US2172877A

US2172877A - Air conditioning system

Info

Publication number: US2172877A
Application number: US127695A
Authority: US
Inventors: Parcaro Michael
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 1937-02-25
Filing date: 1937-02-25
Publication date: 1939-09-12
Anticipated expiration: 1956-09-12

Description

Sept. 12, 1939. h M. PARCARO 2,172,377

AIR CONDITIONING SYSTEM Filed Feb. 25, 1937 2 Sheets-Sheet 1 w & l

IN VENTOR. M/CHA 1 PA ECAEO A TTORNEYS.

Sept. 12, 1939. v PARCARO 2,172,877

AIR CONDITIONING SYSTEM Filed Feb. 25, 1937 2 Sheets-Sheet 2 INVENTOR.

M/CHAEL p/IZCAFO Z/MMQLQ A TTORNEYS.

Patented Sept; 12, 1939 UNITED. STATES AIR CONDITIONING SYSTEM Michael Pal-care, Bloomfield, N. J.,

assigmor to Carrier Corporation, Newark, N. J., a corporation of Delaware Application February 25,

Claims.

This invention relates to air conditioning and is a continuation in part of applicants copending application Serial No. 71,837, filed March 31;

It is well known that one way of reducing the moisture content of air is to cool the air below its dewpoint. Air which has been dehumidified in this way is relatively cold,and therefore it is generally necessary to reheat such air before introducing it into enclosures which are to be conditioned. This is especially true where the conditioned enclosures are intended for human occupancy. One method of effecting such reheating has been to pass the cold and dehumidifled air in heat exchange relation with heaters supplied with steam or similar heating medium. This method of reheating, while it is adapted to produce desired conditions when the operation is suitably controlled and regulated, is relatively expensive since it embraces removing heat from air at considerable cost and then supplying heat to the same air at an additional and considerable cost. a

The general object of the invention is to provide an improved method of and means for reheating air which has been dehumidified by reduction of its temperature below its dewpoint.

It is well known thatthe temperature of compressed refrigerant gas leaving a refrigerant compressor is relatively high. While in conventional systems the heat of such compressed refrigerant gas is dissipated to the condensing medium, applicant employs the heat of compressed refrigerant gas to effect reheating of air which has been dehumidified by the evaporation of the refrigerant.

Accordingly, it is another object of the invention to dehumidify air by cooling the air to a temperature below its dewpoint by evaporating a volatile refrigerant in heat exchange relation therewith, to compress the evaporated refrigerant, whereby its temperature is increased, and to transfer heat from the compressed refrigerant gas to the cold dehumidified air, whereby said air is reheated and its relative humidity reduced.

It is another object of the invention to dehumidify a volume of air by cooling the air below its dewpoint and to reheat said dehumidified air by. mixing-therewith another volume of air which has been heated.

It is another object of the invention to dehumidify a volume of air by cooling the air below its dewpoint, and to reheat said dehumidified air by mixing therewith another volume of air which has been heated by compressed refrigerant 1937, Serial No. 127,695 (01. 62-6) gas evaporated by heat exchange with said dehumidified air.

Another object of the invention is to provide an improved system for reheating air dehumidified by mechanical refrigeration which is, relatively 5 simple, which is inexpensive to install and operate, and whichis adapted greatly to reduce the cost of reheating as heretofore practiced.

A feature of the invention resides in conditioning an enclosure by drawing air from the enclo- 10 sure and/or the outdoor atmosphere, evaporating a volatile refrigerant in heat exchange relation with said air to cool said air below its dewpoint, whereby moisture is precipitated therefrom, drawing other air from the enclosure 15 and/or the outdoor atmosphere, compressing the evaporated refrigerant, circulating said compressed refrigerant gas in heat exchange relation with said other air, mixing said other air and said dehumidified air and supplying said air 'mixture to said enclosure.

Another feature of the invention resides in controlling the relative proportions of dehumidified air and heated air supplied to the enclosure in accordance with changes in either temperature 25 or humidity at any desired point in the air circulating system.

Another feature of the invention resides in controlling the relative proportions of dehumidified air and heated air supplied to the enclosure 30 in accordance with changes in either tempera.- ture or humidity at any desired point in the air circulating system, and controlling the dehumidifying action in accordance with. changes in either temperatureor relative humidity at any desired 35 point in the air circulating system.

