US2249856A - Air conditioning - Google Patents

Description

July 22, 1941. A. w. RUr--F4 'AIR CONDITIONING Filedl Dec. 19, 1935 5 Sheets-Sheet 1 Imventor mowwm Gttomegs A. W. RUFF AIN- CONDITIONING Filed Deo.

yJuly 2.2, 1941.

19, 1933 5 Sheets-Sheet 2 amm Smaentor (GMO my@ 62X). ERM?? a@ l Gttornegs I July 22, 1941. A. w. RUFF AIR CNDITIONING 3 sheets-sheet 3 Filed Dec. 19, 1933 mmm UUUU' Snnentor Patentedv 'July 22,4 194,1l

IUNITED STATES PATENT oFF1cE--;

2.24am l .un coNnmcNmc- Alonzo W. Ru', York, Pa.,

anignmen nulgno tl. to Auditorium Conditioning Corporation, NewYork, N. Y., a oorporetionsoi' New Jersey Application December 19, 1933. Serial No. 7i)3,138 29 0mm. (Cl. cs2-'43) VThis invention relates to air conditioning. or what is sometimes called comfort cooling, and provides a simplined 'arrangement of cooling mechanism and automatic controls therefor.

It hasvfrequently been proposed to control the operation of a comfort cooling plant in response to dry bulb temperature. Such controls are not satisfactory because under certain conditions the dry bulb temperature may fall below the setting of the regulatory thermostat while the humidity is unduly high. The present invention avoids this difficulty by keeping the compressor in operation at a uniform rate when dry bulb temperature or relative humidity, or both, are above the maximum values set for each, and so regulating the device that when humidity is above its chosen value, and dry bulb temperature is below its chosenvalue. the temperature of the evaporator is reduced and at the same time the total refrigerative eiect is reduced. As a con' sequence the refrigerativeevaporator becomes very effective as a dehumidiiier and j relatively ineffective as a 'cooler.

From one point of view the action might be described as starving the evaporative systemby limiting the amount ofy refrigerant fed thereto.

The edect is to reduce the suction pressure and consequently the evaporator temmrature, .and at the same time reduce the total 'refrigerative- Fig. 2 is a similar view showing a modification in which lthe thermostat does not `control the motor which drives the compressor and in which the thermostat exercises a modulated control.

Fig. 3 is a similar view representing a modiilcation of the arrangement shown in Fig. l in which the evaporator surface is not sub-divided I as in Fig. `2i.

Referring first to Fig. 1.

6 represents a housing through which a motor driven fan. diagrammatically indicated at l, cil'-v culates air. The air enters the casing through an intake, indicated at 8, ows upward through the casing and is discharged by the fan at 9.

In the. casing 5 are two refrigerative evaporators il and i2. IThe suction connections I3 and I4 of the two evaporators lead to a common suction line i5, which is connected to the compres- Sor it. A high pressure line l'l leads from the compressorto a combined condenser and receiver, indicated at i8, from which the liquid line i8 leads by way of astrainer 2i. line it supplies refrigerant to the coil ii through an expansion valve 22 of the thermostatically Vcontrolled type. The thermostatic control is exercised by a bulb 23 in thermal contact with the suction connection I3. Pressure developed in thebulb 2l by rise of temperatur'tends to open the valve 22. The particular valve illustrated is one manufactured by the Detroit Lubricator Com-. pany under Patent 1,776,401, issued Sept. 23,- 1930,

but any suitable expansion valve, preferably thermally controlled, might be substituted.

The liquid line I also supplies refrigerant to the evaporator i2 through a similarexpansionl valve 2l having a thermostatic controlling bulb 2l on the suction connection lo.- The liquid linef ii is not. however, connected directly to the expension valve 26. but a solenoid actuated stop valve 26 is interposed, the stop valve being arfyranged to close when' the solenoid 21 is energized.

The compressor It is driven at constant speed by a motor 29, which, in the example illustrated, is an electric motor. startedby a starting mechanism 29, whose specic form is immaterial.

