CA1113731A - Heat pump system - Google Patents
Heat pump systemInfo
- Publication number
- CA1113731A CA1113731A CA372,003A CA372003A CA1113731A CA 1113731 A CA1113731 A CA 1113731A CA 372003 A CA372003 A CA 372003A CA 1113731 A CA1113731 A CA 1113731A
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- CA
- Canada
- Prior art keywords
- refrigerant
- flow
- exchanger
- heat
- circuits
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
Abstract
H E A T P U M P S Y S T E M
ABSTRACT OF THE DISCLOSURE
A reversible vapor compression system having control means associated therewith for automatically routing refrigerant through the heat exchangers in response to a system mode of operation to produce optimum system performance when the system is called upon to produce either heating or cooling.
ABSTRACT OF THE DISCLOSURE
A reversible vapor compression system having control means associated therewith for automatically routing refrigerant through the heat exchangers in response to a system mode of operation to produce optimum system performance when the system is called upon to produce either heating or cooling.
Description
- ~13731 Heat Pump System This invention relates to a reversible refrigeration system which is adapted to deliver optimum performance in either a heating or a cooling mode of operation.
More specifically, this invention relates to a heat pump having control means associated therewith for automatically routing refrigerant to each of the heat exchangers in response to the exchangers' function whereby each exchanger operates efficiently when called upon to serve either as a condenser or as an evaporator.
Most air side heat exchangers employed in refrigeration systems are of the plate fin construction wherein refrigerant is directed through a number of heat transfer zones via flow circuits running through the unit. When the exchanger is used as a condenser, the flow of refrigerant is routed through the circuits so that it passes in series through each zone. On the other hand, when the exchanger is used as an evaporator, the refrigerant is generally routed through each circuit simultaneously to establish a parallel flow through the circuits. As can be seen, the flow geometry associated with a well designed condenser is not compatible with that of a well designed evaporator. -In a heat pump environment, it has been the usual practice to compromise the heat exchanger design in order to permit the exchangers to provide the double duty function required. This, in turn, limited the performance of the entire system. -It is therefor an object of the present invention to improve heat pump systems.
' ---' ' '- - . , -':
-`` 1113731 It is a further object of the present invention to provide a heat pump system for automatically controlling the flow of refrigerant through the system whereby the system performs effectively in either a cooling or a heating mode of operation.
In one aspect of the present invention there is provided in a heat pump system having a compressor, a pair of heat exchangers and means for selectively reversing the flow of refrigerant through the system so that the function of the exchangers is also reversed, the improvement comprising means for separating each exchanger into a plurality of heat transfer zones, each zone containing a number of flow circuits, flow control means for routing refrigerant discharged from the compressor through each of the zones of one exchanger in a series flow progression and routing the refrigerant discharged from said one exchanger into the other exchanger simultaneously through each of the zones of said other exchanger whereby flow is parallel through the zones, and switching means operatively associated with said flow control means for automatically reversing the flow geometry through the exchangers in response to reversing the flow of refrigerant through the system whereby refrigerant flow is parallel through said one exchanger and in series through said other exchanger.
In a further aspect of the present invention there is provided a heat pump system having a compressor, an indoor coil, an outdoor coil, a reversing valve for delivering refrigerant discharged from the compressor to the indoor coil during heating operations and to the outdoor coil during cooling operations, the method of processing refrigerant through the system including the steps separating the indoor and outdoor coils into a plurality of heat ` transfer zones, each zone having a number of flow circuits passing through the coil associated therewith, routing the refrigerant delivered from the compressor to the outdoor coil during the cooling operations so that refrigerant flows through each of the : ' . , ' :' . , - ~ , -,, .
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heat transfer zones in a series progression, delivering the refrigerant discharged from the outdoor coil to each of the heat transfer zones of the indoor coil simultaneously so that the refrigerant flows through the zones in a parallel flow, returning the refrigerant from the indoor coil to the compressor to complete the cycle, and reversing the flow geometry through the indoor and outdoor coils in response to a change in the systems operation whereby refrigerant flows in series through the zones of the indoor coil and in parallel through the zones of the outdoor coil.
These and other objects of the present invention are attained by means of a heat pump system having refrigerant flow control means associated therewith to produce a series flow geometry through the heat transfer zones of either of the heat exchangers when the exchanger is serving as a condenser and a parallel flow geometry through the zones when the exchanger is serving as an evaporator.
For a better understanding of the present invention as well as other objects and further features thereof, reference is had to the following detailed descripton of the invention to be read in connection with the accompany mg drawings, wherein:
Figure 1 is the schematic representation of a reversible refrigeration system utilizing the heat exchanger of the present ::
invention;
.
Figure 2 is a partial perspective view showing a multicircuit heat exchanger utilizing the teachings of the present invention;
Figure 3 is a partial front view of the heat exchanger shown in Figure 2;
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Figure 4 is an end view of the heat exchanger shown in Figure 3;
Figure 5 is a schematic representation illustrating the flow circuits of the exchanger shown in Figures 2 through 4; and Figure 6 is an enlarged view in section illustrating a capillary tube feeding one of the flow circuits of the exchange shown in Figures 2 through 4.
Figure 1 represents the simplest form of the invention being utilized in a reversible vapor compression system, generally referenced 10. The system includes a compressor 11 of any suitable design and two refrigerant heat exchangers 12, 13 which are typically plate fin coils which are specifically fabricated to exchange energy between air moving over the plates and refrigerant moving through the exchanger flow circuits. For purposes of this description, heat exchanger 12 shall be referred to as the indoor coil while heat exchanger 13 shall be referred to as the outdoor coil. The two coils are operatively connected to the compressor by a four-way valve 15, which enables the discharge vapor from the compressor to be selectively directed into either one of the exchangers. When the system is in a cooling mode of operation, the discharge is carried via line 16 into a primary header 17 dissociated with the outdoor coil. At this time, the suction end of the compressor is operatively connected to the primary header 33 by means of line 36. By cycling the four-way valve, the flow of refrigerant through the system is reversed and, accordingly, the role of the heat exchangers is also reversed.
