US2823015A - Heat exchange system for air conditioner - Google Patents

Description

.Feb. 11, 1958 E. P. wHlTLow HEAT EXCHANGE: SYSTEM FOR AIR CONDITIONER 5 Sheets-Sheet 1 Filed Oct. 8, 1951 IN V EN TOR.

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Feb. 11, 1958 E. P. wHlTLow v2,823,015

HEAE` EXCHANGE SYSTEM FOR AIR CONDITIONER 5 Sheets-Sheet 2 Filed Oct. 8v, 1951 INVENTOR.

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Feb. 1l, 1958 E.'P. wHrrLow 2,823,015

HEAT EXCHANGE SYSTEM FOR AIR CONDITIONER Filed Oct. 8, 1951 3 Sheets-Sheet 3 United States IPatent vC HEAT EXCHANGE SYSTEM FOR AIR CONDITIONER Eugene P. Whitlow, Evansville, Ind., assignor, by mesne assignments, to Arkla Air Conditioning Corporation, a corporation of Delaware Application ctober 8, 1951, Serial No. 250,369

4 Claims. (Cl. 257-3) The present invention relates to air conditioning and more particularly to apparatus for heating, cooling or dehumidifying the air in an enclosure as required.

A conventional type of air conditioning apparatus comprises a cooling element and a fan for circulating vair from the enclosure to be conditioned into heat exchange relation with the cooling element and then back to the enclosure. The air is cooled by the cooling element and a portion of the air directly contacting the element is cooled below its dew point to precipitate moisture and thereby dehumidify the air. If the air conditioning apparatus is controlled by the temperature in the enclosure, dehumidiication only occurs when coolingis required. In many localities where the humidity is normally high, such limited dehumidication is not sucient to produce a comfortable atmosphere in the enclosure.

Reheat schemes have heretofore been provided with temperature controlled air -conditioning units to reheat the air after it has been dehumidied by cooling to cause the apparatus to operate for longerperiods. The heat for such reheating of the cooled air may be supplied from any suitable source such as wasteheat rejected from the refrigeration system. A diiticulty with such reheat schemes has been to produce the greatest possible dehumidication with least possible cooling or, in other words, a maximum ratio of latent to sensible heat removal and to control the rate of reheat in accordance with requirements. The .cooling and dehumidifying requirements may vary from hour tohour and from day to day and usually some degree of cooling :is Vrequired when the humidity is high. However, the cooling requirements may be so small that very short periods of operation of the refrigeration system are sufficient to cool the air but continuous operation of the apparatus is necessary to meet the humidity requirements. In an ideal reheat arrangement the refrigeration system would operate continuously at varying cooling and dehumidifying conditions and adjust the ratio of latent to sensible heat removal to exactly balance the cooling and dehumiditying loads until the cooling load approaches zero at which time the air leaving ywould have the same temperature as air entering the apparatus. Suchl an ideal reheat arrangement has not been economically feasible. l

One reheat scheme for approaching this ideal condition comprises a run-around? coil arrangement having a precooling section in front of the evaporator, a reheat sectionv behind the evaporator in the directionqof air flow and a pump for continuously circulating arheat eX- change medium through the coil sections successively. ln operation the precooling coil removes heat from the relatively warm air to reduce its temperature before -it contacts the cooling element and the reheat coil delivers the absorbed heat back to the relatively cold air to increase its temperature after it leaves the cooling element. With such an arrangement the precooling coil will cool the air from room temperature to some tem- ICC perature approaching its dew point so that most of the cooling by the cooling element produces dehumidication but the arrangement inherently cannot compensate for the sensible cooling necessarily accompanying dehumidication by the cooling element. Therefore, the air being conditioned will be cooled and its temperature will gradually `fall even though a high ratio of latent to sensible heat removal is attained to dehumidify at a high rate.

One of the objects of the present invention is to provide a heat exchange system in an air conditioning unit for heating the air to be conditioned or reheating dehumidified air to its initial temperature and maintain the unit in continuous operation until the humidity is decreased to the desired level.

Another object is to provide a reheat arrangement of the type indicated for precooling the air prior to dehumiditication and utilizing the heat removed from the air for reheating the air after dehumidification to reduce the load on the refrigeration system and dehumidify the air at an increased rate.

