The present disclosure relates generally to heating, ventilation, and air conditioning (HVAC) systems, and, more particularly, to configurations of air intake sections of the HVAC system.
A wide range of applications exist for HVAC systems. For example, residential, light commercial, commercial, and industrial systems are used to control temperatures and air quality in residences and buildings. Generally, HVAC systems may circulate a fluid, such as a refrigerant, through a closed loop between an evaporator coil where the fluid absorbs heat and a condenser where the fluid releases heat. The fluid flowing within the closed loop is generally formulated to undergo phase changes within the normal operating temperatures and pressures of the system so that quantities of heat can be exchanged by virtue of the latent heat of vaporization of the fluid. A fan may blow air over, or pull air across, the coils of the heat exchanger(s) in order to condition the air. The volume of air passing over the coils of the heat exchanger may include a portion of air returned from a conditioned space of the residence or building, referred to as “return air” or “indoor air”, and a portion of external or ambient air, referred to as “outdoor air,” which may be used to ventilate the indoor air.
A traditional air economizer of a traditional HVAC system may receive the indoor air and outdoor air, combine the flows thereof, and pass the combined flow over a heat exchange coil. Traditional air economizers may include inefficiencies related to undesired pressure drops within the traditional air economizer. Accordingly, improved air economizers for HVAC systems are desired.
The present disclosure relates to an air economizer of a heating, ventilation, and air conditioning (HVAC) system. The air economizer includes an outdoor air compartment configured to receive outdoor air and an indoor air compartment configured to receive indoor air. The air economizer also includes a partition extending between the outdoor air compartment and the indoor air compartment. The partition is configured to move between a first position and a second position such that a damper of the air economizer receives the indoor air when the partition is in the first position, and such that the damper receives the outdoor air when the partition is in the second position.
A method of controlling an air economizer of a heating, ventilation, and air conditioning (HVAC) system includes determining, via a controller, a desired ratio between a first amount of indoor air received by an indoor air compartment of the air economizer and a second amount of outdoor air received by an outdoor air compartment of the air economizer. The method also includes instructing, via the controller and based on the desired ratio, damper settings of dampers of the air economizer. The method also includes adjusting, via the controller, a position of a partition of the air economizer extending between the indoor air compartment and the outdoor air compartment to assign a first group of the dampers to the indoor air compartment and to assign a second group of the dampers to the outdoor air compartment, such that an additional ratio between a first damper space of the first group of dampers and a second damper space of the second group of dampers is aligned with the desired ratio.
The present disclosure also relates to a heating, ventilation, and air conditioning (HVAC) system having an air economizer. The air economizer includes an air intake having an outdoor intake section and an indoor intake section. The air economizer also includes a partition separating the outdoor intake section from the indoor intake section, where the partition is rotatable to adjust sizes of the outdoor intake section and the indoor intake section based on desired amounts of outdoor air received by the outdoor intake section and indoor air received by the indoor intake section over an operating period of time.
The present disclosure is directed toward a commercial, industrial, or residential heating, ventilation, and air conditioning system (“HVAC system”). More particularly, the present disclosure is directed toward configurations of an air economizer of the HVAC system.
For example, a HVAC system may include an air economizer having an indoor or return air intake section or compartment configured to receive indoor air from a space conditioned by the HVAC system, and an outdoor air intake section configured to receive outdoor air from ambient. The outdoor air may be combined with the indoor air to generate a ventilated and/or cooled combined volume of air. The combined volume of air may pass over a coil of a heat exchanger, such as an evaporator coil, and a refrigerant or other fluid passing through the evaporator coil may absorb heat from the combined volume of air, thereby further coiling the combined volume of air.
The air economizer may be configured such that the indoor air intake section and the outdoor air intake section are positioned adjacent to one another. A bank of dampers may be positioned downstream of the adjacent indoor air intake section and the outdoor air intake section, such that the bank of dampers is configured to receive the combined volume of air described above. The bank of dampers may extend across a damper opening or space. The dampers of the bank may be adjusted or positioned to facilitate an amount of indoor air through the indoor air intake section over a discrete operating period of time, such as a volumetric flow rate of indoor air, and to similarly determine a volumetric flow rate of outdoor air through the outdoor air intake section. The positions of the dampers and corresponding volumetric flow rates of indoor and outdoor air therethrough may be determined based on certain operating conditions, ambient conditions, and/or desired conditions of the space being conditioned. A controller may receive sensor feedback indicative of these conditions, and the controller may instruct positions of the dampers accordingly. For example, if the outdoor air is warmer than the space being conditioned by the HVAC system and cooling is desired, the dampers receiving the outdoor air may be positioned by the controller to reduce the volumetric flow rate of the outdoor air through the outdoor air intake section, such that the outdoor air is just enough to ventilate the indoor air but not substantially heat the indoor air. Alternatively, if the outdoor air is cooler than the space being conditioned by the HVAC system and cooling is desired, the dampers receiving the outdoor air may be positioned by the controller to increase the volumetric flow rate of the outdoor air through the outdoor air intake section to both ventilate and cool the indoor air.
