US2150224A - Refrigerating apparatus - Google Patents

Description

March 14, 1939. H. B. HULL REFRIGERATING APPARATUS Filed July 51, 1953 -3 Sheets-Sheet l INV g 3 m 2 8 8 2 2 S 8 S S 2 8 g 1 8 2 is 8 J 8 u 5.... 2 a

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March 14, 1939. H. B. HULL REFRIGERATING APPARATUS Filed July 31, 1933 3 Sheets-Sheet 2 llll "A" ATTORNEYW Patented Mar. 14, 1939 UNITED STATES 2,150.22; 7, nnraresm'rmo mmzrus Harry B. Hull, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application July 31, 1933, Serial No. 682,9" 7

x X 20 Claims.

ratus and more particularly to apparatus .for

cooling air, as, for instance, in rooms or the like.

One of the objects of the present invention is to provide an improved apparatus for cooling and circulating air in rooms or the like.

Another object'of this invention is to provide an improved apparatus which automatically circulates the air in the room, reduces the humidity and maintains said air at. a predetermined temperature.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein apreferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a vertical cross sectional view, semidiagrammatic in character, of a room cooler or air conditioner embodying my invention;

Fig. 2 is a view somewhat similar to Fig. 1; but disclosing a difierent arrangement of air conditioning coils and casing;

Fig. 3 is a view similar to Fig. 2, but showing automatic controls applied thereo;

Fig. 4' is' a view of a unitary portable air conditioner embodying features disclosed both in Figs. 1 and 2 as'well as further features; f

Fig. 5 is a view in elevation of an apparatus for controlling the operation of the air conditioners herein disclosed in accordance with the temperature of the air; v

Fig. 6 is a cross sectional view of the water valve shown in Fig, 3; n

Fig. '7 is a diagrammatic representation of the application of the device shown in Fig. 5 to the various air conditioner. and

Fig. 8 is a diagrammatic representation of a modified portion of Fig. 7.

In the particular embodiment shown in Fig. 1 air is circulated through a cabinet I by means of an electrically operated fan or means I62 which draws the air through louvers I64, through an air treating zone I66 and discharges the treated air through a screened opening I68 provided in the top of the cabinet I60. A plurality of cooling coils I10 connected in series by means of pipes are adapted to cool the air to a temperature below its dew point so that when the air is rewarmed it will be at the desired relative humidity, which rewarming may be accomplished by a plurality of coils I15 disposed above the from striking occupants of the cooled condenser I95 through pipe I 96.

coils I10 thus preventing cold saturated air room. Refrigerant is circulated in a closed path through the coils I10 by means of a refrigerant circulating element I under the control of an expansion valve I 8|. The element I80 delivers the liquid refrigerant through pipe I and withdraws the gaseous refrigerant through pipe I81. The element I80 comprises a compressor I operatively connected with a motor I9I by belt I92. The motor I9I is controlled by a switch I93 actuated by a thermostat I94 in response to the temperature of pipe I81. The compressor I90 compresses the gaseous refrigerant and delivers it to a wai -fir e gaseous refrigerant is liquefied in the condenser I95 and from which it is delivered through pipe I85 to the coils I10. The heating coils I15 are heated by water passing through cofl 200 used for liquefying the refrigerant in the condenser I95. The coil 200 used for liquefying the refrigerant is provided with an inlet 20L The water then passes through pipe 208, heating coils I15 to an outlet pipe 2| 0. The water inlet' 20| may be connected to any suitable water pressure system while the outlet pipe 2I0 may be connected to the waste system. In the apparatus shown in Fig. 1, the electricallyoperated fan I62 draws the air through the louvers I64 and. some air through cutaway portions of the cabinet I60 as shown at 2I I. The air is then forced through an operiing 2I5 provided in a drip or moisture pan 2| 6 whence the air is forced along the loops of coils I10 and coils I15 and is then discharged through the screened opening I68. A bonnet or hood 2l9 is provided to prevent moisture from the coils from dripping through the opening 2I5. A thermostatic switch of the type shown in Fig. 5- may be employed for controlling the operation of the electrically operated fan I62 and the flow of current to the contacts of the switch I93 as diagrammatically shown in Fig. '7. Thus it will be noted that refrigerant is circulated through the air treated zone for cooling the air to a temperature below its dew point and'that the air is later rewarmed so that the discharged air will have the desired relative humidity and that in rewarming said air a part of the heat, of

treating zone 226. The air is circulated through the treating zone by means of an electrically driven fan or means 238 and is later discharged through duct 23! provided with sound insulating material 232, which duct leads to a screened opening 233 through which the air is discharged into the room being cooled. In the present instance I have provided a water flow apparatus comprising a plurality of longitudinally disposed coils 240 ,connected in series by means of pipes 24! and 242.

