US3246482A

US3246482A - Heat pumps

Info

Publication number: US3246482A
Application number: US422664A
Authority: US
Inventors: James R Harnish
Original assignee: Westinghouse Electric Corp
Current assignee: YORK-LUXAIRE Inc A CORP OF DE
Priority date: 1964-12-31
Filing date: 1964-12-31
Publication date: 1966-04-19
Anticipated expiration: 1983-04-19

Description

April 19, 1966 J, RNfs 3,246,482

HEAT PUMPS Filed Dec. 51, 1964' FIG.I.

l2 REVERSAL '3 VALVE I I I OUTDOOR INDOOR AIR COIL T (f AIR COIL .'28 ACCUMULATOR' CAPILLARY CAPILLARY TUBE TUBE COOLING HEATlNG-- v T I l2 REVERSAL. l4 VALVE n, OUTDOOR \l" moooa AIR con. m AAlRcolL I O T l w I I7 uh COMPRESSOR 28 ACCUMULATOR CAPILLARY OAPILLARY TUBE TUBE GOOLING HEATING--?' INVE NTOR= JAMES R. HARNISH, BY W ATTORNEY United States Patent Oflice.

3,246,482 HEAT PUMPS James R. Harnish, Staunton, Va., assiguor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania 7 Filed Dec. 31, 1964, Ser. No. 422,664

' 8 Claims. (Ci. 62-324) This invention relates to heat pumps which use fixed flow restrictors such as capillary tubes for two-way expansion means.

It is well known that air-to-air heat pumps require larger refrigerant charges during cooling operation than in heating operation. Some such heat pumps use suction line accumulators to store the excess refrigerant during heating operation. Such an accumulator separates lubrieating oil from the suction gas, and a bleeder must be provided at its bottom to meter oil return to the compressor. When such an accumulator is partially filled with refrigerant, the bleeder also meters the flow of a substantial amount of liquid refrigerant mixed with the oil, to the compressor, and may dilute the oil in the crankcase of the compressor, resulting in adequatelubrication. Furthermore, the refrigerant in the crankcase, during defrosting of the outdoor coil, may cause considerable foaming and excess oil pumping, resulting in the compressor losing its oil to the system.

This invention uses heat from the refrigerant liquid,

to boil off refrigerant liquid leaving an accumulator. There is no thermodynamic loss since the heat loss of the liquid provides a greater refrigerating effect. In one embodiment of this. invention, this is accomplished by dividing a capillary tube serving as a two-way expansion means, into two lengths, and by connecting between the two lengths, a larger tube in heat exchange contact with the suction gas line to the compressor. In another embodiment of this invention, a heat exchange coil in'the bot-tom of a suction line accumulator is connected in the tube between the two capillary tube lengths.

An object of this invention is to reduce the quantity of refrigerant liquid flowing from an accumulator into a compressor during heating operation of a heat pump.

This invention will now be described with reference to the annexed drawings, of which:

FIG. 1 is a diagrammatic view of a heat pump embodying this invention, and

FIG. 2 is a diagrammatic view of another heat pump embodying this invention.

Description of FIG. 1

The discharge side of a refrigerant compressor C is connected by discharged gas tube 10 to a conventional reversal valve RV which is connected by tube 11 to one side of an outdoor air coil 12, and by a tube 13 to one side of an indoor air coil 14. The valve RV is also connected by tube 16 to the upper portion of a conventional suction line accumulator 17. Within the accumulator 17 is a U-shaped tube 18 having an open end 19 near the top of the accumulator, and connected at its other end through suction gas tube 20 to the suction side of the compressor C. The base of the tube 18 has an oil bleed hole 29 in its center. The other side of the outdoor air coil 12 is connected by tube 22 to one end of capillary tube 23, the other end of which is connected to 'a tube 24 which is connected to a tube 25 in heat exchange contact with the suction gas tube 20. The tube 25 is connected by tube 26 to one end of another capillary tube 27, the other end of which is connected by tube 28 to the other side of the indoor air coil 14.

Cooling operation of FIG. 1 In the cooling operation of FIG. 1 as shown by the solid-line arrows, discharge gas from the compressor C is supplied through the tube 10, the reversal valve RV, and the tube 11 into the outdoor air coil 12 operating as a condenser. Refrigerant liquid from the coil 12 flows through the tube 22, the capillary tube 23, the

tubes

24, 25 and 26, the capillary tube 27 and the tube 28 into the indoor air coil 14 operating as an evaporator, the

capillary tubes

23 and 27 operating as expansion means. Gas from the indoor coil 14 flows thorugh the tube 13, the reversal valve RV and the tube 16 into the accumulator 17. Gas from the accumulator 17 flows through the

tubes

18 and 20 to the suction side of the compressor C. The refrigerant liquid flowing through the tube 25 heats the suction gas flowing through the tube 20, but there is no thermodynamic loss since the liquid is subcoo-led.

