System and method for a refrigerant subsystem for a heating, ventilation, and air conditioning system

Abstract

The refrigerant subsystem includes a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant-air heat exchanger. The compressor receives and compresses refrigerant. The condenser condenses the refrigerant and transfers heat from the refrigerant to the first fluid. The expansion valve expands the refrigerant. The evaporator evaporates the refrigerant into a first pressure and transfers heat from the second fluid to the refrigerant. The refrigerant-air heat exchanger has a first operating mode and a second operating mode. In the first operating mode, the condenser is adapted to condense a first portion of the refrigerant from a vapor to a liquid, and the refrigerant-air heat exchanger is adapted to condense a second portion of the refrigerant from a vapor to a liquid and transfer heat from the second portion of the refrigerant to air.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. non-provisional patent application No. 17 / 033,409, filed on September 25, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This field generally relates to heating, ventilation and air conditioning systems, and more specifically, to systems and methods for refrigerant subsystems of heating, ventilation and air conditioning systems. Background Technology

[0004] A heating, ventilation, and air conditioning (HVAC) system may include multiple subsystems that enhance the heating, cooling, and dehumidification capabilities of the HVAC system. For example, an HVAC system may include a refrigerant subsystem, a hot water subsystem, and a chilled water subsystem, which improve the efficiency of the HVAC system. The hot water and chilled water subsystems may each include heat transfer devices that are intermittently used to release heat to or absorb heat from the atmosphere, as determined by the operating conditions of the HVAC system. Specifically, the hot water subsystem may include an air cooler for releasing heat to the atmosphere, and the chilled water subsystem may include an air-to-water heat exchanger for absorbing heat from the atmosphere. The air cooler in the hot water subsystem is used to release excess heat when additional cooling is required, and the air-to-water heat exchanger in the chilled water subsystem is used to absorb heat when overcooling occurs. However, the air cooler in the hot water subsystem and the air-to-water heat exchanger in the chilled water subsystem are not used simultaneously. Having idle heat transfer devices increases the operational complexity of the system and increases the capital cost of the HVAC system.

[0005] This background section is intended to introduce the reader to various aspects of the art that may relate to the aspects described below and / or claimed in this disclosure. This discussion is intended to help provide the reader with background information for a better understanding of the various aspects of this disclosure. Therefore, it should be understood that these statements should be read in that context and not as an admission of prior art. Summary of the Invention

[0006] In one aspect, a refrigerant subsystem for a heating, ventilation, and air conditioning (HVAC) system includes a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant-air heat exchanger. The compressor receives uncompressed vapor refrigerant at a first pressure, and the refrigerant exits the compressor as compressed vapor refrigerant at a second pressure higher than the first pressure. The condenser condenses the compressed vapor refrigerant into compressed liquid refrigerant and transfers heat from the compressed vapor refrigerant to a first fluid. The expansion valve expands the compressed liquid refrigerant into uncompressed liquid refrigerant. The evaporator evaporates the uncompressed liquid refrigerant into uncompressed vapor refrigerant at the first pressure and transfers heat from a second fluid to the uncompressed vapor refrigerant. The refrigerant-air heat exchanger has a first operating mode and a second operating mode. In the first operating mode, the condenser is adapted to condense a first portion of the compressed vapor refrigerant from vapor to liquid, and the refrigerant-air heat exchanger is adapted to condense a second portion of the compressed vapor refrigerant from vapor to liquid and transfer heat from the second portion of the compressed vapor refrigerant to air.

[0007] In another aspect, the HVAC system includes a hot water subsystem for circulating a first fluid, a chilled water subsystem for circulating a second fluid, and a refrigerant subsystem for transferring heat from the chilled water subsystem to the hot water subsystem and the environment. The refrigerant subsystem includes a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant-air heat exchanger. The compressor receives uncompressed vapor refrigerant at a first pressure, and the refrigerant exits the compressor as compressed vapor refrigerant at a second pressure higher than the first pressure. The condenser condenses the compressed vapor refrigerant into compressed liquid refrigerant and transfers heat from the compressed vapor refrigerant to the first fluid. The expansion valve expands the compressed liquid refrigerant into uncompressed liquid refrigerant. The evaporator evaporates the uncompressed liquid refrigerant into uncompressed vapor refrigerant at the first pressure and transfers heat from the second fluid to the uncompressed vapor refrigerant. The refrigerant-air heat exchanger has a first operating mode and a second operating mode. In the first operating mode, the condenser is adapted to condense a first portion of the compressed vapor refrigerant from vapor into liquid, and the refrigerant-air heat exchanger is adapted to condense a second portion of the compressed vapor refrigerant from vapor into liquid and transfer heat from the second portion of the compressed vapor refrigerant to air.

[0008] In another aspect, a method of transferring heat from a chilled water subsystem to a hot water subsystem of a heating, ventilation, and air conditioning (HVAC) system using a refrigerant subsystem includes using a compressor to compress uncompressed vapor refrigerant at a first pressure into compressed vapor refrigerant at a second pressure higher than the first pressure. The refrigerant subsystem includes a compressor, a condenser, an evaporator, an expansion valve, and a refrigerant-air heat exchanger. The method further includes using the condenser to condense the compressed vapor refrigerant into a compressed liquid refrigerant and transfer heat from the compressed vapor refrigerant to a first fluid. The method also includes using the expansion valve to expand the compressed liquid refrigerant into an uncompressed liquid refrigerant. The method further includes using the evaporator to evaporate the uncompressed liquid refrigerant into an uncompressed vapor refrigerant at the first pressure and transfer heat from a second fluid to the uncompressed vapor refrigerant. The method further includes, in a first operating mode, using the condenser to condense a first portion of the compressed vapor refrigerant from vapor into liquid, and using the refrigerant-air heat exchanger to condense a second portion of the compressed vapor refrigerant from vapor into liquid and transfer heat from the second portion of the compressed vapor refrigerant to air.