The water flow apparatus is arranged for precooling the air entering the air treating zone 225. The water flow apparatus is provided with an inlet pipe 243 and outlet pipe 244. The air circulating through the treating zone is precooled by the water flow apparatus and is later cooled to the desired temperature by means of a refrigerant circulating apparatus comprising a plurality of longitudinally disposed cooling coils 250 located above the water flow apparatus in the air treating zone 226. Refrigerant is circulated through the coils 250 by means of a refrigerant circulating element 255 under the control of an expansion valve 256. The element 255 delivers refrigerant through a pipe 258 and withdraws the gaseous refrigerant through a pipe 260. The element 255 comprises a compressor 26! operatively connected with a motor 262 by means of belt 263. The motor 262 is controlled by a switch 265 actuated by a thermostat 261 in response to the temperature of pipe 269. The compressor 26l compresses the gaseous refrigerant and delivers it to an air cooled condenser 269 wherein it is liquefied and from which it is delivered to a receiver 21 to which the pipe 258 is connected. If desired, automatic means for controlling the operation of the elec trically operated fan 230 and for controlling the flow of current to contacts of switch 265 of the type shown diagrammatically in Fig. 5 may be employed for controlling the operation of the apparatus shown in Fig. 2 in a manner somewhat similar to that indicated in Fig. 7.

. In Fig. 3 there is shown a modified form of room cooling apparatus, adapted to be placed in a room or enclosure, comprising a cabinet or cooler chamber 215 forming an air treating zone 216. The cabinet is cut away as at 211 which permits air to enter the air treating zone at the lowermost portion thereof whence the air is later discharged through a screened opening 288. The air is circulated through the treating zone by means of an electrically driven fan or means 28 I In the particular apparatus I provide a water flow apparatus comprising a plurality of cooling coils 283 extending across the cooler chamber controlled by an electrically operated valve 284 through which a cooling medium fiows, such as water. I also provide a refrigerant circulating apparatus including a plurality of coils 281 located above the water flow apparatus through which a cooling medium flows, such as a volatile refrigerant. Refrigerant is delivered to the coils 281 by means of a refrigerant circulating element 298 under the control of an expansion valve 29 I The element 290 delivers the liquid refrigerant through a pipe 293 and withdraws gaseous refrigerant through a pipe 294. The element 290 comprises a compressor 295 operatively connected with a motor 296 by belt 291. The motor 296 is controlled by a switch 300 actuated by a thermostat 30I in response to the temperature of pipe 296. The compressor 295 compresses the gaseous refrigerant and delivers it to an air cooled condenser 302 wherein it is liquefied and from which it is delivered to a receiver 384 which is connected to the pipe 293. The water flow coils 283 are provided with an inlet connection 306 and outlet connection 301.

