US 2104851 A
Description (OCR text may contain errors)
Jan. 11, 1938. R. B. P. CRAWFORD 2,104,851
AIR CONDITIONING SYSTEM Filed Nov. 14,V 1952 5 Sheets-Sheet l Wm .m Y o/o@ M w 4, w
Jan. 11, 1938. R, B, P CRAWFORD 2,104,851
IR CONDITIONING SYSTEM Filed Nov. 14, 1952 5 Sheets-Sheet 2 Jan. 11,1938. R B, p, CRAWFORD 2,104,851
AIR CONDITIONING SYSTEM Filed Nov. 14, 1932 5 Sheets-Sheet 3 Patented Jan. 11, 193s UNTED STATES PATENTl OFFICE AIR CONDITIONING SYSTEM Application November 14, 1932, Serial No. 642,483v
This invention relates to air conditioning systems, and more particularly to air conditioning systems in which the air to be conditioned is divided into two portions, only a small quantity 5 of fresh air being conditioned in order to prevent infiltration and provide proper temperature and humidity conditions, and the main body of air being recirculated in a closed circuit conditioning unit to maintain the desired conditions.
The invention is particularly adapted for use in connection with the maintenance of a predetermined condition of air in a single room or space, but may equally Well be converted into a conditioning system for use in a plurality of rooms, such as oiiice buildings, hotels, schools, hospitals, and the like.
lt has been the practice to circulate the entire volume of air used in any given room or space through the conditioning unit, with replacement of air lost or removed being made by introducing varying amounts of fresh, unconditioned air into the` return air from the room before it enters the conditioning unit. This necessitates the use of units of considerable size, and increases both the initial expense of constructing and installing the unit, and also the expense of operating the same. Further, a considerable amount of duct work is necessary in a unit of this type, for bringing fresh air into the conditioner, and for exhausting and recirculating the room air. l
The ordinary type of air conditioning systems on the market at the present time are, for the most part, merely improved heating and ventilating systems, requiring expensive, large-size conditioning units in addition to a complicated system of duct Work. The primary purpose of securing circulation of air for conditioning purposes in these devices is to utilize the air as a carrier of heat and humidity.
The system proposed in the present invention diiers radically from this established practice. This system contemplates very little, if any, duct work, each enclosed space being conditioned separately, so that no recirculated air will carry the odors of any one area over the entire building, and also saves the energy required for moving large volumes of air against duct resistances. The present system, in operation in connection with enclosures which require a low absolute humidity, utilizes a minimum amount of energy for this dehumidifying, and the energy needed for cooling is efficiently applied at a much higher temperature than has been possible heretofore, since the cooling is effected independently of humidity control. Also, in situations requiring a high absolute humidity, the cooling is effected adiabatically without the use of external energy.
The above features are secured by providing a system wherein the temperature is controlled by units Within the enclosure, such as radiant heaters, coolers, or the like. The humidity is controlled by the admission of a small quantity of outside air sufficient to prevent infiltration into the enclosure, this air being passed through a small humidifying unit wherein extreme vconditions of high or low absolute humidity are imparted to the air to effect humidity control of the entire volume of room air, this small quantity of humidied air having no substantial tempering effect upon the air in the room. The two units for effecting temperature and absolute humidity control are not interconnected, and operate entirely independently. It is to be understood, of course, that the system maybe reversed, that is, the humidifying unit may be disposed within the room and the tempering unit may be provided for the small quantity of air admitted into the room to prevent inltration, depending upon the operations carried on within the room or enclosure.
This results in what I term a two-stream" air conditioning system, that is, a conditioning system wherein one portion of the air is conditioned to control the temperature of the air in the enclosure, and a second portionof the air is conditioned to produce and maintain the desired humidity in the air.
It is understood that the general theory of two-stream air conditioning is not to be limited to a control of temperature by one unit, and a control ofhumidity by a second unit. For example, in a modied form of my invention, the temperature and humidity which are desired in the enclosure are maintained by'conditioning a small portion of the air which is used to maintain a pressure sulcient to prevent inltration into the enclosure, this air being admitted by a pressure controlled damper, and a. second closed circuit conditioning unit is used for cleansing the air in the enclosure and removing certain impurities therefrom, while not altering to any appreciable extent the condition of the air th being cleansed.
One object of the present invention is to provide an air conditioning system in which the major portion of the air is not recirculated, and in which the desired conditions are maintained by conditioning only a. relatively small portion of the total amount of air in the enclosure, thus effecting a great savings in the cost o! the conditioning equipment.
