Patent Application
20230392828
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be noted that these statements are to be read in this light, and not as admissions of prior art.
Chiller systems, or vapor compression systems, utilize a working fluid (e.g., a refrigerant) that changes phases between vapor, liquid, and combinations thereof, in response to exposure to different temperatures and pressures within components of the chiller system. A chiller system may place the working fluid in a heat exchange relationship with a conditioning fluid (e.g., water) and may deliver the conditioning fluid to conditioning equipment and/or a conditioned environment serviced by the chiller system. In such applications, the conditioning fluid may be passed through downstream equipment, such as air handlers, to condition other fluids, such as air in a building.
Traditional chiller systems include a refrigerant circuit including, for example, a compressor, a condenser, and an evaporator. In some instances, a chiller system may include multiple refrigerant circuits, and each refrigerant circuit includes a respective compressor, condenser, and evaporator. The multiple refrigerant circuits may operate separately or in conjunction with one another to condition the conditioning fluid for delivery to the conditioning equipment. Unfortunately, existing chiller systems having multiple refrigerant circuits may be arranged in configurations that limit the performance and/or efficiency of the chiller system.
A summary of certain embodiments disclosed herein is set forth below. It should be noted that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.
In an embodiment, a heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) system includes a first refrigerant circuit having a first evaporator configured to place a first refrigerant in a heat exchange relationship with a conditioning fluid, where the first evaporator includes a first set of first tubes and a second set of first tubes configured to direct the conditioning fluid through the first evaporator. The HVAC&R system also includes a second refrigerant circuit having a second evaporator configured to place a second refrigerant in a heat exchange relationship with the conditioning fluid, where the second evaporator includes a first set of second tubes and a second set of second tubes configured to direct the conditioning fluid through the second evaporator. The HVAC&R system further includes a conditioning fluid circuit configured to circulate the conditioning fluid serially through the first set of first tubes, the second set of first tubes, the first set of second tubes, and the second set of second tubes.
In an embodiment, a heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) system includes a first evaporator having a first lower tube bundle and a first upper tube bundle, where the first lower tube bundle and the first upper tube bundle are each configured to place a conditioning fluid in a heat exchange relationship with a first refrigerant, and a second evaporator having a second lower tube bundle and a second upper tube bundle, where the second lower tube bundle and the second upper tube bundle are each configured to place the conditioning fluid in a heat exchange relationship with a second refrigerant. The HVAC&R system also includes a conduit fluidly extending between the first evaporator and the second evaporator and fluidly coupling the first lower tube bundle and the second upper tube bundle and includes a conditioning fluid circuit configured to circulate the conditioning fluid serially through the second lower tube bundle, the second upper tube bundle, the conduit, the first lower tube bundle, and the first upper tube bundle.
In an embodiment, a chiller system includes a first refrigerant circuit having a first evaporator configured to place a first refrigerant in a heat exchange relationship with a conditioning fluid, where the first evaporator includes a first plurality of first tubes and a second plurality of first tubes configured to direct the conditioning fluid through the first evaporator, the first plurality of first tubes defines a lower pass of the first evaporator, and the second plurality of first tubes defines an upper pass of the first evaporator. The chiller system also includes a second refrigerant circuit having a second evaporator configured to place a second refrigerant in a heat exchange relationship with the conditioning fluid, where the second evaporator includes a first plurality of second tubes and a second plurality of second tubes configured to direct the conditioning fluid through the second evaporator, where the first plurality of second tubes defines a lower pass of the second evaporator, and the second plurality of second tubes defines an upper pass of the second evaporator. The chiller system further includes a conduit fluidly coupled between the second plurality of second tubes and the first plurality of first tubes.
Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:
One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be noted that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be noted that 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.