[0009] Various improvements exist to the features proposed in the above aspects. Other features may also be incorporated into the above aspects. These improvements and additional features may exist individually or in any combination. For example, the various features discussed below with respect to any embodiment of the illustrated embodiments may be incorporated into any of the above aspects individually or in any combination. Attached Figure Description

[0010] Figure 1 This is a schematic flowchart of a heating, ventilation, and air conditioning (HVAC) system.

[0011] Figure 2 yes Figure 1 The diagram shows a schematic flow chart of the hot water subsystem.

[0012] Figure 3 yes Figure 1 The diagram shows a schematic flow chart of the cold water subsystem.

[0013] Figure 4 yes Figure 1 The diagram shows a schematic flow chart of the refrigerant subsystem.

[0014] Figure 5 yes Figure 4 The diagram shown is a schematic flowchart of the refrigerant subsystem in the first operating mode.

[0015] Figure 6 yes Figure 4 The diagram shown is a schematic flowchart of the refrigerant subsystem in the second operating mode.

[0016] Figure 7 Is using Figures 4 to 6 The refrigerant subsystem illustrated in the figure transfers heat from... Figure 3 The cold water subsystem illustrated in the figure is transferred to Figure 2 The flowchart illustrates the method for the hot water subsystem.

[0017] Throughout the accompanying drawings, corresponding reference numerals indicate the corresponding parts. Detailed Implementation

[0018] Figure 1 This is a schematic flow diagram of a heating, ventilation, and air conditioning (HVAC) system 100. While HVAC system 100 can be any type of HVAC system, it is more efficient than existing HVAC systems because, compared to existing systems, it includes subsystems 102 to 110 that enhance the heating, cooling, and dehumidifying capabilities of the system. Specifically, HVAC system 100 includes a refrigerant subsystem 102, two water subsystems 104 and 106, a conditioning subsystem 108, and a regeneration subsystem 110. Water subsystems 104 and 106 include a hot water subsystem 104 and a chilled water subsystem 106. Conditioning subsystem 108 removes heat and moisture from the flow of conditioned inlet air 112 and directs the flow of conditioned outlet air 114 to a building or vehicle (not shown). Conditioned outlet air 114 has a lower temperature and humidity than conditioned inlet air 112 because conditioning subsystem 108 has removed heat and moisture from the air. Subsystems 102 to 110 transfer heat and moisture from conditioning subsystem 108 to regeneration subsystem 110. Regeneration subsystem 110 transfers heat and moisture to the flow of regeneration inlet air 116 and directs the flow of regeneration outlet air 118 to the atmosphere.

[0019] The conditioning subsystem 108 cools the conditioned inlet air 112 by using latent heat cooling and sensible heat cooling. Sensible heat cooling lowers the temperature of the conditioned inlet air 112 by removing heat from the conditioned inlet air. Latent heat cooling lowers the temperature of the conditioned inlet air 112 by removing moisture from the conditioned inlet air. As described below, the conditioning subsystem 108 includes a three-way heat exchanger that transfers heat and moisture from the conditioned inlet air 112 while cooling the conditioned inlet air by both latent heat cooling and sensible heat cooling. Furthermore, a chilled water subsystem 106 controls sensible heat cooling, and a hot water subsystem 104 controls latent heat cooling. The refrigerant subsystem 102 described herein switches between chilled water subsystem 106 and hot water subsystem 104 for cooling based on external conditions. More specifically, the HVAC system 100 may need to provide a specific ratio of sensible heat cooling to latent heat cooling to achieve specific temperature and humidity setpoints for the conditioned outlet air 114. The refrigerant subsystem 102 switches between the chilled water subsystem 106 and the hot water subsystem 104 for cooling, thereby adjusting the sensible heat cooling and latent heat cooling of the inlet air 112 to achieve a specific temperature setpoint and a specific humidity setpoint for adjusting the outlet air 114.

[0020] The regulating subsystem 108 shares a first heat exchanger 120 with and interacts with the chilled water subsystem 106 and the regeneration subsystem 110 via the first heat exchanger. In this embodiment, the first heat exchanger 120 is a three-way heat exchanger that transfers heat from the regulating inlet air 112 to a first fluid and transfers both heat and moisture from the regulating inlet air 112 to a second fluid. The first heat exchanger 120 includes a membrane (not shown) that allows both heat and moisture to be transferred from the regulating inlet air 112 to the second fluid, and a membrane 122 that guides the first fluid through the first heat exchanger 120 and transfers heat from the regulating inlet air 112 to the second fluid. In this embodiment, the first fluid is a flow of water circulated by the chilled water subsystem 106, and the second fluid is a flow of liquid desiccant circulated by the regulating subsystem 108 and the regeneration subsystem 110. In an alternative embodiment, the first fluid can be any fluid that enables the conditioning subsystem 108 and the chilled water subsystem 106 to operate as described herein, and the second fluid can be any fluid that enables the conditioning subsystem 108 and the regeneration subsystem 110 to operate as described herein, including but not limited to any type of desiccant. For example, the second fluid can be a solid desiccant in a slurry.

