US20100307172A1

US20100307172A1 - Refrigerant system with reheat refrigerant circuit

Info

Publication number: US20100307172A1
Application number: US12/864,122
Authority: US
Inventors: Alexander Lifson; Michael F. Taras
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2008-01-30
Filing date: 2008-01-30
Publication date: 2010-12-09
Also published as: CN101932883A; WO2009096915A1; EP2250445A1

Abstract

A refrigerant system is provided that includes a cooling refrigerant circuit, a reheat refrigerant circuit, an evaporator fan, and a controller. The evaporator fan forces indoor air in a first direction and a second direction. The indoor air passes across the evaporator before the reheat coil, in the first direction, but passes across the reheat coil before the evaporator, in the second direction. The controller, when in a conventional cooling mode, controls the reheat refrigerant circuit so that the reheat refrigerant circuit is not in fluid communication with the cooling refrigerant circuit and controls the evaporator fan to force the indoor air in the first direction. Conversely, the controller, when in a defrost mode, controls the reheat refrigerant circuit so that the reheat refrigerant circuit is in fluid communication with the cooling refrigerant circuit and controls the evaporator fan to force the indoor air in the second direction.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present disclosure is related to refrigerant systems. More particularly, the present disclosure is related to refrigerant systems having defrost functionality provided by a reheat refrigerant circuit.
2. Description of Related Art
Refrigerant systems are utilized to control the temperature and/or humidity of air in various environments to be conditioned. In a typical refrigerant system operating in a conventional cooling mode, a refrigerant is compressed in a compressor and delivered to a heat rejection heat-exchanger (or, in many cases, an outdoor heat-exchanger). In the heat rejection heat-exchanger, heat is exchanged between outside ambient air and the compressed refrigerant, to remove heat from the compressed refrigerant.
From the heat rejection heat-exchanger, the refrigerant passes to an expansion device, in which the refrigerant is expanded to a lower pressure and lower temperature, and then to an evaporator (or, in typical air conditioning installations, an indoor heat-exchanger). In the evaporator, heat is exchanged between the now cooled lower pressure refrigerant and the indoor air, to remove heat from the indoor air. In this manner, the evaporator cools the air that is being supplied to the conditioned environment.
In addition, as the temperature of the conditioned air is reduced, moisture is also often taken out of the conditioned air. In this manner, refrigerant systems also control the humidity level in the conditioned environment.
In some cases, while the system is operating in the conventional cooling mode, the temperature level of the conditioned air necessary to provide the desired humidity level is lower than the desired temperature of the conditioned air. Thus, many refrigerant systems include a reheat coil or heat-exchanger (hereinafter “coil”) that is placed in the conditioned air stream downstream of the evaporator. In this manner, the reheat coil reheats the conditioned air after the air has been conditioned (e.g., cooled and dehumidified) in the evaporator.
It is also not uncommon for the moisture removed from the air to condense and frequently freeze on the external surfaces of the evaporator, which reduces the efficiency of the refrigerant system, and could also result in a refrigerant system malfunction. As such, many refrigerant systems require specialized defrost systems and equipment (such as, for instance, electric heaters), which increase the cost and complexity of the refrigerant system.
Accordingly, there is continuing need for refrigerant systems and methods of controlling such systems that defrost the evaporator while overcoming one or more of the aforementioned and other deleterious effects of the prior art.