A dry bulb thermostat 3i and humidostat32 are mountedin the room into which the fan 'l discharges. In the example illustrated they are of the electric switch type and receive current from the lines 33 and 34 through a branch 85. The

humidcstat 32 is connected by a line 36 with the starter 2l and conditions the starter to cause the motor 2l to run when humidity exceeds a chosen value. The thermostat 3i receives, current through the same branch 35 and is connested by abi-anch 31 and line 36 with the 5o starter ze in such a way that 1f the dry buit The*v liquid This motor is stopped and ,f I2 will become inactive.

lower suction pressure.

compressor |53.

temperature is above the chosen value the thermostat will condition the starter 29 to cause the motor 28 to run. Thus the motor runs if either temperature or humidity, or both, be above the respective values set for these quantities. 'Ihe return line from the starter is shown at 29.

The thermostat 3| is also connected by a branch line 38 and return line 4I with solenoid v winding 21.- When the thermostat 3| responds to a temperature below the chosen value, and thus tends to permit the starter to stop the motor 28, it energizes` the solenoid v21 and closes the valve 26. If at such time the humidostat 32 calling for refrigeration, the motor 28 will run notwithstanding the action of the thermostat 3|.

Assume that humidity and temperature are both above the chosen value, the motor 28 will run, the valve 26 will be open, and both evapora" tors I and I2 will be effectiveI to 'cool and dehumidify the air. Ii' the humidity alone falls below the chosen value, the system will continue to operate as before. If both humidity and temperature fall below the chosen valuepthe motor 28 will be stopped and Areirlgeratim ceases. 1f temperature alone falls below the minimum value, valve 26 will be closed and the evaporator Since the compressor I 8 continues in action at its normal rate, the

. effect will be 4to reduce the suction pressure ini y, `the evaporator Il, and since. the thermostatic the reduced iiow oi refrigerantv a portion of the evaporator surface becomes inactive.

Such a structure is illustrated by way of example in Fig. 3. In this gure a number of parts conform in detail to parts' in Fig. 1, land are designated by the use of the reference numerals used on Fig. 1 but with the letter b. Such parts as those numbered 6b to 9b, inclusive, |51 to 2lb inclusive, and 25h to 4h inclusive.

-10 In the housing lb is a single evaporator 5|. It

l has a suction connection 52 and a supply connection fed'by an automatic expansion valve 53. `The valve 53 conforms in structure to those previously described, and its operation is regulated by a thermostatic bulb 54 in thermal contact with the suction connection 52. 'I'he suction connection 52 is connected to the suction line |51..

The liquid line I9` is not connected directly to the expansion valve 53 but has two connections therewith, such connections being in parallel with each other. One of these connections is by way of a throttlingvalve 55. This valve is set to a flow capacity less than the normal demand of the evaporator 5I when the compressor I6 is operating at its normal constant speed. The other connection is controlled by the valve 26u. When the'valve 25s is open the supply of refrigerant to the valve 53 is suiilcient to meet the fmaxlmum demand of the coil 5I. 30

As in the structure of Fig. 1, the motor 2B operates at constant speed whenever! the thermostat 3| or the humidostat 32h callsl for refrigeration, and isstopped only-when. both cease calling for refrigeration. However, if thethermostat 3h ceases calling for refrigeration while the humidostat 32s calls for refrigeration, the

of the action whentemperature is below the desired This result can be secured by the arrangementz shown in Fig.. 2 where parts v similar to those shown in Fig. 1 are given the same reference numerals with .the letter a.

It will be observed that there'is no thermostat corresponding to the thermostat 3| and no sole-` noid valve 26, 21. Consequently the starting and stopping of the motor 28. is controlled solely` by the indications 0l the humidostat 32s. Adjacent the air intake 8s there is mounted the actuating bulb of a thermostatic modulating valve whose motor element is indicated at 45 and whose. valve element is indicated at 41. lThe valve 41 is interposed in the suction connection |33. It could just as well be located in the suction connection I4., it being immaterial whichYone of the two evaporators is controlled.

