US2135285A

US2135285A - Heat pump

Info

Publication number: US2135285A
Application number: US185165A
Authority: US
Inventors: Gibson Hal
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1938-01-15
Filing date: 1938-01-15
Publication date: 1938-11-01
Anticipated expiration: 1955-11-01

Description

HEAT PUMP ,Filed Jan. 15, 1938 J Inventor:

H 6.! Gibson b flan 76 H is Attorney.

Patented Nov. 1, 1938 UNITED STATES PATENT OFFICE r HEAT PUMP a g I Ial Gibson, Dallas, Texl, assignor to General Electric Company, a corporation of New York Application January 1938, Serial No. 185,165

7Claims.

My invention relates to systems for conditioning the air within rooms or enclosures, and particularly to such systems which utilize reversible refrigerating machines to supply both heating 5 and cooling medium.

Reversed cycle refrigerating machines or heat pumps, are frequently employed to supply the heating units of air conditioning systems. Heat pumps require a suitable source of heat such as 0 well water, water from city mains, or outdoor air. In such systems, particularly those using city water, it is desirable to utilize the water as economically as possible since it is necessary to circulate considerable quantities of water whenever the refrigerating machine is in operation. Accordingly, it is an object of my invention to provide an air heating system utilizing a reversed cycle refrigerating machine and having an improved arrangement for controlling the 2 supply of fluid constituting the heat source.

Another object of my invention is to provide an air conditioning system utilizing a refrigerating machine for pumping heat between a fluid medium and the air within an enclosure to be conditioned to thereby either heat or cool the air within the enclosure, which system includes an improved arrangement for controlling the supply of fluid medium.

Furtherobjects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accomanying drawing, the single figure of which shows diagrammatically an air conditioning system embodying my invention.

an air conditioning system including a duct it! connected to receive air from an enclosure to be conditioned through an inlet 'II and fresh air from outside the enclosure through an inlet 2,

the wall of the enclosure being indicated at i3 and the outside wall of the building at ll. A

fan I! driven by a motor i3 is provided to circulate air through theduct l0, and into the enclosure or room to 'be conditioned through an outlet Dust and particles of foreign matter are removed by a filter i3 arranged at the entrance provide a heat exchange element l9 arranged- 55 within the duct and comprising a coil connected Referring now to the drawing, 1 have shownin the refrigerant circuit of a reversible refrigerating machine. The refrigerating machine includes a compressor driven by a motor 2i, a heat exchanger or coil 22 which may serve either as a condenser or evaporator depending upon the direction of flow of refrigerant in the circuit, and a liquid receiver 23. The heat exchanger i9 is connected as the second heat exchange element in the refrigerating circuit, andmay be employed either as a condenser or an evaporator depending upon the direction of flow ofrefrigerant in the circuit. A plurality of normally closed spring

biased solenoid valves

24, 25, 26 and 21 are provided in order to control the direction of flow of refrigerant in the refrigerating circuit. These valves are arranged to operate in series, the valves 24 and 25 being opened and the valves 26 and"2'l being closed when it is desired to cool the air passing through the duct i0, and the

valves

26 and 21 being opened and the valves 24 and 25 being closed when it is desired to heat the air passing through the duct i0. A supply of fluid medium, such as well water or water from the city mains, is circulated over the heat exchanger 22 through a suitable casing 28, in order to supply heat thereto when the refrigerating machine is used to heat the air in the duct ill, and to absor heat from the heat exchanger when the refrigerating machine is used to cool the air in the duct l0. Water is supplied to the casing 28 through

pipes

29 and 30, the direction and rate of flow of -the water being controlled in a manner to be hereinafter described.