BRIEF SUMMARY OF THE INVENTION

A refrigerant system is provided that includes a cooling refrigerant circuit, a reheat refrigerant circuit, an evaporator fan, and a controller. The cooling refrigerant circuit includes an evaporator. The reheat refrigerant circuit includes a reheat coil. The evaporator fan is capable of forcing indoor air in a first direction and a second direction. The indoor air passes across the evaporator before the reheat coil in the first direction but passes across the reheat coil before the evaporator in the second direction. The controller, when in a conventional cooling mode, controls the reheat refrigerant circuit so that the reheat refrigerant circuit is not in fluid communication with the cooling refrigerant circuit and controls the evaporator fan to force the indoor air in the first direction. Conversely, the controller, when in a defrost mode, controls the reheat refrigerant circuit so that the reheat refrigerant circuit is in fluid communication with the cooling refrigerant circuit and controls the evaporator fan to force the indoor air in the second direction. In the conventional dehumidification mode the controller controls the reheat refrigerant circuit so that the reheat refrigerant circuit is in fluid communication with the cooling refrigerant circuit and controls the evaporator fan to force the indoor air in the first direction.
In some embodiments, the refrigerant system includes a cooling refrigerant circuit, a reheat refrigerant circuit, an evaporator fan, and a controller. The cooling refrigerant circuit includes an evaporator. The reheat refrigerant circuit includes a reheat coil. The evaporator fan rotates in a first rotational direction to force indoor air in a first direction and rotates in a second rotational direction to force the indoor air in a second direction. The evaporator is positioned upstream of the reheat coil in the first direction. The controller operates the refrigerant system in a conventional cooling mode when the reheat refrigerant circuit is not in fluid communication with the cooling refrigerant circuit and the evaporator fan rotates in the first rotational direction. The controller also operates the refrigerant system in a defrost mode when the reheat refrigerant circuit is in fluid communication with the cooling refrigerant circuit and the evaporator fan rotates in the second rotational direction. The controller operates the refrigerant system in a conventional dehumidification mode when the reheat refrigerant circuit is in fluid communication with the cooling refrigerant circuit and the evaporator fan rotates in the first rotational direction.
In other embodiments, the refrigerant system includes a cooling refrigerant circuit, a reheat refrigerant circuit, an evaporator fan that rotates in a single rotational direction, one or more dampers, and a controller. The cooling refrigerant circuit includes an evaporator. The reheat refrigerant circuit includes a reheat coil. The dampers are in a flow path of the indoor air and have two positions. The first position forces the indoor air in a first direction so the indoor air passes across the evaporator before the reheat coil. The second position forces the indoor air in a second direction so the indoor air passes across the reheat coil before the evaporator. The controller operates the refrigerant system in a conventional cooling mode when the reheat refrigerant circuit is not in fluid communication or at least partially isolated from the cooling refrigerant circuit and the one or more dampers are in the first position. The controller also operates the refrigerant system in a defrost mode when the reheat refrigerant circuit is in fluid communication with the cooling refrigerant circuit and the one or more dampers are in the second position. The controller operates the refrigerant system in a conventional dehumidification mode when the reheat refrigerant circuit is in fluid communication with the cooling refrigerant circuit and the one or more dampers are in the first position.
The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic depiction of an exemplary embodiment of a refrigerant system according to the present disclosure operating in a normal or conventional cooling mode;

FIG. 2 is schematic depiction of the refrigerant system of FIG. 1 operating in a reheat or conventional dehumidification mode;

FIG. 3 is schematic depiction of the refrigerant system of FIG. 1 operating in a defrost mode;

FIG. 4 is schematic depiction of an alternate embodiment of the refrigerant system of FIG. 1 operating in the normal mode and the reheat mode; and