Another object is to remove heat from the air prior to dehumidiiication, deliver the removed heat back into the air after dehu-midification and supply additional heat in accordance with requirements to maintain the air in the enclosure at substantially the same temperature.

Another object is to provide a reheat arrangement of the type indicated which is adapted to vary the ratio of latent to sensible heat removal in accordance with requirements.

Still another object is to provide a reheat arrangement of the type indicated which utilizes waste heat from the refrigeration system to supply the additional heat necessary to maintain the air leaving the apparatus at the same temperature as the air entering the apparatus.

These and other objects will become more apparent from the following description and drawings in which like reference characters denote like parts throughout the several views. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and not al definition of the limitation of the invention, reference being had for this purpose to the appended claims. In the drawings:

Fig. l is a side elevational view of an air conditioning apparatus incorporating the heat exchange system of the present invention.

-Fig 2 is an enlarged sectional View of the selective valve means for shifting from heating to cooling or vice versa.

Fig. 3 is a view of an air conditioning unit similar to Fig. 1 and showing a heat exchange system utilizing waste heat from the refrigeration system to reheat the air cooled and dehumiditied by the latter.

Fig. 4 is adiagrammatic view of the cooling element of a conventional air conditioner and indicating the percent of latent heat removal for a typical condition.

Fig. 5 is a diagrammatic view of the improved heat exchange system of the present invention for dehumidifying air at a higher rate and maintaining the air leaving the apparatus at thensameVV temperature as the air entering the apparatus.

Referring to the drawings, the invention is shown applied to yan air conditioning unit 7 for conditioning air in an enclosure 8. The air conditioning unit 7 comprises a conduit 9 for receiving air from the enclosure 8, a conditioning chamber 10, and a conduit 11 for delivering air back to the enclosure. The air to be conditioned is circulated in the direction indicated by arrows through the enclosure 8, conduit 9, conditioning chamber 10 and conduit 11by means of an electric motor operated blower 12.V As the air flows through the conditioning chamber it is conditioned by elements mounted therein comprising a filter 13, a cooling element 14, and a humidifier 15. The cooling element 14 constitutes the evaporator of a heat operated absorption refrigera Vtion system operated by steam from a suitable source such as the boiler 16 and controlled by a selective valve means 17.

The heat operated refrigeration system is preferably of the type illustrated and described in United States Letters Patent 2,282,503 of Albert R. Thomas et al. issued May 12, 1942, entitled Refrigeration. Such an absorption refrigeration system operates in a partial vacuum and utilizes water as a refrigerant and a salt solution as an absorbent. Sufce it to state herein that the refrigeration system comprises a generator 1.8, a condenser 19, evaporator 14, absorber 20 and heat exchanger 21 intercon nected to provide a closed circuit. The generator 18 has a series of upright tubes 22 connected at their lower ends to an inlet chamber 23 for absorption solution and con nected at their upper end to a separating chamber 24. Surrounding the tubes 22 is a shell 25 providing a heating chamber 26 therebetween.

Steam is supplied to the heating chamber Z6 from the boiler 16 through the selective valve means 17 and conduit 27 and heat is transferred from the steam through the tubes 22 to the absorption solution therein to expel refrigerant vapor therefrom. The refrigerant vapor rises through the tubes 22 at considerable velocity and raises the absorption solution at the sides of the tubes by a climbing film action. The refrigerant vapor ows from the separating chamber 24 to the condenser 19 through a conduit 23 and liquefied refrigerant flows from the condenser through any suitable iiow control arrangement such as the orifice device 29 to the evaporator or cooling element 14. The orifice device is described and claimed in the United States Letters Patent to N. E. Berry 2,563,575 issued August 7, 1951, and entitled Absorption Refrigera tion, and operates to permit concurrent iiow of liquid refrigerant and non-condensable gases from the condenser 19 to the evaporator or cooling element 14 while maintaining a difference in pressure therebetween. The cooling element or evaporator 14 comprises a plurality of finned tubes 14a connected between spaced headers 30 and through which the liquid refrigerant flows by gravity and is evaporated by a heat exchange through the walls of the tubes from the air. Refrigerant vapor flows from the evaporator or cooling element 14 to the absorber 20 through passages or headers 30.