A further object of the present invention is to provide a conditioningunit for conditioning the relatively minor portion of the air circulated into the enclosure for maintaining the desired condition therein through the use of a re1- atively small capacity conditioning unit, preferably ranging between 5 per cent. and 20 per cent. of the capacity of the closed circuit unit used for conditioning the air Within the enclosure. Incarrying out this function, the unit for conditioning the fresh air need not be of large c'apacity, and, hence, the operations entailed in conditioning the relatively small volume of atmospheric air introduced through the unit does not require the use of an expensive apparatus, nor does it require large capacity sources of heat or cold for producing the required conditioning functions. 'Ihis is brought out in more detail in my copending application, Serial No. 375.952, led July 5, 1929, of which application the instant invention is a continuation in part. Reference should be made to the description of Figures 8, 15, and 18 of my copending application, in which I have disclosed an apparatus which is intended to produce the same results as provided by the improved conditioning system of the present invention.
Various other modifications and embodiments of the invention may be made,.and the controlling mechanism may be so operated as to produce any desired condition within the enclosure without increasing the size of the conditioning system, and thus maintaining the economy effected by the use of the two-stream method.
In order that those skilled in the art may understand the construction and operation of my invention in more detail, I shall now describe the same in connection with the accompanying drawings, which illustrate a preferred embodiment of the invention, and in which:
Figure 1 is a diagrammatic view of an enclosure provided with a small conditioning unit for conditioning entering fresh air, and with the recirculating conditioning unit for maintaining proper conditions within the enclosure;
Figure 2 is a sectional view of a recirculating conditioningy unit employed for purification of the air coming from the enclosure;
Figure 3 isa sectional view of an interchanger for introducing fresh air or for cleansing room air and eliminating waste gases, in which no change of temperature lis desired;
Figure 4 shows aconditioning unit for a room where the temperature is maintained constant by the vradiant effect provided by the recirculating conditioning unit;
Figurel 5 shows the application of the system shown in Figure 4 to a building containing a plurality of enclosures;
Figure 6 is a schematic layout of a system for low humidity conditions within the enclosure; and
Figure 7 is a schematic layout of a system for high humidity conditions within the enclosure.
In the embodiment shown in Figure 1 I have indicated an enclosure at A, the enclosure comprising a room, a floor section, or the like, which is preferably provided with openings indicated at I0, these openings vbeingvwindows or the like. A certain amount of infiltration is ordinarily provided by the window openings I 0, and it is the purpose of the present invention that the conditioning unit indicated generally at IIl supply air to the enclosure A under a pressure suillcient to prevent infiltration through these openings, and such that a very small amount of out-filtration may be effected, in order to prevent the entry of any unconditioned fresh air into the 5 enclosure. The major portion of the air is circulated through a closed conditioning unit indicated generally at I2, this unit having no outside communication with atmosphere. The unit II receives air through the fresh air inlet opening I3, there being a damper or louvre I4 positioned therein for controlling the quantity of air passing therethrough and maintaining the average volumetric supply to the enclosure A between predetermined limits such that the temperature for the room, for example, may be held between desired limits by conditioning the fresh air as to temperature. As will be pointed out hereinafter, the fresh air supply may be conditioned as to humidity instead of temperature in order to maintain desired humidity conditions in the enclosure, the temperature of the air in the enclosure being in that case independently controlled.
'I'he opening and closing of the louvre is effected by means of a control mechanism indicated at I5, this control mechanism being actuated by aA pressure responsive switch indicated at I6, this switch corresponding to the switch 242 shown in Figure 8 of my copending application, Serial No. 375,952, filed July 5, 1929, of which this application is a continuation in part. This pressure responsive switch is open to the pressure within the enclosure A at I'I, and is open to atmospheric pressure at I8. The switch is filled with mercury or a similar fluid conducting material, and is provided with the switch contacts I 9 and 20. When the pressure within the enclosure A is sufficient to force the fluid material rearwardly from the opening I1, the contact point 20 is uncovered and the circuit is broken. This means that there is a pressure in the enclosure greater than atmospheric. The fresh air entering the inlet opening I3 past the damper I4 enters a conditioning chamber 2|, wherein the air encounters a plurality of cooling surfaces or heating surfaces, depending upon the relation between the dry bulb temperature of the fresh air and the temperature desired within the enclosure A, and is either raised or lowered to a temperature such that when it is admitted to the enclosure A, it will admix with the air in the enclosure to maintain the desired temperature condition therein. A suitable thermally sensitive element, such as a thermostat, is indicated at 22, and is rconnected to a control mechanism 23 for controlling the temperature of the heat'- ing or cooling means in the conditioning chamber 2I. It is obvious that any suitable control mechanism may be used for this purpose. For example, in my above mentioned copending application, I have disclosed in Figure 8 thereof a temperature sensitive member T which is adapted to control the flow of fluid to a cooling coil 238, which control mechanism might be embodied in the present invention.