In order to provide means for controlling the operation of the electrically driven fan 28l and the electrically operated valve 284 and for controlling the flow of current to contacts 3l0 of switch 300 a thermostatic switch 3 l2 has been provided. As shown in Fig. 5 the thermostatic switch 3|2 is provided with a bimetallic thermostatic coiled blade 3|4 and a plurality of mercury containing tubes or bulbs 3I5 and 316. The switch 3l2 is adapted to control the valve 284 and the fan at a predetermined room temperature which may be determined by the position of the adjustable handle or indicator 320 of switch 3I2. As shown in Fig. 6 the electrically operated valve includes a magnet winding 322 and a movable core 323 which carries the valve proper 325. The valve 284 is provided with an inlet passage 321 in a casing 328 and an outlet passage 329. When the magnet winding 322 becomes energized, the core 323 will be moved upwardly to move the valve proper 325 from the seat to thus allow unrestricted communication between the inlet passage 321 and the outlet passage 329 to thus permit the circulation of Water through the coils 283. The switch 3|2 is adapted to place the magnet winding 322 of valve 284 andthe motor 330 which operates the fan 28! in circuit with the power mains 332 and 333 when the temperature of the room attains a predetermined value, for instance, the temperature as indicated by the indicator 328. Thus when the temperature of the room reaches the point indicated by the indicator 328, the switch 3| 2 will allow the current to be supplied to the magnet winding 322 of valve 284 and to the motor 336 to cause water to circulate in coils 283 and to cause air to circulate through the air treating zone 216 by the operation of fan 28!. The circuit through the magnet winding 322 of valve 284 and through the motor 330 is as follows: Power main 333, wire 340, magnet winding 322, wire 34l, motor 330, wire 342, contacts of mercury containing tube 315 which contacts are completed by the engagement of the mercury drop 345 therewith, and wire 341 which is connected to power main 332. If the temperature of the room continues to increase, for instance, to an increase of five degrees over the desired temperature as indicated by indicator 320, the bimetallic thermostatic blade 3l4 will cause the rotation of the mercurycontaining tube 3 l 6 to thus cause the mercury drop 358' to engage the contacts of the mercury containing tube 3l6 to complete a circuit through the contacts 3| 0 of switch 360 to thus allow current to flow from the power mains to the motor 296 to thereby actuate the compressor 295. The circuit through the motor 296 is power main 333, wire 352, motor 296, contacts 3"] of switch 308, wire 355, wire 354, contacts of mercury containing tube 3|6 and wire 356 which is connected with power main 332. From the foregoing it will be noted that when the temperature of the room attains a predetermined amount above the setting of the indicator 320 of switch 3|2, the electrically operated fan 2! and the electrically operated valve 284 will be actuated to thus cause the flow of water in the coils 283 and the circulation of air through the air treating zone 216. However, should the water fiow apparatus and the fan 28l be unable to maintain the desired temperature in the room to be cooled the refrigerating element 290 would be rendered operative to supply refrigerant to the coils 281 to thus reduce the temperature in the room to the temperature indicated by the indicator 320 of switch 3|2.

I it is delivered to pipe 428 to a water cooled con- When the temperature of the room is reduced to a temperature below that indicated by the means 328, the thermostat 314 will cause the rotation of mercury containing tube 316 to separate the mercury drop 358 from the contacts of the tube 316 to thus interrupt the flow of current to the motor 286 to thereby render the refrigerant circulating element inoperative. In the event the temperature of the room should fall below the desired temperature, as indicated by means 328 of switch 3l2, by the operation of the water flow apparatus and fan alone, the thermostat 3l4 will actuate the mercury containing tube M to thus separate the mercury drop 345 from the contacts of mercury tube M5 to thus interrupt the circuit to the motor 338 and to the magnet winding 322 of valve 284 to thus close the valve to thus prevent the circulation of water in' the coils 283 and render the fan 28l inoperative. By this construction the cooling medium supplied to the banks of coils 283 and 281, extending across the cooler chamber 215, is independently and automatically varied so that the cooling effect of each bank on the air is varied in accordance with refrigeration demands.

If desired, the water inlet pipe 386 may be provided with a manually operable valve 580 as shown in Figure '7, so that the fan 28| may be caused to operate to create an air current in the room without any cooling whatsoever merely by closing the manually operable valve 588 and by operating the manual switch 58| placed acrosst he leads to the automatic control 3| 2. Under such conditions,-

the pointer 328 should be adjusted to a temperature higher than any temperature likely to be reached by the air in the room. When under such setting and condition, the motor 338'will operate continuously and water will be prevented from' flowing through the coil 283 by the valve 588, and

no refrigerant will flow through the coil 281, because the control 3l2 is adjusted above the normal range of the air in the room.

Referring to Fig. 4 there is shown a modified form of room cooling apparatus which comprises a cabinet 315 forming an air treating-zone or upper air cooling and dehumidifying section 318 and is provided with a machinery compartment or lower refrigerant circulating section 319. The

cabinet is provided with louvers 388 through which the air enters the airtreating zone 318. The air is. forced through an opening 382 in a moisture pan 383 by means of an electrically operated fan 385. The air is then forced through a water cooling apparatus comprising coils 388 which pre-cool the'air. The air, when artificial cooling is desired, is then cooled to a temperature below its dew point by refrigerant cooling coils 398 so that when the air is rewarmed it will have the desired relative humidity, which rewarming may be accomplished by utilizing part of the heat of liquefaction which is liberated from the coil 392 to prevent cold saturated air from striking occupants or the room. When the air is treated to the desired temperature said air is discharged through a screened opening 385 provided in-the top of the.

and delivers it to the air cooled condenser or coil 392 where it is partially liquefied and from whence pressor 4l8 compresses the gaseous refrigerant denser 422 are provided with a common inlet 425 and common outlet connection 426. v Thus water will enter inlet 425 and circulate through the coils 388, condenser coil 428 which is connected to a water coil 438 by pipe 43! which water coil 438 is adapted to remove the heat from the machinery compartment 319.