Air heating operation of FIG. 1

As shown by the dashed-line arrows, discharge gas from the compressor C flows through the tube 10, the reversal valve RV and the tube 13 into the indoor air coil 14 operating as a condenser. Refrigerant liquid from the coil 14 flows through the tube 28, the capillary tube 27, the

tubes

26, 25 and 24, the capillary tube 23 and the tube 22 into the outdoor air coil 12 operatingas an evaporator, the

capillary tubes

27 and 23 operating as expansion means. Gas and unevaporated liquid flow from the coil 12 through the tube 11, the reversal valve RV and the tube 16 into the accumulator 17. Gas separated from the liquid within the accumulator enters the open end 19 of the tube 18. Refrigerant liquid Within the accumulator 17 enters the tube 18 through the oil bleed hole 29 so that gas and some liquid flow through the suction gas tube 20- towards the suction side of the compressor C. Heat from the high pressure, liquid flowing through the tube 25 which is in contact with the tube 20, evaporates the refrigerantliquid within the tube 20 so that gas only flows into the suction side of the compressor. The liquid within the tube 25 is subcooled.

, The upstream capillary tube 27, by restricting the fiow of refrigerant liquid from the coil 14, causes some liquid to be backed up in the latter, providing further subcooling, and preventing any high pressure gas from the coil 14 which would reduce the capacity of the system, and increase the power required, from entering the tube 28.

. The downstream capillary tube 23 maintains the pressure and the temperature of the liquid Within the tube 25 high enough to effect the desired heat transfer.

The

capillary tubes

27 and 23 are fixed restrictors, and together have lengths and internal diameters sized for the required expansion during air cooling operation, and are, in effect, two lengths of the usual, single, capillary tube used for two-way expansion.

Description of FIG. 2

FIG. 2 is similar to FIG. 1, except that a coil 30 is placed in the bottom of the accumulator 17, and is connected between the capillary tube 23 and the tube 24. Corresponding components of FIGS. 1 and 2 have the same reference characters applied thereto.

Cooling operation of FIG. 2

The cooling operation of FIG. 2 is the same as that of FIG. 1 except that the liquid from the capillary tube 23 flows through the coil 30 before entering the tube 24 instead of flowing directly into the latter. By charging the system with more refrigerant than is required to satisfy both the indoor coil 14 and the outdoor coil 12, the excess refrigerant liquid will collect in the accumulator 17 in heat exchange contact with the coil 30. Since the compressor C pumps gas boiled olf in both the indoor coil 14 and the accumulator 17, excess liquid flows from the outdoor coil 12, through the tube 22, the capillary tube 23,

Patented Apr. 19, 1966 the coil 30, the

tubes

24, 25 and 26, the capillary tube 27 Heating operation of FIG. 2

The heating operation of FIG. 2 is the same as that of FIG. 1, except that the refrigerant liquid leaving the tube 24, instead of flowing directly into the capillary tube 23, flows through the coil 30 before entering the capillary tube 23. Heat from the refrigerant liquid flowing through the coil 30 evaporatessome of the excess refrigerant liquid flowing from the coil 12 into the accumulator 17, further subcooling the liquid to be evaporated. Again, excess liquid above the evaporation rate is fed to the evaporator, in this instance, the outdoor coil 12, to increase the heat transfer, and the tube 11, the reversal valve RV and the tube 16 flow less gas, reducing the pressure drop, and thereby increasing the efiiciency of the system. Refrigerant liquid is prevented from entering the compressor C.

The system of FIG. 1 could also be provided with an excess charge of refrigerant, since the contact between the

tubes

20 and 25 performs, although to a lesser extent,

the same function that the same contact, and the coil 30 of FIG. 2 perform, and with the same benefits.

