US2969655A

US2969655A - Reversible heat pump system

Info

Publication number: US2969655A
Application number: US814233A
Authority: US
Inventors: James A Salter
Original assignee: Ranco Inc
Current assignee: Robertshaw US Holding Corp
Priority date: 1959-05-19
Filing date: 1959-05-19
Publication date: 1961-01-31
Anticipated expiration: 1978-01-31

Description

Jan. 31, 1961 Filed May 19, 1959 J. A. SALTER REVERSIBLE HEAT PUMP SYSTEM 2 Sheets-Sheet 1 INVENTOR.

ATTOFi/VEX Jan. 31, 1961 J. A. SALTER 2,969,655

REVERSIBLE HEAT PUMP SYSTEM Filed May 19, 1959 2 Sheets-Sheet 2 ATTORNEY United States Patent REVERSIBLE HEAT PUMP SYSTEM James A. Salter, Fort Lauderdale, Fla., assignor to Ranco Incorporated, Columbus, Ohio, a corporation of Ohio Filed May 19, 1959, Ser. No. 814,233

5 Claims. (Cl. 62-324) The present invention relates to improvements in reversible heat pump systems of the type comprising a refrigerant compressor connected in a refrigerating circuit including two heat exchangers, either of which may function as a condenser or an evaporator, depending on the order of flow of refrigerant therethrough, one exchanger arranged to temper the air of a certain area, such as in a room, and the other exchanger arranged to dissipate or absorb heat from air of another area, such as out-ofdoors, and means for reversing the order of flow of refrigerant through the exchangers.

It is well known in the refrigeration art that an enclosure, such as a room, can be either cooled or heated by discharging air thereinto which has been passed over a heat exchanger, sometimes referred to as the indoor coil, of a reversible heat pump of the type'referred to. Cooling of the room is efiected-when the inside coil functions as an evaporator and heating is effected when this coil functions as a condenser. It is also known that for most efiicient operation of such systems, the volumetric capacity of .the inside coil should be approximately two-thirds that of the other exchanger, sometimes referred to as the outside coil because it is generally in heat exchange relation with outdoor air. In some instances, however, it is desirable that the volumetric capacity of the inside coil be somewhat less than two-thirds that of the outside coil and in that event, during the time the inside coil is serving as a condenser for producing a heating cycle, the refrigerant. capacity relative to the volume ofrefrigerant available to the compressor results in the refrigerant pressure exceeding normal operating pressures causing malfunction thereof.

The present invention contemplates the removal of a definite quantity of refrigerant from circulation to the compressor during the heating cycle by the provision of a refrigerant passage between the two exchangers including a refrigerant restrictor, such as a capillary tube, which provides the correct restriction to the flow of refrigerant in one direction to provide for economical and efficient cooling of the inside coil during the cooling cycle, and which passage also includes a liquid reservoir having a second refrigerant restrictor, such as a capillary tube, connected in series therewith, and a valving arrangement such that during the flow of refrigerant from the inside coil to the outside coil for effecting a heating cycle, the refrigerant passes through the first restrictor, into the reservoir, then through the second restrictor to the outside exchanger, but during the flow in the opposite direction for the cooling cycle the refrigerant by-passes the'second restrictor and reservoir and passes directly to the first mentioned restrictor and thence to the inside coil.' By this arrangement, during the cooling cycles the full charge of refrigerant circulates in the system, but when the flow of refrigerant is reversed to provide for heating cycles, a

quantity of refrigerant equal to the-volumetric capacity of the reservoir is removed from circulation and an addi- .tional restriction to the flow between the coils is effected. By locating the liquid reservoir between the two restrictors, complete filling of the reservoir is assured so that a definite amount of refrigerant is removed from circulation in the system. The volume of the liquid reservoir preferably equals approximately the difference in volume of the indoor coil and'two-thirds the volume of the outdoor coil.

In carrying out the invention, the reservoir and second restrictor are arranged in shunt with a check valve which permits direct flow of refrigerant from the outdoor coil to the first restrictor during the cooling cycle of the heat pump system, but during the heating cycle the valve is closed to direct'refrigerant flowing from the first restrictor into the reservoir and then through the second restrictor to'increase restriction to the flow and to remove a definite volume of liquid refrigerant from the system.