FIG. 5 is schematic depiction of the refrigerant system of FIG. 4 operating in the defrost mode.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, and in particular to FIG. 1, an exemplary embodiment of a refrigerant system according to the present disclosure, generally indicated by reference numeral 10, is shown.
Refrigerant system 10 includes a cooling refrigerant circuit 12, a reheat refrigerant circuit 14, and a bypass refrigerant circuit 16. Refrigerant system 10 is configured to utilize reheat refrigerant circuit 14 and bypass refrigerant circuit 16 during the defrosting of the evaporator.
Cooling refrigerant circuit 12 includes a compressor 18, a heat rejection heat-exchanger 20, an expansion device 22, and an evaporator 24, all in fluid communication with one another in a known manner to provide, for instance, a cooling or heating function using a known refrigerant (not shown). Refrigerant system 10 further includes a heat rejection heat-exchanger fan 26, an evaporator fan 28, and a refrigerant system controller 30.
Reheat refrigerant circuit 14 includes a reheat coil 32 and a first reheat valve 34-1 and a second reheat valve 34-2, while bypass circuit 16 includes a bypass valve 36. The first reheat valve 34-1 typically is a three-way valve and the second reheat valve 34-2 is a check valve.
Controller 30 is in electrical communication with the compressor 18, heat rejection heat-exchanger fan 26, evaporator fan 28, first reheat valve 34-1, and bypass valve 36. In some embodiments, the controller 30 can also be in electrical communication with the compressor 18, expansion device 22 and/or second reheat valve 34-2. In this manner, the controller 30 is configured to control the operation of the various components of the refrigerant system 10.
The controller 30 is configured to operate the refrigerant system 10 in a normal or conventional cooling mode (FIG. 1), a reheat or conventional dehumidification mode (FIG. 2), and defrost mode (FIG. 3). Refrigerant system 10 operates in the defrost mode without the need for additional or specialized defrosting devices, such as, for example, an electric heater. Rather, it has been determined by the present disclosure that the refrigerant system 10 can provide the defrost mode of operation by simply making use of the existing components of the reheat refrigerant circuit 14. More particularly, the refrigerant system 10 is configured to control evaporator fan 28 to force air in a first normal direction during the normal mode and the reheat mode of operation, but in a second opposite direction during the defrost mode of operation.
The normal mode of operation for the refrigerant system 10 is described with reference to FIG. 1.
Here, the compressor 18 draws in a low-pressure refrigerant 40, in a vapor form and compresses this low-pressure vapor refrigerant into a high pressure and temperature refrigerant 42. From the compressor 18, the vapor refrigerant flows to the heat rejection heat-exchanger 20. The controller 30 controls the bypass valve 36 to a closed position so that refrigerant 42 flows through the heat rejection heat-exchanger 20 and not through the bypass refrigerant circuit 16. Thus, the controller 30 controls the bypass valve 36 so that the bypass refrigerant circuit 16 is not in fluid communication with cooling refrigerant circuit 12 during the normal mode of operation.
The heat rejection heat-exchanger 20 acts as a condenser, in the subcritical cycle, or as a gas cooler, in a transcritical cycle, where during heat transfer interaction with a secondary fluid, such as outside or ambient air 44 that is forced across the heat rejection heat-exchanger 20 by the heat rejection heat-exchanger fan 26. In this manner, in the subcritical applications, the vapor refrigerant 42 is desuperheated to the point where it condenses to a liquid refrigerant 46 and is typically subcooled, or just simply cooled from the thermodynamic state 42 to the thermodynamic state 46, in the transcritical applications. As known, a liquid pump may substitute the fan 26 to pump secondary loop liquid performing heat transfer interaction in the heat rejection heat-exchanger 20 instead of the outside or ambient air 44.
The refrigerant 46 exits heat rejection heat-exchanger 20 and flows to the expansion device 22. The controller 30 controls the first reheat valve 34-1 to a closed position so that the refrigerant 46 flows through the expansion device 22 and, not, through the reheat refrigerant circuit 14. Thus, the controller 30 controls the first reheat valve 34-1 so that the reheat refrigerant circuit 14 is not in fluid communication with the cooling refrigerant circuit 12 during the normal or conventional cooling mode of operation.
In some embodiments, the second reheat valve 34-2 can be a check valve that ensures the refrigerant 46 does not enter the reheat refrigerant circuit 14. In other embodiments, the second reheat valve 34-2 can be in electrical communication with the controller 30, which controls the second reheat valve 34-2 to the closed position during the normal mode of operation to ensure that refrigerant 46 does not enter the reheat refrigerant circuit 14.
The expansion device 22 expands refrigerant 46 into a lower pressure, lower temperature, two-phase mixture refrigerant 48, which flows into the evaporator 24. In some embodiments, the expansion device 22 is a thermostatic expansion valve or a fixed restriction expansion device, while in other embodiments the expansion device can be an electronic expansion device (EXV) in electrical communication with the controller 30.
The evaporator 24 acts as a heat accepting heat-exchanger where heat transfer interaction occurs between the refrigerant and the indoor air 50 that is forced across the evaporator 24 by the evaporator fan 28 in a first direction 54. In this manner, the refrigerant 48 is evaporated back into a low pressure vapor refrigerant 40, while the indoor air 50 is cooled and usually dehumidified to provide the conditioned air 52 that is supplied to a climate-controlled space or zone. The vapor refrigerant 40, which is typically in a thermodynamic superheated state, then flows from the evaporator 24 back to the compressor 18.