[0021] The chilled water subsystem 106 shares a first heat exchanger 120 with the regulating subsystem 108 and an evaporator 124 with the refrigerant subsystem 102. As described below, the chilled water subsystem 106 transfers heat from the first heat exchanger 120 to the evaporator 124 or to the atmosphere. More specifically, the chilled water subsystem 106 may include additional heat transfer devices to transfer heat to the atmosphere. Residual heat is transferred to the refrigerant subsystem 102 via the evaporator 124. Furthermore, in the illustrated embodiment, the chilled water subsystem 106 is a closed, unpressurized system that prevents substances from the surrounding environment from entering the subsystem, thereby preventing contaminants from entering and contaminating the subsystem. In alternative embodiments, the chilled water subsystem 106 may be an open, unpressurized system. As used herein, unpressurized means that the subsystem operates at a pressure of 5 psig or less.

[0022] The refrigerant subsystem 102 shares an evaporator 124 with the chilled water subsystem 106 and a condenser 126 with the hot water subsystem 104. As described below, the refrigerant subsystem 102 transfers heat from the evaporator 124 to the condenser 126, and the condenser 126 transfers heat to the hot water subsystem 104. Specifically, the refrigerant subsystem 102 directs refrigerant from the evaporator 124 to the condenser 126, and the refrigerant transfers heat from the evaporator 124 to the condenser 126.

[0023] The hot water subsystem 104 shares a second heat exchanger 128 with the regeneration subsystem 110 and a condenser 126 with the refrigerant subsystem 102. As described below, the hot water subsystem 104 transfers heat from the condenser 126 to the second heat exchanger 128 or to the atmosphere. More specifically, the hot water subsystem 104 may include additional heat transfer devices to transfer heat to the atmosphere. Residual heat is transferred to the regeneration subsystem 110 via the second heat exchanger 128. Furthermore, in the illustrated embodiment, the hot water subsystem 104 is a closed, unpressurized system that does not allow substances from the surrounding environment to enter the subsystem, thereby preventing contaminants from entering and contaminating the subsystem. In alternative embodiments, the hot water subsystem 104 may be an open, unpressurized system. As used herein, unpressurized means that the subsystem operates at a pressure of 5 psig or less.

[0024] The regeneration subsystem 110 shares a second heat exchanger 128 with and interacts with the hot water subsystem 104 and the conditioning subsystem 108 via the second heat exchanger. In this embodiment, the second heat exchanger 128 is a three-way heat exchanger that transfers heat from the first fluid to the regeneration inlet air 116 and transfers both heat and moisture from the second fluid to the regeneration inlet air 116. The second heat exchanger 128 includes a membrane (not shown) that allows both heat and moisture to be transferred from the second fluid to the regeneration inlet air 116, and a membrane 122 that guides the first fluid through the second heat exchanger 128 and transfers heat from the first fluid to the regeneration inlet air 116 and the second fluid. In the illustrated embodiment, the first fluid is a flow of water circulated by the hot water subsystem 104, and the second fluid is a flow of liquid desiccant circulated by the conditioning subsystem 108 and the regeneration subsystem 110. In an alternative embodiment, the first fluid may be any fluid that enables the regeneration subsystem 110 and the hot water subsystem 104 to operate as described herein, and the second fluid may be any fluid that enables the regeneration subsystem 110 and the regulation subsystem 108 to operate as described herein.

[0025] Still refer to Figure 1The first heat exchanger 120 and the second heat exchanger 128 are substantially identical. In an alternative embodiment, the first heat exchanger 120 and the second heat exchanger 128 are different. Specifically, in this embodiment, both the first heat exchanger 120 and the second heat exchanger 128 include a membrane 122 for guiding a first fluid through the heat exchanger and for exchanging heat between the first fluid, the second fluid, and the air flow. In one embodiment, the membrane 122 is a non-rigid, flexible material that allows heat transfer to and from the first fluid while preventing the first fluid from mixing with any other fluid, including the second fluid and the air flow. Specifically, the membrane 122 is a non-rigid, flexible material designed to operate without pressure (at or below 5 psig) and is not designed to operate at substantially higher pressures (e.g., 10 psig). More specifically, in this embodiment, membrane 122 comprises a bladder or polymer bag that allows heat transfer to and from the first fluid while preventing the first fluid from mixing with any other fluid, including a second fluid and air, and the bladder or polymer bag operates at or below 5 psig. Membrane 122 is flexible because the material forming the membrane can bend without breaking, and the membrane is non-rigid because it can change size and shape without breaking. As described below, in this embodiment, membrane 122 is flexible and non-rigid because the membrane remains in a contracted configuration. In alternative embodiments, membrane 122 is formed of any material and has any degree of flexibility and rigidity that allows the first heat exchanger 120 and the second heat exchanger 128 to operate as described herein.

[0026] More specifically, membrane 122 is filled with a first fluid and positioned within the first heat exchanger 120 and the second heat exchanger 128, close to the flow of the second fluid and air. In some embodiments, membrane 122 is in physical contact with at least one of the flows of the second fluid and air to facilitate enhanced heat transfer between the flows of the first fluid, the second fluid, and the air. For example, membrane 122 may be immersed in the flows of the second fluid and / or air to facilitate enhanced heat transfer between the flows of the first fluid, the second fluid, and the air. The first heat exchanger 120 and the second heat exchanger 128 are non-pressurized heat exchangers because they include a non-pressurized element (membrane 122), and portions of the heat exchangers are designed to operate non-pressurized (at or below 5 psig).