When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be noted that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
Embodiments of the present disclosure relate to a heating, ventilation, air conditioning, and/or refrigeration (HVAC&R) system, such as a chiller system. The HVAC&R system may include a vapor compression system through which a refrigerant is directed in order to heat and/or cool a conditioning fluid. As an example, the vapor compression system may include a compressor configured to pressurize the refrigerant and to direct the pressurized refrigerant to a condenser configured to cool the pressurized refrigerant. An evaporator of the vapor compression system may receive the cooled refrigerant and may place the cooled refrigerant in a heat exchange relationship with the conditioning fluid to absorb thermal energy or heat from the conditioning fluid, thereby cooling the conditioning fluid. The cooled conditioning fluid may then be directed to conditioning equipment, such as air handlers and/or terminal units, for use in conditioning air supplied to a building or other conditioned space.
Is some embodiments, the vapor compression system may include multiple refrigerant circuits with each refrigerant circuit including a respective condenser, compressor, and evaporator. For example, the evaporators of the multiple refrigerant circuits may cooperatively cool the conditioning fluid for use with the conditioning equipment. In other words, the evaporators may operate to cool a common flow of the conditioning fluid. Some evaporators are configured to cool the conditioning fluid via tubes that form a flow path defining multiple passes through the evaporator. For example, in a two-pass evaporator, the conditioning fluid may be directed through a first tube bundle of the evaporator in a first direction, and the flow of the conditioning fluid may be reversed (e.g., via a water box of the evaporator) and then directed through a second tube bundle of the evaporator in a second direction opposite the first direction.
Existing systems having multiple (e.g., two) refrigerant circuits typically include evaporators packaged together and configured to cool conditioning fluid by directing the conditioning fluid alternatingly between the evaporators. For example, existing systems may direct conditioning fluid sequentially through a first (e.g., lower) tube bundle or pass of a first evaporator and then through a first (e.g., lower) tube bundle or pass of the second evaporator. Thereafter, the flow direction of the conditioning fluid may be reversed, and the conditioning fluid may be directed sequentially through a second (e.g., upper) tube bundle or pass of the second evaporator and then through a second (e.g., upper) tube bundle or pass of the first evaporator. Unfortunately, the configurations of existing systems may result in higher evaporator approach temperatures than desired, which may result in reduced heat transfer between refrigerant and conditioning fluid, higher energy consumption (e.g., of compressors of the multiple refrigerant circuits), and/or reduced capacity of the multiple refrigerant circuits.
Thus, it is presently recognized that there is a need to improve the operation of HVAC systems having multiple refrigerant circuits by reducing the evaporator approach temperature(s) of the HVAC&R system. In this way, refrigerant pressure in the evaporators may be raised, which may reduce a lift (e.g., difference between condenser refrigerant pressure and evaporator refrigerant pressure) of the HVAC&R system and therefore reduce the work performed by compressors of the HVAC&R system. Accordingly, energy consumption of the HVAC&R system is reduced. In order to achieve a reduction in evaporator approach temperature, the evaporators of the multiple refrigerant circuits may be arranged in a serial flow arrangement. As used herein, “serial flow” refers to flow of conditioning fluid first through the passes of one evaporator of the HVAC&R system and subsequently through the passes of another evaporator of the HVAC&R system. In other words, the conditioning fluid received from the conditioning equipment first flows through a first evaporator of the HVAC&R system, then flows through a second evaporator of the HVAC&R system, and is then directed back to the conditioning equipment. As discussed in detail below, the serial flow arrangement of the evaporators in a multiple refrigerant circuit system enables efficiency improvements and reductions in costs associated with the HVAC&R system.
Turning now to the drawings,
The illustrated embodiment shows an HVAC&R system for building environmental management that may utilize heat exchangers. A building 10 is cooled by a system that includes a chiller 12 and a boiler 14. As shown, the chiller 12 is disposed on the roof of building 10, and the boiler 14 is located in the basement; however, the chiller 12 and boiler 14 may be located in other equipment rooms or areas next to the building 10. The chiller 12 may be an air cooled or water cooled device that implements a refrigeration cycle to cool water or other conditioning fluid. The chiller 12 is housed within a structure that may include one or more refrigeration circuits, a free cooling system, and associated equipment such as pumps, valves, and piping. For example, the chiller 12 may be single package rooftop unit. The boiler 14 is a closed vessel in which water is heated. The water from the chiller 12 and the boiler 14 is circulated through the building 10 by water conduits 16. The water conduits 16 are routed to air handlers 18 (e.g., conditioning equipment) located on individual floors and within sections of the building 10.