After the air passing through the conditioning chamber 2l has been heated or cooled to the proper temperature condition, it passes through a blower chamber 24, and from this chamber is forced under pressure into the enclosure A. The temperature of this air is such that, when admixed with the air present in the enclosure A, the temperature of the air in the enclosure A will be at any desired predetermined point, and 75 will be maintained at this point due to the temperature sensing mechanism 22.
Now, in order to provide the proper conditions y of humidity within the enclosure A, I have provided the recirculating conditioning unit I2, which may comprise a nlm evaporator or disc type of humidiner, such as is shown in detail in the copending application of Kemper P. Brace, Serial No. 690,393, iled May 5, 1932, which humidifler is controlled by a humidity sensing device indicated at 25, this device comprising either a dew point sensing mechanism, a hygrostat, or a diiostat, such as is disclosed in the copending application of Otto A. Labus and myself, Serial No. 319,764, led November 16, 1928, and which is adapted to control the motor 26, for controlling the speed of the discs 21 through the gear reduction mechanism 28. A fan 29 may also be provided for the purpose of drawing air through the conditioning unit I2. This fan is also operated from the motor 26, and is eiective only when the dew point or humidity sensing control 25 is actuated to operate the motor 26.
The conditioning' unit II is of relatively small capacity, ranging preferably between 5 per cent. to 20 per cent. of the capacity of the unit I2. The unit II performs the important function of introducing atmospheric air into the enclosure to maintain therein a static pressure higher than atmospheric pressure so as to prevent inilltration of outside unconditioned air into the enclosure through openings, such as the window openings III or the like. l
The conditioning unit II may be of the same type as that disclosed in Figure 18 of my above mentioned copending application, and may be provided with a heating element which is electrically connected to be responsive to the temperature control 22, or may comprise a cooling coil interposed in the chamber 2|, and adapted to have refrigerant or any similar medium circulated through the coil under the control of the temperature control device.
The relatively large conditioning unit I2 may be of any suitable design, and comprisesprimarily the fan 29 and the humidifying or evaporating apparatus 21. When this unit is in operation, the fan 29 circulates a relatively large volume o'f air from the enclosure A through the unit, this air being maintained in a closed circuit substantially out of contact with the atmosphere.
. The principal conditioning operation occurring in this last unit is that of saturating the circulated air therethrough, such being effected by relatively intimate mingling of air with the lm of water carried by the discs 21. If desired, a heating operation might also occur in this unit to supplement the thermal action of the tempered air ventering through the unit II. The recirculating conditioning unit operates only intermittently in accordance with the humidity regulation within the enclosure. If the humidity falls below a. predetermined value, the humidity sensing apparatus 25 establishes a circuit and starts the motor 26. This results in a relatively large Volume of air being drawn from the enclosure,
circulated through the conditioning unit, and returned to the enclosure and in passing through the unit this air is substantially saturated. If the humidity should rise above a predetermined value, this same control apparatus functions to open the circuit and thus prevent the drawing of any more air into the conditioning unit. The air entering throughA the unit II is substantially completely dehumidied byl means of dehumidifying coils or a. chemical absorbent or the like, and, if the humidity within the room A becomes greater than that desired, the dry air being forced in through the unit II will operate to reduce this humidity.
This principle of introducing a suillcient volume of conditioned atmospheric air into the enclosure to prevent infiltration, and of conditioning the air within the enclosure by treatment within a large capacity closed circuit conditioning unit, is capable of numerous adaptations to enclosures requiring diiferent air conditions, and is characterized by the ability to effect a decided economy in equipment and operating expense due particularly to the relatively small refrigerating load necessary to its operation. This can best be illustrated by assuming certain supposed values of temperature and humidity, which illustrate an improved method of adiabatic cooling which may be employed in certain adaptations.