[0027] The first heat exchanger 120 cools the regulated inlet air 112 by lowering the temperature of the regulated inlet air and removing moisture from it using latent heat cooling and sensible heat cooling. Specifically, the first heat exchanger 120 performs sensible heat cooling on the regulated inlet air 112, thereby exchanging heat between the first fluid and the regulated inlet air. The first fluid lowers the temperature of the regulated inlet air 112, and the temperature of the first fluid is controlled by the chilled water subsystem 106. Therefore, the chilled water subsystem 106 controls the sensible heat cooling of the regulated inlet air 112. Furthermore, the first heat exchanger 120 cools the regulated inlet air 112 by removing moisture from it using latent heat cooling. A second fluid removes moisture from the regulated inlet air 112, and a second heat exchanger 128 removes moisture from the second fluid. The temperature of the first fluid circulated by the hot water subsystem 104 determines the amount of moisture removed from the second fluid, which in turn determines the amount of moisture removed from the regulated inlet air 112 by the second fluid within the first heat exchanger 120. Therefore, the temperature control of the first fluid in the chilled water subsystem 106 regulates the sensible heat cooling of the inlet air 112, and the temperature control of the first fluid in the hot water subsystem 104 regulates the latent heat cooling of the inlet air. The refrigerant subsystem 102 described herein switches between the chilled water subsystem 106 and the hot water subsystem 104 to adjust the temperature of the first fluid in both the hot water and chilled water subsystems, thereby regulating the sensible heat and latent heat cooling of the inlet air 112 to achieve specific temperature and humidity setpoints for regulating the outlet air 114.

[0028] Figure 2 This is a schematic flow chart of the hot water subsystem 104. The hot water subsystem 104 includes a second heat exchanger 128, a condenser 126, and a first pump 130. In this embodiment, the first pump 130 is a centrifugal pump that receives a first fluid from the second heat exchanger 128 and pumps the first fluid to the condenser 126 and back to the second heat exchanger. However, in an alternative embodiment, the pump 130 can be any type of pump that enables the hot water subsystem 104 to operate as described herein. During operation, the first pump 130 pumps the first fluid through the condenser 126 and the second heat exchanger 128. The condenser 126 transfers heat from the refrigerant circulating within the refrigerant subsystem 102 to the first fluid. The second heat exchanger 128 transfers heat from the first fluid to the regeneration inlet air 116.

[0029] Figure 3This is a schematic flow diagram of the chilled water subsystem 106. The chilled water subsystem 106 includes a first heat exchanger 120, an evaporator 124, and a second pump 132. In this embodiment, the second pump 132 is a centrifugal pump that receives a first fluid from the first heat exchanger 120 and pumps the first fluid to the evaporator 124 and back to the first heat exchanger. However, in an alternative embodiment, pump 132 can be any type of pump that enables the hot water subsystem 104 to operate as described herein. During operation, the second pump 132 pumps the first fluid through the evaporator 124 and the first heat exchanger 120. The evaporator 124 transfers heat from the first fluid to the refrigerant circulating within the refrigerant subsystem 102. The first heat exchanger 120 transfers heat from the conditioned inlet air 112 to the first fluid.

[0030] Figure 4 This is a schematic flow chart of the refrigerant subsystem 102. The refrigerant subsystem 102 includes an evaporator 124, a condenser 126, a compressor 134, a first expansion valve 136, a second expansion valve 138, a first on / off valve 140, a second on / off valve 142, and a refrigerant-air heat exchanger 144. In this embodiment, the compressor 134 is a scroll compressor. In an alternative embodiment, the compressor 134 can be any type of compressor that enables the refrigeration subsystem 102 to operate as described herein. In this embodiment, the first on / off valve 140 and the second on / off valve 142 are solenoid valves, and the first expansion valve 136 and the second expansion valve 138 are thermal expansion valves. In an alternative embodiment, the first on / off valve 140 and the second on / off valve 142, as well as the first expansion valve 136 and the second expansion valve 138, can be any type of valve that enables the refrigerant subsystem 102 to operate as described herein.

[0031] The refrigerant subsystem 102 has three operating modes: Figure 5 The first operating mode shown in the figure is Figure 6 The diagram illustrates a second operating mode and a third operating mode (not shown). These three operating modes enable the refrigerant subsystem 102 to increase the heat transfer to and from the refrigerant according to the operating requirements of the HVAC system 100. The operating requirements of the HVAC system 100 are determined by the system's setpoint. Specifically, in this embodiment, the operating requirements of the HVAC system 100 are determined by the dry-bulb setpoint and the dew point setpoint of the conditioned outlet air 114. In alternative embodiments, other operating parameters may determine the operating requirements of the HVAC system 100. The dry-bulb setpoint and dew point setpoint of the conditioned outlet air 114 are typically set by the user.

[0032] In this embodiment, the dry-bulb temperature (sensible heat cooling) of the regulated outlet air 114 is determined by the temperature of the first fluid circulating through the cold water subsystem 106. The cooler first fluid transfers more heat from the regulated inlet air 112, thereby lowering the dry-bulb temperature of the regulated outlet air 114. Conversely, the warmer first fluid transfers less heat from the regulated inlet air 112, thereby increasing the dry-bulb temperature of the regulated outlet air 114. Furthermore, in this embodiment, the dew point (latent heat cooling) of the regulated outlet air 114 is determined by the temperature of the first fluid circulating through the hot water subsystem 104. The warmer first fluid ultimately transfers more moisture from the regulated inlet air 112, thereby lowering the dew point of the regulated outlet air 114. Conversely, the cooler first fluid transfers less moisture from the regulated inlet air 112, thereby increasing the dew point of the regulated outlet air 114.