Fig. '1 is a diagrammatic representation to indicate how the controls shown in Figs. 5 and 6 are applied specifically to the apparatus shown in Fig. 3; but it is to be understood that the same controls can be applied to all of the modifications shown in Figs. 1, 2, 3 and 4 inclusive. Similar reference characters have been used in Figs. 7 and 3, so that the various parts in the two figures can be readily identified without further description.

In Fig. 8, a modification of a portion of Fig. 7

is shown in which the motor 286a, driving the any appreciable quantity from flowing past the thermostatic bulb 582. The switch 388a is operated in response to pressure in the refrigerant suction line 294a. by connecting the pipe 583 with the suction line 294a and the bellows 584 of the switch 388a. This modification or arrangement will be readily understood by those skilled in the art, and the remainder of the structure illustrated in Fig. 7 is understood to be incorporated or combined with the structure shown in Fig. 8, the only change thus accomplished being that the compressor motor in Fig. 8 is controlled in accordance with refrigerant pressure in the evaporator, whereas in Fig. '7 the compressor motor is controlled in accordance with the temperature at the outlet end of the evaporator.

In all of the modifications, the controls are preferably set so that the evaporators do not attain a temperature below the freezing point of water, thus preventing. the accumulation of frost on the evaporators.

While the form of embodimentof the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted all coming within the scope of the claims which follow.

What is claimed is as follows:

1. The method of refrigeration which comprises circulating refrigerant in a closed path, condensing said refrigerant in one zone of said path and evaporating said refrigerant in a second zone, circulatingair' to and from a main body along said second zone to thereby cool the air, circulating water in a closed path through said second zonev for removing heat from the air passing through said second zone, and automatically controlling the circulation of the refrigerant, the air and the water in accordance with the temperature of the air.

2. The method of refrigeration which comprises circulating refrigerant in a closed path, condensing said refrigerant in one zone of said path and evaporating. said refrigerant in a second zone, circulating air to and from a main body along said second zone to thereby cool the air, circulating water in a closed path throughsaid second zone for removing heat from the air passing through said second zone, and automatically controlling the circulation of refrigerant in response to predetermined environment temperature, and automatically controlling the circulation of the air and the water at a diflerent predetermined environment temperature.

3. An apparatus for conditioning air including means forming an air treating zone, a refrigerant circulating apparatus having an evaporator in said zone, electrically operated means for forcing air through said zone, a switch adapted to actuate a set of contacts for controlling the operation of said circulating apparatus, means responsive to the pressure in said evaporator for con trolling said switch, and means responsive to the temperature 'of the air for controlling said electrically operated means and for controlling the flow of current to said switch.

4. An apparatus for conditioning air including means forming an air treating zone, a refrigerant .circulating apparatus having an evaporator in said zone, a water flow apparatus having connections for removing heat from the air passing through said zone,valve means for controlling said water flow apparatus, means for circulating air through said zone, and means responsive to the temperature of the air for simultaneously controlling said air forcing means and said valve means.

5. An apparatus forconditioning air including means forming an air treating zone, a refrigerant circulating apparatus having an evaporator in said zone, a water flow apparatus having connections for removing heat from the air passing through said zone, valve means for controlling said water flow apparatus, means for circulating air through said zone, means responsive to the environment temperature for simultaneously controlling said air forcing means and said valve means, said temperature responsive means also controlling said refrigerant circulating apparatus.

6. An apparatus for conditioning air including means forming an air treating zone, a refrigerant circulating apparatus having an evaporator in said zone, a water flow apparatus having connections for removing heat from the air passing through said zone, valve means for controlling said water flow apparatus, means for circulating air through said zone, means including a mercury containing bulb for controlling said air forcing means and said valve means, a second mercury containing bulb for controlling said refrigerant circulating apparatus and a single temperature responsive device for controlling said bulbs.

'7. A unitary portable apparatus for conditioning air comprising a cabinet forming an air treating zone, a liquid refrigerant evaporator in said zone, a water flow coil in said zone below said evaporator, said water flow coil having connections for removing heat from the air passing through said zone, means for forcing air through said zone, and means located over said evaporator for partially condensing the refrigerant by air cooled in said zone.