The operation of the system shall be initially explained with the system in a cooling mode of operation wherein the outdoor coil 13 is called upon to serve as a condenser. The refrigerant vapor collected in the primary or upper header 17 flows downwardly through a refrigerant circuit 19. The refrigerant is caused to - , ~ ' - -- ,- ' -- . . .
. -:, .
.
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~13731 move through two heat transfer zones, an upper zone A and a lower Zone B. The two zones are separated by return bend 14 which functions as an intermediate header for passing refrigerant from one zone to the other.
After passing through the two heat transfer zones, the refrigerant enters a lower secondary header 18 associated with the indoor coil.
The lower header 18 is placed in fluid flow communication with secondary header 31 associated with the indoor coil by means of liquid line 23. It should also be noted that the lower header 18 is also placed in fluid flow communication with the upper header 17 by line 20 which bypasses the heat exchanger circuit. A check valve 21 is positioned in the bypass line. The valve is held closed when the outdoor coil is operating as a condenser by the pressure difference established over the exchanger as the refrigerant changes from a vapor to a liquid. As a result, the liquid refrigerant collected in the lower or secondary header is prevented from flowing back into the primary header via line 20 when the exchanger is serving as a condenser.
The liquid refrigerant collected in header 18 moves along liquid line 23 through another check valve 24. Check valve 24 is arranged to open when the system is in a cooling mode of operation whereby the liquid refrigerant is directed toward the second indoor coil 12. A second check valve 25 also is positioned in the liquid line close to the secondary header 31 associated with the indoor coil.
The check valve 25 is arranged to operate in opposition with check valve 24 whereby the refrigerant is precluded from flowing directly from the liquid line into header 31. The refrigerant is thus forced to move into a distributor 27 positioned forward of check valve 25 in relation to the direction of flow.
:
In the distributor, the flow is split into two separate flow paths by means of a pair of capillary tubes 28, 29. As seen in Figure 1, : ' ,- :
, - , - . ::: . , - . . , -1~13731 the capillary tubes are passed into centrally located return bend 30 which serves as an intermediate header in regard to the indoor coil. In practice the capillaries pass through the return bend and empty deeply into the circuit tubing connected thereto. As a result, a portion of the refrigerant is expanded into upper heat transfer zone C and a portion expanded into lower heat transfer zone D. Because of the pressures involved, a portion of the refrigerant flows upwardly through the flow circuit 34 into the primary header 33 and a portion of the refrigerant flows downwardly into the secondary header 31. As can be seen, the flow geometry of the indoor coil, which is functioning as an evaporator in the cooling mode of operation, consists of two distinct flow passages through which the refrigerant is moved simultaneously, one passage carrying refrigerant through heat transfer zone C and the other through heat transfer zone D.
As in the case of the outdoor exchanger, the indoor exchanger also has a bypass line 34 associated therewith which places the primary header 33 in fluid flow communication with the secondary header 31.
A check valve 35 is located in the bypass line and is arranged to open when the exchanger 12 is operating as a condenser. With check valve 35 open, the two headers 31, 33 are exposed to the suction side of the compressor by means of line 36 thereby completing the cycle. -Changing the system mode of operation, which is accomplished by cycling the four-way valve, reverses the flow of refrigerant through the system. This in turn changes the function of the two exchangers. At this time, the position of the four check valves changes. Bypass line 20 is thus opened while line 34 is closed.
Similarly check valve 25 opens while check valve 24 closes.
The discharge from the compressor passes via line 36 and header 33 through the indoor coil, which is now acting as a condenser, into -:
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- 1~13731 the lower header 31. The refrigerant, as it moves through the indoor coil, passes in series through the two heat transfer zones C
and D. From the header 31, the refrigerant moves down the liquid line toward the outdoor coil. The flow is however blocked by closed check valve 24 causing the refrigerant to move into distributor 37 where the flow is split into two paths by means of capillary tubes 38, 39.
The capillaries pass through the intermediate header or tube bend 14 into the circuits associated with heat transfer zones A and B.
Here again, the flow is split in two directions through the exchanger with part of the flow directed into secondary header 18 and part into primary header 17. The two headers are connected to the suction end of the compressor via open bypass line 20 and line 16 to close the heating loop.
As should be clear from the description above, the flow of refrigerant through the heat exchangers is automatically controlled so that the flow geometry through each exchanger is changed depending on whether the exchanger is being used as a condenser or an evaporator. More specifically, when the heat exchanger is called upon to serve as a condenser, refrigerant is caused to flow in series through the exchanger heat zone. By the same token, the refrigerant is caused to flow simultaneously, or in parallel, through the heat zones when the exchanger is serving as an evaporator. In this manner, the performance of the system can be -optimized for either a heating or cooling mode of operation, a result heretofore unattainable because of limitations placed upon the system as a result of the compromise necessitated by heat exchanger design.
`;
It should be clear from the description above that the system is not necessarily limited by the use of headers in connection with the exchangers when the invention is carried out in connection with .
- 1~13~31 a simple exchanger. In this regard the header can be replaced with standard tubing capable of facilitating the movement of refrigerant into and out of the exchangers.
Similarly, the present invention can be carried out in conjunction with a complex coil in which a multitude of circuits are passed back and forth through the exchanger unit. A complex coil, such as those typically utilized in larger refrigeration systems is illustrated in Figures 2 through 4. For purposes of explanation, the coil shall be deemed to be an outdoor coil utilized in a reversible refrigeration system similar to that described in Figure 1.
