US2296741A

US2296741A - Air conditioning apparatus

Info

Publication number: US2296741A
Application number: US217117A
Authority: US
Inventors: Jr Charles M Sanders
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1938-07-02
Filing date: 1938-07-02
Publication date: 1942-09-22
Anticipated expiration: 1959-09-22

Description

Sept. 22, 1942.

C. M. SANDERS, JR

AIR CONDITIONING APPARATUS FiledJuly 2, 1938 2 sheets-Sheet 1 INVENTOR `Cl-mlzm-:s M. SANDERS, JR.

WITNEssEs: 7?. (L

ATToRNE' Sept- 22; 1942 c. M. SANDERS, JR 2,296,741

AIR CONDITIONING APPARATUS Filed July 2, 1938 2 sheets-snet 2 www wlTNEsSEs: y lNvENToR LVM/b CHARLES M.5ANDER5,JR

#6 FJG. 2. BY

- y ATTORNE;

Patented Sept. 22, 1942V 2,296,141 .un CONDITIONING ArrAaA'rUs Charles M. Sanders, Jr., Oak'Park, Ill., assignor to Westinghouse Electric & Manufacturing Company, of Pennsylvania East Pittsburgh, Pa., a corporation Application July 2, 1938, Serial No. 217,117

c claims;

My invention relates to air conditioning apparatus, and it hasfor an object to provide improved apparatus.

A further object is to provide improved air conditioning apparatus adapted for operation at partial load to maintain more readily a desired temperature of the air in the enclosure.

A further object is to provides. simpler and more flexible method of control, providing a better balance between the amount .of cooling provided by the apparatus and the cooling load of the air conditioned enclosure.

In accordance with my invention, air withdrawn from the enclosure is mixed with outdoor air. One or more cooling elements are disposed vin the path of the outdoor `"air before mixture,. and one or more additional cooling elements are disposed in the path of the mixed' air stream for cooling at least a portion of said stream. Another portion of the mixed air stream may be byepassed around the latter cooling element. The mixed air stream is then delivered to the enclosure.

The apparatus is preferably. provided with a thermostatic control which is subjected to the temperature of the airlin the enclosure and is arranged to initiate operation of the cooling elements in the outdoor air stream successively and then the cooling elements inthe withdrawn air successively as vthe temperature reaches successively higher predetermined values. A further thermostatic control may be provided to terminate operation of theoutdoor air cooling ele- Aments as the outdoor air.v temperature drops,

leaving the air cooling elements in the mixed air stream to carry the cooling load.

The above and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with theaccompanying drawings, forming a part of this application, in which:

Fig. 1 is a diagrammatic View of an air conditioning system arranged in accordance with my invention; and,

. Fig. 2 is a similar view ofv a secondY embodi- Referring to the drawings in detail, an enclosure to be air conditioned is indicated at I0. Air is withdrawn from theenclosure through a duct Hand conveyed to an air conditioning chamber l2. Outdoor air is conveyed through a duct I3, an air conditioning chamber I4 and a duct I5 to the duct il, in which it is mixed' with the return air and ows therewith through the chamber I2 anda duct Ii to the enclosure III. The

(Cl. B2-6) air described is effected in any suitable manner, as by means of fans I4' and I5' arranged in the chambers I 4 and I 5, respectively.

The present air conditioning system includes two refrigerating systems indicated generally at I1 and I8, each including a motor compressor unit I9 and a condenser 20. It also includes an expansion valve 20' of any suitable type known in the art, lfor example, a thermostatic expansion valve which operates in response to the superheat of the 'vaporized refrigerant discharged from the evaporator. The refrigerating system I1 includes an evaporator 2| disposed in the chamber Il and extending entirely across the outdoor air streamflowing therethrough. The

system I8 includes an evaporator 22 disposed in the chamber I2 and extending partially across the mixed air stream. A by-pass 23 may be provided, if desired, between the evaporator 22 and the adjacent wall of the chamber, through whichl by-pass a portion of the mixed air stream may ow without being cooled. A

The evaporator 2i and its refrigerating system I1 are preferably of a capacity to take care Y of the cooling loads which depend upon the temperature of the outside air, that is, the loads due to transmission or leakage of heat, any inltration of outdoor air, and admission of fresh air to the enclosure. The evaporator 22 and its refrigerating system I8 are preferably of sumcient capacity to take care of the loads which do not depend on the outside` air temperature, for example, sun` load, light load, and occupant load.

