Cold Climate Heat Pump with Vapor Injection System

Abstract

Heat pump systems that include vapor injection feature are disclosed. Embodiments may include a heat pump system that has two tandem scroll compressors. Each compressor is paired with a control valve that regulates the flow of vapor to the respective compressor. Both the control valves are in fluid communication with a single or common source for vapor injection and to the controller. During operation, the controller dynamically determines how much vapor injection is needed for each of the compressors based on the operational data of the compressors and, optionally, ambient environment data. The controller then operates the two valves to ensure that the right amount of vapor is injected into each compressor.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefit of U.S. provisional patent application No. 63/647,806 filed May 15, 2024, which is herein incorporated by reference.

FIELD

This disclosure relates generally to cold climate heat pump systems. In particular, embodiments of the disclosure are related to rooftop cold climate heat pump systems with vapor injection.

BACKGROUND

Conventional rooftop heat pump systems can be used in rooftop environments for various air conditioning purposes. Such systems may include vapor injection to aid in compressor operation. However, an amount of vapor injection is typically not controlled when the system has more than one compressor, resulting in inaccurate or uncontrolled amounts of vapor injection provided to the compressor, which results in suboptimal operation of such rooftop systems.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanying drawings. In some instances, the use of the same reference numerals may indicate similar or identical items. Various embodiments may utilize elements and/or components other than those illustrated in the drawings, and some elements and/or components may not be present in various embodiments. Throughout this disclosure, depending on the context, singular and plural terminology may be used interchangeably.

FIG. 1 illustrates a block diagram of a cold climate heat pump system with vapor injection according to an embodiment of the present disclosure.

FIG. 2 illustrates a block diagram of a cold climate heat pump system with vapor injection according to another embodiment of the present disclosure.

FIG. 3. Illustrates a block diagram of a cold climate heat pump system with vapor injection according to yet another embodiment of the present disclosure.

FIG. 4 illustrates a block diagram of a cold climate heat pump system with vapor injection according to an additional embodiment of the present disclosure.

FIG. 5 illustrates a block diagram of a vapor injection control system according to yet another embodiment of the present disclosure.

FIG. 6 illustrates operational mode examples for a heat pump system according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

This disclosure relates generally to cold climate heat pump systems that employ multiple compressors. In particular, embodiments of the present disclosure relate to tandem compressor rooftop cold climate heat pump systems that have vapor injection.

FIG. 1 illustrates a block diagram of a heat pump system 100 with vapor injection according to an embodiment of the present disclosure. Heat pump system 100 includes a first compressor 102 and a second compressor 104. In some embodiments, more than two compressors may be present. Merely for ease of description, the figures illustrate two compressors. In some embodiments, the first compressor 102 and the second compressor 104 may be tandemly operated scroll compressors. Heat pump system 100 may use a fluid (e.g., refrigerants like water, R134A, R454B, R32, Hydrocarbons, Hydrocarbon blends, R717, CO2 R744, R-22, R410A, R600 series, hydrofluoroolefins (HFOs) and HFO blends, and the like) for its operation. The first compressor 102 and the second compressor 104 may have a common input port 136 (e.g., input port manifold) and a common output port 138 (e.g., outlet port manifold). The common input port 136 serves as an input port through which the fluid enters both the first compressor 102 and the second compressor 104. The common output port 138 servers as the output port through which the fluid exits both the first compressor 102 and the second compressor 104. The first compressor 102 has a first vapor injection port 142 and the second compressor 104 has a second vapor injection port 140.

It is be noted that throughout the disclosure, ports described as being in “fluid communication” with each other have one or more refrigerant lines or other appropriate means of fluid communication that facilitate flow of a fluid between these ports. The system 100 includes a reversing valve 106 that is in fluid communication with the common input port 136 and the common output port 138. Reversing valve 106 may be any commonly known reversing valve in the art. The reversing valve 106 changes the direction of refrigerant flow in the system 100 depending on the mode of operation of the system 100. By reversing the flow of refrigerant, the heat pump cycle is changed from cooling to heating or vice versa. The reversing valve 106 may have four ports. A first port 106a of the reversing valve 106 is in fluid communication with the common input port 136 of the first compressor 102 and the second compressor 104. A second port 106b of the reversing valve 106 is in fluid communication with a first port 130a of a first heat exchanger 130. The first port 130a of the first heat exchanger 130 is in fluid communication with the second port 106b of reversing valve 106. A third port 106c of reversing valve 106 is in fluid communication with a first port 108a of a charge compensator 108. The charge compensator 108 increases system efficiency by storing extra refrigerant in the heating mode. The charge compensator 108 returns refrigerant back into circulation in the cooling mode. The fourth port 106d of the reversing valve 106 is in fluid communication with the common output port 138 of the first compressor 102 and the second compressor 104. As is known in the art, reversing valves can be operated in multiple modes in which flow of fluid can be controlled and directed based on the operational requirements of heat pump system 100 (e.g., heating mode and cooling mode).

