US2291029A - Refrigerating apparatus - Google Patents

Description

July 28, 1942. J. EVERETTS, JR 2,291,029

REFRIGERATING APPARATUS Filed April 23, 1940 2 Sheets-Sheet 1 A ToRNEYa.

y 1942- J. EVERETTS, JR 2,291,029

- REFRIGERATING APPARATUS Filed April 23, 1940 2 Sheets-Sheet 2 INVEN sywmqaa ATTORNEYS Patented July 28, 1942 UNITED STATES PATENT OFFICE REFRIGERATING ArrAnA'rUs John Everetts, Jr., Dayton, Ohio, asslgnor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application April 23, 1940, Serial No. 331,195

9 Claims.

This invention relates to refrigerating apparatus and more particularly to. an air .con-

ditioning system in which a secondary refrigerant circuit is used for reheating the conditioned-air.

It is common practice to provide a simple refrigerating system for cooling'the air and to control the amount of cooling by starting and stopping the refrigerating system". In a system of this type the air leaving the evaporator is of necessity very cold when the refrigerating system is in operation but is relatively warm when the refrigeration system is not in operation. Furthermore, in a system of'this type soon after the refrigerat- 1 ing apparatus stops, the warm air fiowing over the evaporator coil tends to reevaporate some of the condensate formed on the evaporator'coil during the cooling cycle whereby the air discharged into the conditioned space becomes op- Another object of this invention is to provide a reheating system which may be readily adapted to existing refrigerating systems without decreasing the capacity of the refrigerating system.

Still another object of this invention is to provide improved means for controlling the rehea system.

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

In the drawings:

Fig. l is a diagrammatic showing of a preferred modification in which a volatile refrigerant is used in-the secondary circuit;

Fig. 2 is a diagrammatic view of another modification in which water or the like may be used as the secondary refrigerant;

Fig. 3 is a diagrammatic view of a further modiflcation showing a different type of control; and Fig. 4 is also a diagrammatic view showing a still further modified arrangement.

As shown in Fig. 1 I have provided an air cirevaporator I2 and thereafter over the reheat coll it, both of which are disposed within the air duct l 5. The refrigerant vaporized in the evaporator l2 may be withdrawn therefrom by means of any conventional refrigerant compressor. For, purposes of illustration, I have shown a hermetically sealed motor-compressor unit ii, the motor of which is controlled by a conventional thermostat is which may be placed in the return air duct or directly within the conditioned space. The compressed refrigerant. vapor discharged from the compressor l6 flowsthr'ough a heat interchanger l8 which is arranged in series with a conventional condenser unit 20. Liquid refrigerant from the condenser 20 is supplied to the evaporator 12 through the automatic thermostatic expansion valve 22 which isof conventional construction. As shown in the drawings,

the valve 22 includes the usual thermostatic bulb 20 24 which serves to shut oil the flow of refrigerant to the evaporator when the liquid refrigerant reaches the outlet of the evaporator.

A secondary volatile refrigeration system which includes the reheat coil M has been provided for transferring heat from the compressed gas flowing through the heat interchanger l8 to the air stream flowing over the reheat coil ll. This secondary system includes a liquid refrigerant receiver 26, a thermostatically controlled valve-28 and a heat exchange coil 30 which serves as an.

evaporator for the secondary system. This secondary system is charged with any suitable volatile refrigerant which will evaporate at the temperatures normally prevailing in the heat interchanger l8 and which will be condensed in the reheat coil H by thecold air coming from the main evaporator I2.

The valve 28 is opened and closed in response to the temperature of the air flowing over the bulb 32 placed in the incoming air stream. Valve 28 may be of an on-ofi type or it may be a modulating type of valve. When the temperature of the incoming air is excessively high, the valve 28 reduces the flow of refrigerant in the secondary, system. When the valve 28 is completely closed the cold air leaving the coil I2 will tend to condense all of the refrigerant vapor in the secondary system and this condensed refrigerant will be stored in the receiver 26. Thermostats l8 and 32 are so calibrated as to cause the compressor of the primary refrigeration system to operate continuously except at such times when no conculating fan II) which blows air over the main maximum amount of heat is returned to the air stream at such times when the temperature of the air flowing over the bulb 32 indicates that very little cooling is required.