For example, it will be assumed that the small conditioning unit I I introduces air into the enclosure at a 70 degree saturated temperature. It will also be assumed that when the conditioning unit I2 commences operation the air drawn into such unit from. the enclosure has a dry bulb temperature of 88 degrees, a dew point temperature of 74 degrees, and a wet bulb temperature of 78 degrees. It will be noted that there is no external control of the temperature of the water in the large conditioning unit, since this water assumes the Wet bulb temperature of the air. This recirculated air, in passing through the conditioning unit, will be substantially saturated,
with a result that its dry bulb dew point and saturated temperatures will all be approximately 78 degrees when this air is recirculated back into the enclosure. The adiabetic cooling effected in such a unit is equal to the heat equivalent of the water evaporated between the change from a 74 degree dew point to a 78 degree dew point. Hence, by virtue of this adiabatic cooling occurring within the large conditioning unit I2, the refrigerating load imposed upon the small conditioning unit II is greatly reduced. The relatively low temperature of the air introduced from this small conditioning unit II into the enclosure affords not only a comparatively dry cooling of the air handled by the unit II', but also results in a larger adiabatic cooling in the unit I2. The above method of conditioning can be obtained with either a fixed or iluctuating dry bulb temperature within the enclosure A,`de pending upon whether a xed thermostatic control, or a fluctuating dew point control is used at 22.
In Figure 2 I have illustrated a modified conditioning unit for use in the closed conditioning circuit connected with the enclosure A. This unit is indicated generally by the reference numeral I2', and comprises a heat interchanger 30, preferably of the same form as the interchanger indicated at 3II in Figure 17 of my copending application, which is supplied with a liquid, such as water, through the supply pipe 3I, the supply being controlled by the control valve 32 actuated in`accordance with. humidity conditions within the enclosure as sensed by the humidity sensingdevice 33.
The interchanger 36 comprises a plurality of coils through which the liquid is adapted to circulate, and the coils are spaced apart so that air entering the inlet 3| of the unit will pass about the coils and will thus assume the temperature of the liquid circulating therethrough. If desired,
suitable radiating fins may be formed'integral with the coils in order to provide a greater surface contact between the air and the liquidcooled coil surfaces. From the outlet of the interchanger 30, the liquid passes through the conduit to a plurality of spray nozzles projecting from the spray pipe 31. Any remaining liquid is conducted away through the drain pipe or outlet 38. Interposed between the spray pipe: 31 and the interchanger 38 are a plurality of Wire screens or grids indicated at 39 which are adapted to have disposed thereon suitable material for removing from the air any undesirable constituents entrained therein.
For example, the screens or grids may contain chemical absorbents for removing undesirable gases which might be formed in the enclosure A due to certain types of processes being carried on therein. After passing through the screens or grids, the air encounters the spray nozzles carried by the spray pipe 31, and is thoroughly saturated in the same manner as described in connection with the embodiment of Figure 1.
I am thus able to provide an effective cleansing and purifying means, in conjunction with the humidiiying means, for cleansing and purifying the recirculated air in the enclosure A to rid it of any undesirable impurities that may be entrained therein. The humidity control device 33 regulates the quantity of water passing through the spray pipe 31, and 1f-l'ius regulates the humidity within the enclosure A. Further, the use of the interchanger or tempering coil 30 serves to impart to the air a. temperature such that the desired humidifying condition may be 'readily imposed upon the air. 'Ibis/conditioning unit operates in conjunction with a. conditioning unit such as the unit l I of Figure 1, and the operation need not be described in detail here.
In the embodiment shown yin Figure 3, I have provided a temperature interchanger in place of the conditioning unit l2'. In this embodiment, the conditioning unit Il supplies to the enclosure A atmosphere which has been properly dehumidif'led and conditioned to provide the desired air conditions within the enclosure. However, it may be desirable towithdraw air from the enclosure A at certain times, due to any processes which produce undesirablegases or odors within the enclosure. This is effected by the interchanger indicated at 40 in Figure 3, which interchanger is similar in form to the interchanger 25| described in detail in connection with Figure 8 of my abovementioned copending application. Tne interchanger 40 is adapted to permit fresh pure air to enter through the inlet opening 4I of the interchanger, and out through the outlet opening 42 thereof into the enclosure A. The air which it is desired to remove enters the inlet 43 formed in the conditioning unit I2', passes along in proximity to the air entering through the interchanger, and is exhausted out of the outlet opening 44 formed in the unit. The air entering at 4l may be unconditioned fresh air, or may be air which has been previously conditioned in order to render the same dryl and cool. The interchanger performs the function of permitting the entering air to assume the temperature of the exhausted. air before it is admitted to the enclosure, thus eliminating the necessity of a heating or cooling medium.