Absorption solution weak in refrigerant or, in other words, a concentrated salt solution, flows by gravity from the separating chamber 24 to the top of the absorber 2t) in a path of iiow including the conduit 31, heat exchanger 21 and conduit 32. The solution absorbs the refrigerant vapor in the absorber 20 and this solution strong in refrigerant, or, in other words, dilute salt solution, ows by gravity from the bottom of the absorber 20 to the inlet chamber 23 at the bottom of the generator 18 in a path of ow including the conduit 33, heat exchanger 21, conduit 34, leveling vessel 35 and conduit 36. The absorption of refrigerant Vapor in absorber 20 maintains a relatively low pressure and temperature in the evaporator 14 to produce a refigerating effect and the low pressure in the evaporator and absorber is maintained by liquid columns in the conduits 32 and 33.

The absorber 20 and condenser 19 are cooled by cooling water from any suitable source such as a city water main or cooling tower. The cooling water enters the cooling coils 37 in the absorber 20 through a conduit 38 and is discharged from the absorber through a conduit 39 connected to the condenser 19. Cooling water is discharged from the condenser 19 through a conduit 40 for flow back to the cooling tower or to a suitable waste pipe. Thus, the cooling water passes through the absorber 20 and condenser 19 in succession to cool both of the heat rejecting parts of the refrigerating system.

In accordance with the present invention, a heat exchange system in the form of a closed run-around circuit is provided which is adapted to heat the air during winter operation or to reheat dehumidied air from the cooling element 14 during summer operation. The closed heat exchange system comprises a heat exchange element or section 42 in front of the cooling element 14 in the conditioning chamber 10, a second heat exchange element or section 43 behind the cooling element 14 in the direction of air flow and a third heat exchange element 44 remote from the cooling element 14 and out of the path of air flow. Each of the heat exchange sections 42 and 43 is illustrated in the form of serpentine coils and preferably one end of a series of such coils is connected by a header 45 and the opposite ends of the coils are connected by a header 46. The heat exchange section 44 is also in the form of a coil 47 enclosed in a heating chamber 48 and connected at one end to the outlet Afrom the coil 42 by a conduit 49 and connected at its other end to the inlet to the coil 43 by a conduit 5t). The outlet from the coil 43 is connected to the inlet of the coil 42 by a conduit 51 to provide a closed circuit. The closed heat exchange system contains a fluid `such as water which is circulated by means of a pump 52 in the direction shown by arrows. The coils 42 and 43 are connected and arranged in the closed heat exchange system to ow the heat exchange fluid in a direction countercurrent to the direction of air flow through the conditioning7 chamber 10 as shown in Figs. l and 5.

The selective valve means 17 illustrated in detail in Fig. 2 is the same as that described and claimed in a copending application of Lowell McNeely, Serial No. 44,381, tiled August 14, 1948, now Patent No. 2,581,122, granted January l, 1952, and entitled Air Conditioning. The selective valve means comprises a chamber 53 having an inlet port 54 connected to the boiler 16 by a steam pipe 55, an outlet port 56 connected to the heating chamber 26 of the generator 18 by conduit 27, an outlet port 57 connected to the heating chamber 48 of the heat exchange section 44 by a conduit 58 and a valve element 59 for selectively closing one of the ports 56 or 57 and opening the other port, respectively. The valve element 59 is mounted on a shaft 60 having one end projecting through the chamber 53. A crank arm 61 on the end of the shaft 60 is connected by a link 62 to the crank of a motor 63 .for shifting the valve element from one to the other of its two positions. Thus, when the valve element 59 is in the position illustrated in Fig. 2, steam is delivered from the boiler to the generator 18 of the refrigeration system and when the valve element is shifted to close the port 56, steam is delivered from the boiler to the heating chamber 48 of the heat exchange system.

The selective valve 17 is also adapted to supply heat to the closed heat exchange system simultaneously with the supply of heat to the generator 8 of the refrigeration system. For this purpose the selective valve 17 is provided with a by-pass conduit 64 connecting the chamber 53 to the conduit 58 around the valve element 59. An orifice 65 is provided in the by-pass conduit 64 to limit the amount of steam which may flow therethrough and a second throttling valve 66 is provided in the by-pass conduit for modulating the flow of steam therethrough. The by-pass conduit 64 has a depending loop 67 for receiving condensate from the heating chamber 48 and a drain valve 68 connected to the bottom of the loop. The depending loop 67 provides a liquid trap to block the .conduit when the drain valve 68 is closed and open the conduit for the flow of steam therethrough when the drain valve is open.