As can be seen, reheat coil 32 is positioned downstream, with respect to the flow of indoor air 50 in the first direction 54 induced by the evaporator fan 28. However, since the reheat valves 34-1, 34-2 are in the closed position, the flow of conditioned air 52 through the reheat coil 32 does not result in any further conditioning or reheating of this conditioned air.
Accordingly, during the normal mode of operation for the refrigerant system 10, the controller 30 activates the compressor 18, activates the heat rejection heat-exchanger fan 26, closes the bypass valve 36, closes the reheat valves 34-1 and 34-2, activates, when necessary, the expansion valve 22, and activates the evaporator fan 28 to force the indoor air 50 across the evaporator 24 and the reheat coil 32 in the first direction. Since the controller 30 controls the evaporator fan 28 to force indoor air 50 in the first direction 54, the indoor air is forced first across the evaporator 24 then across the reheat coil 32.
In the embodiment illustrated in FIG. 1, the refrigerant system 10 is configured to force the indoor air 50 in the first direction 54 by controlling the evaporator fan 28 to rotate in a first rotational direction 56. It has to be pointed out that the evaporator fan 28 may be of a variable speed type so that the controller 30 may also control the speed of the evaporator fan 28 if desired.
The reheat mode of operation for the refrigerant system 10 is described with reference to FIG. 2.
Generally, the refrigerant system 10 operates in substantially the same manner in the reheat mode as in the normal mode, except that the controller 30 controls the first reheat valve 34-1 to an open position so that the refrigerant 46 flows first through the reheat refrigerant circuit 14 and only then through the expansion device 22. Thus, the controller 30 controls the first reheat valve 34-1 so that the reheat refrigerant circuit 14 is in fluid communication with the cooling refrigerant circuit 12 during the reheat mode of operation.
In use, the compressor 18 draws in a low pressure refrigerant 40, in a vapor form and compresses this low pressure vapor refrigerant into a high pressure and temperature refrigerant 42. From the compressor 18, the vapor refrigerant flows to the heat rejection heat-exchanger 20.
The controller 30 may control the bypass valve 36 to a closed or partially/fully open position so that the vapor high pressure and high temperature refrigerant 42 can flow through the heat rejection heat-exchanger 20 and, not, the bypass refrigerant circuit 16, or through both the heat rejection heat-exchanger 20 and bypass refrigerant circuit 16. Thus, the controller 30 controls the bypass valve 36 so that the bypass refrigerant circuit 16 may or may not be in fluid communication with the cooling refrigerant circuit 12 during the reheat mode of operation. As stated above, depending on the dehumidification demands in the climate-controlled space, in some embodiments, the controller 30 can control the bypass valve 36 to a partially open position so that a portion of refrigerant 42 flows through the heat rejection heat-exchanger 20 and a remaining portion flows through the bypass refrigerant circuit 16.
The heat rejection heat-exchanger 20 acts as a condenser, in a subcritical cycle, or as a gas cooler, in a transcritical cycle, where during heat transfer interaction with outside or ambient air 44 that is forced across the heat rejection heat-exchanger 20 by the heat rejection heat-exchanger fan 26. In this manner, in the subcritical applications, the vapor refrigerant 42 is desuperheated to the point where it condenses to a liquid refrigerant 46 and is typically subcooled, or just simply cooled from the thermodynamic state 42 to the thermodynamic state 46, in the transcritical applications. Once again, a liquid pump may substitute the fan 26 to pump secondary loop liquid performing heat transfer interaction in the heat rejection heat-exchanger 20 instead of the outside or ambient air 44.
The refrigerant 46 exits the heat rejection heat-exchanger 20 and flows to the first reheat valve 34-1. The controller 30 controls the first reheat valve 34-1 to an open position so that the refrigerant 46 flows through the reheat coil 32, through the second reheat valve 34-2, and only then into the expansion device 22.
In some embodiments, the second reheat valve 34-2 can be a check valve that allows the refrigerant 46 to exit the reheat refrigerant circuit 14 back into the cooling refrigerant circuit 12. In other embodiments, the second reheat valve 34-2 can be in electrical communication with the controller 30, which controls the second reheat valve 34-2 to the open position during the reheat mode of operation to allow the refrigerant 46 to reenter the cooling refrigerant circuit 12.
Since the refrigerant 46 has not yet been expanded by the expansion device 22, the heat capacity of the refrigerant 46 can be used to reheat the conditioned air 52 in the manner discussed in more detail below.
The expansion device 22 expands the refrigerant 46 into a low pressure, low temperature, two-phase mixture refrigerant 48 and flows into the evaporator 24. The evaporator 24 acts as a heat accepting heat-exchanger where heat transfer interaction occurs between the refrigerant and the indoor air 50 that is forced across the evaporator 24 by the evaporator fan 28. In this manner, the refrigerant 48 is evaporated back into a low pressure vapor refrigerant 40, while the indoor air 50 is cooled and usually dehumidified to provide the conditioned air 52 that is supplied to a climate-controlled space or zone. The vapor refrigerant 40, which is typically in the superheated thermodynamic state, then flows from the evaporator 24 back to the compressor 18.
As can be seen, the reheat coil 32 is positioned downstream, with respect to the flow of indoor air 50 induced by the evaporator fan 28 in the first direction 54. Since the refrigerant 46 is flowing through the reheat coil 32, the flow of conditioned air 52 through the reheat coil 32 results in the reheat coil 32 acting as a heat rejecting heat-exchanger, where heat transfer is taking place from the refrigerant to air re-heating the air, and where the conditioned air 52 is forced across the reheat coil 32 by the evaporator fan 28. In this manner, the conditioned air 52 can be reheated to a desired temperature by the reheat coil 32 while maintaining the desired humidity by the evaporator 24 to provide a reheated air 58.