A second port 108b of the charge compensator 108 is in fluid communication with a first port 110a of a second heat exchanger 110. In some embodiments, the second heat exchanger 110 can be an outdoor heat exchanger that is located external to the premises being served by heat pump system 100 or otherwise is in thermal communication (e.g., via one or more air ducts) with the outdoor ambient environment. The second heat exchanger 110 can act as a condenser or an evaporator depending on the mode of operation of heat pump system 100. A third port 108c of the charge compensator 108 is in fluid communication with a second port 130b of the first heat exchanger 130 at a point 144 between a second expansion valve 126 and the second port 130b. Charge compensator 108 can be any device of its type known in the art. In various implementations, the charge compensator 108 may be omitted.

A second port 110b of the second heat exchanger 110 is in fluid communication with a first expansion valve 112. The first expansion valve 112 may be realized using known devices in the art. The first expansion valve 112 removes pressure from the fluid and allows expansion or change of state of the fluid. In some embodiments, a first check valve 114 may be positioned in parallel to the first expansion valve 112 to provide a bypass path for the fluid in heat pump system 100. The check valve 114 prevents fluid flowing from a filter drier 116 to the second heat exchanger 110 and helps to direct the fluid from the filter drier 116 to the first expansion valve 112 during the heating operation mode. In other embodiments, the first check valve 114 may be integrated into the first expansion valve 112.

The expansion valve 112 is in fluid communication with a first port 116a of the filter drier 116. The filter drier 116 is a filtration device that is designed to remove contaminants, including moisture, from the fluid. Filter drier 116 may be realized using any known device in the art. A second port 116b of the filter drier 116 is in fluid communication with a first port 118a of a third heat exchanger 118.

In one embodiment, the third heat exchanger 118 (or any other heat exchanger described herein) may be a brazed plate heat exchanger. As a brazed plate heat exchanger, the third heat exchanger 118 may be configured for exchanging heat between water and refrigerant for heating water as a part of a water heating system. In another embodiment, the third heat exchanger 118 may be realized by using a flash tank, a shell and tube heat exchanger, tube-in-tube heat exchanger, or any other suitable heat exchanger. One skilled in the art will realize that other types of heat exchangers that serve a similar purpose may also be used. The specific type of heat exchanger used is not germane to the disclosure. For ease of explanation of the various embodiment of the present disclosure, a brazed plate heat exchanger is used herein.

The third heat exchanger 118 has four ports. The first port 118a of the third heat exchanger 118 is in fluid communication with the second port 116b of the filter drier 116 and in fluid communication with a second solenoid valve 124. A fourth port 118d of the third heat exchanger 118 is in fluid communication with a first solenoid valve 122 and in fluid communication with the second expansion valve 126. A second port 118b of the third heat exchanger 118 is in fluid communication with a third expansion valve 120. A third port 118c of the third heat exchanger 118 is in fluid communication with a first control valve 132 and a second control valve 134. The first solenoid valve 122 is in fluid communication with the fourth port 118d of the third heat exchanger 118. The first solenoid valve 122 is also in fluid communication with the third expansion valve 120. The second solenoid valve 124 is in fluid communication with the first port 118a of the third heat exchanger 118. The second solenoid valve 124 and the first solenoid valve 122 are in fluid communication with the same port of the third expansion valve 120. In other words, the third expansion valve 120 is fluid communication with both the first solenoid valve 122 and the second solenoid valve 124, as is clearly shown in FIG. 1.