Another feature of the invention resides in the provision of means including a refrigerant evaporator for dehumidifying a volume of air, means for supplying other air to be mixed with said dehumidified air, a heating coil in heat exchange relation with said other air, a compressor for compressing the evaporated refrigerant, and means for supplying said compressed refrigerant to said heating coil and then to a condenser where it is liquefied prior to a repetition of the refrigerating cycle.

Another feature of the invention resides in the provision of a refrigerating system including an evaporator, a compressor and a condenser for 5 dehumidifying air, means for supplying other air to be mixed with said dehumidified air, a heater for heating said other air prior to mixture with said dehumidified air and means for routing refrigerant gas from said compressor through air whenever the load on said heater and then through said condenser or directly to said condenser.

Another feature of the invention resides in dehumidifying air by the evaporation of a volatile 5 refrigerant, compressing the evaporated refrig- 15 invention will be more apparent from the following 'description to be read in connection with the accompanying drawings, in which- Fig. 1 diagrammatically represents an air conditioning system in accordance with the invention. 20 Fig. Zrepresents a modification of the system of Fig. 1, in which compressed refrigerant gas is adapted to be circiilated directly to the condenser,

or to the reheater and then through .the con- 25 denser.

Fig. 3 is a modification of the invention adapted to supply hot refrigerant gas to the heater when the load on the refrigerant compressor falls below a predetermined point.

and.

Fig. 5 diagrammatically illustrates an alternative duct arrangement for supplying air to be mixed with the dehumidified air.

Referring to the drawings, similar designations referring to similar parts, numeral l designates an enclosure conditioned by air supplied thereto through duct ll under the influence of fan l2. Air is withdrawn from the enclosure l0 through 40 duct l3 and is supplied to air conditioning casing ll. Preferably, duct 13 connects to the outdoor atmosphere through a duct l so that outdoor air as well as return air from the enclosure l0 may be supplied to the air conditioning casing II. It

5 is preferred to provide dampers IS in the duct l5 and dampers l1 in the duct IS, the dampers i6 and I1 being differentially connected, to control the relative proportions of outdoor air and return air supplied to the conditioning casing through 50 duct l3. Control of the dampers i6 and 11 may be effected manually or automatically, as desired, but it is preferred that at least a small quantity of outdoor air be supplied to the conditioner casing H at all times. Within the conditioner cas- 55 ing I4 is provided a dehumidifying coil l8 supplied with liquid refrigerant through supply line 19 leading from refrigerant condenser 20. Air supplied to the conditioner casing it through duct i3 contacts the coils l8 and is thereby de- 60 humidified. The precipitated moisture may be drained from the bottom" of the casing l4 in any desired manner.

A duct 2i connects duct I3 with the conditioner casing I4 at a point beyond the coils Hi. The

5 duct 2| constitutes a bypass for supplying room air to the conditioner to be'mixed with the air dehumidified by coils l8 before the dehumidified air is supplied to the enclosure. If desired, duct 2| may be connected to the outdoor atmosphere 70 through a connection similar to duct l5, and in such case it is preferred to provide dampers cor-.

responding to dampers l6 and I1 associated with duct i3.

As will be understood, the dry bulb temperature of the dehumidifled air is relatively low, and it is Fig. 4 isa modification of the system of Fig. 3,

avast":

generally desirable that this air be reheated to a substantial degree before it is supplied to the enclosureto be conditioned. To effect such reheating applicant provides a heater 22 in duct 2|, which is supplied with hot refrigerant gas discharged by compressor 23 through line 24. The heat of the hot compressed refrigerant gas is partially removed by air circulating through duct 21 and this air is accordingly reheated, and hence reheats the dehumidifled air upon its mixture therewith in mixing chamber 25 of the conditioner casing. It will thus be observed that reheating of the dehumidified air is accomplished without resort to the use of steam reheaters or the like, which, as is well known, are exceedingly expensive to operate.

A preferred form of the invention includes dampers or the like, for regulating the relative proportions of dehumidifled air and heated air supplied to the mixing chamber 25. Such dampers may be of any desired design but should be differentially connected or arranged, so that when the supply of air to the mixing chamber from one source is decreased, the supply of air from the other source will be increased and vice versa. As illustrated, dampers 26 will operate in this manner since when the dampers are opened to provide a greater supply of dehumidifled air to the mixing chamber 25, the supply of heated air to the mixing chamber is reduced; and conversely, when the dampers 26 are closed somewhat to reduce the supply of dehumidified air, the supply of heated air is increased. Dampers 26 may be controlled manually, if desired, but in a preferred form of the invention they are automatically controlled responsive to variations in either temperature or humidity at any desired point in the air circulating system. In some applications it may be desired to position the control element 21 in the'supply duct H, as shown in Fig. 1. However, the control element may be positioned at any desired point in the enclosure, in the return duct or within the air conditioning casing it without departing from the scope of the invention. The control element 21 may be either a hygrostat or a thermostat controlling the dampers 26 through damper motor 28 of any desired type. Similarly, the dehumidifying action may be also. controlled manually or automatically, but