Otherobjects and advantages of the invention will be apparent from the following description of a preferred form, reference being made to the accompanying drawings wherein Figs. 1 and 2 show schematically, a reversible heat pump system embodying the invention, Fig. 1 showing the system according to the flow of refrigerant during the cooling cycle and Fig. 2 showing the flow in the opposite direction.

Since the components comprising the invention and heat pump systems are well known in the art, the invention is illustrated schematically for sake of clarity. Refer ring to the drawings, a conventional reversible cycle heat pump system is shown of the compressor, condenser-expander type and it includes a refrigerant compressor -10 having the discharge thereof connected by a pipe 11v to the intake of 'a reversing valve V. One reverse flow port of the reversing valve is connected by pipe 16 to one end of a coil type heat exchanger 17 which comprises a serpentine arranged tube 18 having a fin structure 19 assembled therewith comprising closely spaced parallel fins so that air may be passed between the fins to provide good heat exchange between the air and the refrigerant in the tubes. The exchanger 17 is preferably located or arranged so that it is subjected to outdoor air and is hereinafter referred to as the outdoor coil.

A second reverse flow port of reversing valve V is connected by a pipe 20 to one end of a heat exchanger 21 which is similar to that described with reference to outdoor coil 17 having a serpentine coil 22 enclosed in a fin structure 23 of parallel, closely spaced fins, and which is disposed to have air passed between the fins and discharged into an enclosure, such as a room, and for this reason this exchanger is hereinafter referred to as .the indoor coil.

Coils 18 and 22 are interconnected by a refrigerantpassage which comprises a first restrictor 25 in the form of a capillary tube having one end connected with coil 22 and the other end connected with the outlet of acheck valve 26 the inlet of which is connected with one end of coil 18. Check valve 26 permits flow of refrigerant from coil 18 to restrictor 25 but prevents flow from the restrictor to the coil so that this flow of refrigerant is forced to by-pass the check valve and flow into a reservoir or tank 27, the bottom of which is connected with the-right hand end of capillary tube 25 by a tube 28. The top of'tank 27 is connected to one end of a second restrictor 29 which comprises a capillary tube, the other end of which is connected to coil 18 upstream from check valve 26 relative to the flow from the coil through the valve. By this --ar'- rangement, refrigerant flowing from coil 18 to coil 22 passes through restrictor 25' and bypasses restrictor 29 and reservoir 27. Flow of-refrigerant in the' opposite'.direction, on the other hand, is throughre'strictor 2'5, 29 so that the restriction to flow in the latter direction is increased.

The volumetric capacity of tank 27 is preferably equal to the differences in volumetric capacity of the indoor coil and two-thirds the capacity of the outdoor coil, the purpose of which is explained hereinafter.

The intake of compressor is connected by a pipe 30 to the exhaust port of reversing valve V, which port is selectively connected with either of the reverse flow pipes 16 or 20 by a sliding shoe type valve member 31 which is shifted in the valve body by suitable mechanism, not shown because such mechanisms are well known in the art. When valve member 31 is in the position shown in Fig. l, which is the position for a cooling cycle, the discharge of the compressor is connected to the upper end of outdoor coil 18 and the suction or intake of the compressor is connected to the upper end of indoor coil 18, through check valve 26 to restrictor 25, which restricts the flow of gaseous refrigerant to cause liquification thereof, whereupon the liquid refrigerant flows into coil 22 where it is vaporized and returned to the intake of the compressor. It will be apparent that restrictor 29 and reservoir 27 are by-passed by the refrigerant and all liquid which might possibly be in the reservoir is drained therefrom and fed by syphon action into the system. Thus, the whole of the refrigerant is circulated through the system during the cooling cycle.

When valve V is reversed to effect a heating cycle, that is by causing the indoor coil 22 to function as a condenser, refrigerant then fiows from the discharge of the compressor to valve V, through pipe 20 into coil 22, to restrictor 25, and, due to the closure of check valve 26, refrigerant from the restrictor is forced upwardly through reservoir 27 and thence through restrictor 29 to the lower end of outdoor coil 18. Restrictors'25 and 2 act to increase the pressure of the refrigerant to liquify the same so that reservoir 27 will be completely filled with liquid refrigerant before it passes through restrictor 29 to coil 18. Coil 18, receiving liquid refrigerant in its lower end, now functions as an evaporator, and the vaporized refrigerant is withdrawn through pipe 16 and returned to the intake of the compressor through valve V and pipe 30.