When the refrigerating machine is employed to heat the air passing through the duct iii, the compressed refrigerant is discharged from the condenser through a conduit 3i. 'I'hevalves 26 and 21 being opened and the valves 24 and 25 closed, the hot compressed refrigerant flows through the coils of the heat exchanger l9 and heats the air in the duct. The refrigerant is thereby cooled and liquefied and flows out through a connection 32 and a check valve 33 to the liquid receiver 23. A check valve 34 is provided to preventfiow of the refrigerant through a conduit 35 by-passing the valve 33. Manual shut-off

valves

36 and 31 on either side of the receiver 23 are maintained open'whenever the refrigerating machine is in use. A normally closed solenoid operated valve 38 belowthe receiver 23 remains closed during the heating operation and the liquid refrigerant flows through a check valve 39 in a by-pass around the valve 38 and through a scale trap 40 to a thermostatic valve is provided with a thermostatic element 42 adjacent the outlet of the coil 22 on the side opposite the valve 4|. The valve 4|, therefore, controls the flow oi. liquid refrigerant to the heat exchanger 22 which acts as an evaporator. Refrigerant within the coil 22 is vaporized by the absorption of heat from the water circulating through the casing 28 and the vaporized refrigerant returns through a conduit 43 and the open valve to the intake of the compressor.

When the refrigerating machine is operated to cool the air passing through the duct ID, the valves 24 and 25 are opened, and the hot compressed refrigerant flows through the conduit 3| and valve 24 to the coil 22 through conduit 43. The refrigerant is cooled and condensed in the coil 22 and flows through the now open valve 35 to the liquid receiver 23, the check valve 35 preventing the flow of refrigerant through the scale trap 45. The liquid refrigerant flows from receiver 23 through check valve 34 and a scale trap 45 to a thermostatic expansion valve 45 which controls the flow of refrigerant to the coil l5, the valve 45 being provided with a thermostatic element 46 adjacent the outlet side of the coil IS. The check valve 33 prevents the liquid refrigerant by-passing the scale trap 44 and the thermostatic expansion valve 45. The liquid refrigerant in the coil 15 absorbs heat from the air passing through the duct W and cools the air, the refrigerant being thereby vaporized. The vaporized refrigerant returns to the compressor 25 through open valve 25.

In order to humidity the air passing through the duct in when it is being heated, I provide a humidifier 41. Water is admitted to the humidifier 41 through a pipe 48 under control of a solenoid valve 49. In order to heat the water supplied to the humidifier 41 I provide a suitable enclosure such as a casing 55 around a coil 5| formed in the discharge conduit 3| of the compressor. The water flowing through the pipe 48 is therefore heated by the hot compressed gases flowing through the conduit 3|. Water which flows to the humidifier 41 is distributed over a screen 52 from a pan 53, any excess water which has not been absorbed in the air being removed from the duct |0 through a drain 54.

In order to control the operation of the refrigerating machine, I provide a thermostat 55, which may be utilized to maintain the desired temperature within the enclosure during both the heating and cooling operations. Power for driving the motors I5 and 2| and for energizing the control circuits of the system is supplied through lines 55 which are connected to supply lines 51, a normally closed switch 55 being provided in one side of the lines 55 to deenergize the power and control circuits whenever the temperature of the water circulating over the exchanger 22 is reduced sufliciently to endanger freezing thereof within the casing 25.

When it is desired to heat the air passing through the duct III, the control and power circuits are'prepared by closing

manual switches

55 and 55, the switch 55 preparing the thermostatic control and the switch 55 starting the motor |5 to drive the fan I5. When there is a demand for heat, the thermostat 55 engages its left-hand contact to connect a coil 5| of a relay 52 across the secondary of a transformer 53, the primary of which is connected across the lines 55. The relay 52 is thereby picked up, the upper arm closing a holding circuit for the coil Bi, and the lower arm connecting the coils of solenoid valves 25 and 21 across lines 55 to open the refrigerating machine.

the valves, and also energize and pick-up a switch 54 which energizes a coil 55 of a time delay switch 55. The time delay switch closes after a predetermined interval determined by a dashpot or other suitable time delay mechanism 51 and, on closing, starts the motor 2| to drive The time delay mechanism is provided so that the solenoid valves 25 and 21 will be opened before the compressor 25 is started. The refrigerating machine, therefore, operates to supply hot compressed refrigerant to the coil |5 to heat the air passing through the duct -|5 in the manner described above. When the thermostat 55 is satisfied due to the heating of the air of the enclosure to a predetermined temperature, it engages its righthand contact and short circuits the coil 5| thereby causing the relay 52 to drop out and deenergize the control and motor circuits thereby stopping the supply of hot refrigerant to the coil l5. During the heating of the air in the enclosure, should there be a demand for an increase in humidity, a humidostat 55 will close its contact to connect a coil 55 across the lines 55. Coil 55 opens the valve 45 to supply water to the humidifler 41, the water being heated by the coil 5| during its passage through the casing 55. When the humidostat 58 is satisfied, it opens to break the circuit of the coil 55 and stop the supply of water to the humidifier.