The air handlers 18 are coupled to ductwork 20 that is adapted to distribute air between the air handlers 18 and may receive air from an outside intake (not shown). The air handlers 18 include heat exchangers that circulate cold water from the chiller 12 and hot water from the boiler 14 to provide heated or cooled air to conditioned spaces within the building 10. Fans within the air handlers 18 draw air through the heat exchangers and direct the conditioned air to environments within building 10, such as rooms, apartments, or offices, to maintain the environments at a designated temperature. A control device, shown here as including a thermostat 22, may be used to designate the temperature of the conditioned air. The control device 22 also may be used to control the flow of air through and from the air handlers 18. Other devices may be included in the system, such as control valves that regulate the flow of water and pressure and/or temperature transducers or switches that sense the temperatures and pressures of the water, the air, and so forth. Moreover, control devices 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.
Some examples of working fluids that may be used as refrigerants in the vapor compression system 30 are hydrofluorocarbon (HFC) based refrigerants, for example, R-410A, R-407, R-134a, hydrofluoro-olefin (HFO), “natural” refrigerants like ammonia (NH3), R-717, carbon dioxide (CO2), R-744, or hydrocarbon based refrigerants, water vapor, refrigerants with low global warming potential (GWP), or any other suitable refrigerant. In some embodiments, the vapor compression system 30 may be configured to efficiently utilize refrigerants having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit or less) at one atmosphere of pressure, also referred to as low pressure refrigerants, versus a medium pressure refrigerant, such as R-134a. As used herein, “normal boiling point” may refer to a boiling point temperature measured at one atmosphere of pressure.
The vapor compression system 30 may further include a control panel 44 (e.g., controller) that has an analog to digital (A/D) converter 46, a microprocessor 48, a non-volatile memory 50, and/or an interface board 52. In some embodiments, the vapor compression system 30 may use one or more of a variable speed drive (VSDs) 54 and a motor 56. The motor 56 may drive the compressor 36 and may be powered by the VSD 54. The VSD 54 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 56. In other embodiments, the motor 56 may be powered directly from an AC or direct current (DC) power source. The motor 56 may include any type of electric motor that can be powered by the VSD 54 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 36 compresses a refrigerant vapor and may deliver the vapor to an oil separator 58 that separates oil from the refrigerant vapor. The refrigerant vapor is then directed toward the condenser 38, and the oil is returned to the compressor 36. The refrigerant vapor delivered to the condenser 38 may transfer heat to a cooling fluid at the condenser 38. For example, the cooling fluid may be ambient air 60 forced across heat exchanger coils of the condenser 38 by condenser fans 62. The refrigerant vapor may condense to a refrigerant liquid in the condenser 38 as a result of thermal heat transfer with the cooling fluid (e.g., the ambient air 60).
The liquid refrigerant exits the condenser 38 and then flows through a first expansion device 64 (e.g., expansion device 40, electronic expansion valve, etc.). The first expansion device 64 may be a flash tank feed valve configured to control flow of the liquid refrigerant to the flash tank 32. The first expansion device 64 is also configured to lower the pressure of (e.g., expand) the liquid refrigerant received from the condenser 38. During the expansion process, a portion of the liquid may vaporize, and thus, the flash tank 32 may be used to separate the vapor from the liquid received from the first expansion device 64. Additionally, the flash tank 32 may provide for further expansion of the liquid refrigerant due to a pressure drop experienced by the liquid refrigerant when entering the flash tank 32 (e.g., due to a rapid increase in volume experienced upon entering the flash tank 32).