If desired, the air being exhausted at the outlet 44 of the unit may be led through a suitable cleansing or purifying apparatus, and may then be returned to the inlet 4| of the interchanger,
and will assume the Vtemperature of the air passing through the outlet 43 from the enclosure before it is `admitted through inlet 42 to the enclosure. This recirculation and purification of the major portion of the air in the room may be controlled by means of a fan or other blower means, which may be operated by a humidity sensing device, a suitable time control, or similar means which will insure that the impurities contained in the air being exhausted from the room will be removed as soon as practicable, and will be replaced either by fresh pure air, or by the air exhausted from the enclosure afterv it passes through suitable purifying apparatus.
Considering now in detail the embodiment of my invention shown in Figure 4, I have disclosed therein a room or enclosure indicated at A', which is adapted to receive a suicient quantity of air through the inlet opening 50 to prevent infiltration through any window cracks or crevices in the enclosure, the pressure within the enclosure being just suiliciently greater than atmospheric pressure to prevent this infiltration. Suitable dampers 5|, positioned in the inlet, may be op;V
erated by a suitable pressure responsive device to insure that air will be supplied to the room when the pressure drops to atmospheric pressure or below. In this embodiment, the humidity of the air is determined by the conditioning unit 52, which preferably comprises suitable dehumidifying means, and which is controlled by a suitable humidity sensing device positioned within the enclosure A', the unit 52 being shown only diagrammatically in this embodiment.
The temperature control within the enclosure A' is effected by means of radiant cooling or heating produced by the coil of pipes indicated at 53, which are positioned in a recessed portion of the wall 54 of the enclosure. This coil of pipes 53 is of sufficient surface area so as to form a radiator, through which either cool orl Warm fluid may be passed, in accordancev with the temperature requirements within the enclosure A as determined by the temperature sensitive device 55.
The temperature sensitive device 55 is responsive to temperatures within the enclosure A', and is connected through suitable means to the pump 56 to control the operation thereof to permit more or less water to be forced into the radiant coolingcoils 53. The pump 56 is adapted to withdraw water from the coils 53 and to force this water upwardly into suitable discharge nozzles positioned in the cooling tower 51. This cooling tower 51 is similar to the cooling tower disclosed in my copending application, Serial No. 594,754, filed February 23, 1932.
Since the fluid withdrawn from the coils 53 is at a higher temperature than the water formed in the sump 58 of the cooling tower, it will be evident that the control of the fluid passing through this system Will function to control the temperature of the air within the enclosure A. The water withdrawn from the sump 58 is preferably forced through a coil 59 interposed in the conditioning unit 52, this water passing through the coil 59 being colder than the incoming air entering the conditioning unit, and thus providing a dehumidifying action within the unit. Of course it is to be understood that any suitable cooling means might be provided for regulating the temperature of the water in the coils 53 in accordance with the temperature of the thermally sensitive control device 55. A/
This particular method of two-stream air conditioning is particularly applicable to hotels, of-
ce buildings and the like, in which there are a plurality of rooms, each of which yis adapted to receive primarily conditioned air under suitable pressure conditions to prevent infiltration of the air from outside sources. Thus, I provide a conditioning unit indicated at 52 in Figure 5, corresponding to the conditioning unit 52 of Figure 4, which opens into a central hall or corridor 6U of an office building, hotel or the like. From the hall 60, this air is forced through suitable grilles or past the door opening into the individual rooms 6| in just suflicient quantities to prevent infiltration of outside air. This quantity is determinedby means of the pressure control switch 62, which corresponds to the switch |6 of Figure 1. This switch controls the dampers or louvres 5| for allowing suiiicient air to pass into the corridor 60 to prevent the aforesaid inltration. It is to be understood that any suitable blower means or fan means might be employed in both the embodiments of Figures 4 or 5, to provide the necessary pressure for forcing this air into the enclosure. The air thus forced into the rooms is under temperature and humidity conditions found to be generally desirable.
Disposed within each of the rooms 6| is a radiant cooling surface 64, which preferably is corrugated to present considerable area to the air within the room. A suitable temperature sensitive device 65 is positioned in each room adjacent the cooler 64, and may be adjustable to provide for different temperature conditions within each of the rooms, at the option of the occupant of the room. These temperature sensitive devices 65 are connected to suitable control valves 66, for regulating iniiow of vcoolant to the coils 64, these valves corresponding generally to the valve 32 shown in Figure 2. The coolant or tempering uid leaves the cooling tower 51' by means of the conduit 61, passes through the conditioning unit 52' to provide a dehumidifying coil therein, then passes through the inlet pipe 68 to each of the individual cooling coils disposed within the respective enclosures. Suitable outlets lead from each of the radiant coolers 64, and are connected by means of the return pipe 69 to the pump 56', which withdraws the water and forces it into the top of the cooling tower substantially as described in connection with Figure 4.