Operation of the air conditioning unit 7 may be controlled manually or by any suitable control means such as that disclosed in the McNeely application Serial No. 44,381 referred to above. For example, a selective controller 70 may be provided having a lever 71 for manually selecting heating or cooling with thermostatic switch means for starting and stopping the selected system, or a thermostatic switch means may be provided for automatically shifting from heating to cooling. Dehumidication may be controlled by a humidistatic switch 72 for initiating operation of the refrigeration system when the temperature in the enclosure is satisfactory but the humidity is high. Such control means are shownV in the McNeely application referred to above and in other patents but are not essential to the present invention except to initiate operation of the heating and cooling systems as required.

However, the regulation of the amount of additional heat supplied to the heating system during a reheating operation is a feature of the present invention. As illustrated in'Fig. l, this regulating means comprises a thermostat having a bulb 73 subjected to thetemperature of the circulating air, a bellows 74, see Fig. 2, connected to operate the throttling valve 66 in the by-pass conduit 64 and a spring 75 opposing the movement of the bellows 74. The bulb 73 of the thermostat may be located anywhere in the path of the circulating air and is adapted to operate the valve 66 to supply heat to the heating system at the rate required to reheat the dehumidified air to the temperature of the air entering the conditioning unit. It will be understood that the controller 70 will operate through the motor 63 to actuate the selective valve means 53 for heating or cooling as required and that the humidistatic switch 72 will initiate operation of the refrigeration system, blower 12 and circulating pump 52 when dehumidication without cooling is desired. One form of the invention having now been described in detail, the mode of operation is explained as follows.

When it is desired to heat the enclosure S the selective valve element 59 is shifted from the position illustrated in Fig. 2 to close port 56 and open port 57 operation of blower 12 is initiated to circulate air in the enclosure 8 through the conditioning chamber in the direction indicated by arrows; operation of pump 52 is initiated to circulate the iluid in the closed heat exchange system and through heat exchange coils 43 and 42 in a direction counter-current to the direction of air flow; and a heating means is initiated to heat the boiler 16 and generate steam. As explained above, such functions may be performed manually or automatically through a suitable control means such as the thermostatic controller 70 illustrated in the enclosure 8 to be conditioned. Steam from the boiler 16 then ows through the steam pipe 55, chamber 53 yof selective valve means 17, port 57 and conduit 58 to the heating chamber 48 of the heat exchange system. Fluid in coil 47 of the heat exchange section 44 is heated by the exchange of the latent heat of the steam condensing on the coil and llowing through the walls thereof'. The heated fluid is continuously circulated by pump 52 through the conduit 5u, heat exchange coil section 43, conduit 51, heat exchange coil section 42 and conduit 49 back to the coil 47 of the heat exchange section 44. Coil 42 preheats the air flowing through the conditioning chamber 10 and coil 43 further heats the air to its nal temperature. It will be noted that the fluid in the closed heat exchange system at all times flows in a direction countercurrent to the direction of air ow so that there will be a temperature gradient between all portions of the heat transfer sections 42 and 43 and the air flowing in heat exchange relation thereto. The apparatus continues to operate in the manner described until the air in the enclosure 8 is increased to the desired temperature at which time the heating period is terminated. Thus, the apparatus operates intermittently to maintain a substantially constant temperature in the enclosure 8 and the periods of operation vary in accordance with the load as affected by the outside temperature.

When it is desired to cool the enclosure 8 the selective valve element 59 is shifted to the position illustrated in Fig. 2 to open port 56 and close port 57. The heating means for the boiler 16,- the pump 52 and the blower 12 are initiated as previously explained. Steam then flows from the boiler 16 to the generator 18 of the heat operated absorption refrigeration system through the steam pipo 5S, chamber 53' and Vport S6 of thevselective .valve means 17 and conduit 27 tothe heating chamber'26. Heat applied to the generator 18 supplies refrigerant to the cooling element 14 and absorbent to the absorber 20. Thev high ainity of the refrigerant for absorbent reduces the vapor pressure and temperature of evaporation of the refrigerant in the evaporator or cooling element 14.