Pressure developed in the bulb 45 on rise of' temperature operates through motor 4S to gradually open the valve 41. Thus as the tempera- Vture of air entering at sii-decreases the evaporasolenoid 21s will be energized and the valve 26h will be closed. Consequently, the supply of refrigeration to the evaporator 5I- is limited to the 'capacity of the 'oriiice at the valve 55, and since this is less than the normal evaporative capacity of the evaporator the suction pressure is reduced.

and the refrigerative effect is also reduced. While the entire evaporative surface is nominally' active, the fact is that only a portion of the surface of the evaporator 5I is effective. Consequently, justas in the case of the structure of Fig. 1, dehumidication is intensied but refrigeration of the air is reduced.

'I'he operative principles underlying all three embodiments are essentially similar, but various tor llt is progressively shut down by throttling n its suction connection. The eiect of this is to reduce the suction pressure developed by the described with reference to Fig. 1 except that it is progressive.

It is not -strlctly necessary to subdivide the evaporator surface into two distinct units, as a The action is similar to that single unit may lbe used and starvedA under low temperature conditions in the conditioning space to reduce its refrigerating effect and also its tem- I perature. what actually happensis that with forms have been illustrated to indicate the breadth of the invention, and also to indicate different types of installation suitable for somewhat diilerent conditions.

To indicate quantitatively conditions which may exist when the entire evaporative surface is eilective and when only a portion of the evaporative surface is effective, the following tabulation,

based on quantitative tests is given.

This tabulation shows two examples falling Vwithin the scope of the invention. In order to offer a strict comparison between conditions with fully eiective evaporator and partially effective evaporator, the same dry bulb temperature and the same relative humidity are assumed for room conditions, neglecting the fact that automatic regulation implies variationvof these.qu antities. The purpose of the examples is to demonstrate that shift in Ydistribution between sensible heat tonnage and moisture condensation tonnage must occur as the result of using fully and partially eilective evaporator. In each. example column A gives conditions of fully eil'ective evaporator and column B" conditions with partially effective evaporator.

Example #l Example I2 Full Partial Full Partial A B A B Room-dry bulb deg-rees-. ,75 75 75 75 Room-relative humidity" 60 60 50 50l Boom-dew iroint 60.2 60.2 55.2 55.2 Grains olmo ture/#inroom/air.- 78.5 78.5 66 66 Baturatioir'temperature 54.5 47 52 43.

. Temperature oi' refrigerant 48.5 34 46 31.

Cagacity oi reirlgerating mac inc r-.l ..tons 1.18 0.85 1.13 0.80 D bulb sir leaving unit.-...'... 56.6 63. 4 53. 9 62. 7

tive humidity-air leaving unit 9e 75 04 66 Dew point-air leaving unit 55. l 55.3 52. 3 5l. 3 Grains of moisturel# air leaving Aiilinit .a r.. l 65.8 66.1 59 56.8

temperature op t roug unit 18.4 11.6 21.1 12.3 Moisture removed through unit grain/#air 12.7 Y12.4 7.0 9.2 C. F. .ofalr 500 500 500 500 Sensible heat tonnage .84, 516 94 55 Moisture condensation tonnage. 34 334 19 25 i moisture condensed per hour of continuous operation 3.86 3.79 2.16 2.84

It is important to observe that air leaving the `unit is not saturated and carries fewer grains of moisture per pound of air than does the air in the room. The eiiect of progressive mixture with air in the room is to reduce the number of grains of moisture per pound' of air inthe room. This reduction of moisture, occurring as it does without a commensurate reduction of dry bulb temperature in the 'room produces a reduction of relative humidity which will ultimately reach the low setting of the humidostat and shut down the machine.

It must be remembered that comfort cooling units ordinarily arenot used under conditions whichpreclude the access of heat to the cooled space, and that under normal conditions'of use the removal of moisture results in reduction of 32. or 32s) preferably responds to relative hu' midity rather than absolute humidity it can, and in' practice does, shut down the machine periodically when operating under humidity control alone. When operating under humidity control the machine runs in cycles. the total periods ofoperation being longer than under thermostat control, without lowering the dry bulb temperature to an uncomfortable point because the temperature drop'through the unit isless than'when o rating on a fully flooded coil as is the condit on when the thermostat is in control.