A coil of complex circuitry containing a plurality of refrigerant flow circuits is illustrated in Figures 2 through 4. The coil includes two vertically aligned rows of finned tubes, an inner row 40 and outer row 41 which extend back and forth through the heat exchanger. The rows are interconnected by return bends 42 to form a number of individual refrigerant flow circuits of predetermined geometry. Typically, the two terminal ends of each circuit are brought out of the coil assembly through one of the assembly tube sheets as for example tube sheet 45, so that both the entrance and discharge opening to each circuit is conveniently located along one side of the exchanger.
In the complex coil herein described, the coil contains seven flow circuits that are arranged to pass through three heat transfer zones. It should become obvious, however, from the discussion below, that the number of circuits and heat transfer zones may vary depending upon the capacity of the unit involved and other design -considerations.
Positioned along the side of the coil adjacent to the tube sheet 45 is a header network adapted to operate in conjunction with two .: ' .. :
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.
:
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1~.13731 check valves to route the flow of refrigerant through the heat exchanger in a prescribed manner when the exchanger is acting in the system as a condenser and in a different manner when it is acting as an evaporator. The header includes a primary header 47, a dummy or intermediate header 48, a secondary header 49 and a liquid header 46. It should be noted that the primary and secondary headers are axially aligned with the interior chambers of each header being separated by means of a check valve 51. The lower end of primary header 47 is joined in fluid flow communication with a compressor line 50 that is operatively connected to the compressor by means of a four-way valve (not shown).
When the coil is serving as a condenser, high temperature and pressure vapor is delivered into the primary header via line 50 thereby causing check valve 51 to close. The closing of the valve in effect isolates the chamber of header 47 from that of header 49.
The now isolated primary header is thus caused to feed refrigerant into four flow circuits by means of feeder tubes 52 operatively associated therewith. The four circuits fed by header 47 are positioned in the lower section of the coil and make up a first heat transfer zone, herein referenced zone E.
A simplified schematic illustration of the flow through the heat exchanger is shown Figure 6. It is believed that the use of the schematic in conjunction with the drawing of Figures 2 through 4 will help in better understanding the flow geometry through the exchanger. After passing through the four flow circuits making up heat transfer zone E, the refrigerant is passed into the dummy header 48 via discharge lines 53. Because of the pressure differential involved, the refrigerant moves upwardly through the dummy header and is discharged into the two uppermost circuits in the coil by means of feeder tubes 54. The two upper refrigerant :
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flow circuits combine to establish a second, smaller heat transfer region F.
After passing through the coil assembly, the refrigerant from the two upper circuits is routed to the secondary header 49 via discharge line 56. The refrigerant is collected in header 49 and fed into the last flow circuit by means of a single feeder tube 58.
The last circuit passes through the third and final heat transfer zone, zone G, and is discharged into the liquid header 46.
Preferably, the final heat transfer zone is located in the central portion of the coil to enhance the heat transfer characteristics of the coil. For the purposes of clarity, the final heat transfer zone is illustrated at the top of the heat exchanger assembly.
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The refrigerant, which is now in a liquid phase is collected in the liquid header 46 and is passed through opened check valve 61 into a T-connector 62. At the connector, the refrigerant moves down liquid line 60 toward the indoor coil (not shown).
As can be seen from the description above, the header network, acting in concert with the check valves, operates to direct the refrigerant from the compressor through the heat transfer zones in a series flow progression. Furthermore, the number of flow circuits in each zone diminishes in the direction of flow. By zoning the coil in this manner, the flow geometry of the coil is regulated in response to the increase in density of the fluid to obtain optimum coil performance when operating as a condenser.
When the systems mode of operation is reversed, the coil's function is similarly reversed. In the heating mode, liquid refrigerant is moved along liquid line 60 toward check valve 61. The valve, however, is automatically moved to a closed position because of the change in pressure felt over the valve. The refrigerant is thus . ' .
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forced to move into distributor 63 that is connected to T-connector 62. At the distributor, the flow is separated into seven flow paths by means of capillary tubes 65. It should be noted that the number of capillary tubes are equal in number to the number of flow circuits passing through the coil.
As best illustrated in Figure 6, six of the capillary tubes pass through the dummy and pass into feeder tubes 54 associated with the four circuits contained in heat transfer zone E and the discharge tubes 53 associated with the two circuits associated with heat transfer zone F. The capillary tubes extend deeply into the various flow circuit tubes to insure that the refrigerant passing through the capillaries is expanded well within each circuit.
This, in turn, precludes the refrigerant from being passed between circuits by the dummy header. Because the dummy header is at a substantially uniform pressure, the refrigerant is fed evenly into each circuit.
The seventh capillary tube is passed into the liquid header 46 which is at relatively the same pressure as the dummy header.
Header 46, in turn, feeds into the circuit associated with heat transfer zone G.
It should be noted that at this time check valve 51, positioned between the primary and secondary headers 47 and 49 is now moved to an open position so that the headers are cojoined to establish a single flow passage leading to the compressor via line 50. As best illustrated in Figure 5, the seven flow circuits are arranged to empty into the headers 47, 49 when the coil is serving as an evaporator. The circuits associated with zones G and F empty into header 49 via lines 56 and 58 while the four circuits associated with zone E empty into header 47 via lines 52.
,, ,. , .,.. .. . .. , : - . , : : .
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- . .
.. . . . .
.
. . .. ~, , Accordingly, when the heat exchanger is called upon to serve as an evaporator in the system, the flow geometry through the coil is automatically changed whereby refrigerant is caused to flow through all the circuits, and thus all the heat transfer zones, simultaneously in a parallel flow arrangement. By maintaining this parallel flow arrangement through the coil, optimum performance of the exchanger can be obtained when utilized as an evaporator.