automatic control is preferred, and in a preferred form of the invention the supply of refrigerant to the coil I8 is controlled by a valve 29, which is regulated by a control element 30. Control element 30 may be either a hygrostat or a thermostat and, as described in connection with control element 21, may be' located at any desired point in the air circulating system. As illustrated in Fig. 1, control element 30 is located in the air supply duct ll. When the control element 21 is a thermostat the control element 30 is a hygrostat, and when the control element 21 is a hygrostat the control element 30 is a thermostat.

In Fig. 2 is illustrated a modification of the system of. Fig. 1, wherein line 3i connects compressed gas line 24 with the inlet to condenser 20 in a course by-passing heater 22. A valve 32 is adapted to supply compressed refrigerant gas delivered from the compressor to either the heater 22 and thence to condenser 20, or directly to condenser 20 through line 3|. A check valve 32 is provided in line 34, connecting heater 22 and condenser 20, to permit fluid flow from the heater-to the condenser and to prevent fluid flow in a reverse direction. By means of this arrange- I ment compressed refrigerant gas may be supplied 15 plied to condenser 29 heating of the dehumidified air is desired. The

valve 32 is preferably of the three-way type, well known in the art and therefore requiring no detailed description here, but, if desired, it may be replaced by other suitable fiow control means. For example, a shut-off valve in the line 3| and a shut-off valve in the line 24, beyond the junction point of lines 24 and 3|, might be used to effect the same results as are provided by valve 32.

Fig. 3 illustrates a modification of the invention in which a multi-cylinder compressor is used, and in which refrigerant gas is used for heating purposes only when the load on the compressor falls below a predetermined point. Suction line 35 supplies evaporated refrigerant to cylinders 23a and 23b of compressor 23 and refrigerant gas discharged from the compressor may be supthrough line 36. Line 24a communicates with discharge connection 3'! of compressor cylinder 23b. A cut-out valve 38 in line 24a is under the control of control element 39 which responds to changes in conditions in the gas suction line or in the enclosure conditioned by the system. Control element 39 may be a thermostat or apressurestat or similar de-- vice and is operative'to open the valve 38 whenever the load on the compressor falls below a predetermined point. A check valve 40 permits flow from compressor element 23b to line 36 but prevents how in. a reverse direction. A .similar system is disclosed in applicants copending application Serial No. 71,837, filed March 31, 1936, for recirculating gas through the compressor whenever the load on the compressor falls below a predetermined point and, as disclosed in said copending application, a three-way valve at the junction of lines 31 and 24a may be substituted, if desired, for the valve 38 and the check valve 49, such three-way valve being regulated by control element 39. In a preferred embodiment of the invention the line 24a. is provided with a connection 4| to' the intake side of the compressor and a valve 42 is used to route refrigerant as to either heater 22 or to the intake of compre'ssor 23 through line 4.|. A check valve 43 is provided in gas line 44 to permit flow fromthe heater 22 to the inlet ofcondenser 20 and to prevent fluid flow in a reverse direction.

If desired, valve 42 may be manually adjusted or may be controlled automatically by a temperatureor humidity-responsive device 45 located at any desired point in the system.

In the arrangement of Fig. 4, gas discharged from compressor element 23b may be supplied directly to condenser 29 through line 36 or to heater 22 through line 24a and thence to condenser 20 through line 44, the routing of the compressedrefrigerant gas being controlled by valve 46, which may be controlled manually or automatically, as desired. A check valve 41 permits flow from the heater 22 to the inlet of condenser 29 but prevents flow in a reverse direction. It will be noted that the arrangement of Fig. 4 is similar to the arrangement of Fig. 2, except that in Fig. 4 at least. one of the compressor elements discharges directly to the condenser at all times,

whereas in the arrangement of Fig. 2, all of the gas discharged from the compressor may be routed through the heater 22, and then to the condenser 29.