In accordance with present embodiments, a partition may extend between a portion of the indoor air intake section and a portion of the outdoor air intake section. For example, a wall may separate the indoor air intake section from the outdoor air intake section. A gap may be positioned between an end of the wall and the bank of dampers. The partition may extend within the gap from the end of the wall to the bank of dampers. The partition may be movable, based on instruction from the controller, toward the indoor air intake section and away from the outdoor air intake section in order to contract a volume of the indoor air intake section, and in order to expand a volume of the outdoor air intake section. Likewise, the partition may be movable, based on instruction from the controller, toward the outdoor air intake section and away from the indoor air intake section in order to contract the volume of the outdoor air intake section, and in order to expand the volume of the indoor air intake section. A position of the partition may be determined based on the position of the dampers, which, as described above, may be determined based on operating conditions and/or ambient or environmental conditions. A controller that instructs the damper positions and the movement of the partition may also assign which dampers correspond with the indoor air intake section and which dampers correspond with the outdoor air intake section, as assignment of the dampers to the appropriate air intake section is dependent on the position of the partition. By selectively positioning the partition based on the positions and assignments of the dampers, pressure drops within the air economizer may be reduced, and stratification of the air beyond the dampers may be reduced, thereby improving an efficiency of the air economizer. These and other features will be described in detail below.
Turning now to the drawings,
The HVAC unit 12 is an air cooled device that implements a refrigeration cycle to provide conditioned air to the building 10. Specifically, the HVAC unit 12 may include one or more heat exchangers across which an air flow is passed to condition the air flow before the air flow is supplied to the building. In the illustrated embodiment, the HVAC unit 12 is a rooftop unit (RTU) that conditions a supply air stream, such as environmental air and/or a return air flow from the building 10. After the HVAC unit 12 conditions the air, the air is supplied to the building 10 via ductwork 14 extending throughout the building 10 from the HVAC unit 12. For example, the ductwork 14 may extend to various individual floors or other sections of the building 10. In certain embodiments, the HVAC unit 12 may be a heat pump that provides both heating and cooling to the building with one refrigeration circuit configured to operate in different modes. In other embodiments, the HVAC unit 12 may include one or more refrigeration circuits for cooling an air stream and a furnace for heating the air stream.
A control device 16, one type of which may be a thermostat, may be used to designate the temperature of the conditioned air. The control device 16 also may be used to control the flow of air through the ductwork 14. For example, the control device 16 may be used to regulate operation of one or more components of the HVAC unit 12 or other components, such as dampers and fans, within the building 10 that may control flow of air through and/or from the ductwork 14. In some embodiments, other devices may be included in the system, such as pressure and/or temperature transducers or switches that sense the temperatures and pressures of the supply air, return air, and so forth. Moreover, the control device 16 may include computer systems that are integrated with or separate from other building control or monitoring systems, and even systems that are remote from the building 10.
As shown in the illustrated embodiment of
The HVAC unit 12 includes heat exchangers 28 and 30 in fluid communication with one or more refrigeration circuits. Tubes within the heat exchangers 28 and 30 may circulate refrigerant, such as R-410A, through the heat exchangers 28 and 30. The tubes may be of various types, such as multichannel tubes, conventional copper or aluminum tubing, and so forth. Together, the heat exchangers 28 and 30 may implement a thermal cycle in which the refrigerant undergoes phase changes and/or temperature changes as it flows through the heat exchangers 28 and 30 to produce heated and/or cooled air. For example, the heat exchanger 28 may function as a condenser where heat is released from the refrigerant to ambient air, and the heat exchanger 30 may function as an evaporator where the refrigerant absorbs heat to cool an air stream. In other embodiments, the HVAC unit 12 may operate in a heat pump mode where the roles of the heat exchangers 28 and 30 may be reversed. That is, the heat exchanger 28 may function as an evaporator and the heat exchanger 30 may function as a condenser. In further embodiments, the HVAC unit 12 may include a furnace for heating the air stream that is supplied to the building 10. While the illustrated embodiment of
The heat exchanger 30 is located within a compartment 31 that separates the heat exchanger 30 from the heat exchanger 28. Fans 32 draw air from the environment through the heat exchanger 28, where the heat exchanger 28 may be framed within the cabinet 24 of the HVAC unit 12 and/or containers 29 below the fans 32. Air may be heated and/or cooled as the air flows through the heat exchanger 28 before being released back to the environment surrounding the rooftop unit 12. A blower assembly 34, powered by a motor hidden from view behind the blower assembly 34, draws air through the heat exchanger 30 to heat or cool the air. The heated or cooled air may be directed to the building 10 by the ductwork 14, which may be connected to the HVAC unit 12. Before flowing through the heat exchanger 30, the conditioned air flows through one or more filters 38 that may remove particulates and contaminants from the air. In some embodiments, an air economizer may be disposed in an area 33 of the HVAC unit 12 upstream of the filters 38. Further, in certain embodiments, the filters 38 may be disposed on the air intake side of the heat exchanger 30 to prevent contaminants from contacting the heat exchanger 30.