The heat supplied to the air passing through the duct I5 is pumped by the refrigerating machine from the water passing through the casing 25, the rate of flow of water being controlled by a valve 15 in response to the pressure within the return or suction line 43 of the compressor, a pressure responsive switch 1| being employed for this purpose. The direction of the flow of water through the casing 25 is controlled by three-

way solenoid valves

12 and 13, and the position of these valves is determined by the lower arm of a switch 14. The

valves

12 and 13 are provided with actuating coils 12a and 150 respectively. The direction of flow of water through the casing 25 is maintained in counterflow to the direction of refrigerant flowing through the coil 22, so that there is a maximum efflciency of heat exchange between the water and refrigerant during both the heating and cooling operations. The valves 12 and 13-reverse the water circuit when the refrigerant circuit is reversed. When the switch 14 is in its drop out position, which is its position during the heating operation, the coil 13a of the solenoid of the valve 15 is connected across the lines 55' and the coil 12a of the valve 12 is not energized. The coils 12a and 13a cannot be energized simultaneously. During the heating operation with the coil 13a energized, water flows from a supply pipe 15 through the valve 12 to the pipe 25, the valve 15 being connected in the pipe 25 to control the flow of water therethrough. A manual valve 15 is provided to shut off the flow of water through the pipe 25 if desired. Water flows from the pipe 25 through the casing 25 to the pipe and thence through the valve 15 to a return pipe 11. The pressure control switch 1| cooperating with a control mechanism 15 of the valve 15 maintains a predetermined pressure within the evaporator coil 22. The control mechanism 15 includes a reversible induction motor 15 of the shaded pole type. The motor drives the valve through a worm and pinion 55 and 5| respectively. Cams 52 and 55 are provided to operate limit switches to determine the limiting position of the valve 18 at either end of its movetion of rotation of the motor. As long as both the

windings

86 and 81 are open circuited, the motor remains stationary. As soon as one of the

windings

86 or 81 is short-circuited, torque is developed and the motor rotates the valve until the short circuit is opened by the pressure switch or until one of the cams 82 and 83 operates its corresponding one of

limit switches

88 and 89 respectively. The pressure responsive switch 1| operates to short-circuit the

windings

86 and 81 depending upon the pressure within the conduit 43. When the pressure increases to a predetermined value, the switch 1| closes its upper set of contact and short-circuits coil 86 causing the valve 18 to rotate in a direction to decrease the flow of water through the casing 28. When the pressure within the conduit 43 decreases to a predetermined low value, the switch 1| closes its lower set of contacts to short the coil 81 and cause the valve 18 to rotate in a y direction to increase the flow of water through the casing 28. It is, therefore, evident that by selecting the desired range of limits for the operation of the switch 1|; the pressure within the evaporator 22 may be maintained within any desired range and thus limit the load on the compressor. 'The required supply of heat to the evaporator 22 is thereby maintained with a minimum flow of water through the casing 28 for whenever there is more water flowing through the casing than required, the supply is limited by operation of the valve 18. More efiicient operation of the refrigerating machine is obtained because the temperature of the evaporator is not permitted to become too low, and more economical operation is obtained by not permitting the temperature of the evaporator to become too high. Should the water in the casing 28 for any reason, such as the failure of the operating coil 9| of switch 14 is also energized deenergize the motor and control circuits and stop the operation of the system';

When it is desired to cool the air within the enclosure, a manual switch98 is closed, switch 58 being open, and the switch 68 is closed in order to drive the motor l6. The closing of the switch 98 prepares the motor and control circuits for the cooling operation. During the cooling operation, the relay 62 falls to its drop out position when there is a demand for cooling, since the thermostat 55 engages its right-hand contact whenever the room temperature reaches a predetermined high value and short-circuits the coil 6!. On a demand for cooling, when the relay 62 is in its drop out position, the coils of solenoid valves 24 and 25 are connected across the lines 56 through the switch 98 and the bottom arm of the relay 62, and the valves 24 and 25 are thereby opened.