While this invention has been described with reference to the structure herein disclosed, it is not confined to the specific details as set forth. For example, in place of the capillary tubes wherein employed any expansion device capable of carrying out the flow splitting and throttling process can be similarly employed provided such modifications come within the scope of the following claims.
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More specifically, this invention relates to a heat pump having control means associated therewith for automatically routing refrigerant to each of the heat exchangers in response to the exchangers' function whereby each exchanger operates efficiently when called upon to serve either as a condenser or as an evaporator.
Most air side heat exchangers employed in refrigeration systems are of the plate fin construction wherein refrigerant is directed through a number of heat transfer zones via flow circuits running through the unit. When the exchanger is used as a condenser, the flow of refrigerant is routed through the circuits so that it passes in series through each zone. On the other hand, when the exchanger is used as an evaporator, the refrigerant is generally routed through each circuit simultaneously to establish a parallel flow through the circuits. As can be seen, the flow geometry associated with a well designed condenser is not compatible with that of a well designed evaporator. -In a heat pump environment, it has been the usual practice to compromise the heat exchanger design in order to permit the exchangers to provide the double duty function required. This, in turn, limited the performance of the entire system. -It is therefor an object of the present invention to improve heat pump systems.
' ---' ' '- - . , -':
-`` 1113731 It is a further object of the present invention to provide a heat pump system for automatically controlling the flow of refrigerant through the system whereby the system performs effectively in either a cooling or a heating mode of operation.
In one aspect of the present invention there is provided in a heat pump system having a compressor, a pair of heat exchangers and means for selectively reversing the flow of refrigerant through the system so that the function of the exchangers is also reversed, the improvement comprising means for separating each exchanger into a plurality of heat transfer zones, each zone containing a number of flow circuits, flow control means for routing refrigerant discharged from the compressor through each of the zones of one exchanger in a series flow progression and routing the refrigerant discharged from said one exchanger into the other exchanger simultaneously through each of the zones of said other exchanger whereby flow is parallel through the zones, and switching means operatively associated with said flow control means for automatically reversing the flow geometry through the exchangers in response to reversing the flow of refrigerant through the system whereby refrigerant flow is parallel through said one exchanger and in series through said other exchanger.
In a further aspect of the present invention there is provided a heat pump system having a compressor, an indoor coil, an outdoor coil, a reversing valve for delivering refrigerant discharged from the compressor to the indoor coil during heating operations and to the outdoor coil during cooling operations, the method of processing refrigerant through the system including the steps separating the indoor and outdoor coils into a plurality of heat ` transfer zones, each zone having a number of flow circuits passing through the coil associated therewith, routing the refrigerant delivered from the compressor to the outdoor coil during the cooling operations so that refrigerant flows through each of the : ' . , ' :' . , - ~ , -,, .
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heat transfer zones in a series progression, delivering the refrigerant discharged from the outdoor coil to each of the heat transfer zones of the indoor coil simultaneously so that the refrigerant flows through the zones in a parallel flow, returning the refrigerant from the indoor coil to the compressor to complete the cycle, and reversing the flow geometry through the indoor and outdoor coils in response to a change in the systems operation whereby refrigerant flows in series through the zones of the indoor coil and in parallel through the zones of the outdoor coil.
These and other objects of the present invention are attained by means of a heat pump system having refrigerant flow control means associated therewith to produce a series flow geometry through the heat transfer zones of either of the heat exchangers when the exchanger is serving as a condenser and a parallel flow geometry through the zones when the exchanger is serving as an evaporator.
For a better understanding of the present invention as well as other objects and further features thereof, reference is had to the following detailed descripton of the invention to be read in connection with the accompany mg drawings, wherein:
Figure 1 is the schematic representation of a reversible refrigeration system utilizing the heat exchanger of the present ::
invention;
.
Figure 2 is a partial perspective view showing a multicircuit heat exchanger utilizing the teachings of the present invention;
Figure 3 is a partial front view of the heat exchanger shown in Figure 2;
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Figure 4 is an end view of the heat exchanger shown in Figure 3;
Figure 5 is a schematic representation illustrating the flow circuits of the exchanger shown in Figures 2 through 4; and Figure 6 is an enlarged view in section illustrating a capillary tube feeding one of the flow circuits of the exchange shown in Figures 2 through 4.
Figure 1 represents the simplest form of the invention being utilized in a reversible vapor compression system, generally referenced 10. The system includes a compressor 11 of any suitable design and two refrigerant heat exchangers 12, 13 which are typically plate fin coils which are specifically fabricated to exchange energy between air moving over the plates and refrigerant moving through the exchanger flow circuits. For purposes of this description, heat exchanger 12 shall be referred to as the indoor coil while heat exchanger 13 shall be referred to as the outdoor coil. The two coils are operatively connected to the compressor by a four-way valve 15, which enables the discharge vapor from the compressor to be selectively directed into either one of the exchangers. When the system is in a cooling mode of operation, the discharge is carried via line 16 into a primary header 17 dissociated with the outdoor coil. At this time, the suction end of the compressor is operatively connected to the primary header 33 by means of line 36. By cycling the four-way valve, the flow of refrigerant through the system is reversed and, accordingly, the role of the heat exchangers is also reversed.
The operation of the system shall be initially explained with the system in a cooling mode of operation wherein the outdoor coil 13 is called upon to serve as a condenser. The refrigerant vapor collected in the primary or upper header 17 flows downwardly through a refrigerant circuit 19. The refrigerant is caused to - , ~ ' - -- ,- ' -- . . .
. -:, .
.