The vapor in the flash tank 32 may exit and flow to the compressor 36. For example, the vapor may be drawn to an intermediate stage or discharge stage of the compressor 36 (e.g., not a suction stage). A valve 66 (e.g., economizer valve, solenoid valve, etc.) may be included in the refrigerant circuit 34 to control flow of the vapor refrigerant from the flash tank 32 to the compressor 36. In some embodiments, when the valve 66 is open (e.g., fully open), additional liquid refrigerant within the flash tank 32 may vaporize and provide additional subcooling of the liquid refrigerant within the flash tank 32. The liquid refrigerant that collects in the flash tank 32 may be at a lower enthalpy than the liquid refrigerant exiting the condenser 38 because of the expansion in the first expansion device 64 and/or the flash tank 32. The liquid refrigerant may flow from the flash tank 32, through a second expansion device 68 (e.g., expansion device 40, an orifice, etc.), and to the evaporator 42. In some embodiments, the refrigerant circuit 34 may also include a valve 70 (e.g., drain valve) configured to regulate flow of liquid refrigerant from the flash tank 32 to the evaporator 42. For example, the valve 70 may be controlled (e.g., via the control panel 44) based on an amount of suction superheat of the refrigerant.
The liquid refrigerant delivered to the evaporator 42 may absorb heat from a conditioning fluid, which may or may not be the same cooling fluid used in the condenser 38. The liquid refrigerant in the evaporator 42 may undergo a phase change to become vapor refrigerant. For example, the evaporator 42 may include one or more tube bundles fluidly coupled to a supply line 72 and a return line 74 that are connected to a cooling load. The conditioning fluid of the evaporator 42 (e.g., water, oil, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporator 42 via the return line 74 and exits the evaporator 42 the via supply line 72. The evaporator 42 may reduce the temperature of the conditioning fluid in the tube bundle via thermal heat transfer with the refrigerant so that the conditioning fluid may be utilized to provide cooling for a conditioned environment. The tube bundle in the evaporator 42 can include a plurality of tubes and/or a plurality of tube bundles. In some embodiments, the tubes or tube bundles may define multiple passes through the evaporator 42. In any case, the refrigerant vapor exits the evaporator 42 and returns to the compressor 36 by a suction line to complete the refrigerant cycle.
In some circumstances, an HVAC&R system may include multiple refrigerant circuits configured to separately and/or cooperatively cool the conditioning fluid. As disclosed herein, present embodiments include an HVAC&R system having multiple refrigerant circuits in which the evaporators of the multiple refrigerant circuits are arranged in a serial flow arrangement (e.g., relative to a flow of conditioning fluid through the evaporators). In other words, the evaporators are arranged, fluidly coupled, and/or packaged such that the conditioning fluid received from the cooling load first flows through one evaporator of one refrigerant circuit, then flows through another evaporator of another refrigerant circuit, and is then directed back to the cooling load. For example, the conditioning fluid may first be sequentially directed through multiple passes of one evaporator and subsequently be sequentially directed through multiple passes of another evaporator. In this way, the evaporator approach temperature(s) of the HVAC&R system may be reduced, which results in efficiency improvements and reductions in costs associated with the HVAC&R system.
With this in mind,
As mentioned above, the first and second evaporators 110 and 120 of the HVAC&R system 100 are arranged in a serial flow arrangement. Specifically, the first and second evaporators 110 and 120 are configured to define a portion of a conditioning fluid flow path or circuit 124 that extends from a cooling load 122 (e.g., air handlers 118), sequentially through evaporators 110 and 120, and back to the cooling load 122. As described in further detail below, each of the first and second evaporators 110 and 120 may include multiple passes (e.g., tube passes, tube bundles, sets of tubes, etc.) configured to direct conditioning fluid therethrough. In accordance with the serial flow arrangement, the HVAC&R system 100 is configured to direct conditioning fluid received from the cooling load 122 first through the passes of one evaporator and subsequently through the passes of another evaporator before directing the conditioning fluid back to the cooling load 122. For example, in the illustrated embodiment, the HVAC&R system 100 (e.g., the conditioning fluid circuit 124) is configured to direct conditioning fluid first through the second evaporator 120, then through the first evaporator 110, before directing the conditioning fluid back to the cooling load 122. However, in other embodiments, the HVAC&R system 100 may be configured to direct the conditioning fluid through the first evaporator 110, then through the second evaporator 120, before directing the conditioning fluid back to the cooling load 122. The disclosed serial flow arrangement enables a reduction in the separate and/or combined evaporator approach temperature of the first evaporator 110 and/or the second evaporator 120. Thus, the refrigerant pressure within the first evaporator 110 and/or the second evaporator 120 may be raised, which may reduce a lift of the first refrigerant circuit 102 and/or the second refrigerant circuit 112, respectively. Accordingly, energy consumption of the first compressor 104 and/or the second compressor 114 may be reduced, which enables a reduction in costs associated with operating the HVAC system 100.