It is apparent, by the use of this system, that the temperature and humidity within each of the enclosures 6I may be varied within a limited range to suit the requirements of the occupant of the particular enclosure, the humidity being determined by the conditioning unit 52', and the temperature being determined by the radiant cooling surfaces 64.
In Figure 6 I have disclosed the principle of two-stream air conditioning applied to a situation wherein it is desired to maintain a relatively loW humidity, such as in drying rooms and similar locations wherein it is undesirable to have an appreciable quantity of moisture Ventrained in the air. Generally, in such situations it is desired that the humidity be kept below that present in the outdoor atmosphere, and in such situations the humidity in the enclosure is not ordinarily subjected to much variation. In such an adaptation, the small conditioning unit, indicated in this embodiment by the reference numeral 1D, will be provided with dehumidifying means, such as cooling coils, cold sprays, chemical absorbents, chilled surfaces or the like. By way of example, I have shown a series of cooling coils, indicated at 1|, disposed in the path of the incoming air stream,
and provided with a sluicing spray from the nozzles l2 for washing and sluicng the cooling coils in order to remove any frost or condensation that may be formed thereon. The ow of refrigerant to the cooling coils 1| is controlled by means of a control valve 13, responsive to conditions sensed by the humidity sensitive control device 14 positioned within the enclosure B.
Thus, when the humidity in the enclosure B falls below a predetermined point, the humidity control 14 will operate to shut olf flow of refrigerant to the coils 1|, by means of the control valve 13.
The humidity sensing device 14 is also adapted to control the operation of a pressure diaphragm mechanism indicated diagrammatically at 15, which is connected through a suitable control mechanism 16 for operating the damper or louvers 11 controlling the admission of air into the enclosure B from the conditioning unit 10. Suitable blower means may be provided for maintaining a pressure suicient to force the air into the enclosure, and a pressure responsive switch such as the switch I6 of Figure 1, may be employed for controlling this blower means.
A second conditioning unit, indicated at 80, is provided in proximity to the enclosure B and is closed to outside atmosphere. This conditioningunit comprises the coils 8| disposed within the unit and directly communicating with the enclosure B. The coils are adapted to serve as a radiant heating or cooling means for controlling the temperature in the enclosure in accordance with temperature sensing as determined by the thermal control member 83. This control member 83 is of the two-contact type, andin one position actuates the control valve 84 for admitting hot water to the coils 8|, and in its other position is adapted to actuate the control valve 85 for admitting cold water to the coils 8|. Suitable check valves 86 and 81 are interposed in the respective hot water and cold water supply lines 88 and 89 for preventing flow of water between these lines upon actuation of the respective control valves 84 and 85.
In an arrangement-such as disclosed in this embodiment, the dehumidifying action of the unit 10 will be subjected to the control of the humidity controlling device 14, whereby the air introduced into the enclosure by this unit will be at a relatively low dew point. Moreover, the spray apparatus, such as the spray pipe 31 of Figure 2, or the humidier 21 of Figure 1, will be eliminated from the large conditioning unit 80, and this unit will have heating and cooling means characterized by dry surfaces. For example, when the temperature is below that desired in the enclosure, warm water will be circulated through the coils 8| in order to raise the temperature of the air within the enclosure, without affecting the humidity thereof. When the temperature is above that desired, the thermally sensitive device 83 will function to actuate the valve 85 for controlling the iiow of cold refrigerant or liquid through the coils 8| in orderto lower the temperature in the enclosure B without aiecting the humidity of the air therein.
This principle is also adaptable to high humidity conditions within the enclosure, and I have shown a modified form of conditioning system for this purpose in Figure '7. In this gure I have `shown an enclosure B', corresponding to the enclosure B of Figure 6, which is provided with the closed conditioning unit 90, corresponding to the conditioning unit 88 for conditioning the air recirculated within the enclosure B', and which also has the small capacity conditioning unit indicated at 9|, which is adapted to torce atmospheric air, properly conditioned, into the enclosure B to maintain a pressure therein suicient to prevent iniiltration of outside unconditioned air.
In this embodiment, the entering fresh air passes into the inlet opening 92 of the conditioning unit 9|, and passes over the pre-cooling coils 93 positioned in this inlet. '.lhese coils 93 are adapted to effect a preliminary cooling upon the enteringuncondltioned outside air, and the air then passes into the dehumidifying chamber 9 4, passing over the coils 95 which are `adapted to contain liquid refrigerant circulated vthrough the compressor 96, the refrigerating load being maintained substantially constant. From Yhere the air is withdrawn by the blower 91, and forced into a heating chamber 99, wherein it passes over the coils 99 and is heated to the proper temperature, and forced in through the inlet opening |00 into the enclosure B'.