It will be seen that during the heating cycle, a definite amount of liquid is removed from effective circulation in the system so that the most efficient volume is utilized, and when the cycle is shifted to the cooling phase, the pressure across the reservoir and restrictor 29 is equalized so that the liquid in the reservoir is syphoned into the system for eflicient operation during the cooling cycle. By this arrangement, it will be apparent that a definite volume of refrigerant is removed from the system during the heating cycle and that the total restriction imposed upon the flow of refrigerant from coil 22 to coil 18 is increased by directing the flow through restrictor 29 as well as restrictor 25 so that the efficiency of the heat pump system during the heating cycle is relatively high. The proper diameters and lengths of the restrictor tubes depend upon various other factors in the system and can be determined by those skilled in the art.

Although but one form of the invention has been shown, it is to be understood that other adaptations, modifications and uses could be employed, all falling within the scope of the claims which follow.

I claim:

1. In a heat pump system comprising a refrigerant compressor and first and second coil type heat exchangers connected with the compressor in a refrigerating circuit and including means to selectively reverse the order of flow of refrigerant through the exchangers, means forming a refrigerant passage between said exchangers including a first restrictor, a liquid reservoir, a second restrictor connected in series with said reservoir, and means to direct refrigerant flow from said first exchanger successively through said first restrictor, said reservoir and second restrictor and to said second exchanger whereby said reservoir is filled to capacity with liquid and to cause the flow of refrigerant from said second exchanger to said first exchanger to by-pass said second restrictor and reservoir and to flow through said first restrictor.

2. A heat pump system as defined in claim 1 in which the volumetric capacity of the first heat exchanger is less than two-thirds the volumetric capacity of the second heat exchanger, and the volumetric capacity of said reservoir is about two-thirdsof the difference in capacities of the two exchangers.

3. In a heat pump system comprising a refrigerant compressor and first and second coil type heat exchangers connected with the compressor in a refrigerating circuit and including means to selectively reverse the order of flow of refrigerant through the exchangers, one end of the first exchanger .being connected to one end of the second exchanger through a refrigerant restrictor and a valve connected in series therewith, a liquid reservoir hav ing one end connected with said restrictor between said restrictor proper and valve, and a second restrictor connected at one end with said reservoir and at the other end with said second exchanger at .a point whereby said reservoir and second restrictor forms a shunt refrigerant fiow circuit around said valve, said valve operative to close when the flow of refrigerant is from said first exchanger and through the first mentioned restrictor to said second exchanger and to open when the flow is from said second exchanger to said first exchanger.

4. In a heat pump system comprising a refrigerant compressor and first and second coil type heat exchangers connected with the compressor in a refrigerating circuit and including means to selectively reverse the orderof flow of refrigerant through the exchangers, one end of the first exchanger being connected to one end of the second exchanger through a first capillary restrictor tube and a check valve connected in series therewith, a liquid reservoir having its lower end connected with said restrictor adjacent to said valve, and a second capillary tube restrictor connected at one end with the top of said reservoir and at the other end with said second exchanger at a point to thereby form a by-pass around said valve, said valve operative to close when the fiow of refrigerant is from said first exchanger and through the first mentioned restrictor to said second exchanger and to open when the flow is from said second exchanger to said first ex changer.

5. In a heat pump system comprising a refrigerant compressor and first and second coil type heat exchangers connected with the compressor in a refrigerating circuit and including means to selectively reverse the order of flow of refrigerant through the exchangers, one end of the first exchanger being connected to one end of the second exchanger through a refrigerant restrictor and a valve connected in series, a liquid reservoir having one end connected with said restrictor between said restrictor proper and valve, and a second restrictor connected with said reservoir and said second exchanger at a point to permit flow of refrigerant around said valve, said reservoir and second restrictor forming a shunt around said valve, said valve operative to close when the flow of refrigerant is from said first exchanger and through the first mentioned restrictor to said second exchanger, and to open when the flow is from said second exchanger to said first exchanger.

References Cited in the file of this patent UNITED STATES PATENTS