US3358470A

US3358470A - Heating and cooling apparatus

Info

Publication number: US3358470A
Application number: US551431A
Authority: US
Inventors: James F Frediani
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 1966-05-19
Filing date: 1966-05-19
Publication date: 1967-12-19
Anticipated expiration: 1984-12-19

Description

1957 J. F. FREDIANI 3,

' HEATING AND COOLING APPARATUS Filed May 19, 1965 INVENTOR. JAMES F. FREDIANI.

ATTORNEY.

United States Patent ABSTRACT OF THE DISCLOSURE Refrigerant flow control for heat pump incorporating a distributor for each heat transfer coil together with a thermal expansion valve associated therewith. Each distiibutor has an inlet conduit and an outlet conduit connecting its associated valve and the other valve respectively.

This invention relates broadly to refrigeration systems employed in heating and cooling apparatus. More particularly, this invention relates to an improved refrigeration system suitable for use in apparatus for heating and cooling air within an enclosure in order to maintain comfort conditions within the enclosure relative to the ambient. Still more particularly, this invention pertains to a refrigeration system of the kind described wherein improved refrigerant flow control means are provided rendering the system particularly useful in apparatus for heating or cooling air circulating within an enclosure so as to be useful and operable throughout a wide range of ambient temperatures.

In heating and cooling apparatus of the kind described, there are provided indoor and outdoor heat exchangers commonly referred to as indoor and outdoor coils together with a compressor and suitable expansion means to form a closed refrigerant flow circuit. Also included in the arrangement described are means for operating the indoor coil as either a condenser or an evaporator to heat or cool air flowing in heat transfer relation therewith. 4

One of the problems encountered with apparatus of the kind described is the provision of suitable refrigerant expansion means between the high and low pressure sides of the refrigerant circuit. It is necessary that the refrigerant expansion means be designed so as to permit flow of refrigerant in two directions between the indoor and outdoor coil, the particular direction depending upon the cycle of operation of the apparatus.

In the refrigeration system disclosed in United States Patent No. 2,976,696, there is shown a refrigerant expansion means, interposed between two heat transfer coils, including two thermal expansion valves and two check valves. The check valves are arranged so that one of the thermal expansion valves is bypassed during one cycle of operation while the other is bypassed during the other cycle of operation.

This invention has for its chief object the provision of an improved refiigeration system operable under the reverse cycle principle for use in heating and cooling apparatus, more particularly, a refrigeration system operable under the reverse cycle principle, including improved refrigerant expansion means permitting efiicient flow of refrigerant during both heating and cooling cycle operation.

Another object of this invention is the provision of an improved heating and cooling apparatus of the kind described wherein liquid refrigerant distribution members employed for the purpose of supplying liquid refrigerant to the heat transfer coils are employed together with appropriate conduits in combination with refrigerant expansion valves in such a manner as to bypass one of the valves and render the other effective during heating cycle Patented Dec. 19, 1%67 operation while reversing the procedure during cooling operation without the necessity of including check valves as a part of the assembly.

In equipment of the kind described where capacities in excess of three tons of cooling are encountered, it is often desirable to provide liquid distributors between the refrigerant expansion valve and the heat transfer coil in order to assure efficient flow of liquid refrigerant in the heat transfer coil served by the distributor. This invention contemplates utilizing two refrigerant expansion valves of the well-known thermostatic type between the indoor and outdoor coils of a heat pump together with a liquid distribution member interposed between each refrigerant expansion valve and its associated coil. To obtain the desired bypass effect, it is contemplated that means providing a passage between each distributor and the valve opposite that associated therewith be provided. Thus, when the heat transfer coil associated with a particular distributor is serving as a condenser, liquid refrigerant collecting in the distributor may pass directly to refrigerant expansion valve serving the other coil now functioning as an evaporator effectively bypassing the refrigerant expansion valve associated with the liquid refrigerant distributor.

These and other objects of the invention will be apparent upon consideration of the ensuing specification and drawing schematically illustrating a preferred embodiment of the invention.