A pressure responsive switch, such as the switch I6 of Figure 1, may be employed for determining the quantity of air admitted to the inlet opening I 00 in the enclosure B',and may be connected to the fan 91 for regulating the speed thereof to y force a greater or lesser quantity of air into the enclosure, depending upon. the vpressure maintained within the enclosure with respect to atmospheric pressure. Thermally sensitive devices 0| and |02 'are adapted-to work conjointly fcr regulating the speed of a motor |99 connected to a pump |04. 'I'he pump |90 is adapted to force water through the coils 99 and thence through the coils 99 and back to the pump.
Considering now in detail the operation of the conditioning unit 9|, it will be assumed that air enters the inlet opening 92 having approximately a 95 degree dry bulb temperature and a 75 degree wet bulb temperature. This air passing over the coils 93 has its temperature reduced from 95 degrees dry bulb to 80 degrees dry bulb, while its wet bulb temperature is reduced to 69 degrees. After passing through the dehumidifying chamber 94, over the cooling coils 195, the air reaches the blower 91 having a 60 degree dry bulb temperature and a 56 degree dew point temperature. 'I'he air is then heated, by passing over the coils 99, which are substantially at the same temperature as the coils 93, and therefore are at a temperature of about degrees, wherein the air is heated to a temperature of approximately 70 degrees dry bulb, and since no humidity is added, retains the 56 degree dew point temperature. This air is admitted into the enclosure B. The coil 99 leading to the pump |94 is thus at a temperature of approximately 70 degrees, since the temperature of the liquid circulating in the coils 99 is reduced from 80 degrees to 70 degrees, due to the work done in raising the air from 60 degrees to 70 degrees. This liquid is circulated by the pump |04 back into the coils 93, at a temperature of approximately 70 degrees, and has its temperature raised to 80 degrees before it leaves these coils, due to the work done in cooling the air down to 80 degrees. This counter-current heating and cooling effect is brought out more in detail in the copending application of Kemper P. Brace, Serial No. 527,954, :tiled April 6, 1931. The temperature responsive devices 9| and |02 are adapted to control the operation of the motor |03, for controlling the rate of iiow of liquid to the coils 99 and 99, thus regulating the temperature produced in the air stream forced into the enclosure B' through the inlet opening |00. It is thus apparent that the temperature of the air may be accurately maintained by the use of this small capacity conditioning equipment It is to be understood that vthe conditioning unit 9|, with its controls |0| and |02, may be used in connection with any of the previous embodiments described. Forexample, this conditioning unit might be utilized in the embodiment of Figure 4, replacing unit 52, and the dehumidifying coils 95 might receive a supply of refrigerating iluid from a cooling tower 5l, as described in connection with Figure 4. The controls |0| and |02 can be adjusted to regulate the ow of fluid through coils 93 and 99 in any desired manner, depending upon the conditions required Within enclosure B.
In order to control the humidity of the air, the larger lrecirculatng conditioning unit is 'employed, and has disposed therein a plurality of spray pipes |06, whichare adapted to discharge directly into the path of the recirculating air streams. The ow of liquid to these pipes is controlled by means of the humidity sensitive device |0`|, which actuates the control valve |08 for regulating the ow of liquid to the spray pipes Under these conditions there will be a cooling eiected within the enclosure corresponding to the quantity of air supplied through the unit 9|, times the speciiic heat of air, times the difference between the interior temperature within the enclosure B' and the temperature of the entering air from the conditioning unit 9|, (assuming an 80 degree temperature in the enclosure there will be a diierence of 10 degrees), plus the water evaporated in the unit 90, times the latent heat of evaporation. This cooling, effected within the enclosure and within the conditioning unit 90, will greatly diminish the refrigerating load which must be carried by the conditioning unit 9|. 'I'he use of the same circulating system for both pre-` cooling and heating coils effects a great saving in the cost of constructing and operating the conditioning unit 9|.
If desired, the temperature control |02 may be changed to a humidity sensitive device, and the pump |04 may be controlled either by the thermostat in the delivery duct |00, indicated at |0|, to prevent the entering air from being too cold, or may be controlled by the humidostat |02 within the enclosure to prevent the room humidity from being too high.