- : . . : : - :
~13731 move through two heat transfer zones, an upper zone A and a lower Zone B. The two zones are separated by return bend 14 which functions as an intermediate header for passing refrigerant from one zone to the other.
After passing through the two heat transfer zones, the refrigerant enters a lower secondary header 18 associated with the indoor coil.
The lower header 18 is placed in fluid flow communication with secondary header 31 associated with the indoor coil by means of liquid line 23. It should also be noted that the lower header 18 is also placed in fluid flow communication with the upper header 17 by line 20 which bypasses the heat exchanger circuit. A check valve 21 is positioned in the bypass line. The valve is held closed when the outdoor coil is operating as a condenser by the pressure difference established over the exchanger as the refrigerant changes from a vapor to a liquid. As a result, the liquid refrigerant collected in the lower or secondary header is prevented from flowing back into the primary header via line 20 when the exchanger is serving as a condenser.
The liquid refrigerant collected in header 18 moves along liquid line 23 through another check valve 24. Check valve 24 is arranged to open when the system is in a cooling mode of operation whereby the liquid refrigerant is directed toward the second indoor coil 12. A second check valve 25 also is positioned in the liquid line close to the secondary header 31 associated with the indoor coil.
The check valve 25 is arranged to operate in opposition with check valve 24 whereby the refrigerant is precluded from flowing directly from the liquid line into header 31. The refrigerant is thus forced to move into a distributor 27 positioned forward of check valve 25 in relation to the direction of flow.
:
In the distributor, the flow is split into two separate flow paths by means of a pair of capillary tubes 28, 29. As seen in Figure 1, : ' ,- :
, - , - . ::: . , - . . , -1~13731 the capillary tubes are passed into centrally located return bend 30 which serves as an intermediate header in regard to the indoor coil. In practice the capillaries pass through the return bend and empty deeply into the circuit tubing connected thereto. As a result, a portion of the refrigerant is expanded into upper heat transfer zone C and a portion expanded into lower heat transfer zone D. Because of the pressures involved, a portion of the refrigerant flows upwardly through the flow circuit 34 into the primary header 33 and a portion of the refrigerant flows downwardly into the secondary header 31. As can be seen, the flow geometry of the indoor coil, which is functioning as an evaporator in the cooling mode of operation, consists of two distinct flow passages through which the refrigerant is moved simultaneously, one passage carrying refrigerant through heat transfer zone C and the other through heat transfer zone D.
As in the case of the outdoor exchanger, the indoor exchanger also has a bypass line 34 associated therewith which places the primary header 33 in fluid flow communication with the secondary header 31.
A check valve 35 is located in the bypass line and is arranged to open when the exchanger 12 is operating as a condenser. With check valve 35 open, the two headers 31, 33 are exposed to the suction side of the compressor by means of line 36 thereby completing the cycle. -Changing the system mode of operation, which is accomplished by cycling the four-way valve, reverses the flow of refrigerant through the system. This in turn changes the function of the two exchangers. At this time, the position of the four check valves changes. Bypass line 20 is thus opened while line 34 is closed.
Similarly check valve 25 opens while check valve 24 closes.
The discharge from the compressor passes via line 36 and header 33 through the indoor coil, which is now acting as a condenser, into -:
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- 1~13731 the lower header 31. The refrigerant, as it moves through the indoor coil, passes in series through the two heat transfer zones C
and D. From the header 31, the refrigerant moves down the liquid line toward the outdoor coil. The flow is however blocked by closed check valve 24 causing the refrigerant to move into distributor 37 where the flow is split into two paths by means of capillary tubes 38, 39.
The capillaries pass through the intermediate header or tube bend 14 into the circuits associated with heat transfer zones A and B.
Here again, the flow is split in two directions through the exchanger with part of the flow directed into secondary header 18 and part into primary header 17. The two headers are connected to the suction end of the compressor via open bypass line 20 and line 16 to close the heating loop.
As should be clear from the description above, the flow of refrigerant through the heat exchangers is automatically controlled so that the flow geometry through each exchanger is changed depending on whether the exchanger is being used as a condenser or an evaporator. More specifically, when the heat exchanger is called upon to serve as a condenser, refrigerant is caused to flow in series through the exchanger heat zone. By the same token, the refrigerant is caused to flow simultaneously, or in parallel, through the heat zones when the exchanger is serving as an evaporator. In this manner, the performance of the system can be -optimized for either a heating or cooling mode of operation, a result heretofore unattainable because of limitations placed upon the system as a result of the compromise necessitated by heat exchanger design.
`;
It should be clear from the description above that the system is not necessarily limited by the use of headers in connection with the exchangers when the invention is carried out in connection with .
- 1~13~31 a simple exchanger. In this regard the header can be replaced with standard tubing capable of facilitating the movement of refrigerant into and out of the exchangers.
Similarly, the present invention can be carried out in conjunction with a complex coil in which a multitude of circuits are passed back and forth through the exchanger unit. A complex coil, such as those typically utilized in larger refrigeration systems is illustrated in Figures 2 through 4. For purposes of explanation, the coil shall be deemed to be an outdoor coil utilized in a reversible refrigeration system similar to that described in Figure 1.
A coil of complex circuitry containing a plurality of refrigerant flow circuits is illustrated in Figures 2 through 4. The coil includes two vertically aligned rows of finned tubes, an inner row 40 and outer row 41 which extend back and forth through the heat exchanger. The rows are interconnected by return bends 42 to form a number of individual refrigerant flow circuits of predetermined geometry. Typically, the two terminal ends of each circuit are brought out of the coil assembly through one of the assembly tube sheets as for example tube sheet 45, so that both the entrance and discharge opening to each circuit is conveniently located along one side of the exchanger.