In order to illustrate a preferred embodiment of the invention, attention is directed to the drawing illustrating a heating and cooling apparatus incorporating a mechanical refrigeration system operable under the reverse cycle principle. Apparatus of this type includes two heat transfer coils, one disposed in the area to be served by the apparatus and the other disposed outside of the area usually in the ambient. The two coils act as either a condenser and evaporator or an evaporator and condenser respectively. The apparatus is provided with conventional control means (not shown) for regulating refrigerant flow throughout the refrigeration circuit so that the indoor coil may act as a condenser on heating cycle and outdoor coil act as an evaporator on the heating cycle. When desired to operate the apparatus to cool the air within the enclosure, the control mechanism is manipulated so that the outdoor coil serves as a condenser and the indoor coil serves as an evaporator.

Referring to the figure, a refrigeration system 10 of the kind described includes compressor 12, discharge line 14, refrigerant flow reversing valve 16, and a first heat transfer member 18, disposed outside of the area being served by the apparatus so as to be called an outdoor coil. Refrigerant flow conduits 21 connect the outdoor coil 18 with line 19 connected to valve 16. From the outdoor coil 18, lines 23 connect to liquid refrigerant distribution member 22. A conduit 24 provides a passage for liquid refrigerant to expansion valve 28 serving coil 36 located within the enclosure being served by the apparatus. Refrigerant expansion valve 26 is located adjacent distributor 22. Both

refrigerant control valves

26 and 28 are of the kind normally referred to as thermostatic expansion valves and include means for regulating the flow of refrigerant to the coil associated therewith via its associated distributor, to establish and maintain a pressure relationship between the high and low pressure sides of the refrigeration system. Each expansion valve includes an external equalizer line 30.

Located between expansion valve 28 and the heat transfer member 36 referred to as the indoor coil is a liquid refrigerant distributor 32 for supplying liquid refrigerant in substantially equal amounts to individual refrigerant flow circuits in the coil 36, via lines 34. Liquid refrigerant 3 distributors 22 and. 32 are conventional in the art and are provided with heat transfer coils having a plurality of circuits for the passage of refrigerant therethrough.

Line 38 receives refrigerant via branch lines 37 from the coil 36 and provides a passage for the refrigerant to the valve 16 from where the refrigerant flows to suction line 4%? connected to the compressor 12 to complete the refrigerant flow circuit.

An important feature of this invention involves the provision of the described means for conducting flow between coils 13 and 36. The manner in which the arrangement described accomplishes efficient flow of refrigerant may best be understood by a description of the operation of the apparatus. \Vhen it is desired to operate the apparatus to heat the air flowing within an enclosure such as a room inhabited by individuals, a control (not shown) is manipulated so that reversing valve 16 permits flow of hot gaseous refrigerant from line 14 directly to the indoor coil 36 via line 38. The hot gaseous refrigerant is liquefied in the indoor coil as air in the enclosure is passed in heat transfer relation therewith under the influence of a fan 42. Liquid refrigerant formed in the coil 36 flows via lines 34 to the distributor 32 associated with the indoor coil. As shown in the figure, there is provided a passage 25 connecting the liquid refrigerant distributor with the expansion valve 26 serving the outdoor coil 18. Thus, the liquid refrigerant formed in coil 36 during the heating cycle operation bypasses the expansion valve 28 associated with that coil and is fed directly to expansion valve 26. This path of refrigerant flow ensues because valve 28 senses the relatively high pressure if the hot gaseus refrigerant flowing in line 38 into branch line 37 through external equalizer line 30 connected thereto and assumes a closed position preventing flow of liquid refrigerant in a reverse direction through the valve 28.

High presure liquid refrigerant delivered to the valve 26 is expanded through the valve, line 26, and collects in distributor 22 for supply to the outdoor coil 13 via distributor lines 23. In the outdoor coil, refrigerant is vaporized as it passes 'in heat transfer relation with ambient air flowing under the influence of fan 44. The vaporous refrigerant flows via branch lines 21 through conduit 19 and the reversing valve 16 to the suction line 40 where it enters the compressor completing the cycle.