Accordingly, during the reheat mode of operation for the refrigerant system 10, the controller 30 activates the compressor 18, activates the heat rejection heat-exchanger fan 26, controls the bypass valve 36, opens the first reheat valve 34-1, activates, when necessary, the expansion valve 22, and activates the evaporator fan 28 to force the indoor air 50 across the evaporator 24 and the reheat coil 32 in the first direction 54. Thus, the controller 30 controls the evaporator fan 28 to force the air in the first direction 54 so that the indoor air 50 is forced first across the evaporator 24 then across the reheat coil 32 to provide the reheated air 58.
The refrigerant system 10 is configured, in the embodiment illustrated in FIG. 2, to force the indoor air 50 in the first direction 54 by controlling the evaporator fan 28 to rotate in the first rotational direction 56.
It has to be recognized that many reheat circuits schematics are known in the air conditioning art. Therefore, the FIG. 2 schematic is exemplary, and any refrigerant system incorporating any other reheat circuit configuration could equally benefit from the disclosure.
The defrost mode of operation for the refrigerant system 10 is described with reference to FIG. 3.
Generally, the refrigerant system 10 operates in substantially the same manner in the defrost mode as in the reheat mode, except that the controller 30 preferably controls the bypass valve 36 to an open position so that at least a portion of the high pressure and temperature refrigerant 42 flows through the bypass refrigerant circuit 16 instead of flowing through the heat rejection heat-exchanger 20 and reverses the direction of flow of the indoor air 50 across the evaporator 24 from a first direction 54 (FIGS. 1 and 2) to a second direction 60 (FIG. 3). Further, the bypass refrigerant circuit 16 can be designed such that predominantly all the vapor refrigerant 42 flows through the bypass refrigerant circuit 16, or alternatively, a shutoff solenoid valve (not shown) can be placed upstream of the heat rejection heat-exchanger 20 to prevent any flow of the vapor refrigerant 42 through the heat rejection heat-exchanger 20.
During the defrost mode of operation, the compressor 18 draws in the low pressure refrigerant 40, in a vapor form and compresses this low pressure vapor refrigerant into the high pressure and high temperature refrigerant 42. From the compressor 18, the vapor refrigerant 42 flows towards the heat rejection heat-exchanger 20 and the bypass refrigerant circuit 16.
The controller 30 preferably controls the bypass valve 36 to the open position so that at least a portion of the vapor refrigerant 42 does not flow through heat rejection heat-exchanger 20 but rather flows through the bypass refrigerant circuit 16. Further, the controller 30 can, in some embodiments, control the heat rejection heat-exchanger fan 26 to an off state to prevent any active heat exchange between the refrigerant and ambient air in the heat rejection heat-exchanger 20. In this manner, the controller 30 preferably places the bypass refrigerant circuit 16 in fluid communication with the cooling refrigerant circuit 12 during the defrost mode of operation so that the high pressure and high temperature refrigerant 42 flows into the reheat refrigerant circuit 14 providing greater heat capacity during the defrost mode of operation.
However, in some embodiments, the controller 30 can control the bypass valve 36 to a partially open position so that a portion of the vapor refrigerant 42 flows through heat rejection heat-exchanger 20 and a remaining portion flows through bypass circuit 16. Further, the controller 30 can, in some embodiments, control the heat rejection heat-exchanger fan 26 to an off state to prevent any active heat exchange between the refrigerant and ambient air in the heat rejection heat-exchanger 20. Also, it has to be noted that, under some circumstances, such as excessive refrigerant charge migration at some environmental conditions, the controller 30 may control the bypass valve 36 to a closed position.
The high pressure and temperature refrigerant 42A exits the bypass refrigerant circuit 16 and/or the heat rejection heat-exchanger 20 and flows to the first reheat valve 34-1. The controller 30 controls the first reheat valve 34-1 to the open position so that the high pressure and temperature refrigerant 42A flows through the reheat coil 32, through the second reheat valve 34-2, and only then into the expansion device 22.
In some embodiments, the second reheat valve 34-2 can be a check valve that allows the refrigerant 42B to exit the reheat refrigerant circuit 14 back into the cooling refrigerant circuit 12. In other embodiments, the second reheat valve 34-2 can be in electrical communication with the controller 30, which controls the second reheat valve 34-2 to the open position during the defrost mode of operation to allow the refrigerant 42B to reenter cooling refrigerant circuit 12.
The present disclosure has determined that the heat of the refrigerant 42A (supplemented by the heat provided by the evaporator fan 28) can be used to defrost the evaporator 24 in the manner discussed in more detail below by simply reversing the direction of flow of the indoor air 50 across the evaporator 24 from first direction 54 (FIGS. 1 and 2) to second direction 60 (FIG. 3).
Since the refrigerant 42A is flowing through the reheat coil 32 and indoor air 50 is forced in second direction 60, the indoor air 50 is heated by the refrigerant flowing through the reheat coil 32 into a heated indoor air 62, which is subsequently forced across the evaporator 24.
Here, the reheat coil 32 acts as a heat rejecting heat-exchanger where the heat is transferred from the refrigerant 42A to the indoor air 50 that is forced across the reheat coil 32 by the evaporator fan 28. In this manner, the indoor air 50 can be heated to a desired temperature so that the heated indoor air 62 can melt any frost that has formed on the outside surfaces of the evaporator 24.