The HVAC unit 12 also may include other equipment for implementing the thermal cycle. Compressors 42 increase the pressure and temperature of the refrigerant before the refrigerant enters the heat exchanger 28. The compressors 42 may be any suitable type of compressors, such as scroll compressors, rotary compressors, screw compressors, or reciprocating compressors. In some embodiments, the compressors 42 may include a pair of hermetic direct drive compressors arranged in a dual stage configuration 44. In the illustrated embodiment, the compressors 42 include two dual stage configurations 44. However, in other embodiments, any number of the compressors 42 may be provided to achieve various stages of heating and/or cooling. As may be appreciated, additional equipment and devices may be included in the HVAC unit 12, such as a solid-core filter drier, a drain pan, a disconnect switch, an economizer, pressure switches, phase monitors, and humidity sensors, among other things.
The HVAC unit 12 may receive power through a terminal block, which is hidden from view behind the illustrated control board 48. For example, a high voltage power source may be connected to the terminal block to power the equipment. The operation of the HVAC unit 12 may be governed or regulated by the control board 48. The control board 48 may include control circuitry connected to a thermostat, sensors, and alarms. One or more of these components may be referred to herein separately or collectively as the control device 16. The control circuitry may be configured to control operation of the equipment, provide alarms, and monitor safety switches. Wiring may connect the control board 48 and the terminal block to the equipment of the HVAC unit 12.
When the system shown in
The outdoor unit 58 draws environmental air through the heat exchanger 60 using a fan 64 and expels the air above the outdoor unit 58. When operating as an air conditioner, the air is heated by the heat exchanger 60 within the outdoor unit 58 and exits the unit at a temperature higher than it entered. The indoor unit 56 includes a blower or fan 66 that directs air through or across the indoor heat exchanger 62, where the air is cooled when the system is operating in air conditioning mode. Thereafter, the air is passed through ductwork 68 that directs the air to the residence 52. The overall system operates to maintain a desired temperature as set by a system controller. When the temperature sensed inside the residence 52 is higher than the set point on the thermostat, or the set point plus a small amount, the residential heating and cooling system 50 may become operative to refrigerate additional air for circulation through the residence 52. When the temperature reaches the set point, or the set point minus a small amount, the residential heating and cooling system 50 may stop the refrigeration cycle temporarily.
The residential heating and cooling system 50 may also operate as a heat pump. When operating as a heat pump, the roles of heat exchangers 60 and 62 are reversed. That is, the heat exchanger 60 of the outdoor unit 58 will serve as an evaporator to evaporate refrigerant and thereby cool air entering the outdoor unit 58 as the air passes over outdoor the heat exchanger 60. The indoor heat exchanger 62 will receive a stream of air blown over it and will heat the air by condensing the refrigerant.
In some embodiments, the indoor unit 56 may include a furnace system 70. For example, the indoor unit 56 may include the furnace system 70 when the residential heating and cooling system 50 is not configured to operate as a heat pump. The furnace system 70 may include a burner assembly and heat exchanger, among other components, inside the indoor unit 56. Fuel is provided to the burner assembly of the furnace 70 where it is mixed with air and combusted to form combustion products. The combustion products may pass through tubes or piping in a heat exchanger, separate from heat exchanger 62, such that air directed by the blower 66 passes over the tubes or pipes and extracts heat from the combustion products. The heated air may then be routed from the furnace system 70 to the ductwork 68 for heating the residence 52.
In some embodiments, the vapor compression system 72 may use one or more of a variable speed drive (VSDs) 92, a motor 94, the compressor 74, the condenser 76, the expansion valve or device 78, and/or the evaporator 80. The motor 94 may drive the compressor 74 and may be powered by the variable speed drive (VSD) 92. The VSD 92 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 94. In other embodiments, the motor 94 may be powered directly from an AC or direct current (DC) power source. The motor 94 may include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.
