is cooled, means for supplying the cooled fluid from the reheat ing means to the condenser of the second refrigerating apparatus to increase the heat dissipating efiect of that condenser, means responsive to the cooling efiect of the sensible cooling means for controlling the operation of the first refrigerating apparatus, means responsive to the cooling effect of the latent cooling means for controlling the operation of the second ref rigerating apparatus, means responsive to the temperature of the air in the enclosure for controlling the cooling efiect of the sensible cooling means,

and means responsive to the moisture content of the air in the enclosure for controlling the reheating efiect of the reheating means.

ROBERT B. P. CRAWFORD.

CERTIFICATE OF CORRECTION. Ptent no. 2,286,6Q5. v June 16, 19!;2.

ROBERT B. P.- CRAWFORD.

It iahreby certified that error appears 1p the printed specification of the above numbered patent requiring correction as-fo1lows:. Page ondpqlumn, line'lfi t rike' out "tube associated";'- line. 214., .after -the word gobling insert --coilline 58, for at 12'' read --at' 18-- page Lt, second column, line 28, for' "stem" read-steam-.-; 1111 6 58, for. the, wo rd "with" reed 'wi .thin'--; a a that the said Letters Patent should be read with fihis -cqrrectibh therein that the same may conform to the record of the as in the ,r teht Office.

4 si nedem seal d this 5th day of Januai'y, A. D. 19%.

san 7 Henry: Van Aradale, I

n Acting Gonmisiqneigof Patents.

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