Valves

26 and 21 cannot be energized since the switch 59 is open. Ari

and the switch 14 is picked up. The upper arm of the switch 14 closes a circuit of the coil 65 and the time delay switch 66 closes after an interval to start the motor 2| and operate the refrigerating machine to supply liquid refrigerant to the heat exchange element l9. The lower arm of invention.

the switch 14 in its pick-up position energizes the coil 12a and opens the circuit of the coil 1311, thereby reversing the positions of the

valves

12 and 13. Water from the supply pipe 15 flows through the valve 12 and through a pipe 92 to the pipe 38. A manual valve 93 is provided in the' pipe 92. to close the pipe and prevent the flow of water therethrough when desired. The

valve 13 is in position to prevent the flow of water therethrough from the pipe 38 and the water flows from the pipe 38 to the casing 28 and thence through the pipe 29 and a pipe 94 to the outlet 11 through the valve 13. In order to control the flow of water through the pipe 94, I provide a valve 95 operated by a pressure element 96 which is in communication with the discharge pipe 3| of the compressor 28. The valve 95 is, therefore, controlled in response to the head pressure of the compressor, the flow of water through the casing 28 being increased on a rise in head pressure and vice versa. It will be noted that the water flowing through the casing 28 flows in the opposite direction from that of the. refrigerant flowing through the coil 22. refrigerating machine is operating to cool the air passing through the duct l8, compressed refrigerant is discharged through the conduit 43 and the pressure element 1| is thereby maintained at a. relatively high pressure. The upper contacts will then be closed and the motor 19 will operate until the cam 82 opens the circuit of the coil 86 thereby preventing further rotation of the motor and holding it in its limiting position pending a subsequent reduction of the pressure in the element 1|. The motor 19 is, therefore, not operated during the cooling operation.

During the operation of the. refrigerating machine, should the back pressure at any time be reduced to a predetermined minimum, a pressure responsive switch 91 will operate to open its contacts and stop further operation of the motor 2| until the pressure has again increased to normal. This is the type of back pressure control commonly employed in refrigerating machines to prevent excessive low pressures and temperatures.

From the foregoing, it is evident that I have provided an air conditioning system utilizing a refrigerating machine as a heat pump to'either heat or cool the air within an enclosure and-that the system is so arranged as to provide the most eflicient use of the cooling medium which is utilized to cool the condenser during the cooling operation or to supply heat to the refrigerating machine during the heating operation.

While I have described a particular embodiment of my invention in connection with an air conditioning system, other modifications will be apparent to those skilled in the art. I do not, therefore, desire my invention to be limited to the particular construction shown and described and I intend in the appended claims to cover all modifications within the spirit and scope of my What I claim -'as new and desire-to secure b Letters Patent of the United States is:

1. A fluid heating system including a reversed cycle refrigerating machine having a compressor evaporator to supply heat to said system, and- While the means dependent upon the pressure of the vaporized refrigerant withdrawn from said evaporator for controlling the rate of flow of said heat supplying fluid over said evaporator to limit the load on said compressor.

2. A system for heating the air within an enclosure including a duct, a reversed cycle refrigerating machine having a compressor and an evaporator and a condenser, said compressor being arranged to supply compressed refrigerant to said condenser and towithdraw vaporized refrigerantfrom said evaporator, means for circulating air through said duct and into said enclosure, means including said condenser for heating the air circulated through said duct, means for circulating a fluid over said evaporator to supply heat to said system, and means dependent upon the pressure of vaporized refrigerant withdrawn from said evaporator for controlling the rate of flow of said fluid over said evaporator to limit the load on said compressor.