The compressor 74 compresses a refrigerant vapor and delivers the vapor to the condenser 76 through a discharge passage. In some embodiments, the compressor 74 may be a centrifugal compressor. The refrigerant vapor delivered by the compressor 74 to the condenser 76 may transfer heat to a fluid passing across the condenser 76, such as ambient or environmental air 96. The refrigerant vapor may condense to a refrigerant liquid in the condenser 76 as a result of thermal heat transfer with the environmental air 96. The liquid refrigerant from the condenser 76 may flow through the expansion device 78 to the evaporator 80.
The liquid refrigerant delivered to the evaporator 80 may absorb heat from another air stream, such as a supply air stream 98 provided to the building 10 or the residence 52. For example, the supply air stream 98 may include ambient or environmental air, return air from a building, or a combination of the two. The liquid refrigerant in the evaporator 80 may undergo a phase change from the liquid refrigerant to a refrigerant vapor. In this manner, the evaporator 80 may reduce the temperature of the supply air stream 98 via thermal heat transfer with the refrigerant. Thereafter, the vapor refrigerant exits the evaporator 80 and returns to the compressor 74 by a suction line to complete the cycle.
In some embodiments, the vapor compression system 72 may further include a reheat coil in addition to the evaporator 80. For example, the reheat coil may be positioned downstream of the evaporator relative to the supply air stream 98 and may reheat the supply air stream 98 when the supply air stream 98 is overcooled to remove humidity from the supply air stream 98 before the supply air stream 98 is directed to the building 10 or the residence 52.
It should be appreciated that any of the features described herein may be incorporated with the HVAC unit 12, the residential heating and cooling system 50, or other HVAC systems. Additionally, while the features disclosed herein are described in the context of embodiments that directly heat and cool a supply air stream provided to a building or other load, embodiments of the present disclosure may be applicable to other HVAC systems as well. For example, the features described herein may be applied to mechanical cooling systems, free cooling systems, chiller systems, or other heat pump or refrigeration applications.
Further, in accordance with present techniques, a system, assembly, or apparatus for dynamically sizing compartments of an economizer of an air intake section of the HVAC unit 12 may be incorporated into any one of the systems illustrated in
Continuing with the embodiment illustrated in
In traditional embodiments, sizes of indoor and outdoor air compartments may be static or fixed. When the volumetric flow rate of the indoor air and outdoor air differs in a traditional embodiment, a pressure drop across the dampers may occur, since the relative amounts of air do not correspond with the amount of available damper space receiving the air. In other words, if the sizes of indoor and outdoor air compartments are equal and static, such as in traditional embodiments, a pressure drop may occur when the compartments receive relatively different volumetric flow raters of air. Air stratification across the dampers of the traditional embodiment may also occur because of these differences. Air stratification and pressure drops generally reduce an efficiency of the economizer.
In accordance with embodiments of the present disclosure, the partition 110 illustrated in
As noted above, the controller 122 may determine and set positions of the dampers 120, where “positions of the damper 120” refers to an amount of opening or restriction of the damper 120. For example, the controller 122 may determine and set the positions of the dampers 120 based on sensor feedback received from a sensor 123 or series of sensors of the air economizer 100 or HVAC system. The sensor(s) 123 may detect, for example, ambient conditions, operating conditions, conditions of the space requiring conditioning by the HVAC system, or a combination thereof. Ambient conditions may include a temperature of the outdoor air 105, a contaminant content of outdoor air 105, a humidity of outdoor air 105, or a combination thereof. Conditions of the space requiring conditioning may include a temperature of indoor air 103, a contaminant content of indoor air 103, a humidity of indoor air 103, or a combination thereof. Operating conditions may include current damper 120 positions, current partition 110 position, or other conditions.
In accordance with the present disclosure, the controller 122 may also set the position of the partition 110 to align sizes of the indoor and outdoor air compartments 102, 104 with the positions of the dampers 120, which may be referred to as “settings” of the dampers 120. In general, the positions/settings of the dampers 120 determine the volumetric flow rates of air through the indoor and outdoor air compartments 102, 104. For example, the anchor point 116 of the partition 110 may be coupled to a motor 117, which is communicatively coupled with the controller 122. The controller 122 may instruct the motor 117 to drive the anchor point 116 to rotate, which moves the partition 110 toward an appropriate partition position. Thus, the controller 122 aligns the sizes of the compartments 102, 104 not only with the positions/settings of the dampers 120, but with the corresponding volumetric flow rates of the indoor air 103 and outdoor air 105 that are dependent on the positions/settings of the dampers 120. Put differently, a percentage of the amount of available damper space 130 devoted to receipt of the indoor air 103 may correspond with the percentage of the amount of total air volume 124 formed by the received indoor air 103 over an operating period of time. By extension, a percentage of the amount of available damper space 130 devoted to receipt of the outdoor air 105 may correspond with the percentage of the amount of total air volume 124 formed by the received outdoor air 105 over the operating period of time.