In one embodiment, the third heat exchanger 118, the first solenoid valve 122 and the second solenoid valve 124 and third expansion valve 120 together define an economizer 165. The economizer 165 allows efficient exchange of thermal energy between two fluids passing through the third heat exchanger 118. In some implementations, the economizer 165 may be replaced with a flash tank or other structure for providing a supply of vapor to one or more vapor injection ports of one or more compressors. The two fluids may either flow in the same direction within the third heat exchanger 118 as shown in FIG. 1 or the two fluids may flow in opposite directions (counter flow) within the third heat exchanger 118 as shown in FIG. 2. The first solenoid valve 122, the second solenoid valve 124, and the third expansion valve 120 form a vapor injection circuit. In the embodiment shown in FIG. 1, the first solenoid valve 122 and the second solenoid valve 124 are shown as solenoid valves, though any other suitable shut-off valve may be used, such as needle valves, ball valves, gate valves, or the like.

The second expansion valve 126 is in fluid communication with the fourth port 118d of the third heat exchanger 118. The second expansion valve 126 is also in fluid communication with the second port 130b of the first heat exchanger 130. In some embodiments, the first heat exchanger 130 may be located indoor in the premises being served by heat pump system 100 or otherwise is in thermal communication (e.g., via one or more air ducts) with the indoor ambient environment.

In some embodiments, a second check valve 128 may be disposed in parallel to the second expansion valve 126. In other embodiments, the second check valve 128 may be integrated into the second expansion valve 126.

Each of the first control valve 132 and the second control valve 134 are in fluid communication with the third port 118c of the third heat exchanger 118 for receiving vapor from the economizer 165, a flash tank, or other such structure. The first control valve 132 is in fluid communication with the first vapor injection port 142 of the first compressor 102 and the second control valve 134 is fluid communication with the second vapor injection port 140 of the second compressor 104. The first control valve 132 and the second control valve 134 may be specialized valves that allow for precise control of an amount of vapor that is to be injected in each of the first compressor 102 and the second compressor 104. In some embodiments, a special control loop may be implemented in order to control the amount of vapor injected into the first compressor 102 and the second compressor 104. Details of the structure and operation of such a control system are provided below with references to FIGS. 5 and 6.

FIG. 1 illustrates operation of heat pump system in a first mode of operation (e.g., heating mode). Specifically, FIG. 1 illustrates a heating mode of operation. In this mode, hot and compressed vapor of a fluid (e.g., refrigerants like R454B, R32, water, R134A, Hydrocarbons, R717, CO2 R744, R-22, R410A, R600 series, and the like) is output by the first compressor 102 and the second compressor 104. Reversing valve 106 is placed in one of its states in which it receives the fluid output from the compressors and directs the fluid to the first port 130a of the first heat exchanger 130 (e.g., a condenser in the first mode of operation) via the second port 106b. In the first heat exchanger 130, the fluid transfer its heat to another fluid, such as, air, that may be circulated by a blower unit (not shown) that is coupled to the first heat exchanger 130 for circulating heated air within a premises. The fluid then travels via the second check valve 128 towards the third heat exchanger 118. Before the fluid reaches the third heat exchanger 118, the fluid is split into two portions. A first portion of the fluid travels via the first solenoid valve 122, which is open in this mode. The second solenoid valve 124 is closed in this mode, so the first portion of the fluid cannot travel via the second solenoid valve 124. The second portion of the fluid enters the third heat exchanger 118, via the fourth port 118d and along the primary refrigerant flow path 166.

The first portion of the fluid that travels via the first solenoid valve 122 and passes through the third expansion valve 120. Here the first portion of the fluid expands and cools down to generate a two-phase fluid of liquid and vapor refrigerant. The first portion of the fluid then exits the third expansion valve 120 and enters the third heat exchanger 118 via the second port 118b and along the vapor injection path 167. Within the third heat exchanger 118, the first portion of the fluid is heated by the second portion of the fluid into vapor and that vapor is then output from the third heat exchanger 118 via the third port 118c. The vapor is then directed towards the first vapor injection port 142 of the first compressor 102 and/or the second vapor injection port 140 of the second compressor 104 via the first control valve 132 or the second control valve 134, respectively. As is common knowledge in the art, vapor injection is used to cool down the compressor so that the compressor can function efficiently in cold ambient temperatures without overheating, such as below 30° F.

As can be seen in FIG. 1, the primary refrigerant flow path 166 and the vapor injection flow path 167 are in counter-flow directions. In other words, the primary refrigerant flow path 166 and the vapor injection flow path are in opposite directions to each other within the third heat exchanger 118.