It will be apparent, in the embodiment shown in Figures 6 and 7, that a great saving is eiected, due to the relatively small size of the conditioning units 10 and 9|, and also due to the fact that the refrigerating load on these units is relatively small, since only a small percentage of the total quantity of air is being handled. It is to be understood that various other means of controlling the operation of the conditioning unit might be employed in place of the thermally sensitive controls and the humidity sensitive controls, and the controls might be adapted to actuate other mechanism than that shown and described.
The embodiment shown in Figure 7 is also applicable to situations wherein the humidity of the air entering through the primary unit is controlled in accordance with the humidity desired within the enclosure, and the secondary unit subsequently adiabatically cools and humidies the circulated air. This is especially true in high humidity systems, wherein the vapor pressure within the room is greater than in outdoor atmosphere. In such situations, the water vaporized into the air by the secondary unit may be disposed of in one of two ways. For example, if the process being carried on within the enclosure utilized moisture absorbent materials, the excess vapor pressure derived from th'e secondary unit may be reduced by absorption.
However, for such installations I preferably provide, in a portion oi the walls defining the enclosure, a semi-permeable membrane, which might be earthenware, Jena Gerate permeable glass, or the like, and by the differential vapor pressure between the air in the enclosure and outdoor atmosphere, the vapor pressure in the room may be maintained at a desired constant value.
I do not intend to be limited to the exact detailsy shown and described in connection with th'e illustrated embodiments of my invention, inasmuch as the invention is directed broadly to the use of one conditioning unit to temper and condition only outdoor or atmospheric air to prevent infiltration, with another unit to react to conditions within the enclosure and to act upon the air handled and distributed by the first conditioning unit to effect an air energy saving due to the adiabatic cooling involved; and also to the use of. a system such as described, with direct superficial cooling in tlre enclosure. The invention is therefore to be construed as limited only by the spirit and scope of the appended claims.
l. Means for conditioning air in an enclosure to maintain a predetermined humidity temperature value by means of two streams of air currents intermingling within the enclosure, one of which streams is produced by an influx of fresh air at a pressure suicient to maintain exfiltration of the air from the enclosure to satisfy ventilation requirements and the other of which is produced by means setting up a circulatory stream within the enclosure, comprising means for introducing the stream of fresh air into the enclosure including a conduit and a fan, means responsive to humidity conditions in the enclosure for controlling the introduction of said fresh air through said conduit and further means responsive to pressure differences within and without said enclosure controlling the introduction of fresh air through said conduit when said humidity controlling means permits the introduction of fresh air, means for conditioning the fr esh air to impart the desired humidity thereto, said humidity responsive means also controlling said last mentioned means, means within said enclosure to produce the second stream of air to circulate and commingle with the first stream of air, means for supplying heating or cooling mediums to said last-named air stream producing means and a temperature responsive device in the enclosure for controlling the supply of the heating or cooling mediums thereto, whereby tlre required ventilation, humidity and tem-v perature are maintained in the enclosure.
2. The combination with an enclosure to be conditioned, of a conditioning chamber having substantially closed circuit communication with said enclosure for drawing air from said enclosure, passing it through said chamber, and returning it to said enclosure, means for creating such circulation of air through said chamber, means for Varying such circulation, means in said chamber for conditioning the air passing therethrough, a second conditioning chamber drawing air from the atmosphere and discharging into said enclosure, means in said second chamber for conditioning the air passing therethrough, and means responsive to humidity in said enclosure for controlling the circulation of air through one conditioning chamber.
3. The combination with an enclosure to be conditioned, of a conditioning chamber having substantially closed circuit communication with said enclosure for drawing air from said enclosure, passing it through said chamber, and returning it to said enclosure, means for creating such circulation of air through said chamber, means for varying such circulation, means in said chamber for conditioning the air passing therethrough, a second conditioning chamber drawing air from the atmosphere and discharging into said closure, means in said second chamber for modifying the humidity of the air passing therethrough, and means responsive to one of the conditions in said enclosure for controlling the circulation of air through one conditioning chamber.
4. The combination with an enclosure to be conditioned, o-f a conditioning chamber having substantially closed circuit communication with said enclosure for drawing air from said enclosure, passing it through said chamber, and returning it to said enclosure, a fan for creating such circulation of air through said chamber, means for varying such circulation, spray means in said chamber for conditioning the air passing therethrough, a second conditioning chamber drawing air from the atmosphere and discharging into said enclosure, means in said second chamber for conditioning the air passing therethrough, and means responsive to humidity in said enclosure for controlling the circulation of airthrough one conditioning chamber.
ROBERT B. P. CRAWFORD.