While theregulation secured by the method and apparatus herein' disclosed may inotbe as precise as that'theoretically attainablef'by other methods, it does produce commercially satisfactory conditions'. The simplicity of the installation and of the controlling mechanism commend it both from the standpoint of initial cost and from the standpoint of maintenance.

What is claimed is:

method comprising keeping the compressing means substantially uniformly in action, and re- A ducing the effective -area of the evaporator in response to reduction of temperature' of the air in the conditioned space below a .critical value whereby the temperature of the evaporator is reduced.

2. The method of regulating an air conditioning'plant of the refrigerative type, including comcompressing means and a refrigerative evaporator in heat exchanging relation with air undergoing conditioning, said evaporator being connected to supply refrigerant vapor to said means, such method comprising keeping the compressing means substantially uniformly in action, and reducing the rate of evaporation of refrigerant in response to reduction of temperature of the air in the conditioned space below a critical value, whereby the temperature of the evaporator is reduc/ed.

4. The method of regulating an air conditioning plant of the refrigerative type, including compressing means and a refrigerative evaporator in heat exchanging relation with air undergoing conditioning, said levaporator being connected to supply refrigerant vapor to said means, such method comprising keeping the compressing means substantially uniformly ln action, and varying' the rate of evaporation of refrigerant in the evaporator in response to variation of air temperature in the conditioned space.

5. The method of regulating an' air conditioning plant of the refrigerative type, including compressing means and a refrigerative evaporator connected to supply refrigerant vapor to said means, such method comprising, startingV and stopping the compressing means in response to variation of atmospheric humidity in the conditioned space above and below a' chosen value, causing said compressing means to operate uniformly when running, and reducing the effective area-of the evaporator in response to reduction of temperature of the air in the conditioned space below a critical value whereby the temperature of the evaporator is reduced.

6. The method ot regulating an air conditiojning plant ofthe refrigerative type, including compressing means and a refrigerative evaporator connected to supply refrigerant vapor to said means, such method comprising starting and 'stopping the' compressing means in response v'to variation of atmospheric humidity in the conf 'ditioned space above and below a chosen value,

causing said compressing means to operate unlformly when running. and varying the effective 1. The method of regulating an" air conditioning plant of the refrigerative type, including compressing means and a refrigerative evaporator in heat exchanging relation with `air undergoing tor connected to supply refrigerant vapor to saidmeans, such method comprising starting and stopping the vcompressing means in response to variation of atmospheric humidity in the conditioned space above and below a chosen value, causing said compressing means to operate uniformly when running, and reducing the rate of evaporation of refrigerant in response to reduction of temperature of the air in the conditioned space below a critical value, whereby the temperature of the evaporator is reduced.

8. The method of regulating an air conditioning plant of the refrigerative type, including compressing means and a refrigerative evaporav13. The combination dened in claim 12, m which means responsive to the humidity of the l treated air is provided to control the starting and tor connected to supply refrigerant vapor to said means, such method comprising starting and stopping the compressing means in response to variation of atmospheric humidity in the conditioned space above and below a chosen value,.

causing said compressing means to'operate uniformly when running, and varying the rate of evaporation of4 refrigerant in the evaporator in response to variation of air temperature in the conditioned space.

` 9. 'I'he method of regulating an air conditioning plant of the refrigerative type, including compressing means and a refrigerative evaporator connected to supply refrigerant vapor to said means, such method comprising controlling the compressing means in response to atmospheric temperature and humidity in the conditioned spage, so as to operate the compressing means at a uniform rate when either or both temperature and humidity exceed chosen respective values and stop the compressor when bot-h are below such values, and reducing the effective area of the evaporatonwhen such temperature alone is below such chosen value.