The capacity of the secondary system is preferably such that substantially allof the heat removed frorn'the air may be returned to the air whereby the refrigerating apparatus may be used for removing large volumes of moisture from the air without materially reducing the dry bulb temperature of the air in the conditioned space. The main condenser 20 has 9. capacity suflicient to condense all of the liquid refrigerant of the primary system at such times when the secondary system is not operating as a reheat system. Whenever the secondary system is operating, the heat interchanger 18 has the eifect of reducing the condensing pressure. This results in a more efllcient operation of the primary system.

In Fig. 2 I have shown a slightly different modification in which the primary system is identical with the primary system disclosed in Fig. l but in which the secondary system employs a non-volatile refrigerant, such as water, which is circulated between a reheat coil Il|,-correspnd ing to reheat coil M in Fig. 1, and a heat absorbing coil I 30 disposed within the heat interchanger It by means of a pump 50 located in the line between the reheat coil Ill and the heat absorbing coil I30. It should be noted that like reference characters have been used for designating like parts in the various modifications. The pump 50 is arranged to circulate the fluid in the direction of the arrow shown in Fig. 2. The fluid leaving the heat absorber I30 discharges into a surge tank 52. The surge tank 52 is provided with. a sight glass 54, an atmospheric vent 55 and a make-up water pipe 58, all of which are of conventional design and serve their usual functions. The amount of reheating taking place is controlled by a three-way valve 60 which is adapted to connect the inlet of the pump 50 either to the reheat coil I H or the by-pass 62 which makes it possible to by-pass all of the secondary refrigerant around the reheat coil whereby no heat is returned to the air stream. The valve 50 is controlled by means of a dry bulb thermostat 64 located in the incoming air stream or directly within the space to be conditioned. In order to simplify the disclosure I have shown no means for controlling the operation of the pump 50 in this or any of the other modifications. It is within the purview of this invention, however, to provide further automatic control of the pump 50 whereby the pump 50 automatically stops when no reheat whatsoever is required.

In Fig. 3 I have shown a modification which is very similar to the modification shown in Fig. 2 except that in place of by-passing the secondary heat exchange coil I I have provided a by-pass N for by-passing the compressed refrigerant vapor of the primary system around the heat interchanger H8 whenever reheating is not required. The by-pass III is controlled by a three-way valve 12, which in turn is under control of the dry bulb thermostat 14 located in the incoming air stream. The valve 12 may be an on-ofi type of valve or it may be a modulating type of valve.

While I have shown a pump 50 in a modification shown in Fig. 3 it is apparent that in the arrangement shown in Fig. 3 a volatile refrigerant may be used in the secondary system in which case the pump 50, the surge tank 52 and its associated parts may be dispensed with.

In Fig. 4 I have shown a still further modification in which the secondary system may employ either a volatile refrigerant or a circulatin liquid. In this modification the amount of reheat is controlled by means of a three-way valve 80 which is controlled by dry bulb thermostat 84 located in the incoming air stream or directly within the enclosure to be conditioned. This three-way valve 80 is arranged so as to direct the flow of secondary refrigerant either through the reheat coil I 4 or through the coil 88 which is cooled by the same means which cools the main condenser 20. The coil 88 and the condenser 20 may be cooled by means of any conventional cooling medium. For purposes of illustration, I have shown a fan unit 90 for circulating a stream of air over the coil 88 and the condenser Zll. By virtue of this arrangement the secondary system at all times assists in lowering the condensing pressure. In the modification shown in Fig. 4 the pump 5|! may be omitted when using a volatile refrigerant in the secondary system.

While I have shown dry bulb control instruments only throughout this application, it is within the purview of thisinvention to substitute other types of control instruments such as wet bulb, a combination of wet and dry bulb, humidity, or effective temperature instruments for the dry bulb instruments shown. It is also within the purview of this invention to arrange the instruments so as to be responsive to the discharge air temperatures or to the temperatures of the air outside the space to be conditioned.

While the form of embodiment of the 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. In combination, a primary evaporator, a primary compressor, a primary condenser, a heat interchanger having a plurality of separate passages, primary refrigerant flow connections between said primary evaporator, primary compressor, primary condenser and one passage of said heat interchanger, a secondary condenser in refrigerant flow relationship with another passage of said heat interchanger, means for circulating air to be conditioned in thermal exchange relationship with said primary evaporator and thereafter in thermal exchange relationship with said secondary condenser, and means for bypassing the flow of secondary refrigerant around said secondary condenser.