The control comprises a thermostatic switch T1 which isresponsive to the temperature of the withdrawn air flowing through the duct Ii and is arranged to close its contacts 2Q and 25 successively as the temperature of the withdrawn air rises to successively higher predetermined values, which -diiler but slightly and represent substantially the temperature desired to be maintained in the enclosure I0. A second thermostat T2 is responsive to the temperature of the outdoor air before it passes over the Vevaporator coil 2i, and is arranged to open contacts 26 as the temperature of the outdoor air decreases below a predetermined value. The latter predetermined value represents the temperature of the outdoor air at which the entire heat load can be taken careof, by the evaporator 22. -If

the evaporators are proportioned as. suggestedV iiow of 55 pendent upon outdoor air temperature, then such by the evaporator 2 through the chamber I2,

predetermined value is the temperature desired to be maintained within the enclosure I0. The thermostats are of any suitable type known in the vart and, of course, are adjustable.

'The refrigerating system I1 is controlled by a circuit which extends from the line conductor L1 conductor La. 'I'he control has been shown in a simplified manner in order tha-t the inventive thought may be more readily understood, and it is to be understood that the usual expedients and instrumentalities used in the. control of apparatus of this nature, including relays, protective devices, are to be used in the usual manner in which such expedients and instrumentalities are commonly used in the art.

Operation Assuming the contacts 25 of the thermostat T2 to be closed by reason of a sufliciently high outdoor temperature, the operation of the evaporators is controlled by the thermostat T1 in response to the temperature of the air in the enclosure I to maintain said temperature at substantially the desiredvalue. A demand for cooling is Yindicated by a rise in temperature in the enclosure. As the temperature reaches the r`st predetermined value, the contacts 24 close, completing the circuit for the refrigerating system I1. Operation of thev latter is effected to supply refrigerant to the evaporator 2|, which serves to cool all of the outdoor air passing through the chamber I4. The temperature not yet having reached the second predetermined value, the contacts 25 are open, rendering the refrigerating system I8 of the evaporator 22 inactive. In this case, therefore, the outdoor air is cooled and dehumidiiied by the evaporator 2l, mixed with air withdrawn from the enclosure, and the mixture is delivered `Without' further cooling to the enclosure III. Upon decrease in temperature below the first predetermined value, the contacts 24 are opened to terminate operation of the refrigerating system I1 and the evaporator 2|, whereupon a mixture oi uncooledbutdoorand return air is delivered to the enclosure.

An increase in the cooling load of the enclosure beyond-the capacity of the evaporator 2| is represented by an increase in temperature to the second predetermined value at which both of the

contacts

24 and 25 are closed, resulting in operation of both refrigerating' systems and both evaporators. The entire outdoor air streamis cooled I as before. In the duct II it is mixed with the air stream from' the enclosure and the portion of the mixture flows over and is cooled and dehumidiiled by the evaporator 22. The two portions of the mixed air stream passing over mixed air stream then in which the major aznar-11 If the temperature of the outdoor air drops to the predetermined value at which the contacts Figure 2 Provision may also be made for varying the amount of cooling eiiected in the chamber I4 and in the chamber I2, preferably by varying the effective evaporator cooling surface. For example, as illustrated in Fig. 2, evaporators 2|a and 2lb are arranged in parallel in the chamber I4, and evaporators 22a and 22h are arranged in parallel in the chamber I2. It is to be understood, however, `that any other suitable provision for dividing the evaporator surface or for varying the effective evaporator surface may be provided. All of the evaporators are connected to a common refrigerating `system 3|, including a variable capacity compressor 32.

In this embodiment, the several evaporators are provided with solenoid valves which control 'the evaporator 22 and through the by-pass 23,

respectively, then mix ,and are delivered to the enclosure Il through the lduct I5.

As thetemperature of the air in the enclosure I0 decreases below the second predetermined value, the contacts 25 open to terminate operation of the refrigerating system Il and the evapo-v rator 22, leaving the refrigerating. system I1 and evaporator 2| alone in operation to supply C001- the supply of liquid refrigerant thereto. The solenoid valves for the evaporators 2Ia, 2lb, 22a

and 22h are designated 33, 34, 35 and 36, re'

spectively. The thermostat 'I l is arranged to yenergize the solenoids 33 to 36 in response to successively and slightly higher. predetermined values representing substantially the tempera-ture desired to be maintained in the enclosure III. The thermostat Ta is arranged to open the circuit of-the solenoid 33 as the outdoor temperature decreases to a value such that the entire cooling load can be taken care of without the evaporator 2 la. It opens the circuits oi

solenoids

33 and 34 when the outdoor temperature de'- creases to astill lower value such that the entire cooling load can be taken care of by the evaporators 22al and 22h. Y

'Ihe operation of the compressor 32 is controlled in accordance with the total load oi' those Aevaporators which are in operation. It is provided with Iseveral unloader mechanisms 31 which are adapted to render the associated cylinders of the compressor ineffective to compress refrigerant. They are controlled by a suitable control mechanism 38 which is responsive to the pressure in thesuction line 33 connecting the outlets of the several evaporators with the inlet of the compressor. As the suction pressure increases, the cylinders are successively loaded and as the suction pressure decreases, the cylinders are successively unloaded, thereby maintaining a substantially constant suction pressure. As the suction pressure reaches a predetermined minimum value, operation of the compressor is terminated by opening the motor circuit 4|. 'I'he particular mechanism for controlling `the capacity of the compressor forms no part of the present invention; the invention contemplating any suitable mechanism whereby compressor ca` pacity may be suitably controlled.