[0033] However, in a typical HVAC system, the temperature of the first fluid in the chilled water subsystem 106 is related to the temperature of the first fluid in the hot water subsystem 104. For example, when the temperature of the first fluid in the chilled water subsystem 106 decreases, the temperature of the first fluid in the hot water subsystem 104 increases because a typical refrigeration subsystem increases the load on the compressor to achieve the lower temperature in the chilled water subsystem, and heat must be discharged to the hot water subsystem. Without additional heat dissipation and absorption capacity, the HVAC system 100 will not have sufficient operational freedom to adjust both the dry bulb setpoint and dew point setpoint of the outlet air 114.

[0034] For example, if the temperature of the first fluid in the hot water subsystem 104 causes the dew point of the regulating outlet air 114 to be at the setpoint, but the dry-bulb temperature of the regulating outlet air 114 is higher than the setpoint, the system will lower the temperature of the first fluid in the cold water subsystem 106 to reduce the dry-bulb temperature of the regulating outlet air 114 to the setpoint. However, as mentioned above, lowering the temperature of the first fluid in the cold water subsystem 106 will increase the temperature of the first fluid in the hot water subsystem 104. Without additional heat dissipation capacity, the HVAC system 100 will not be able to achieve both the dry-bulb setpoint and the dew point setpoint of the regulating outlet air 114.

[0035] The refrigerant subsystem 102 described herein includes a refrigerant-air heat exchanger 144, which operates as an additional condenser or evaporator to enable the HVAC system 100 to regulate both the dry-bulb setpoint and dew-point setpoint of the outlet air 114. Specifically, in a first operating mode, the refrigerant-air heat exchanger 144 functions as a condenser to additionally transfer heat from the refrigerant, and in a second operating mode, it functions as an evaporator to additionally transfer heat to the refrigerant. In other words, the refrigerant-air heat exchanger 144 enables the HVAC system 100 to increase its sensible heat cooling capacity in the first operating mode and its latent heat cooling capacity in the second operating mode. Furthermore, the inclusion of a dual-mode refrigerant-air heat exchanger 144 in the refrigerant subsystem 102 reduces the complexity of the hot water subsystem 104 and the chilled water subsystem 106, as a single refrigerant-air heat exchanger replaces multiple heat transfer operations typically included in the hot water and chilled water subsystems. Moreover, because the latent heat cooling capacity and sensible heat cooling capacity of the HVAC system 100 have been transferred from the hot water subsystem 104 and the chilled water subsystem 106 to the refrigerant subsystem 102, the overall latent heat cooling and sensible heat cooling requirements of this HVAC system are reduced compared to existing HVAC systems, making this HVAC system more efficient.

[0036] Furthermore, some operating conditions may require a specific ratio of sensible heat cooling to latent heat cooling. Specifically, if the HVAC system 100 needs to provide a specific ratio of sensible heat cooling to latent heat cooling, the temperatures of the first fluids in the hot water subsystem and the chilled water subsystem are adjusted to achieve this specific ratio. For example, if less sensible heat cooling is required for a fixed amount of latent heat cooling, the refrigerant-air heat exchanger 144 operates as an evaporator to raise the chilled water temperature, which in turn reduces the available sensible heat cooling for the regulating inlet air 112. However, if more sensible heat cooling is required for a fixed amount of latent heat cooling, the refrigerant-air heat exchanger 144 operates as a condenser to lower the hot water temperature, which in turn reduces the amount of latent heat cooling for the regulating inlet air 112.

[0037] In both the first and second operating modes, compressor 134 receives uncompressed vapor refrigerant 146 and 148 at a first pressure and compresses the uncompressed vapor refrigerant into compressed vapor refrigerant 150 and 152 at a second pressure higher than the first pressure. Condenser 126 receives a first portion 150 of the compressed vapor refrigerant 150 and 152 and condenses the first portion of the compressed vapor refrigerant into a first portion 154 of compressed liquid refrigerant 154 and 156. First expansion valve 136 and second expansion valve 138 receive the compressed liquid refrigerant 154 and 156 and expand the compressed liquid refrigerant into uncompressed liquid refrigerant 158 ​​and 160. Evaporator 124 receives the uncompressed liquid refrigerant 158 ​​and 160 and evaporates the uncompressed liquid refrigerant into uncompressed vapor refrigerant 146 and 148 at the first pressure. The first on / off valve 140 and the second on / off valve 142 enable the refrigerant subsystem 102 to be reconfigured between a first operating mode and a second operating mode.

[0038] Figure 5 This is a schematic flowchart of the refrigerant subsystem 102 in a first operating mode. In the first operating mode, the refrigerant-air heat exchanger 144 acts as a condenser to additionally transfer heat from the refrigerant, increasing the sensible heat cooling capacity relative to the fixed latent heat cooling capacity of the HVAC system 100. A first on / off valve 140 is open and a second on / off valve 142 is closed, thereby allowing a second portion 152 of compressed vapor refrigerant 150, 152 to flow to the refrigerant-air heat exchanger 144. The refrigerant-air heat exchanger 144 condenses the second portion 152 of compressed vapor refrigerant 150, 152 into a second portion 156 of compressed liquid refrigerant 154, 156. Specifically, the refrigerant-air heat exchanger 144 transfers heat from the second portion 152 of compressed vapor refrigerant 150, 152 to the flow of air 162, thereby condensing the second portion of compressed vapor refrigerant into a second portion 156 of compressed liquid refrigerant 154, 156. The refrigerant-air heat exchanger 144 is used as a second condenser within the refrigerant subsystem 102 in the first operating mode, thereby increasing the sensible heat cooling capacity for a fixed amount of latent heat cooling capacity of the HVAC system 100.