In connection with Figs. 3 and 4, it is to be understood that while only two compressor elements have been illustrated, the arrangement may be extended to apparatus embracing three,

or more cylinders. In such case, two or more compressor elements or cylinders wouldbe arranged to supply compressed refrigerant gas to the heater.

In the various forms of the invention above described, substantially all of the by-passed air circulated through duct 2| contacts with heater 22. Fig. 5 illustrates an arrangement in which a portion only of the by-passed air is passed in contact with the heater 22, the remainder of the air circulated through by-pass duct 2| being by-- passed around-the heater 22. Preferably, a partition 48 is provided in the duct to provide two air passages, designated 49 and 50, therein. Duct section 49, as illustrated, contains the heater 22.

Duct sections

49 and 50 are provided with differentially connected dampers 5| and 52 so that as air flow through one of the duct sections is increased, air flow through the other duct section will be decreased, and vice versa. The dampers 5| and 52 may be adjusted manually, if. desired, but preferably they are automatically controlled. The adjustment of the dampers 5| and 52 may be controlled by a thermostat or hygrostat located at any desired point in the system,

as described in connection with control element 21. Such temperatureor humidity-responsive control of the dampers 5| and 52 is preferably used in conjunction with the automatic control of dampers 26 as above described.

While the heater 22, to which hot refrigerant gas is supplied, Has been described as being positioned within the duct 2| and adapted to be contacted directly by the air passing through this duct, it will be apparent to those skilled in the art that the heater 22 might be located without theduct 2| and utilized for the purpose of heating water or other suitable medium which might then be routed through a surface-type heat exchanger located within the'duct 2|. Similarly, the evaporator coils, while they have been described as being-within the air conditioning cas ing, might be used to cool a conditioning medium,

such as brine, instead of directly cooling the ditioner casing. Accordingly, in the claims the expression heat exchange relation shall be understood to refer to both direct and indirect heat exchange.

Since many modifications may be made in the invention without departing from its scope, applicant intends that the above description and accompanying drawings be considered as' illustrative only, applicant limiting himself only as indicated in the appended claims.

I claim:

1. In an apparatus of the character described,

an evaporator, a compressor, a condenser, means for passing a first volpme of air in heat exchange relation with said evaporator whereby said first volume of air is dehumidified, means for supplying to and mixing with said first volume of dehumidified air a second volume of air, a heater arranged in heat exchange relation with said second volume of airand adapted to heat said second volume of air prior to mixture with said first volume of dehumidified air, said heater being connected between the outlet of said compressor and the inlet of said condenser, and means for supplying compressed refrigerant gas to said heater responsive to falling of the pressure at the inlet to said compressor below a predetermined point and for supplying compressed refrigerant gas to said condenser in a course by-passing said heater responsive to rising of the pressure at the inlet to said compressor above said point.

2. In an apparatus for conditioning air under summer operating conditions, means for withdrawing air from the enclosure, means including a refrigerant evaporator for dehumidifying a portion of said withdrawn air, means for supplying liquid refrigerant to said evaporator, compressor apparatus for withdrawing refrigerant gas from said evaporator and for compressing said refrigerant gas, means for passing said compressed refrigerant gas in heat exchange relation with another portion of said air withdrawn from the enclosure responsive to decreases of the load on said compressor apparatus below a predetermined point, means for mixing said portions of the air withdrawn from the enclosure, means for supplying the resultant air mixture to said enclosure, and means for controlling the relative proportions of said different air portionsin said result-,

accordance with variations in a condition of ir at a point in the system.

3. In an apparatus of the character described, an evaporator, a compressor comprising a plurality of compressing elements, a condenser, means for passing air in heat exchange relation with said evaporator whereby said air is dehumidified, means including a heater adapted to supply heat to said air subsequent to dehumidification thereof, means for routing compressed refrigerant from at least one bf said compressing ant mixture 1 elements constantly and at all times during operation of the apparatus directly to said condenser in a course by-passing said heater, means for routing compressed refrigerant gas from at least another of said compressing elements through said heater and thence to said condenser in response to a decrease of the load on said compressor below a predetermined point, and for routing refrigerant gas from said last-mentioned compressing element directly to said condenser in a course by-passing said heater in response to an increase of the load on said compressor above a predetermined point.