Figure Z-Operation .'I'he operation of the embodiment shown in Fig. 2 is, infa general way, similar to thatof Fig. 1. Assuming the temperature of the outdoor air to be suiliciently high to cause the thermostat T2 to close the several contacts, the operation of the several evaporators isf controlled by the thermostat T1. As lthe temperature increases to successively higher values, the several solenoid valves are sucessively opened in order to render the evaporators 2Ia, 2lb, 22a and 22h eective in the order named. Conversely, upon decrease in temperature, the evaporators are rendered ineffective in the reverse order. The amount of cooling is thus automatically controlled to maintain substantially the desired temperature in the enclosure Il).

If either the evaporator 2Ia or both the evaporators 2Ia and 2lb are rendered inoperable by the thermostat T2, then the cooling load is Vcarried by the remaining evaporators under control of the thermostat T1, as will be fully apparent from the description that has already been given.

While I have shown my invention in several forms, it will be obvious to those skilled in the art that it is not so limited but is susceptible'of various other changes and modications Without departing .from the spirit thereof, and I desire,

therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specically set forth in the appended claims.

What I claim is:

1. In an air conditioning system for an enclosure, the combination of means for eifecting flow of a streamof air from the enclosure and' a stream of outdoor air, mixing the two'streams and delivering the'mixed air stream to the enclosure, i'lrst means for cooling the outdoor airiirst and the second air cooling means automatically in response to successively higher predetermined values of a heat load condition of the enclosure.

2. In an' air conditioning system for an enclosure, the combination of means for effecting flow of a stream of air from the enclosure and a stream of outdoor air, mixing 4the two streams and delivering the mixed air stream to the enclosure, first means-for cooling the outdoor air stream before mixing, second means forcooling` the mixed air stream, means :for-successively intiating operation of the first and the second successively higher predetermined values of a heat load condition of the enclosure, and means responsive to a predetermined minimum temperature of the outdoor air Yfor terminating operation of the irst air cooling means independently v of the last-mentioned means.

3. In an air conditioning system 'for an enclosure, the combination of means effecting iiowv of a stream of air from the enclosure and a.

and delivering the mixed air stream to the enc1osure,a plurality of air cooling elements for cooling the outdoor airstream beforemixing, a plurality of air cooling elements for cooling the mixed ai'r stream, mea increases in a heat load condition of the enclosure for successively initiating operationof the outdoor air cooling elements'and then the mixed air coolingelements, and means responsive to successively lower outdoor air temperatures for4 air stream before mixture, a second evaporator disposed in the'path of the mixed air stream and a variable capacity compressor connected to said evaporators; means for successively initiating flow of refrigerant through the rst and the second evaporator automatically in response to successively higher values of a heat load condition of the enclosure; and means responsive to thesuction pressure in the refrigerating `system for controlling the capacity or output of the compressor.

5. In an air conditioning system for an en`- closure, the combination of means for 'effecting flow Aof a stream of air from the enclosure and a stream of outdoor air, mixing'the two streams and delivering 4the mixed air stream to the 4enclosure; a refrigerating system including a plurality of evaporators disposed'in the path of the outdoor air stream before mixture,a plurality of evaporators disposed in the path of the mixed air stream, and a variable capacity compressor connected to said-evaporators; means responsive to successively higher values of a heat load condition of the enclosure for vsuccessively initiating flow of refrigerant through the outdoor air evaporators and then the mixed air evaporators; and means responsive to the suction pressure in the refrigerating system for controlling the capacity 'air cooling means automaticallyin response-to or output of the compressor.

6. Refrigerating apparatus comprising a plurality of evaporator elements, individually operable valves for respectively controlling flow of refrigerant thereto, means including a common temperature-responsive element for controlling a plurality of said valves,l a. multi-cylinder compressor common to said evaporator elements, for withdrawing vaporized refrigerant therefrom, means for condensing the compressed refrigerant discharged from the compressor, and meansfor varying the capacity or output of said compressor lin response to suction pressure by unloading one stream of'outdoor air, mixing the two streams or more cylinders, whereby the Acomiiuessor output' is varied in accordance with evaporator load while substantially constant pressure and temperature of the refrigerantis maintained in thel evaporator elements whose valves are open. l

MCHARLES M; .ne

responsive to successive4 f