Of course, because the dampers 120 associated with the indoor air compartment 102 and the outdoor air compartment 104 may change depending on the position of the partition 110, the controller 122 determines the assignment of certain dampers 120 to the indoor air compartment 102 and certain dampers 120 to the outdoor air compartment 104. For example,
It should be noted that, in the embodiments illustrated in
Since the step size between the available positions of the partition 110 is such that the partition 110 may not be set, in the embodiments illustrated in
Additionally, it should be noted that more than four dampers 120 may be included. Including more dampers 120 in the available damper space 130 facilitates a reduced and improved step size between available partition positions. In other words, more dampers 120 may enable a more accurate dynamic sizing of compartments 102, 104, as a function of segmenting the damper space 130. Put differently, more dampers 120 may enable a more precise assignment of dampers 120 to the corresponding compartments 102, 104, as a function of the amounts of air 103, 105 desired to pass through the compartments 102, 104, respectively. Three, four, five, six, seven, eight, nine, ten, or more dampers 120 may be included. For example, if ten dampers 120 are included in the available damper space 130, eleven positions for the partition 110 are possible. Indeed, the partition 110 could be positioned to assign 0% of the dampers 120 to the indoor air compartment 102, 10% of the dampers 120 to the indoor air compartment 102, 20% of the dampers 120 to the indoor air compartment 102, and so on up to 100%. In general, the number of available positions of the partitions 110 may be equal to the number of dampers 120 plus one.
In
Alternatively, as shown in
The method 200 also includes determining and instructing positions/settings of the dampers, as indicated by block 204. As previously described, the “position of the damper” refers to the setting indicative of an extent of opening or restriction of the damper, as opposed to literal movement of the damper between locations inside the air economizer. The positions of the dampers may be determined and instructed by the controller, based on the sensor feedback noted in block 202 above.
The method 200 also includes determining and instructing assignment of the dampers to the indoor air compartment and to the outdoor air compartment, as indicated by block 206. For example, as previously described, certain dampers of the bank of dampers are assigned to the indoor air compartment and certain dampers of the bank of dampers are assigned to the outdoor air compartment. The dampers assigned to the indoor air compartment are controlled by the controller to include the desired damper positions for the indoor air compartment, and the dampers assigned to the outdoor air compartment are controlled by the controller to include the desired damper positions of the outdoor air compartment.
The method 200 also includes determining and instruction a partition position, as indicated by block 208. For example, as noted above in block 206, the dampers of the bank of dampers are assigned to the indoor air compartment and the outdoor air compartment. The assignments of the dampers are dependent on the position of the partition, which segments the total damper space into the indoor damper space, which includes the dampers that receive the indoor air, and the outdoor damper space, which includes the dampers that receive the outdoor air. The partition position and the assignment of the dampers align a first ratio indicative of the relative amounts of air flow through the indoor damper space and the outdoor damper space with a second ratio indicative of the relative lengths of the indoor damper space and outdoor damper space. It should be noted that “align” may refer to a minimization of a difference between the relative amounts of air and the relative lengths noted above. “Matching” the first ratio indicative of the relative amounts of indoor and outdoor air with the second ratio indicative of the relative lengths of the indoor and outdoor damper space may refer to an embodiment where the first ratio and the second ratio are equal.
One or more of the disclosed embodiments, alone or in combination, may provide one or more technical effects useful in enhancing efficiency of a heat exchanger of an HVAC system. For example, in general, embodiments of the present disclosure include an air economizer having dynamically sized or modified indoor/outdoor air compartments. The dynamic sizing/modification of the indoor/outdoor air compartments and corresponding control features may enable alignment of the air flow conditions through the compartments with the sizes of the compartments, thereby reducing pressure differentials and air stratification in the air economizer.
While only certain features and embodiments of the present disclosure have been illustrated and described, many modifications and changes may occur to those skilled in the art without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.
This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 62/431,136, filed Dec. 7, 2016, entitled “DYNAMIC SIZING OF ECONOMIZER COMPARTMENTS AND CONTROLS STRATEGY,” the disclosure of which is hereby incorporated by reference in its entirety for all purposes.
Number | Date | Country | |
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62431136 | Dec 2016 | US |