8. A unitary portable apparatus for conditioning air comprising a cabinet forming an air treating zone, a refrigerant circulating apparatus said apparatus having an evaporator in said zone, a water flow apparatus having connections for removing heat from the air passing through said zone, said water flow apparatus being located in said zone below said evaporator, means for forcing air through said zone, said refrigerant circulating apparatus having means in said zone above said evaporator for partially condensing the refrigerant by air cooled in said zone, and a water cooled condenser in said zone.

9. An apparatus for conditioning air comprising a unitary casing, a fan and an evaporator in said casing, an air inlet and an air outlet arranged to permit air to be conditioned to flow through said inlet, outlet, fan and evaporator, a refrigerant liquefying unit connected in refrigerant flow relationship with said evaporator at least a portion of which refrigerant liquefylng unit is enclosed in a machinery compartment having an air space, and a-water coil in the air space 01' said machinery compartment separate from said liquefying unit.

10. An apparatus for conditioning air comprising a unitary casing, a fan and an evaporator in said casing, an air inlet and an air outlet arranged to permit air to be conditioned to flow through said inlet, outlet, fan and evaporator, a refrigerant liquefyingunit connected in refrigerant flow relationship with said evaporator and including a motor, compressor and condenser, said motor and condenser being placed in a machinery compartment having an air space, and a water coil in the air space of said machinery compartment separate from said liquefying unit.

11. An apparatus for conditioning air comprising a unitary casing, a fan and an evaporator in said casing, an air inlet and an air outlet arranged to permit air to be conditioned to flow through said inlet, outlet, fan and evaporator, a refrigerant liquefying unit connected in refrigerant flow relationship with said evaporator and including a motor, compressor and condenser, said motor and condenser being placed in a ma chinery compartment having an air space, a water coil in the air space of said machinery compartment separate from said liquefying unit, and water flow connections causing the flow of cooling water through said condenser and water coil,

12. In an air conditioning apparatus, in combination with an enclosure in which conditioned air is used, a cooler chamber, a fan for passing air to be supplied to the enclosure through said chamber, a plurality of cooled surfaces extending in the path of the air flowing through said chamher, means for supplying cooling medium inside stream through said chamber, a plurality of cooled surfaces across the cross section of said cooler in the path of said air stream, means for supplying cooling medium inside said surfaces,

.means for-modifying the supply of cooling medium to one of said surfaces in accordance with a psychrometrlc function of air and means for modifying the supply of cooling medium to another of said surfaoesin accordance with a psychrometric function of air.

14.-An air conditioning apparatus, inv combination with anfienclosure in which conditioned air is used, air-flow means for air to be conditioned for said enclosure, a water-flow coil in said means cooling air passing through said means, an evaporator ,in

said means cooling air passing through q tor in said upper section;

said means, a refrigerant condensing unit connected to said evaporator, and a common source of water supply connected to said water-flow coil and to said condensing unit.

15. An air conditioning apparatuain' combination with an enclosure in which conditioned air is used, air-flow means for air to be conditioned for said enclosure, a water-flow coil in said means cooling air passing through said means, an evaporator in said means cooling air passing through saidmeans, and means controlling the flow of water through said water-flow coil in accordance with a temperature condition, and means conwhereby a current of cooled air is forced through said duct.

17. A unitary room cooler and dehumidifier to be used in a room or the like where refrigeration is desired to maintain the temperature and humidity of the air in said room or the like within the values bounding the human comfort range, comprising a cabinetwith upright substantially vertical walls with an upper air cooling and dehumidifying section and a lower'refrigerant circulating section; a refrigerant evaporator in said upper section; a refrigerant compressor, an electric compressor motor drivingly connected to said compressor anda refrigerant condenser in said lower section; said evaporator, compressor and condenser being connected in refrigerant flow relationship; air intake forming means in said cabinet located a substantial distance above the floor of said room to introduce air from said room into the lower part of said upper section; air discharge forming means in the upper part of said upper section; an air circulato'r and an electric air circulator motor drivingly connected to said air circulator causing the flow of air from said room into said air intake forming means, past said evaporator, and out of said air discharge forming means; control means including a switch for causing operation of said air circulator motor whenever said compressor motor operates, and a device responsive to a psychrometric function of air conditions in said room controlling theoperation of said compressor; said air circulator, evaporator, compressor and condenser being correlated with each other to maintain said evaporator temperature above freezing and below the minimum dew point temperature prevailing at a time when artificial air cooling is desired, whereby the accumulation of frost on said evaporator is prevented and moisture may be condensed from tHe air passing over said evaporator.,