In addition, the reheat coil 32 acts as a heat rejection heat-exchanger where during heat transfer interaction with the indoor air 50 so that the vapor refrigerant 42A is desuperheated to the point where it condenses to liquid refrigerant 42B that is then typically subcooled, in the case of a condenser, and is simply cooled to the thermodynamic state 42B, in the case of a gas cooler. The expansion device 22 expands refrigerant 42B into a low pressure, low temperature two-phase mixture refrigerant 48 and flows it into the evaporator 24. The evaporator 24 acts as a heat accepting heat-exchanger where heat transfer interaction is taking place between the refrigerant 48 and heated indoor air 62 that is forced across the evaporator 24 by the evaporator fan 28. In this manner, the refrigerant 48 is evaporated back into a low pressure vapor refrigerant 40, while the heated indoor air 62 is cooled to provide the air 64. The vapor refrigerant 40 then flows from the evaporator 24 back to the compressor 18.
Accordingly, during the defrost mode of operation for the refrigerant system 10, the controller 30 activates the compressor 18, deactivates, when necessary, the heat rejection heat-exchanger fan 26, opens, if desired, the bypass valve 36, opens the first reheat valve 34-1, controls, if necessary, the expansion valve 22, and causes the evaporator fan 28 to force the indoor air 50 across the evaporator 24 and the reheat coil 32 in the second direction 60.
In the embodiment illustrated in FIG. 3, the refrigerant system 10 can force the indoor air 50 in the second direction 60 by controlling the evaporator fan 28 to rotate in a second rotational direction 66, which is opposite the first rotational direction 56.
It should be recognized that the refrigerant system 10 is described above by way of example providing the indoor air 50 in the first and second directions 54, 60 by changing the rotational direction of the evaporator fan 28 between the first and second rotational directions 56, 66. Of course, it is contemplated by the present disclosure for the refrigerant system 10 to be configured in any manner to provide the indoor air 50 in the first and second directions 54, 60. It has to be understood that when the controller 30 operates the refrigerant system 10 in the defrost mode and moves the indoor air 50 in the second direction 60, the air 64 exiting the evaporator 24 may be directed either outdoors, indoors or to any other specified location.
It has to be recognized that the axial fans and transverse fans are mostly suitable for switching airflow direction, the former—by simply switching the rotational direction of the fan and the latter—by implementation of a special design feature (typically, a lever) within the fan housing. The preferable design configuration for the centrifugal fans is described hereinbelow. Further, the design options and various configurations of the refrigerant system 10 are feasible as well as within the scope and can equally benefit from the disclosure.
By way of example, an alternate embodiment of a configuration of the refrigerant system 10 that provides the indoor air 50 in the first and second directions 54, 60 is shown in FIGS. 4 and 5. Here, only portions of the refrigerant system 10 are shown for purposes of clarity but air duct configuration is depicted in more detail.
In this embodiment, the controller 30 controls the evaporator fan 28 to rotate in a single direction, such as the first rotational direction 56. Further, the controller 30 controls the position of one or more dampers 70 to change the direction of the flow of indoor air 50 through the indoor components of the refrigerant system 10.
Thus, dampers 70 are positioned so that when the refrigerant system 10 is in the normal mode of operation or the reheat mode of operation shown in FIG. 4, the indoor air 50 can be forced in the first direction 54 to result in the indoor air 50 being forced first across the evaporator 24 to form a conditioned air 52, which is then forced across the reheat coil 32. In the normal mode of operation, the conditioned air 52 is not reheated by the reheat coil 32, which is disengaged, so that the cooled and typically dehumidified air 52 is provided to the conditioned environment in the manner discussed above. In the reheat mode of operation, the conditioned air 52 is reheated by the reheat coil 32 so that reheated air 58 is provided to the conditioned environment in the manner discussed above.
Conversely, the dampers 70 are positioned so that when the refrigerant system 10 is in the defrost mode of operation shown in FIG. 5, the indoor air 50 can be forced in the second direction 60 to result in the indoor air 50 being forced first across the reheat coil 32 to form the heated indoor air 62, which is then forced across the evaporator 24 to defrost the evaporator.
It should be understood that the refrigerant system 10 is illustrated by way of example in FIGS. 4 and 5 reversing the direction of airflow through the use of four dampers 70. Of course, it is contemplated by the present disclosure for the refrigerant system 10 and associated air duct system including dampers 70 to have various configurations and additional design features. All these configurations are within the scope and can equally benefit from the disclosure.
It should also be understood that the refrigerant system 10 exhibited in FIGS. 1 through 3 may have various options and enhancement features, all of which are contemplated within the scope of and can equally benefit from the present disclosure.
For example, the reheat refrigerant circuit 14 is illustrated in selective fluid communication with the cooling refrigerant circuit 12 at a location between the heat rejection heat-exchanger 20 and the expansion device 22. However, it is contemplated by the present disclosure for the refrigerant system 10 to have any configuration of the reheat circuit 14 provided that the reheat coil 32 is positioned downstream with respect to the flow of indoor air 50 induced by the evaporator fan 28 during the normal and reheat modes of operation.
It should also be understood that the terms “first”, “second”, “third”, “upper”, “lower”, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated.
While the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.