[0039] In the first operating mode, as described above, the condenser 126 also receives and condenses a first portion 150 of compressed vapor refrigerant 150, 152. A second portion 156 of compressed liquid refrigerant 154, 156 flows out from the refrigerant-air heat exchanger 144 to mix with the first portion 154 of compressed liquid refrigerant 154, 156. In the first operating mode, the second portion 156 of compressed liquid refrigerant 154, 156 bypasses the second expansion valve 138. Specifically, the refrigerant subsystem 102 also includes a check valve 155 that bypasses the second expansion valve 138 and guides the compressed liquid refrigerant 156 around the second expansion valve. The first expansion valve receives the mixed compressed liquid refrigerant 154, 156 and expands the compressed liquid refrigerant into a first portion 158 of uncompressed liquid refrigerant 158, 160. A first portion 158 of uncompressed liquid refrigerant 158 ​​and 160 flows to evaporator 124, whereby the evaporator evaporates the uncompressed liquid refrigerant into a first portion 146 of uncompressed vapor refrigerant 146 and 148 at a first pressure. Compressor 134 receives the first portion 146 of uncompressed vapor refrigerant 146 and 148 at the first pressure and compresses the uncompressed vapor refrigerant into compressed vapor refrigerant 150 and 152 at a second pressure higher than the first pressure.

[0040] Figure 6This is a schematic flowchart of the refrigerant subsystem 102 in a second operating mode. In the second operating mode, the refrigerant-air heat exchanger 144 is used as an evaporator to transfer additional heat to the refrigerant, reducing the sensible heat cooling capacity relative to the fixed amount of latent heat cooling capacity of the HVAC system 100. The first on / off valve 140 is closed and the second on / off valve 142 is open, thereby preventing the second portion 152 of the compressed vapor refrigerant 150, 152 from flowing to the refrigerant-air heat exchanger 144. Instead, all the refrigerant compressed by the compressor 134 flows to the condenser 126 as the first portion 150 of the compressed vapor refrigerant 150, 152. The condenser 126 condenses the first portion 150 of the compressed vapor refrigerant 150, 152 into the first portion 154 of the compressed liquid refrigerant 154, 156. The first portion 150 of the compressed vapor refrigerant 150, 152 is diverted, such that the first expansion valve 136 expands the first portion of the compressed liquid refrigerant into the first portion 158 of uncompressed liquid refrigerant 158 ​​and 160, and the second expansion valve 138 expands the first portion of the compressed liquid refrigerant into the second portion 160 of uncompressed liquid refrigerant 158 ​​and 160. The first expansion valve 136 controls the flow of the uncompressed liquid refrigerant 158 ​​and 160 into the first portion 158 of the evaporator 124, and the second expansion valve 138 controls the flow of the uncompressed liquid refrigerant 158 ​​and 160 into the second portion 160 of the refrigerant-air heat exchanger 144.

[0041] Refrigerant-air heat exchanger 144 receives a second portion 160 of uncompressed liquid refrigerant 158 ​​and 160 and transfers heat from air 162 to the second portion of the uncompressed liquid refrigerant, thereby evaporating the second portion of the uncompressed liquid refrigerant into a second portion 148 of uncompressed vapor refrigerant 146 and 148. In a second operating mode, refrigerant-air heat exchanger 144 functions as a second evaporator within refrigerant subsystem 102, thereby reducing the sensible heat cooling capacity relative to a fixed amount of latent heat cooling capacity of HVAC system 100. Furthermore, evaporator 124 receives a first portion 158 of uncompressed liquid refrigerant 158 ​​and 160 and transfers heat from air to the first portion of the uncompressed liquid refrigerant, thereby evaporating the second portion of the uncompressed liquid refrigerant into a first portion 146 of uncompressed vapor refrigerant 146 and 148. The first and second portions 146 and 148 of uncompressed vapor refrigerant 146 and 148 mix and flow to compressor 134.

[0042] When the refrigerant absorbs more heat from the chilled water subsystem 106 than it can be discharged to the regeneration inlet air 116, the first operating mode enables the refrigerant subsystem 102 to discharge heat to the atmosphere without deviating from the dew point setpoint of the regulated outlet air 114. Specifically, if too much heat is transferred from the regulated inlet air 112 to the chilled water subsystem 106, such that heat cannot be discharged to the regeneration inlet air 116 without deviating from the dew point setpoint of the regulated outlet air 114, the refrigerant-air heat exchanger 144 acts as an additional condenser to discharge the excess heat to the atmosphere. Conversely, when the temperature of the first fluid in the chilled water subsystem 104 is too cold and the temperature of the regulated outlet air 114 deviates from its dry-bulb setpoint, the second operating mode enables the refrigerant subsystem 102 to absorb heat from the atmosphere. Specifically, if the dew point of the regulated outlet air 114 is at the setpoint and the temperature of the first fluid in the chilled water subsystem 104 is too cold, causing the temperature of the regulated outlet air 114 to be below the dry-bulb setpoint, the refrigerant-air heat exchanger 144 acts as an additional evaporator to absorb additional heat from the atmosphere and increase the temperature of the first fluid and the regulated outlet air 114 without changing the dew point of the regulated outlet air. Therefore, the operating mode of the refrigerant-air heat exchanger 144 allows the HVAC system 100 to simultaneously regulate the regulated outlet air 114 to both the dry-bulb setpoint and the dew point setpoint. In other words, the operating mode of the refrigerant-air heat exchanger 144 provides additional degrees of freedom to allow the system to simultaneously achieve both the dry-bulb setpoint and the dew point setpoint in a single heat transfer unit.