The apparatus described continues to operate continuously on heating cycle operation until a thermostat or other control element is satisfied at which time, operation of the compressor is terminated. When it is desired to operate the apparatus on the cooling cycle, an appropriate control element (not shown) is actuated so that refrigerant flow through the circuit is for the most part reversed. This is accomplished through a connection between the valve 16 and the control.

Under cooling cycle operation, refrigerant flowing in the discharge line 1 is directed via valve 16 to the outdoor coil 18 where it is condensed as it rejects heat to the outdoor air flowing under the influence of fan 44. The liquid refrigerant thus formed passes via lines 23 to the distributor 22. From the distributor 22, liquid refrigerant flows via line 24 directly to the inlet of expansion valve 28 serving the indoor heat transfer coil 36. During this cycle of operation, expansion valve 26 is closed as it senses the high pressure refrigerant in the

lines

19 and 21 via its external equalizer line 31 This assures flow of liquid refrigerant through line 24 to valve 28 bypassing the valve 26. From valve 28, liquid refrigerant is expanded and flows through line 28' and the distributor 32 to the indoor coil 35 through lines 34. The refrigerant flowing in coil 36 is converted to vapor as it absorbs heat from air passed thereover by fan 42. The vaporous refrigerant flows via line 38 and reversing valve 16 to the suction line 43 to complete the refrigerant fiow circuit. Under these circumstances, the air flowing 1 under the influence of fan 42 is cooled. Operation of the apparatus on cooling cycle continues under the control of a thermostat forming a part of conventional mechanism (not shown).

Heretofore, it has been proposed to combine liquid refrigerant distributors with thermal expansion valves (note United States Letters Patent No. 3,110,162) to provide refrigerant expansion means in a heat pump. Such an arrangement is particularly useful when the two heat transfer coils are located at a substantial distance from one another for it permits the use of a single run of conduit for refrigerant flow between the expansion valves (note 19 of the patent). Unfortunately, such a combination still requires check valves subject to malfunction by jamming or striking open due to lodging of foreign material therein. With the invention disclosed, it will be obvious that the check valves associated with the refrigerant expansion means shown in the aforementioned United States patents have been eliminated resulting in a more economical arrangement for regulating refrigerant flow between heat transfer coils.

While I have described a preferred embodiment of my invention, it is to be understood that the invention is not limited thereto since it may be otherwise embodied within the scope of the following claim.

I claim: 7

A refrigeration system operable under the reverse cycle principle to provide either heating or cooling including a refrigerant flow circuit comprising first and second heat transfer members, said first and second heat transfer members acting to absorb and reject heat respectively; a compressor interposed between the outlet of said first heat transfer member and the inlet of said second heat transfer member for withdrawing refrigerant fluid from said first heat transfer member and delivering it to said second heat transfer member; means for passing a heat transfer medium of at least one of said heat transfer members to effect the desired transfer of heat between the medium and the refrigerant fluid flowing within said heat transfer member; means for interchanging the heat transfer functions of said first and second heat transfer members so that the first heat transfer member will reject heat and the second heat transfer member will absorb heat; first and second liquid refrigerant distributors for selectively delivering liquid refrigerant to the heat transfer members at a plurality of locations throughout the member; first and second refrigerant flow control members for regulating refrigerant flow to the first and second liquid refrigerant distributors respectively, each of the refrigerant flow control members being provided with an external equalizer line enabling flow of high pressure refrigerant to the member when its associated heat transfer member functions as a condenser; a first conduit connecting the first refrigerant distributor directly with the second refrigerant flow control member so that liquid refrigerant formed in the heat transfer member associated with said first liquid refrigerant distributor may flow via the distributor to the second refrigerant flow control member for passage to said second liquid refrigerant distributor through a first path of flow; and a second conduit directly connecting the second liquid refrigerant distributor to the first refrigerant flow control member so that liquid refrigerant formed in the heat transfer member in communication with said second liquid refrigerant distributor may flow directly to the second liquid refrigerant flow control member through a second path of flow independent of first path of flow.

References Cited UNITED STATES PATENTS 3,132,490 5/ 1964 Schmidt 62-324 X WILLIAM J. WYE, Primary Examiner.