Claims

1. A refrigerant system comprising:

a cooling refrigerant circuit including a heat rejection heat-exchanger and an evaporator in serial fluid communication with one another;

a reheat refrigerant circuit including a reheat heat-exchanger in selective fluid communication with said cooling refrigerant circuit;

an evaporator fan being configured to force indoor air in a first direction and in a second direction, the indoor air passing across said evaporator before passing across said reheat heat-exchanger in said first direction and passing across said reheat heat-exchanger before passing across said evaporator in said second direction; and

a controller being configured to operate the refrigerant system in one of a cooling mode and a defrost mode,

wherein said controller, when the refrigerant system is in said cooling mode, controls said reheat refrigerant circuit so that said reheat refrigerant circuit is at least partially isolated from said cooling refrigerant circuit and controls said evaporator fan to force the indoor air in said first direction, and

wherein said controller, when the refrigerant system is in said defrost mode, controls said reheat refrigerant circuit so that said reheat refrigerant circuit is in fluid communication with said cooling refrigerant circuit and controls said evaporator fan to force the indoor air in said second direction.

2. The refrigerant system of claim 1, wherein said controller is further configured to operate the refrigerant system in a reheat mode by controlling said reheat refrigerant circuit so that said reheat refrigerant circuit is in fluid communication with said cooling refrigerant circuit and controlling said evaporator fan to force the indoor air in said first direction,

3. The refrigerant system of claim 1, further comprising a heat rejection heat-exchanger fan being configured to selectively force outdoor air across said heat rejection heat-exchanger, said controller being configured to control said heat rejection heat-exchanger fan not to force said outdoor air across said heat rejection heat-exchanger, when the refrigerant system is in said defrost mode.

4. The refrigerant system of claim 1, further comprising a bypass refrigerant circuit to bypass at least a portion of refrigerant around said heat rejection heat-exchanger in selective fluid communication with said cooling refrigerant circuit.

5. The refrigerant system of claim 4, wherein said controller controls said bypass refrigerant circuit so that said bypass refrigerant circuit is at least partially isolated from said cooling refrigerant circuit, when the refrigerant system is in said defrost mode.

6. The refrigerant system of claim 4, wherein said controller controls said bypass refrigerant circuit so that said bypass refrigerant circuit is in fluid communication with said cooling refrigerant circuit, when the refrigerant system is in said defrost mode.