What is claimed is: I

1. A heat pump comprising a refrigerant compressor, reversal valve means, a discharge gas tube connecting the discharge side of said compressor to said valve means, an outdoor air coil, a second tube connecting. said valve means to said coil, an indoor air coil, a third tube connecting said valve means to said indoor coil, a suction line accumulator, a fourth tubeconnecting said valve means to said accumulator, a first fixed restrictor having a rela tively large resistance to refrigerant flow, a fifth tube having a relatively small resistance to refrigerant flow connecting said restrictor to said outdoor coil, a second fixed restrictor having a relatively large resistance to refrigerant flow, a sixth tube having a relatively small resistance to refrigerant flow connecting said secondrestrictor to said indoor coil, a seventh tube having a relatively small resistance to refrigerant flow connecting said restrictors, and a suction gas tube connecting said accumulator to the suction side of said compressor, said seventh tube being in heat exchange contact with said suction gas tube, said restrictors serving as two-way expansion means.

2. A heat pump as claimed in claim 1 in which said restrictors are capillary tubes.

3. A heat pump as claimed in claim 2 in which there is provided a heat exchange coil in the bottom of said accumulator, and in which said heat exchange coil is connected in said seventh tube in series with said capillary tubes.

4. A heat pump as claimed in claim 1 in which there is provided a heat exchange coil in the bottom of said accumulator, and in which said heat exchange coil is connected in said seventh tube in series with said restrictors.

5. A heat pump comprising a refrigerant compressor, reversal valve means connected to the discharge side of said compressor, an outdoor air coil connected to said reversal means, an indoor air coil connected to said reversal means, a suction line accumulator connected to said reversal means, a suction gas tube connecting said accumulator to the suction side of said compressor, a second tube having a relatively small resistance to refrigerant flow in heat exchange contact with said suction gas tube, means including a first fixed restrictor having a relatively large resistance to refrigerant fiow connected to said outdoor coil and to one end of said second tube, and means including a second fixed restrictor having a relatively large resistance to refrigerant flow connected to said indoor coil and to the other end of said second tube, said restrictors serving as two-way expansion means.

6. A heat pump as claimed in claim 5 in which said restrictors are capillary tubes.

7. A heat pump as claimed in claim 6 in which there is provided a heat exchange coil in the bottom of said accumulator, and in which said heat exchange coil is connected in said second tube in series with said capillary tubes.

8. A heat pump as claimed in claim 5 in which there is provided a heat exchange coil in the bottom of said accumulator, and in which said heat exchange coil is connected in said second'tube in series with said restrictors.

References Cited by the Examiner UNITED STATES PATENTS 2,342,566 2/ 1944 Wolfert 62-324 2,589,384 3/1952 Hopkins 62-160 3,110,164 11/1963 Smith 62'324 3,128,607 4/1964 Kyle 62-324 3,153,913 10/1964 Brody 62324 WILLIAM J. WYE, Primary Examiner.

Claims

1. A HEAT PUMP COMPRISING A REFRIGERANT COMPRESSOR, REVERSAL VALVE MEANS, A DISCHARGE GAS TUBE CONNECTING THE DISCHARGE SIDE OF SAID COMPRESSOR TO SAID VALVE MEANS, AN OUTDOOR AIR COIL, A SECOND TUBE CONNECTING SAID VALVE MEANS TO SAID COIL, AN INDOOR AIR COIL, A THIRD TUBE CONNECTING SAID VALVE MEANS TO SAID INDOOR COIL, A SUCTION LINE ACCUMULATOR, A FOURTH TUBE CONNECTING SAID VALVE MEANS TO SAID ACCUMULATOR, A FIRST FIXED RESTRICTOR HAVING A RELATIVELY LARGE RESISTANCE TO REFRIGERANT FLOW, A FIFTH TUBE HAVING A RELATIVELY SMALL RESISTANCE TO REFRIGERANT FLOW CONNECTING SAID RESTRICTOR TO SAID OUTDOOR COIL, A SECOND FIXED RESTRICTOR HAVING A RELATIVELY LARGE RESISTANCE TO REFRIGERANT FLOW, A SIXTH TUBE HAVING A RELATIVELY SMALL RESISTANCE TO REFRIGERANT FLOW CONNECTING SAID SECOND RESTRICTOR TO SAID INDOOR COIL, A SEVENTH TUBE HAVING A RELATIVELY SMALL RESISTANCE TO REFRIGERANT FLOW CONNECTING SAID RESTRICTORS, AND A SUCTION GAS TUBE CONNECTING SAID ACCUMULATOR TO THE SUCTION SIDE OF SAID COMPRESSOR, SAID SEVENTH TUBE BEING IN HEAT EXCHANGE CONTACT WITH SAID SUCTION GAS TUBE, SAID RESTRICTORS SERVING AS TWO-WAY EXPANSION MEANS.