In the complex coil herein described, the coil contains seven flow circuits that are arranged to pass through three heat transfer zones. It should become obvious, however, from the discussion below, that the number of circuits and heat transfer zones may vary depending upon the capacity of the unit involved and other design -considerations.
Positioned along the side of the coil adjacent to the tube sheet 45 is a header network adapted to operate in conjunction with two .: ' .. :
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.
:
:
.
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1~.13731 check valves to route the flow of refrigerant through the heat exchanger in a prescribed manner when the exchanger is acting in the system as a condenser and in a different manner when it is acting as an evaporator. The header includes a primary header 47, a dummy or intermediate header 48, a secondary header 49 and a liquid header 46. It should be noted that the primary and secondary headers are axially aligned with the interior chambers of each header being separated by means of a check valve 51. The lower end of primary header 47 is joined in fluid flow communication with a compressor line 50 that is operatively connected to the compressor by means of a four-way valve (not shown).
When the coil is serving as a condenser, high temperature and pressure vapor is delivered into the primary header via line 50 thereby causing check valve 51 to close. The closing of the valve in effect isolates the chamber of header 47 from that of header 49.
The now isolated primary header is thus caused to feed refrigerant into four flow circuits by means of feeder tubes 52 operatively associated therewith. The four circuits fed by header 47 are positioned in the lower section of the coil and make up a first heat transfer zone, herein referenced zone E.
A simplified schematic illustration of the flow through the heat exchanger is shown Figure 6. It is believed that the use of the schematic in conjunction with the drawing of Figures 2 through 4 will help in better understanding the flow geometry through the exchanger. After passing through the four flow circuits making up heat transfer zone E, the refrigerant is passed into the dummy header 48 via discharge lines 53. Because of the pressure differential involved, the refrigerant moves upwardly through the dummy header and is discharged into the two uppermost circuits in the coil by means of feeder tubes 54. The two upper refrigerant :
'' ,. . . ' 1~1373~
flow circuits combine to establish a second, smaller heat transfer region F.
After passing through the coil assembly, the refrigerant from the two upper circuits is routed to the secondary header 49 via discharge line 56. The refrigerant is collected in header 49 and fed into the last flow circuit by means of a single feeder tube 58.
The last circuit passes through the third and final heat transfer zone, zone G, and is discharged into the liquid header 46.
Preferably, the final heat transfer zone is located in the central portion of the coil to enhance the heat transfer characteristics of the coil. For the purposes of clarity, the final heat transfer zone is illustrated at the top of the heat exchanger assembly.
.~ ' .
The refrigerant, which is now in a liquid phase is collected in the liquid header 46 and is passed through opened check valve 61 into a T-connector 62. At the connector, the refrigerant moves down liquid line 60 toward the indoor coil (not shown).
As can be seen from the description above, the header network, acting in concert with the check valves, operates to direct the refrigerant from the compressor through the heat transfer zones in a series flow progression. Furthermore, the number of flow circuits in each zone diminishes in the direction of flow. By zoning the coil in this manner, the flow geometry of the coil is regulated in response to the increase in density of the fluid to obtain optimum coil performance when operating as a condenser.
When the systems mode of operation is reversed, the coil's function is similarly reversed. In the heating mode, liquid refrigerant is moved along liquid line 60 toward check valve 61. The valve, however, is automatically moved to a closed position because of the change in pressure felt over the valve. The refrigerant is thus . ' .
, :. - ,... .. . ..
,: . - : , ::.
: : ~ , -. , ~ ,. . : , 1~1373~
forced to move into distributor 63 that is connected to T-connector 62. At the distributor, the flow is separated into seven flow paths by means of capillary tubes 65. It should be noted that the number of capillary tubes are equal in number to the number of flow circuits passing through the coil.
As best illustrated in Figure 6, six of the capillary tubes pass through the dummy and pass into feeder tubes 54 associated with the four circuits contained in heat transfer zone E and the discharge tubes 53 associated with the two circuits associated with heat transfer zone F. The capillary tubes extend deeply into the various flow circuit tubes to insure that the refrigerant passing through the capillaries is expanded well within each circuit.
This, in turn, precludes the refrigerant from being passed between circuits by the dummy header. Because the dummy header is at a substantially uniform pressure, the refrigerant is fed evenly into each circuit.
The seventh capillary tube is passed into the liquid header 46 which is at relatively the same pressure as the dummy header.
Header 46, in turn, feeds into the circuit associated with heat transfer zone G.
It should be noted that at this time check valve 51, positioned between the primary and secondary headers 47 and 49 is now moved to an open position so that the headers are cojoined to establish a single flow passage leading to the compressor via line 50. As best illustrated in Figure 5, the seven flow circuits are arranged to empty into the headers 47, 49 when the coil is serving as an evaporator. The circuits associated with zones G and F empty into header 49 via lines 56 and 58 while the four circuits associated with zone E empty into header 47 via lines 52.
,, ,. , .,.. .. . .. , : - . , : : .
- : - . . , , :: : :
- . .
.. . . . .
.
. . .. ~, , Accordingly, when the heat exchanger is called upon to serve as an evaporator in the system, the flow geometry through the coil is automatically changed whereby refrigerant is caused to flow through all the circuits, and thus all the heat transfer zones, simultaneously in a parallel flow arrangement. By maintaining this parallel flow arrangement through the coil, optimum performance of the exchanger can be obtained when utilized as an evaporator.
While this invention has been described with reference to the structure herein disclosed, it is not confined to the specific details as set forth. For example, in place of the capillary tubes wherein employed any expansion device capable of carrying out the flow splitting and throttling process can be similarly employed provided such modifications come within the scope of the following claims.
.
.