3. ,A system for conditioning the air within an enclosure including a duct, a reversed cycle refrigerating machine having a compressor and an evaporator and a condenser, said compressor being arranged to supply compressed refrigerant to said condenser and to withdraw vaporized refrigerant from said evaporator, means for circulating air through said duct and into said enclosure, means including said condenser for heating the air circulated through said duct, means for circulating a fluid over said evaporator to supply heat to said system, means dependent upon the pressure of vaporized refrigerant withdrawn from said evaporator for controlling the rate of flow of said fluid over said evaporator to limit the load ,on said compressor, means for reversing the operation of said refrigerating machine to supply liquid refrigerant to said condenser to cool the air circulating through said duct and to supply heat to the fluid circulated over said evaporator, and means dependent upon the pressure of refrigerant discharged by said compressor for controlling the flow of said fluid over said evaporator to limit the load on said compressor when the operation of said refrigerating machine is reversed.

4. A system for conditioning the air within an enclosure including a duct, a reversed cycle refrigerating machine having a compressor and an evaporator and a condenser, said compressor being arranged to supply compressed refrigerant to said condenser and to withdraw vaporized refrigerant from said evaporator, means for circulating air through said duct and into said enclosure, means including said condenser for heating the air circulated through said duct, means for circulating a fluid over said evaporator to supply heat to said system, means dependent upon the pressure of vaporized refrigerant withdrawn from said evaporator for controlling the rate of flow of said fluid over said evaporator to limit the load on said compressor, means for reversing the operation of said refrigerating machine to supply liquid refrigerant to said condenser to cool the air circulating through said duct and to supply heat to the fluid circulated over said evaporator, means for reversing the direction of flow of fluid over said evaporator, and means dependent upon the pressure of refrigerant dischargedby said compressor for controlling the rate of flow of said fluid in said reversed direction.

5. A system for heating the air within an enclosure including a duct, a reversed cycle refrigerating machine having a compressor and an evaporator and a condenser, said compressor being arranged to supply compressed refrigerant to said condenser and to withdraw vaporized refrig- -erant from said evaporator, means for circulating air through said duct and into said enclosure, means including said condenser for heating the air circulated through said duct, means dependent upon the temperature of the air within said enclosure for controlling the operation of said refrigerating machine, means for circulating a fluid over said evaporator to supply heat to said system, and means dependent upon the pressure of vaporized refrigerant withdrawn from said evaporator for controlling the rate of flow of said fluid over said evaporator to limit the load on said compressor.

6. A system for heating the air within an enclosure including a duct, a reversed cycle refrigerating machine having a compressor and an evaporator and a condenser, said compressor being arranged to supply compressed refrigerant to said condenser and to withdraw vaporiud'refrigerant from said evaporator, means for circulating air through said duct and into said enclosure, means including said condenser for heating the air circulated through said duct, means arranged within said duct for supplying moisture to the air circulating therethrough for increasing the .relative humidity of the air within said enclosure, means for supplying water for said humldifying means, means utilizing a portion of the heat of compression of the refrigerant discharged from said compressor for heating the water supplied to said humldifying means, means dependent upon the relative humidity of the air within said enclosure for controlling the flow of water to said humidifying means, means for circulating a fluid over said evaporator to supply heat to said system, and means dependent upon the pressure of vaporized refrigerant withdrawn from said evaporator for controlling the rate of flow of said fluid over said evaporator to limit the load on said compressor.

7. A system for heating the air within an enclosure including a duct, a reversed cycle refrigerating machine having a compressor and an evaporator and a condenser, said compressor being arranged to supply compressed refrigerant to said condenser and to withdraw vaporized refrigerant from said evaporator, means for circulating air through said duct and into said enclosure, means including said condenser for heating the air circulated through said duct, means for circulating a fluid over said evaporator to supply heat to said system, means dependent upon the pressure of vaporized refrigerant withdrawn from said evaporator for controlling the rate of flow of said fluid over said evaporator to limit the load on said compressor, said flow controlling means being arranged to vary the rate of flow of fluid over said evaporator substantially in proportion to the change of pressure of said vaporized refrigerant.

HAL GIBSON.