18. A unitary room cooler and dehumidifier to be used in a room or the like where refrigeration is desired to maintain the temperature and humidity of the air in said room or the like thehuman comfort within the values bounding with upright subrange, comprising a cabinet stantially yertical walls with an upperair cooling and a lower refrig" and dehumidifying section erant circulating section; a refrigerant evaporaupper section located a refrigerant com-- air toprecool the air beforeit flows past said pressor, an electric compressor motor drivingly connected to said compressor and a refrigerant condenser in said lower section; said evaporator, compressor and condenser being connected in refrigerant flow relationship; air intake forming means in said cabinet located a substantial distance ,above the floor of said room to introduce air from said room into the-lower part of said upper section; air discharge forming means in the upper part of said upper section; an air circulator and an electric air circulator motor drivingly connected to said air circulator causing the flow of air from said room into said air intake forming means, past said evaporator, and

out of said air discharge forming means; control means including a switch for causing operation of said air circulator motor whenever said compressor motor operates, and a device responsive to a psychrometric function of air conditions in said room controlling the operation of said compressor; said air circulator, evaporator, compressor and condenser being correlated with each other to maintain said evaporator temperature above freezing and below the minimum dew point temperature prevailing at a time when artificial air cooling is desired, whereby the accumulation of frost on said evaporator is prevented and moisture may be condensed from the air passing over said evaporator; and a water circulating, air cooling apparatus in said upper section located in the path of said flow of air to precool the air before it flows past said evaporator. 19. A unitary room cooler and dehumidifier to be used in a room or the like where refrigeration is desired to maintain the temperature and humidity of the air in said room or the like within the values bounding the human comfort range, comprising a cabinet with upright substantially vertical walls with an upper air cooling and de- .humidifying section and a lower refrigerant circulating section; a refrigerant evaporator in said upper section; a refrigerant compressor, an electric compressor motor drivingly connected to said compressor and a refrigerant condenser in said .lower section; said evaporator, compressor and condenser being connected in refrigerant flow relationship cabinet located a substantial distance above the floor of said room to introduce air from said room into the lower part of said upper section; air discharge forming means in the upper part of said upper section; an air circulator and an electric air circulator motor drivingly connected to said air circulator causing the flow of air "from said room into said air intake forming means, past said evaporator, and out of said air discharge forming means; control means including a switch for causing operation of said air sirculator motor whenever said compressor motor operates, and a device responsive to a psychro- .metric function of air conditions in said room may be condensed from the air passing over said evaporator; said condenser being water cooled;

air intake forming means in saida water circulating air cooling apparatus in said in the path of said flow of evaporator, and a source of supply of water for said water circulating, air cooling apparatus and said condenser.

20. A unitary room cooler and dehumidifier to be used in a room or the like where refrigeration .is desired to maintain the temperature and humidity of the air in said room or the like within the values bounding the human comfort range, comprising a cabinet with upright substantially vertical walls with an upper air cooling and dehumidifying section and a lower refrigerant circulating section; a refrigerant evaporator in said upper section; a refrigerant compressor, an electric compressor motor drivingly connected to said compressor and a refrigerant condenser in said lower section; said evaporator, compressor and condenser being connected in refrigerant flow relationship; air intake forming means in said cabinet located a substantial distance above the floor of said room to introduce air from said room into the lower part of said upper section; air discharge forming means in the upper part of said upper section; an air circulator and an electric air circulator motor drivingly connected to said air circulator causing the flow of air from said room into said air intake forming means, past said evaporator, and out of said air discharge forming means; control means including a switch for causing operation of said air circulator motor whenever said compressor motor operates, and a device responsive to a psychrometric function of air conditions in said room controlling the operation of said compressor; said air circulator, evaporator, compressor and condenser being correlated with each other to maintain said evaporator temperature above freezing and below the minimum dew point temperature prevailing at a time when artificial air cooling is desired, whereby the accumulation of frost on said evaporator is prevented and moisture may be condensed from the air passing over said evaporator; and an air reheating coil in said upper section located in the path of said flow of air to reheat the air after it flows past said evaporator, said air reheating coil utilizing part of the heat of liquefaction of the refrigerant circulated by said compressor.

HARRY B. HULL.

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