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Claims (16)
1. In a heat pump system having a compressor, a pair of heat exchangers and means for selectively reversing the flow of refrigerant through the system so that the function of the exchangers is also reversed, the improvement comprising means for separating each exchanger into a plurality of heat transfer zones, each zone containing a number of flow circuits, flow control means for routing refrigerant discharged from the compressor through each of the zones of one exchanger in a series flow progression and routing the refrigerant discharged from said one exchanger into the other exchanger simultaneously through each of the zones of said other exchanger whereby flow is parallel through the zones, and switching means operatively associated with said flow control means for automatically reversing the flow geometry through the exchangers in response to reversing the flow of refrigerant through the system whereby refrigerant flow is parallel through said one exchanger and in series through said other exchanger.
2. The heat pump system of claim 1 further including expansion means associated with each of the exchangers for expanding refrigerant flowing from one of said exchangers to the other into each of the circuits of said other exchanger.
3. A heat pump system having a compressor, an indoor coil, an outdoor coil, a reversing valve for delivering refrigerant discharged from the compressor to the indoor coil during heating operations and to the outdoor coil during cooling operations, the method of processing refrigerant through the system including the steps separating the indoor and outdoor coils into a plurality of heat transfer zones, each zone haying a number of flow circuits passing through the coil associated therewith, routing the refrigerant delivered from the compressor to the outdoor coil during the cooling operation so that refrigerant flows through each of the heat transfer zones in a series progression, delivering the refrigerant discharged from the outdoor coil to each of the heat transfer zones of the indoor coil simultaneously so that the refrigerant flows through the zones in a parallel flow, returning the refrigerant from the indoor coil to the compressor to complete the cycle, and reversing the flow geometry through the indoor and outdoor coils in response to a change in the systems operation whereby refrigerant flows in series through the zones of the indoor coil and in parallel through the zones of the outdoor coil.
4. The method of claim 3 further including the step of expanding the refrigerant directly into each of the circuits of the heat transfer zones to establish a parallel flow therethrough.
5. A reversible refrigeration system adapted for heating and cooling, comprising:
a motor compressor unit;
an indoor heat exchanger and an outdoor heat ex-changer each including a plurality of circuits;
a valve for reversing the flow of refrigerant through said system to operate said system in a heating or cooling mode with each of said heat exchangers arranged inter-changeably as a condenser or as an evaporator;
a circuit interconnecting the outlets of said heat exchangers;
means connecting the circuits in each of said heat exchangers in series between a heat exchanger inlet line and an outlet line when a heat exchanger operates as a condenser; and means connecting the circuits in each of said heat exchanger in parallel between said conduit and said reversing valve when a heat exchanger operates as an evaporator.
a motor compressor unit;
an indoor heat exchanger and an outdoor heat ex-changer each including a plurality of circuits;
a valve for reversing the flow of refrigerant through said system to operate said system in a heating or cooling mode with each of said heat exchangers arranged inter-changeably as a condenser or as an evaporator;
a circuit interconnecting the outlets of said heat exchangers;
means connecting the circuits in each of said heat exchangers in series between a heat exchanger inlet line and an outlet line when a heat exchanger operates as a condenser; and means connecting the circuits in each of said heat exchanger in parallel between said conduit and said reversing valve when a heat exchanger operates as an evaporator.
6. The reversible refrigeration system recited in claim 5 wherein:
means including a pair of one way valves arranged between said heat exchanger outlet lines and said conduit to allow passage of refrigerant into said conduit from said coils when a heat exchanger is operating as a condenser and for preventing series flow of refrigerant through said circuits from said conduit when a heat exchanger is operating as an evaporator.
means including a pair of one way valves arranged between said heat exchanger outlet lines and said conduit to allow passage of refrigerant into said conduit from said coils when a heat exchanger is operating as a condenser and for preventing series flow of refrigerant through said circuits from said conduit when a heat exchanger is operating as an evaporator.
7. The reversible refrigeration system recited in claim 5 wherein:
a plurality of distribution means connected at one end to said conduit and at the other end to each of said circuits to arrange said circuits in parallel when a heat exchanger operates as an evaporator.
a plurality of distribution means connected at one end to said conduit and at the other end to each of said circuits to arrange said circuits in parallel when a heat exchanger operates as an evaporator.
8. The reversible refrigeration system recited in claim 5 wherein:
means including valves arranged between said circuits and said heat exchanger inlet lines for permitting parallel refrigeration flow through each of said circuits between said conduit and said heat exchanger inlet line when a heat exchanger is operating as an evaporator; and for directing all of said refrigerant flow from said heat exchanger inlet line to said series connected circuits when a heat exchanger: is operating as a condenser.
means including valves arranged between said circuits and said heat exchanger inlet lines for permitting parallel refrigeration flow through each of said circuits between said conduit and said heat exchanger inlet line when a heat exchanger is operating as an evaporator; and for directing all of said refrigerant flow from said heat exchanger inlet line to said series connected circuits when a heat exchanger: is operating as a condenser.