[0043] In the third operating mode, the refrigerant-air heat exchanger 144 is bypassed, and the refrigerant subsystem 102 operates like a typical refrigerant subsystem. The refrigerant-air heat exchanger 144 is bypassed, and the refrigerant subsystem 102 operates like a typical refrigerant subsystem, achieving the dry-bulb setpoint and dew point setpoint without requiring additional heat dissipation or absorption.

[0044] Figure 7This is a flowchart of method 200 for transferring heat from a chilled water subsystem to a hot water subsystem of a heating, ventilation, and air conditioning (HVAC) system using a refrigerant subsystem. The refrigerant subsystem includes a compressor, a condenser, an evaporator, an expansion valve, and a refrigerant-air heat exchanger. Method 200 includes using the compressor to compress uncompressed vapor refrigerant at a first pressure 202 into compressed vapor refrigerant at a second pressure higher than the first pressure. Method 200 also includes using the condenser to condense the compressed vapor refrigerant at a condenser ... Method 200 further includes, in a first operating mode, using a condenser to condense a first portion of the compressed vapor refrigerant from vapor 210 into a liquid, and using a refrigerant-air heat exchanger to condense a second portion of the compressed vapor refrigerant from vapor 210 into a liquid and transfer heat from the second portion of the compressed vapor refrigerant to the air.

[0045] The described example HVAC system includes multiple subsystems for removing heat and moisture from the airflow. The HVAC system includes a refrigerant subsystem, a hot water subsystem, and a chilled water subsystem, which improve the efficiency of the HVAC system. The hot water and chilled water subsystems are closed systems without additional heat transfer capabilities. Conversely, the described refrigerant subsystem includes a refrigerant-air heat exchanger with multiple operating modes, which transfers heat to or absorbs heat from the environment depending on the operational needs of the HVAC system. The multiple operating modes of the refrigerant-air heat exchanger increase the operational flexibility of the refrigerant subsystem and the HVAC system, while reducing the operational complexity of the hot water and chilled water subsystems. Furthermore, because the refrigerant-air heat exchanger replaces multiple heat transfer devices within the hot water and chilled water subsystems, the capital cost of the HVAC system described herein is reduced compared to existing HVAC systems. Furthermore, because some of the heat transfer capacity of the HVAC system has been transferred from the hot water and chilled water subsystems to individual devices within the refrigerant subsystem, the overall heat transfer requirement of this HVAC system is reduced compared to existing HVAC systems, and it is also more efficient. Therefore, the HVAC system described in this paper is less complex, has lower capital costs, and is more efficient than existing HVAC systems.

[0046] The foregoing has described in detail exemplary embodiments of an HVAC system and methods for operating the system. The system and methods are not limited to the specific embodiments described herein; rather, components of the system and methods can be used independently and separately from other components described herein. For example, the system described herein can be used in systems other than HVAC systems.

[0047] When elements of this disclosure or embodiments thereof are introduced, the articles “a,” “an,” “the,” and “described” are intended to indicate the presence of one or more elements. The terms “comprising,” “including,” “containing,” and “having” are intended to be inclusive and mean that additional elements may be present in addition to the listed elements. The use of terms indicating a particular orientation (e.g., “top,” “bottom,” “side,” etc.) is for ease of description and not to require any particular orientation of the object being described.

[0048] Since various changes can be made to the above structures and methods without departing from the scope of this disclosure, it is intended that all content contained in the above description and shown in the accompanying drawings should be interpreted as illustrative rather than restrictive.

Claims

1. A heating, ventilation, and air conditioning (HVAC) system, the HVAC system comprising: A hot water subsystem is provided for circulating a first fluid between a first heat exchanger and a condenser, wherein the first heat exchanger transfers moisture and heat between a liquid desiccant and air, and transfers heat from the first fluid to the liquid desiccant and the air. A chilled water subsystem for circulating a second fluid between a second heat exchanger and an evaporator, wherein the second heat exchanger transfers moisture and heat between the liquid desiccant and the air, and transfers heat from the liquid desiccant and the air to the second fluid; and A refrigerant subsystem, wherein the refrigerant subsystem is used to transfer heat from the cold water subsystem to the hot water subsystem, the refrigerant subsystem comprising: A compressor that receives uncompressed vapor refrigerant at a first pressure, wherein the refrigerant exits the compressor as compressed vapor refrigerant at a second pressure higher than the first pressure; A condenser for condensing the compressed vapor refrigerant into a compressed liquid refrigerant and transferring heat from the compressed vapor refrigerant to the first fluid; At least one expansion valve, the at least one expansion valve being used to expand the compressed liquid refrigerant into an uncompressed liquid refrigerant; An evaporator for evaporating the uncompressed liquid refrigerant into the uncompressed vapor refrigerant at the first pressure and transferring heat from the second fluid to the uncompressed vapor refrigerant; A refrigerant-air heat exchanger having a first operating mode and a second operating mode, wherein, in the first operating mode, the condenser is adapted to condense a first portion of compressed vapor refrigerant from vapor into liquid, and the refrigerant-air heat exchanger is adapted to condense a second portion of compressed vapor refrigerant from vapor into liquid and transfer heat from the second portion of compressed vapor refrigerant to the air; and In the second operating mode, the evaporator is adapted to evaporate a first portion of the uncompressed liquid refrigerant from liquid into vapor, and the refrigerant-air heat exchanger is adapted to evaporate a second portion of the uncompressed liquid refrigerant from liquid into vapor and transfer heat from the air to the second portion of the uncompressed liquid refrigerant.