In the illustrated configuration, the HVAC&R system 100 (e.g., the conditioning fluid circuit 124) is configured to direct a conditioning fluid from the cooling load 122 first through the second evaporator 120, then through the first evaporator 110, and then back to the cooling load 122. The first and second evaporators 110 and 120 are each configured as two-pass heat exchangers. That is, the first evaporator 110 includes a first pass 152 and a second pass 154, and the second evaporator 120 include a first pass 156 and a second pass 158. Each of the passes 152, 154, 156, and 158 may be defined by a respective set of tubes (e.g., a respective tube bundle) configured to direct the conditioning fluid therethrough.
In each of the first and second evaporators 110 and 120, heat is exchanged between the conditioning fluid and a respective refrigerant directed through the first and second evaporators 110 and 120. That is, a first refrigerant flowing through the first refrigerant circuit 102, as indicated by arrow 160, may be directed into a shell 162 of the first evaporator 110, and heat may be transferred from the first refrigerant 160 to the conditioning fluid flowing through the tubes of the first and second passes 152 and 154 of the first evaporator 110. Similarly, a second refrigerant directed through the second refrigerant circuit 112, as indicated by arrow 164, may be directed into a shell 166 of the second evaporator 120, and heat may be transferred from the second refrigerant 164 to the conditioning fluid flowing through the tubes of the first and second passes 156 and 158 of the second evaporator 120. In some embodiments, the first evaporator 110 and/or the second evaporator 120 may be configured as a flooded evaporator, while in other embodiments the first evaporator 110 and/or the second evaporator 120 may be configured as a falling film evaporator.
In the illustrated embodiment, the serial flow arrangement 150 of the first evaporator 110 and the second evaporator 120 receives the conditioning fluid, represented by arrow 168, via an inlet 170 of the second evaporator 120. That is, conditioning fluid from the cooling load 122 is directed into the serial flow arrangement 150 via the inlet 170. The inlet 170 directs the conditioning fluid into a first water box 172 of the second evaporator 120. The first water box 172 is divided into a first section 174 and a second section 176 by a baffle 178 that enables fluid separation of the first section 174 and the second section 176. From the first section 174 of the first water box 172, the conditioning fluid is directed through a first tube bundle 180 (e.g., a set of tubes) defining the first tube pass 156 of the second evaporator 120, as indicated by arrow 182. In the illustrated embodiment, the first tube pass 156 is a lower tube pass of the second evaporator 120, but in other embodiments the first tube pass 156 may be an upper tube pass or an intermediate tube pass.
From the first tube pass 156, the conditioning fluid is directed into a second water box 184 of the second evaporator 120. The second water box 184 reverses the flow direction of conditioning fluid through the second evaporator 120, as indicated by arrow 186, to direct the conditioning fluid through the second pass 158 of the second evaporator 120. Specifically, the conditioning fluid is directed through a second tube bundle 188 (e.g., a set of tubes) of the second pass 158, as indicated by arrow 190, which is an upper pass of the second evaporator 120. The conditioning fluid is then directed into the second section 176 of the first water box 172, from which the condition fluid is discharged from the second evaporator 120 via an outlet 192 of the second evaporator 120.