2. In combination, a primary evaporator, a primary compressor, a primary condenser, a heat interchanger having a plurality of separate passages, primary refrigerant flow connections between said primary evaporator, primary compressor, primary condenser and one passage of said heat interchanger, a secondary condenser in refrigerant flow relationship with another passage of said heat interchanger, means for circulating air to be conditioned in thermal exchange relationship with said primary evaporator and thereafter in thermal exchange relationship with said secondary condenser, means for bypassing the'flow of secondary refrigerant around said secondary condenser, and means responsive to the dry bulb temperature for controlling said by-pass means.

3. In combination,'a primary evaporator, a

primary compressor, a heat interchanger having a plurality of passages, a primary condenser, primary refrigerant flow connections between said primary evaporator, said primary compressor, a first passage of said heat interchanger and said primary condenser, means for circulating air to be conditioned in thermal exchange relationship with said primary evaporator, a reheat coil in thermal exchange relationship with the air cooled by said primary evaporator, a surge tank, means for circulating a secondary fluid through said reheat coil, a second passage of said heat interchanger and said surge tank in series, and means for by-passing said reheat coil.

4. In combination, a primary evaporator, a primary compressor, a heat interchanger having a plurality of passages, a primary condenser, primary refrigerant flow connections between said primary evaporator, said primary compressor, a first passage of said heat interchanger and said primary condenser, means for circulating air to be conditioned in thermal exchange relationship with said primary evaporator, a reheat coil in thermal exchange relationship with the air cooled by said primary evaporator, a surge tank, means for circulating a secondary fluid through said reheat coil, a second passage of said heat interchanger and said surge tank in series, means for by-passing said reheat coil, and means responsive to the dry bulb temperature of the air to be conditioned controlling said by-pass.

5. In combination, a primary evaporator, a primary compressor, a heat interchanger having a plurality of passages, a primary condenser, primary refrigerant flow connections between said primary evaporator, said primary compressor, a first passage of said heat interchanger and said primary condenser, means for circulating air to be conditioned in thermal exchange relationship with said primary evaporator, a reheat coil in thermal exchange relationship with the air cooled by said primary evaporator, a surge tank, means for circulating a secondary fluid through said reheat coil, a second passage of said heat interchanger and said surge tank in series, means for by-passing said reheat coil, means responsive to the dry bulb temperature of the air to be conditioned controlling said by-pass, means for ventme said surge tank, and means for adding makeup fluid to said secondary circulating system.

6. In combination, a primary evaporator, a primary compressor, a heat interchanger, a pri mary condenser, refrigerant flow connections between said primary evaporator, primary compressor, heat interchanger and primary condenser, means for circulating air to be conditioned in thermal exchange relationship with said primary evaporator, means for flowing a cooling fluidover said primary condenser, secondary condenser means having one portion arranged in thermal exchange relationship with the air flowing over said primary evaporator and a second portion arranged to be cooled by the condenser cooling fluid, and secondary evaporator means in refrigerant flow relationship with said secondary condenser means, said secondary evaporator means comprising means forming one portion of said heat interchanger.

means for circulating air to be conditioned in thermal exchange relationship with said primary evaporator, means for flowing a cooling fluid over said primary condenser, secondary condenser means having one portion arranged in thermal exchange relationship with the air flowing over said primary evaporator and a second portion arranged to be cooled by the condenser cooling fluid, secondary evaporator means in refrigerant flow relationship with said secondary condenser means, said secondary evaporator means comprising means forming one portion of said heat interchanger, and means for controlling the flow of secondary refrigerant through one of said portions.

8. In combination, a primary evaporator, a primary compressor, a heat interchanger, a primary condenser, refrigerant flow connections between said primary evaporator, primary compressor, heat interchanger and primary condenser, means for circulating air to be conditioned in thermal exchange relationship with said primary evaporator, means for flowing a cooling fluid over said primary condenser, secondary condenser means having one portion arranged in thermal exchange relationship with the air flowing over said primary evaporator and a second portion arranged to be cooled by the condenser cooling fluid, secondary evaporator means in refrigerant flow relationshi with said secondary condenser means, said secondary evaporator means comprising means forming one portion of said heat interchanger, and means for controlling the flow of secondary refrigerant through one of said portions, said last named means comprising a thermostat responsive to the temperature of the air.

9. In combination, a closed primary refrigerant system including a heat dissipating portion and a heat absorbing portion, a closed secondary refrigerant system including a condenser and an evaporator, said evaporator being in heat exchange relation with the heat dissipating portion of the primary refrigerant system, means for circulating air to be conditioned in thermal relationship with said primary evaporator and thereafter in thermal exchange relationship with said secondary condenser, and means for bypassing the flow of secondary refrigerant around said secondary condenser.

JOHN EVERE'I'I'S, JR.

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