9. A reversible refrigeration system adapted for heating and cooling, comprising:
a motor compressor unit;
an indoor heat exchanger and an outdoor heat ex-changer each including a plurality of circuits;
a valve for reversing the flow of refrigerant through said system to operate said system in a heating or cooling mode with each of said heat exchangers arranged inter-changeably as a condenser or as an evaporator, means connecting the circuits in each of said heat exchangers in series between a heat exchanger inlet line connected to said reversing valve and an outlet line when a heat exchanger operates as a condenser;
a conduit connecting the outlets of said heat ex-changers;
means including a pair of one way valves arranged between said heat exchanger outlet lines and said conduit to allow passage of refrigerant into said conduit from said coils when a heat exchanger is operating as a con-denser and for preventing series flow of refrigerant through said circuits from said conduit when a heat exchanger is operating as an evaporator;
a plurality of distribution means connected at one end to said conduit and at the other end to each of said circuits to arrange said circuits in parallel when a heat exchanger operates as an evaporator;
means including valves arranged between said circuits and said heat exchanger inlet lines for permitting parallel refrigerant flow through each of said circuits between said conduit and said heat exchanger inlet line when a heat ex-changer is operating as an evaporator; and for directing all of said refrigerant flow from said heat exchanger inlet line to said series connected circuits when a heat exchanger is operating as a condenser.
a motor compressor unit;
an indoor heat exchanger and an outdoor heat ex-changer each including a plurality of circuits;
a valve for reversing the flow of refrigerant through said system to operate said system in a heating or cooling mode with each of said heat exchangers arranged inter-changeably as a condenser or as an evaporator, means connecting the circuits in each of said heat exchangers in series between a heat exchanger inlet line connected to said reversing valve and an outlet line when a heat exchanger operates as a condenser;
a conduit connecting the outlets of said heat ex-changers;
means including a pair of one way valves arranged between said heat exchanger outlet lines and said conduit to allow passage of refrigerant into said conduit from said coils when a heat exchanger is operating as a con-denser and for preventing series flow of refrigerant through said circuits from said conduit when a heat exchanger is operating as an evaporator;
a plurality of distribution means connected at one end to said conduit and at the other end to each of said circuits to arrange said circuits in parallel when a heat exchanger operates as an evaporator;
means including valves arranged between said circuits and said heat exchanger inlet lines for permitting parallel refrigerant flow through each of said circuits between said conduit and said heat exchanger inlet line when a heat ex-changer is operating as an evaporator; and for directing all of said refrigerant flow from said heat exchanger inlet line to said series connected circuits when a heat exchanger is operating as a condenser.
10. A heat exchanger suitable for use in a heat pump wherein the exchanger acts as a condenser when the flow of refrigerant through the exchanger is in one direction and as an evaporator when the flow of refrigerant through the exchanger is in the opposite direction, the exchanger including one or more refrigerant flow circuits contained within the exchanger, means to separate the circuits into a plurality of heat transfer zones that are arranged so that when air flows through the heat exchanger, the air flows through the heat transfer zones in parallel, and control means operatively associated with the last mentioned means for routing refrigerant in series through the heat transfer zones when the flow of refrigerant through the exchanger is in one direction and to route the refrigerant simultaneously through each of the zones when the flow of refrigerant is in the opposite direction.
11. A method of routing refrigerant through a heat exchanger arranged to serve as a condenser when the flow of refrigerant to the exchanger is in one direction and as an evaporator when the flow to the exchanger is in the opposite direction, the steps including dividing the heat exchanger into a plurality of heat transfer zones arranged so that when air flows through the heat exchanger the air flows through the zones in parallel paths, directing refrigerant in a series flow progression through each of the heat transfer zones when the flow to the exchanger is in one direction, and rerouting the refrigerant through each of the heat transfer zones simultane-ously when the flow to the exchanger is in the opposite direction.
12. The method of Claim 11 further including the step of expanding the refrigerant simultaneously into each of the circuits when the flow is in the opposite direction.
13. In a heat pump system having a compressor, a pair of heat exchangers and means for selectively reversing the flow of refrigerant through the system so that the function of the exchangers is also reversed, the improvement comprising means for separating each exchanger into a plurality of heat transfer zones, flow control means for routing refrigerant discharged from the compressor through each of the zones of one exchanger in a series flow progression and routing the refrigerant discharged from said one exchanger into the other exchanger simultaneously through each of the zones of said other exchanger whereby flow is parallel through the zones, and switching means for reversing the flow geometry through the exchangers whereby refrigerant flow is parallel through said one exchanger and in series through said other exchanger.
14. The heat pump system of claim 13 further including expansion means associated with each of the exchangers for expanding refrigerant flowing from one of said exchangers to said other exchanger.
15. A heat pump system having a compressor, an indoor coil, an outdoor coil, a reversing valve for delivering refrigerant discharged from the compressor to the indoor coil during heating operations and to the outdoor coil during cooling operations, the method of processing refrigerant through the system including the steps separating the indoor and outdoor coils into a plurality of heat transfer zones, routing the refrigerant delivered from the compressor to the outdoor coil during the cooling operation so that refrigerant flows through each of the heat transfer zones in a series progression, delivering the refrigerant discharged from the outdoor coil to each of the heat transfer zones of the indoor coil simultaneously so that the refrigerant flows through the zones in a parallel flow, returning the refrigerant from the indoor coil to the com-pressor to complete the cycle, and reversing the flow geometry through the indoor and outdoor coils to change the systems operation whereby refrigerant flows in series through the zones of the indoor coil and in parallel through the zones of the outdoor coil.
16. The method of claim 15 further including the step of expanding the refrigerant directly into the heat transfer zones to establish a parallel flow therethrough.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA372,003A CA1113731A (en) | 1976-09-07 | 1981-02-27 | Heat pump system |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/720,721 US4057975A (en) | 1976-09-07 | 1976-09-07 | Heat pump system |
| US720,721 | 1976-09-07 | ||
| CA285,811A CA1106198A (en) | 1976-09-07 | 1977-08-30 | Heat pump system |
| CA372,003A CA1113731A (en) | 1976-09-07 | 1981-02-27 | Heat pump system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1113731A true CA1113731A (en) | 1981-12-08 |
Family
ID=27165258
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA372,003A Expired CA1113731A (en) | 1976-09-07 | 1981-02-27 | Heat pump system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1113731A (en) |
-
1981
- 1981-02-27 CA CA372,003A patent/CA1113731A/en not_active Expired
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| MKEX | Expiry |