7. The refrigerant system of claim 1, wherein said controller controls a rotational direction of a fan motor driving said evaporator fan to force the indoor air in said first and second directions, respectively.

8. The refrigerant system of claim 1, wherein said controller controls a position of one or more dampers with respect to said evaporator fan to force the indoor air in said first and second directions, respectively.

9. The refrigerant system of claim 1, wherein said evaporator fan is a variable speed fan.

10. A refrigerant system comprising:

a cooling refrigerant circuit including an evaporator;

an evaporator fan being configured to rotate in a first rotational direction to force indoor air in a first direction and configured to rotate in a second rotational direction to force the indoor air in a second direction, said evaporator being positioned upstream of said reheat heat-exchanger in said first direction; and

a controller being configured to operate the refrigerant system in a cooling mode, where said reheat refrigerant circuit is at least partially isolated from said cooling refrigerant circuit and said evaporator fan rotates in said first rotational direction and in a defrost mode, where said reheat refrigerant circuit is in fluid communication with said cooling refrigerant circuit and said evaporator fan rotates in said second rotational direction.

11. The refrigerant system of claim 10, wherein said controller is further configured to operate the refrigerant system in a reheat mode, where said reheat refrigerant circuit is in fluid communication with said cooling refrigerant circuit and said evaporator fan rotates in said first rotational direction.

12. A refrigerant system comprising:

a cooling refrigerant circuit including an evaporator;

an evaporator fan being configured to rotate in a single rotational direction;

one or more dampers being in a flow path of the indoor air, said one or more dampers having a first position and a second position, said first position being configured to force the indoor air in a first direction where the indoor air passes across said evaporator before said reheat heat-exchanger and said second position being configured to force the indoor air in a second direction where the indoor air passes across said reheat heat-exchanger before said evaporator; and

a controller being configured to operate the refrigerant system in at least one of a cooling mode, where said reheat refrigerant circuit is at least partially isolated from said cooling refrigerant circuit and said one or more dampers are in said first position and in a defrost mode, where said reheat refrigerant circuit is in fluid communication with said cooling refrigerant circuit and said one or more dampers are in said second position.

13. The refrigerant system of claim 12, wherein said controller is further configured to operate the refrigerant system in a reheat mode, where said reheat refrigerant circuit is in fluid communication with said cooling refrigerant circuit and said one or more dampers are in said first position.

14. A method of controlling a refrigerant system comprising:

controlling a reheat refrigerant circuit so that said reheat refrigerant circuit is at least partially isolated from a cooling refrigerant circuit and controlling an evaporator fan to force indoor air in a first direction across an evaporator then across a reheat heat exchanger, when the refrigerant system is in a cooling mode; and

controlling said reheat refrigerant circuit so that said reheat refrigerant circuit is in fluid communication with said cooling refrigerant circuit and controlling said evaporator fan to force the indoor air in a second direction across said reheat heat exchanger then across said evaporator, when the refrigerant system is in a defrost mode.

15. The method of claim 14, further comprising controlling said reheat refrigerant circuit so that said reheat refrigerant circuit is in fluid communication with said cooling refrigerant circuit and controlling said evaporator fan to force the indoor air in said first direction, when the refrigerant system is in a reheat mode.

16. The method of claim 14, wherein controlling said evaporator fan to force the indoor air in said first direction comprises controlling said evaporator fan to rotate in a first rotational direction, and

wherein controlling said evaporator fan to force the indoor air in said second direction comprises controlling said evaporator fan to rotate in a second rotational direction.

17. The method of claim 14, wherein controlling said evaporator fan to force the indoor air in said first direction comprises controlling said evaporator fan to rotate in a first rotational direction and moving one or more dampers to a first position, and

wherein controlling said evaporator fan to force the indoor air in said second direction comprises controlling said evaporator fan to rotate in said first rotational direction and moving said one or more dampers to a second position.

18. The method of claim 14, further comprising controlling a heat rejection heat-exchanger fan not to force outdoor air across a heat rejection heat-exchanger, when the refrigerant system is in said defrost mode.

19. The method of claim 14, further comprising at least partially isolating a bypass refrigerant circuit from said cooling refrigerant circuit, when the refrigerant system is in said defrost mode.

20. The method of claim 14, further comprising placing a bypass refrigerant circuit in fluid communication with said cooling refrigerant circuit, when the refrigerant system is in said defrost mode.