2. The HVAC system according to claim 1, wherein, The at least one expansion valve includes a first expansion valve, wherein the refrigerant subsystem further includes a second expansion valve, and wherein, in the first operating mode, the first expansion valve expands the compressed liquid refrigerant into the uncompressed liquid refrigerant.

3. The HVAC system according to claim 2 further includes a check valve, the check valve being configured to bypass the second expansion valve, and wherein, In the first operating mode, the check valve guides a first portion of the compressed liquid refrigerant to bypass the second expansion valve.

4. The HVAC system according to claim 2, wherein, In the second operating mode, the first expansion valve controls the entry of the uncompressed liquid refrigerant into the first part of the evaporator, and the second expansion valve controls the entry of the uncompressed liquid refrigerant into the second part of the refrigerant-air heat exchanger.

5. The HVAC system according to claim 2, further comprising a first on / off valve and a second on / off valve, wherein, In the first operating mode, the first on / off valve opens to direct the second portion of the compressed vapor refrigerant from the compressor to the refrigerant-air heat exchanger, and the second on / off valve closes.

6. The HVAC system according to claim 5, wherein, In the second operating mode, the second on / off valve opens to guide a second portion of the uncompressed vapor refrigerant from the refrigerant-air heat exchanger to the compressor, and the first on / off valve closes.

7. The HVAC system according to claim 5, wherein, The first on / off valve and the second on / off valve are solenoid valves.

8. The HVAC system according to claim 2, wherein, The first expansion valve and the second expansion valve are thermal expansion valves.

9. The HVAC system according to claim 1, wherein, The refrigerant-air heat exchanger is a refrigerant-air coil.

10. The HVAC system according to claim 1, wherein, The hot water subsystem includes the condenser, the first pump, and the first heat exchanger, wherein the first pump receives the flow of the first fluid from the first heat exchanger and pumps the flow of the first fluid to the condenser.

11. The HVAC system according to claim 10, wherein, The chilled water subsystem includes the evaporator, the second pump, and the second heat exchanger, wherein the second pump receives the flow of the second fluid from the second heat exchanger and pumps the flow of the second fluid to the evaporator.

12. The HVAC system according to claim 1, wherein, The first fluid and the second fluid are water.

13. A method for transferring heat from a chilled water subsystem of a heating, ventilation, and air conditioning (HVAC) system to a hot water subsystem of the HVAC system using a refrigerant subsystem, the hot water subsystem including a first heat exchanger, the chilled water subsystem including a second heat exchanger, and the refrigerant subsystem including a compressor, a condenser, an evaporator, an expansion valve, and a refrigerant-air heat exchanger, the method comprising: The flow of the first fluid is circulated between the first heat exchanger of the hot water subsystem and the condenser of the refrigerant subsystem; The first heat exchanger is used to transfer moisture and heat between the liquid desiccant and the air; The first heat exchanger is used to transfer heat from the first fluid circulating in the hot water subsystem to the liquid desiccant and air; The flow of the second fluid is circulated between the second heat exchanger of the cold water subsystem and the evaporator of the refrigerant subsystem; The second heat exchanger is used to transfer moisture and heat between the liquid desiccant and the air; The second heat exchanger is used to transfer heat from the liquid desiccant and the air to the second fluid circulating in the cold water subsystem; The compressor of the refrigerant subsystem compresses uncompressed vapor refrigerant at a first pressure into compressed vapor refrigerant at a second pressure higher than the first pressure. The condenser of the refrigerant subsystem condenses the compressed vapor refrigerant into a compressed liquid refrigerant and transfers heat from the compressed vapor refrigerant to the first fluid; The expansion valve of the refrigerant subsystem is used to expand the compressed liquid refrigerant into an uncompressed liquid refrigerant; The evaporator of the refrigerant subsystem evaporates the uncompressed liquid refrigerant into the uncompressed vapor refrigerant at the first pressure and transfers heat from the second fluid to the uncompressed vapor refrigerant; as well as In the first operating mode, the condenser is used to condense a first portion of the compressed vapor refrigerant from vapor into liquid, and the refrigerant-air heat exchanger of the refrigerant subsystem is used to condense a second portion of the compressed vapor refrigerant from vapor into liquid and transfer heat from the second portion of the compressed vapor refrigerant to the air; as well as In the second operating mode, the evaporator is used to evaporate a first portion of the uncompressed liquid refrigerant from liquid to vapor, and the refrigerant-air heat exchanger is used to evaporate a second portion of the uncompressed liquid refrigerant from liquid to vapor and transfer heat from the air to the second portion of the uncompressed liquid refrigerant.

14. The method according to claim 13, wherein, The expansion valve includes a first expansion valve, the refrigerant subsystem includes a second expansion valve, and the method further includes: in the first operating mode, using the first expansion valve to expand the compressed liquid refrigerant into the uncompressed liquid refrigerant.

15. The method of claim 14, further comprising: In the second operating mode, the first expansion valve is used to control the entry of the uncompressed liquid refrigerant into the first part of the evaporator, and the second expansion valve is used to control the entry of the uncompressed liquid refrigerant into the second part of the refrigerant-air heat exchanger.

16. The method of claim 14, wherein, The refrigerant subsystem further includes a check valve that bypasses the second expansion valve, and the method further includes: in the first operating mode, using the check valve to guide a first portion of the compressed liquid refrigerant to bypass the second expansion valve.

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