After the conditioning fluid is circulated through the second evaporator 120, the conditioning fluid is then circulated through the first evaporator 110. Specifically, as indicated by arrow 193, the conditioning fluid is directed from the second evaporator 120 to the first evaporator 110 via a conduit (e.g., transfer conduit) 194 that fluidly couples the outlet 192 of the second evaporator 120 with an inlet 196 of the first evaporator 110. The first evaporator 110 has a similar construction and/or configuration as the second evaporator 120, and the conditioning fluid is directed through the first evaporator 110 in a manner similar to that described above with reference to the second evaporator 120. For example, the inlet 196 of the first evaporator 110 directs the conditioning fluid into a first water box 198 of the first evaporator 110. The first water box 198 is divided into a first section 200 and a second section 202 by a baffle 204 that enables fluid separation of the first section 200 and the second section 202. From the first section 200 of the first water box 198, the conditioning fluid is directed through a first tube bundle 206 defining the first tube pass 152 of the first evaporator 110, as indicated by arrow 208. In the illustrated embodiment, the first tube pass 152 is a lower tube pass of the first evaporator 110, but in other embodiments the first tube pass 152 may be an upper tube pass or an intermediate tube pass.
From the first tube pass 152, the conditioning fluid is directed into a second water box 210 of the first evaporator 110. The second water box 210 reverses the flow of conditioning fluid through the first evaporator 110, as indicated by arrow 212, to direct the conditioning fluid through the second pass 154 of the first evaporator 110. Specifically, the conditioning fluid is directed through a second tube bundle 214 of the second pass 154, as indicated by arrow 216, which is an upper pass of the first evaporator 110. The conditioning fluid is then directed into the second section 202 of the first water box 198, from which the conditioning fluid is discharged from the first evaporator 110 via an outlet 218 of the first evaporator 110, as indicated by arrow 220. Thereafter, the conditioning fluid is directed back to the cooling load 122 for use in conditioning air or another fluid.
As mentioned above, the serial flow arrangement 150 of the first evaporator 110 and the second evaporator 120 enables a reduction in the evaporator approach temperature(s) of the first evaporator 110 and/or the second evaporator 120. As will be appreciated, respective temperature differences of the entering and exiting conditioning fluid for each of the first and second evaporators 110 and 120 may also be reduced. For example, a difference between the temperature of the conditioning fluid leaving the second evaporator 120 via the outlet 192 and a saturated evaporating temperature of the second refrigerant 164 may be less than that of the existing systems described above. As a result, a pressure of the second refrigerant 164 exiting the second evaporator 120, and therefore a suction pressure of the second refrigerant 164, may be greater than that of existing systems, which enables a reduced energy consumption of the second compressor 114. Similarly, a difference between the temperature of the conditioning fluid leaving the first evaporator 110 via the outlet 218 and a saturated evaporating temperature of the first refrigerant 160 may be less than that of existing systems. As a result, a pressure of the first refrigerant 160 exiting the first evaporator 110, and therefore a suction pressure of the first refrigerant 160, may be greater than that of existing systems, which enables a reduced energy consumption of the first compressor 104. In this way, operating costs of the HVAC&R system 100 may be reduced. Indeed, while the average refrigerant and/or conditioning fluid temperatures of the first evaporator and second evaporators 110 and 120 may be somewhat increased, an overall benefit and efficiency improvement of the HVAC&R system 100 may be realized with the serial flow arrangement 150 described herein by virtue of the advantages described above.
A further benefit of the serial flow arrangement 150 of the first and second evaporators 110 and 120 relates to manufacture of the HVAC&R system 100. As mentioned above, the first evaporator 110 and the second evaporator 120 have similar configurations and/or constructions and are connected via the conduit 194. Thus, in some embodiments, a common or single design of a heat exchanger may be manufactured and mass produced for use as each of the first evaporator 110 and the second evaporator 120. Thus, costs of design and manufacture of the HVAC&R system 100 may be reduced. Further, depending on desired configurations, packaging, and/or implementations of the HVAC&R system 100, positions of the first evaporator 110 and the second evaporator 120 relative to one another may be selected, and a suitable embodiment of the conduit 194 may be cost-effectively manufactured or produced to enable fluid coupling of the first evaporator 110 and the second evaporator 120. Similarly, configurations and/or orientations of the inlets 170 and 196 and outlets 192 and 218 may be readily selected or adjusted accordingly.