Air circulated by the blower 12 from the enclosure 8l When the cooling load is low and the humidity is high, the periods of operation of the refrigeration system maynot be enough to sufficiently dehumidify the air for comfort conditions. In other words, when the temperature in the enclosure 8 is satisfactory, it is many times desirable to dehumidify the air to reduce the humidity. When dehumidication without cooling is desired, the refrigeration system is initiated either manually or by means of a humidistatic switch 72.. Simultaneously, operation of the pump 52 and blower 12 is initiated and the drain valve 68 is opened to drain the liquid trap in the by-passk conduit 64 around the selective valve element 59. Steam is then supplied from the boiler 16 to both the generator 18 of the refrigeration system and heating chamber 48 of the heat exchange element 44, the steam owing to heating chamber 48 from chamber 53 of the selective valve means 17 through the by-pass conduit 64 to conduit 58.

Air flowing through the conditioning chamber 10 is iirst precooled by the heat exchange coil 42 to reduce its temperature prior to its contact with the cooling element 14 of the refrigeration system. The air next contacts the relatively cold tubes 14a of the cooiing element 14which reduces the temperature of a large portion of the air below its dew point to precipitate moisture therefrom and' thereby dehurnidify the air. The relatively cold dehumidihed air then contacts the reheat coil section 43 of the closed heat exchange system which reheats the air to its initial temperature. The heat delivered by the reheat coil section 43 is supplied by the huid -circulating in the closed heat exchange system. All of the heat removed from the air by the precooling coil section 42 is contained in the circulating fluid and is delivered back to the air by the reheat coil section 43'andonly an amount of heat is supplied to the uid by the heat exchange coil 47V that is necessary to compensate for the sensible heat removed by the cooling element 14 of the refrigeration system. Therefore, with the closed heat exchange system of the present invention, the load on the refrigeration system is decreased by the amount of cooling performed by the precooling coil 42.

Usually when dehumidiication is required, some cooling is also necessary and the ratio of latent to sensible heat removal varies from hour to hour and from day to day. Thus, the amount of additional heat supplied to the circulating iluid in the closed heat exchange system must be varied in accordance with particular operating conditions. To this end, steam is supplied from chamber 53 of thev selective valve means 17 to the heating chamber 48 of the heat exchange element 44 at a rate controlled by the orifice 65 and throttling valve 66 in by-pass conduit 64. The oriiice 65 will supply steam to the heatingl chamber 48 at a maximum rate required for reheat and the throttling valve 66 is adjusted in accordance with operating conditions to vary the amount of steam supplied. To

7 this end, bulb 73 of the control thermostat responds to the temperature of the circulating air and operates through the bellows 74 to adjust the throttling valve 66. At a lower temperature limit, for example, 79 F., the throttling valve 66 will be wide open and at an upper temperature limit, for example, 82 F., the throttling valve will be closed. At some temperature between 79 and 82 F. an equilibrium condition will be reached at which the throttling valve 66 will supply the required amount of additional heat to reheat the air to its original temperature. The apparatus continues to Operate in the manner described to dehumidify and reheat the air until the humidity in the enclosure 8 is decreased to a desired value and the throttling valve 66 is constantly adjusted during such dehumidication to vary the amount of heat added. As in the case of heating as explained above, the iluid circulating in the closed heat exchange system always flows in a direction countercurrent to the direction of air ilow so that the coolest air contacts the coolest portion of the precooling coil section 42 and the hottest air contacts the hottest portion of the reheat coil 43 to provide a temperature diierential between all portions of the coil sections and the air flowing therethrough.

The improvement in the ratio of latent to sensible heat removal and control of the outlet air temperature is shown in the diagrammatc views illustrated in Figs. 4 and S of the drawings. Fig. 4 illustrates the effect of the cooling element 14 of a standard absorption refrigeration system in dehumidfying the air at one typical set of operating conditions. It will be noted that air enters the cooling element 14 at a dry bulb temperature of 80 F. and leaves the unit at a dry bulb temperature of 61 F. and that the latent heat removal or amount of cooling used for dehumiditication is 28%. Fig. 5, on the other hand, illustrates applicants reheat arrangement ap plied to the cooling element of the same standard refrigeration system for conditioning air under the same operat ing conditions and shows a decrease in the sensible heat removal from 41,500 B. t. u. to 29,555 B. t. u., and an increase in the latent heat removal from 16,100 B. t. u. to 21,750 B. t. u. r an increase from 28% to 42.4% latent heat removal by cooling element 14 and an overall latent heat removal of 100%.