10. The method of regulating an air conditioning plant of the refrigerative type, includingcompressing means and a refrigerative evaporator `connected to supply refrigerant vapor to said means, such method comprising controlling the compressing means in lresponse to atmosstopping of the means which drives the compresser.

14. 'I'he combination defined in claim 12, in which the thermostat responsive to dry bulb temperature and a humidostat responsive to the humidity of the treated air, conjointly control the means for drivingthe compressor and are arranged to keep said means in action when either or both the thermostat and the humidostat call for refrigeration.

15. The combination defined in claim 12,'

in which the evaporating means is subdivided and the thermostat responsive to dry bulb temperature functions below a critical value to terminate the supply of refrigerant to one subdivision. I

16. The combination defined in claim 12, in which the evaporating means is subdivided and the thermostat responsive to dry bulb temperature controls the suction connection of one subdivision in such a way as progressively to open said connection on rise of temperature and progressively close it on fall of temperature, within chosen limits.

` 1'7. The combination dened in claim 12, in

which the thermostat responsive to dry bulb temperature functions to restrict the rate of flow Y of refrigerant to said evaporating means when dry bulb temperature is be ow a chosen minimum. I A

18. The combination defined in claim l2, in which the evaporating means is constructed as a single unit, and is fed through an expansion valve of the thermally controlled type, there being two supply paths from said receiver to said expansion valve, one of which is constantly open pheric temperature and humidity in the conditioned space, so as to operate the compressing means at a uniform rate when either or both temperature and humidity exceed chosen respective values and stop the compressor when'both are below such values, and reducing the rate of,

'the combinaticn of refrigerative evaporating means; means for circulating air to be treated, over said evaporating means; a compressor fed by said evaporating means; means for driving said compressor at a. substantially constant rate; condensing means for condensing vapor discharged by said compressor; and thermostatic means responsive to the dry bulb temperature of the treated air and eifective upon a reduction of.

temperature thereof to reduce the temperature ofvat least a portion of the evaporating means and also the total refrigerative eiiect. i

and of capacity less than the capacity of the expansion valvefand the other of which is controlled by said thermostat and is closed thereby when the temperature of the treated air falls below a chosen minimum.

19. The combination dened in claim 12, in which the evaporating means is Adivided into twav sections each fed independently of the other by a, thermostatic expansion valve subject to temperature of the vapor leaving the sections of the evaporator,and in which supply of refrigerant to one of said expansion valves is controlled by a stop valve closed by said thermostat when the temperature of the treated air is below .a'chosen 20. The process of cooling and dehumidifying air which comprises causing air, which is to be conditioned, to circulate in` heat exchange rellation with a portion of an evaporator of a mechanical refrigerator and in heat exchange rellation with another portion of the evaporator;

causing all of refrigerant, flowing from one of the portions., to flow through the other whenever the refrigeratorA is in operation; and while refrigerant vthus flows through the evaporator,

I vcausing a device to respond-to a drop in dry bulb temperature of the air below a predetermined minimum while the humidity content of the air is above a. predetermined minimum to vary the effectiveness ofone of` said portions of the evaporator.

21. The process of coolingand dehumidifying air which comprises causing air, which is toA be conditioned, to circulate in heat exchange relation with a portion 'of an evaporator of a mechanical refrigerator and-in heat exchange relation with another portion of the evaporator;

- control means in one direction causingl all of refrigerant, ilowingfrom one of tion with a portion of an evaporator of a mechanical refrigerator and in heat exchange relation with another portion of the evaporator; causing all of refrigerant, flowing from one of the portions to ow through the other whenever l the refrigerator is in operation; and whilerefrigerant thus flows through the evaporator, causing a device to respond to/temperature of the air to vary the effectiveness of one of said portions of the evaporator.

23. The process of cooling and dehumidying air. which comprises causing air, which' is to be conditioned, to circulate in heat exchange relaf tion with a portion of an evaporator of a mechanical refrigerator and in heat exchange relation with another portion of the evaporator;

causing all of refrigerant, flowing from one of the por-.tions to flow through the other whenever the refrigerator is in operation; and while refrigerant flows through the evaporator, causing a device to respond to temperature of the air to vary the rate of evaporation of refrigerant in one of said portions of the evaporator.