The controller 240 may be configured to control operation of components of the HVAC&R system 100, such as the components of the first refrigerant circuit 102 and the second refrigerant circuit 104 described herein. In some embodiments, the controller 240 may adjust operation of the HVAC&R system 100 based on feedback received by the controller 240, such as feedback received from sensors 246 of the HVAC&R system 100. One or more of the sensors 246 may be configured to detect operating parameters of the HVAC&R system 100, such as a temperature or pressure of the first refrigerant 160 circulated by the first refrigerant circuit 102, a temperature or pressure of the second refrigerant 164 circulated by the second refrigerant circuit 104, a temperature of the conditioning fluid, an operating mode of the HVAC&R system or a component thereof, an operating load or capacity of the HVAC&R system, an ambient temperature, another suitable operating parameter, and/or any combination thereof. Further, one or more of the sensors 246 may be positioned at any desirable location in order to detect an operating parameter, such as any desirable location along the first refrigerant circuit 102, the second refrigerant circuit 104, and/or the flow path of the conditioning fluid (e.g., the conditioning fluid circuit 124).
Based on the feedback received, the controller may adjust operation of the HVAC&R system 100. In some embodiments, operation of the first and second refrigerant circuits 102 and 104 may be adjusted based on an operating load of the HVAC&R system 100. For example, when the HVAC&R system 100 is operating at a 50 percent capacity, the first refrigerant circuit 102 and the second refrigerant circuit 104 (e.g., the compressors 104 and 114) may each be operated, via the controller 240, at 50 percent capacity. As another example, when the HVAC&R system 100 is operating at 75 percent capacity, the first refrigerant circuit 102 may be operated at 100 percent capacity, and the second refrigerant circuit 104 may be operated at 25 percent capacity.
In some circumstances, the controller 240 may control operation of the HVAC&R system 100 such that one refrigerant circuit operates and the other refrigerant circuit does not operate. For example, at 25 percent capacity of the HVAC&R system 100, the controller 240 may suspend operation of the second refrigerant circuit 104 and may operate the first refrigerant circuit 102. To this end, the HVAC&R system 100 (e.g., the conditioning fluid circuit 124) may include a bypass line configured to route the conditioning fluid from the cooling load 122, through the first evaporator 110, and back to the cooling load 122, such that the flow of conditioning fluid bypasses the second evaporator 120. In the illustrated embodiment, a bypass valve (e.g., a three-way valve) 248 is disposed along the conduit 194 and may be actuated (e.g., via the controller 240) to enable bypass of the second evaporator 120 and enable flow of the conditioning fluid from the cooling load 122 to the first evaporator 110, as indicated by arrow 250.
Technical effects of the embodiments and features described above include improvements to operation and manufacture of HVAC&R systems (e.g., chillers) having multiple refrigerant circuits, such as improvements in operating efficiency and cost reduction associated with operation and manufacture of the HVAC&R systems. Specifically, the serial flow arrangement of the evaporators of multiple refrigerant circuits enables a reduction in the evaporator approach temperature of the HVAC&R system. In this way, refrigerant pressure in the evaporators may be raised, which may reduce a lift of the HVAC&R system and therefore reduce the work performed by compressors of the HVAC&R system. Accordingly, energy consumption of the HVAC system is reduced. Additionally, the serial flow arrangement enables cost-effective manufacture of the HVAC&R system in multiple different structural configurations or arrangements.
While only certain features of present embodiments have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be noted that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the disclosure. Further, it should be noted that certain elements of the disclosed embodiments may be combined or exchanged with one another.
The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).
| Number | Date | Country | Kind |
|---|---|---|---|
| 202011172089.1 | Oct 2020 | CN | national |
| 202022441285.6 | Oct 2020 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/057099 | 10/28/2021 | WO |