With the arrangement illustrated in Fig. 1, a portion of the steam generated in boiler 16 is bled through the by-pass conduit 64 to the heating chamber 48 of the heat exchange element 44 With a resulting loss to the capacity of the refrigeration system. Although this loss to the refrigeration system may be avoided by providing an additional heater for the boiler 16, such additional heat constitutes a loss in the overall operating eciency of the air conditioning unit. In accordance with the arrangement illustrated in Fig. 3 of the drawings, waste heat from the refrigeration system is utilized to provide the additional heat to the heat exchange reheat system.

The air conditioning unit illustrated in Fig. 3 is substantially identical with that illustrated in Figs. l and 2 except that an additional heat exchange element 80 is provided in the circuit of the closed heat exchange system between the sections 42 and 43 in the direction of uid ow, the by-pass conduit 64 yof the selective valve means 17 is eliminated, the cooling water from the condenser 19 is caused to flow in heat exchange relation with the heat exchange element 80 and a different control arrangement 81 is provided for regulating the amount of heat added to the fluid in the heat exchange system. The heat exchange element 80 is substantially identical with the heat exchange element 44 and comprises a coil 82 and a heating chamber 83 enclosing the coil. The inlet end of the coil 82 is connected to the outlet from the coil section 42 by a conduit 49 and the outlet from the coil is connected to the pump 52. Conduit 40 for the cooling water from condenser 19 is connected to the bottom of the heating chamber S3 and a conduit 85 connects the top of the heating chamber :to a cooling tower or waste pipe. A by-pass conduit 86 connects conduits 40 and 85 and a throttling valve 87 at the junction of conduits 40 and 86 regulates the flow of cooling uid through the by-pass. When the valve 87 is closed all 0f the cooling fluid from the condenser will ow through the heating chamber 83 in heat exchange relation with the coil S2. When the valve is fully open substantially all of the fluid will liow through the by-pass 86. At any intermediate positions of the valve 87 the uid will iiow proportionately through the heating chamber 83 and by-pass 86, respectively. Valve 87 is controlled by a thermostat having a bulb S8 responsive to the temperature of the air in the enclosure 8, a bellows 89 connected to open valve 87 and a spring 90 opposing bellows 89 for actuating the valve toward closed position.

The arrangement illustrated in Fig. 3 operates to heat or cool the air in enclosure 8 in the same way as the arrangement illustrated in Fig. 1 and described above. When dehumidication without cooling is desired the air to be conditioned is precooled by the fluid in heat exchange coil 42 and the heat removed is delivered back to the air by the reheat coil 43. However, in the embodiment of the invention illustrated in Fig. 3, the .additional heat is supplied to the circulating fluid by the heat exchange element utilizing waste heat from the refrigeration system. To this end, cooling water from the condenser 19 is delivered through conduit 40, heating chamber 83 of heat exchange element 80 and `outlet conduit 85'. The relatively warm cooling water, for example, F., flows in heat exchange relation with the fluid in coil 82 at 73 F. to supply the additional heat to the uid. When the temperature of the circulating air increases, valve 87 is operated to divert a portion of the cooling water from the condenser 19 through the by-pass conduit 86 to decrease the amount of heat added in the heat exchange element 80. As the temperature of the air decreases, the valve S7 is operated to decrease the amount of uid owing through the by-pass 86 and increase the amount of uid owing through the heating chamber 83, Thus, the control S1 operates to vary the amount of heat added to the closed heat exchange system in accordance with requirements to maintain a substantially constant air temperature in the enclosure 8.

It will now be observed that the present invention provides a closed heat exchange system adapted to heat the air in the winter and cooperate with the cooling element to dehumidify and reheat the air in the summer. It will also be observed that the present invention provides a heat exchange system of the type indicated which operates to dehumidify the air at a high rate and deliver air back to the enclosure without decrease in temperature. It will also be observed that the heat exchange system of the present invent-ion precools air prior to dehumidiiication and utilizes the heat removed from the air to reheat the air after dehumidication to reduce the load on the refrigeration system. It will still further be observed that the present invention provides a reheat arrangement which utilizes waste heat from the refrigeration system to increase the overall thermal eciency of the air conditioning unit and decrease the load on a cooling tower when used.