4. Inv an apparatus of the character described,

a refrigerant evaporator, a compressor compris-- ing a plurality of compressing elements, a condenser, means for passing a first volume of air in heat exchange relation with said evaporator whereby to effect dehumidiflcation of said first volume of air, means for supplying to and mixing with said first volume of dehumidified air a second volume of air, a heater arranged in heat exchange relation with said second volume of air adapted to heat said second volume of air prior to mixture of said second air volume with said first air volume, means for routing compressed refrigerant from at least one of said compre'sslng elements constantly and at all times during operation of the apparatus directly to said condenser in a course by-passing said heater, means for routing compressed refrigerant gas from at least another of said compressing elements through said heater and thence to said condenser whenever the load on said compressor 'falls below a predetermined point, and for routing refrigerant gas from said last-mentioned compressing element directly to said condenser in a course bypassing said heater whenever the load on said compressor exceeds a predetermined point.

5. In an apparatus of the character described,

an evaporator, a compressor, a condenser, means for passing a first volume of air in heat exchange relation with said evaporator whereby said first volume of air is dehumidified, means for supplying to 'and mixing with said first volume of dehumidified air a second volume of air, a heater arranged in heat exchange relation with said second volume of air and adapted to heat said second volume of air prior to mixture of said second air volume with said first air volume, said heater being connected between the outlet of said compressor and the inlet of said condenser, and means for supplying compressed refrigerant gas to said heater responsive to a decrease in the temperature at the inlet to said compressor below a predetermined point and for supplying compressed refrigerant gas to said condenser in a course by-passing said heater in response to an increase in the temperature at the inlet to said compressor above said point.

6. In an apparatus of the character described, an evaporator, a compressor, a condenser; means for passing air in heat exchange relation with said evaporator whereby said air is dehumidified, a heater adapted to supply heat to said air subsequent to the dehumidification thereof, said I heater being connected between the outlet of said compressor and the inlet of said condenser, a control element responsive to changes in the condition of refrigerant gas supplied to said compressor, and means under the control of said control element for selectively routing compressed gas from said compressor directly to said condenser or through said heater and thence to said condenser.

7. In an apparatus of the character described, a refrigerant evaporator, a compressor comprising a plurality of compressing elements, a condenser, means for passing a first volume of air in heat exchange relation with said evaporator whereby to effect dehumidification of said first volume of air, means for supplying to and mixing with said first volume of dehurnidified air a second volume of air, a heater arranged in heat exchange relation with said second volume of air adapted to heat said second volume of air prior to mixture thereof with said first air volume, means for routing compressed refrigerant from at least one of said compressing elements constantly and at all times during operation of the apparatus directlyto said condenser in a course by-passing said heater, and means for selectively routing compressed refrigerant gas from at least another of said compressing elements either through said heater and thence to said condenser, or directly 'to said condenser in a course by-passing said heater.

1}. In an apparatus of the character described, a refrigerant evaporator, a compressor comprising a plurality of compressing elements, a condenser, means for passing a first volume of air in heat exchange relation with said evaporator whereby to effect dehumidification of saidfirst volume of air, means for supplying to and mixing with said first volume of dehumidified air a second volume of air, a heater arranged in heat an evaporator, a compressor, a condenser, means another of said compressing elements either through said heater and thence to said condenser, or directly to said condenser in a course bypassing said heater, said last-mentioned means including control means actuated in'response to changes in a condition of refrigerant delivered to said compressor.

9. In an apparatus of the character described,

for passing a first volume of air in heat exchange relation with said evaporator whereby said first volume of air is dehumidified, means for supplyinganother volume of air for mixture with said first volume of air subsequent to dehumldification of said first volume of air, a heater adapted to heat said other volume of air subsequent to mixture thereof with said first volume of air, said heater being connected between the outlet of said compressor and the inlet of said condenser, a control element responsive to changes in a condition of. refrigerant gas supplied to said compressor, andmeans under the control of said control element for selectively routing compressed gas from said compressor directly to said condenser or through said heater and thence to said condenser.

10. In an apparatus of the character described, a refrigerant evaporator, a compressor comprising a plurality of compressing elements, a condenser, means for passing air in heat exchange relation with said evaporator whereby to efiect dehumidification thereof, a heater adapted to supply heat to said air subsequent to dehumidification thereof, means for routing compressed refrigerant from at least one of said compressing elements constantly and at all times during operation of the apparatus'directly to said condenser in a course by-passing said heater, and

means for routing selectively compressed refrigerant gas from at least another of said elements, whenever the load on said compressor is below a predetermined point, either to 'the inlet of said compressor or to said heater, and means for delivering compressed refrigerant gas from said last-mentioned compressor element directly to said condenser when the load on said compressor exceeds a predetermined point.

MICHAEL PARCARO.