24. 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 iluidto said cooling means, control means for varying the now of cooling fluid through said cooling means, control means for varying the operation of said cooling iluid supplying means.- temperattu'e responsive means for substantially simultaneously actuating both of said control means, and humidity responsive means for actuating one only of said independently of said temperature responsive means. l

v 25. A method of controlling thetemperature and humidity of air consisting in circulating air to be conditioned in heat exchange relation with heat exchange surfaces, circulating refrigerant through said surfaces, causing sensible and latent from the air circulated in contact with the surfaces, means operative responsive to a drop in temperature of the air in the enclosure below a predetermined point for controlling the flow of refrigerant so'that sensible heat removal from the air circulated, in contact with the surfaces will be reduced and latent heat removal relatively increased, and means operative responsive to a drop in the humidity content of the air in the enclosure below a predetermined point to interrupt the circulation of refrigerant to said surfaces.

27. In an air conditioning system `for producing desired conditions of temperature ,and humidity in the atmosphere of an enclosure, a conditioner casing, an evaporator within the casing, a compressor and condenser operatively associated with the evaporator to carry out arefrlgeration cycle, means for` circulating air through the casing, a temperature responsive device, a humidity responsive device, said devices being operative responsive to changes in temperature and humidity conditions within the enclosure, and means controlledby the temperature responsive device for-limiting the ow of refrigerant to the evaporator whereby the suc` heat to be removed from the air passing in con- 4 tact with said surfaces when the dry bulb temperature of the air and absolute humidity per unit thereof `exceed predetermined minimums, and causing the circulation of refrigerant to be restricted when the dry bulb temperature drops 1 l below the predetermined minimum to limit subv sequent removal of senaibleheat from the airand relatively increase subsequent removal of latent heat therefrom.` v l 26. A system for conditioning air comprising in combination a conditioning chamber, heat exchange surfaces within thechamber, a refrigerant source, means for supplying refrigerant from said source to said heat exchange surfaces. means for circulating air from an enclosure to vbe conditioned through said chamber incntact withresponsive to texnthesurfaces, means operative peratureand humidity conditions within the enclosure for maintaining a maximum flow of' ref frigerant from said source throush said surfaces whereby sensible and latent heatwill be removed tion pressure within. the evaporator will be re-y duced relatively to increase the removalI of latent heat from air passing through the casing in contact with a portion of the evaporator, said ing of inactive surface wherein substantially no 'evaporation of refrigerant takes place.

28. A method of increasing reduction of the latent heat of air while decreasing reduction of the sensible heat thereof consisting in circulating refrigerant to be evaporated through heat exchange surfaces by compressing means, circu-` latingI air in contact with the heat exchange surfaces, continuing said last two steps until the temperature of the air is reduced to a predetermined minimum, then diminishing the supply of refrigerant to said surfaces without substantially affecting the operation of the compressing means to cause a decrease in pressure within said surfaces whereby a portion --of said surfaces will be decreased in temperature to increase the rate of removal of latent heat from air contacting said portion of the surfaces, the remainder of the air passing in contact with the remainder of the surfaces having its latent and sensible heat content remain substantially unaffected.

29. A system for conditioning air comprising a compressor', a condenser, and an evaporator operatively associated to carry out a refrigeration cycle, a casing within which said evaporator is positioned,.a fan for drawing air through the casing and delivering the air to an enclosure to be conditioned, means operative responsive to a y within the enclosure below predetermined minimums to interrupt the supply of refrigerant to saidv evaporator, means operative responsive to a drop in temperature below the predetermined minimum while the humidity of the air remains above the predetermined minimum to regulate the supply of refrigerant to the evaporator whereby a portion thereof will remain active and another portion substantially inactive, and means responsive to a rise in temperature above said minimum for'causing the evaporator to become f active.

my ALONZO W. RUF?.

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