While two embodiments of the invention are herein illustrated and described, it is to be understood that further modications may be made in the construction and arrangement of elements without departing from the spirit or scope of the invention. Therefore without limitation in this respect, the invention is detined by the following claims.

I claim:

l. In an air conditioner, conduit means providing a conditioning chamber through which a stream of air passes, a heat operated refrigeration system having a cooling element in the chamber, a heating system containing a heat exchange tluid and having a heat exchange section in the chamber at the front of the cooling element in the direction of the air stream, a heat exchange section in the chamber at the rear of the cooling element, a heat exchange section outside the air stream, conduits connecting the sections to provide a closed run-around circuit, means for circulating the fluid through the heating system, a source of heat, and selective means for delivering heat from said source to the refrigeration system or the heat exchange section of the heating system outside the air stream or to both the refrigeration system and heat exchange section of the heating system simultaneously.

2. In an air conditioner, a path for air to be conditioned, means for owing air through said path, a heat yoperated refrigeration system having a cooling element in the path of air llow, a heating system providing a closed circuit for a heat exchange fluid and comprising a heat exchange section in front of the cooling element in the path of air flow, a heat exchange section at the rear of the cooling element and a heat exchange section `outside the path of air llow, means for circulating the heat exchange fluid through the heating system, a source f heat, selective valve means for delivering heat from said source to the heat operated refrigeration system or heat exchange section of the heating system remote from the cooling element, a by-pass around the valve means for supplying heat to the refrigeration system and heating system simultaneously, and auxiliary valve means in the by-pass for regulating the amount of heat supplied from said source through the bypass.

3. In an air conditioner, an air conditioning chamber, means for circulating air through the chamber, a heat operated refrigeration system having a cooling element in the chamber, a heating system providing a closed circuit for a heat exchange lluid and having a heat exchange section in the chamber at the front of the cooling element in the direction of air flow, a heat exchange section in the chamber at the rear of the cooling element in the direction of air llow and a heat exchange section outside the chamber, means for circulating the heat exchange lluid through the heating system, a source of heat, selective valve means for delivering heat from said source to the heat operated refrigerati-on system or heat exchange section of the heating system outside the chamber, a by-pass around the valve means for supplying heat from said source to the heating system simultaneously with its supply to the refrigeration system, a

throttling valve in said by-pass, and means responsive to the temperature of the circulating air for controlling the throttling valve in the by-pass to regulate the amount of heat supplied to the heating system.

4. In an air conditioner, a heat operated refrigeration system having a low temperature cooling element and a high temperature heat rejecting element, a heating systern providing a closed circuit for a rst heat exchange fluid and having a first heat exchange section in front of the cooling element, a second section at the rear of the cooling element and a plurality of sections remote from the cooling element, means for circulating air through the first section, cooling element and second section of the heating system in succession, means for circulating the heat exchange fluid through the plurality of remote sections, the second and rst sections of the heating system in succession, a source of heat, selective valve means for directing heat from said source to the heat operated refrigeration system or one of the remote heat exchange sections of the heat-ing system, respectively, means for circulating a second heat exchange lluid in heat exchange with the heat rejecting element 4of the refrigeration system and other remote section of the heating system, and means responsive to the temperature of the circulating air for regulating the amount of the second heat exchange luid delivered from the heat rejecting element of the refrigeration system to the heat receiving element of the heating system.

References Cited in the le of this patent UNITED STATES PATENTS Re. 22,100 Brace May 26, 1942 2,094,221 Shaller Sept. 28, 1937 2,112,520 Crawford Mar. 29, 1938 2,200,118 Miller May 7, 1940 2,216,475 Metcalf Oct. 1, 1940 2,244,551 Crawford June 3, 1941 2,257,975 Miller et al Get. 7, 1941 2,286,605 Crawford June 16, 1942 2,304,243 Crawford Dec. 8, 1942 2,352,930 Anderson July 4, 1944 FOREIGN PATENTS 468,931 Great Britain July 15, 1937

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