The second portion of the fluid travels via the third heat exchanger 118 along the primary refrigerant flow path 166 and exits the third heat exchanger 118 via the first port 118a. The second portion of the fluid is then directed to the second port 116b of the filter drier 116. The second portion of the fluid exits the filter drier 116 via the first port 116a and passes via the first expansion valve 112 to the second port 110b of the second heat exchanger 110. The first check valve 114 is configured such that it prevents flow of the second portion of the fluid through it.

At the second heat exchanger 110, the second portion of the fluid is heated or boiled, such as, by blowing warm outdoor air over the second heat exchanger 110 using a fan (not shown). The second portion of the fluid leaves the second heat exchanger 110 via the first port 110a as a slightly super-heated vapor. Superheating occurs when the temperature of the vapor rises above the boiling point of the corresponding liquid. Thus, in this instance, the vapor of the fluid is heated above its boiling point. This vapor passes through the charge compensator 108 and enters the reversing valve 106 via the third port 106c. The reversing valve directs the slightly super-heated vapor, via the first port 106a, to the common input port 136 of the first compressor 102 and the second compressor 104.

The slightly super-heated vapor that is used for vapor injection is directed from the third heat exchanger 118 via the third port 118c toward the first control valve 132 and the second control valve 134. Depending on the operational data of the first compressor 102 and the second compressor 104, the first control valve 132, the second control valve 134, or both are operated to allow a precise amount of vapor to be injected into each of the first compressor 102 or the second compressor 104. The operational data may include one or more of discharge temperature, injection pressure, or the compressor speed. The first control valve 132 and the second control valve 134 may be specialized control valves that allow precise control of amount of vapor that is injected into each of the first compressor 102 and the second compressor 104. In some embodiments, the first control valve 132 and the second control valve 134 may be vapor mass flow controllers. The first control valve 132 and the second control valve 134 may be operated in the range of between 0-100%, wherein 0% may indicate that the valve is fully closed and 100% may indicate that the valve is fully open. In some embodiments, the first control valve 132 and the second control valve 134 may be controllable in 1% increments to allow precise control of vapor flow through the valves. In other embodiments an even finer or coarser control of the valves may be possible. The choice of a particular type of control valve may depend on the nature and operation of heat pump system 100.

In some implementations, the heat pump system 100 may be for a water heating system. In such implementations, the reversing valve may be omitted, the system may operate in the heating mode, and the first heat exchanger acts as a condenser and is a refrigerant-to-water heat exchanger. The refrigerant-to-water heat exchanger may be a wrapped condenser heat exchanger (e.g., condenser tubing wrapped around a water storage tank), a brazed plate heat exchanger with a water circuit and a refrigerant circuit, a shell and tube heat exchanger, or any other suitable refrigerant-to-water heat exchanger. Please expand on this as needed. This is also applicable to any other heat pump system described herein.

FIG. 2 illustrates structure and operation of heat pump system 100 in a second mode of operation according to an embodiment of the present disclosure. In particular, FIG. 2 illustrates operation of heat pump system 100 in a cooling mode. In this mode, the premises being served by heat pump system is to be cooled and the outside ambient air temperature is warmer than inside the premises.

In this mode, the first compressor 102, or the second compressor 104, or both output compressed and vaporized fluid (e.g., refrigerants like R454B, R32, water, R134A, Hydrocarbons, R717, CO2 R744, R-22, R410A, R600 series, and the like) to the reversing valve 106. Reversing valve 106 receives this fluid via the fourth port 106d. Reversing valve 106 is placed in a state in which it directs the vaporized fluid to charge compensator 108 via its third port 106c. Charge compensator 108 receives the fluid at the first port 108a and outputs the fluid from the second port 108b. From there the fluid flows through to the second heat exchanger 110. The second heat exchanger 110 receives the fluid via the first port 110a and outputs the fluid via the second port 110b. In some embodiments, the second heat exchanger 110 can be located externally to the premises being served or otherwise is in thermal communication (e.g., via one or more air ducts) with the outdoor ambient environment. After exiting the second heat exchanger 110, the fluid passes through the first check valve 114. In some embodiments, the first check valve 114 can be integrated with the first expansion valve 112. The fluid exits the first check valve 114 and enters the filter drier 116 via the first port 116a. The fluid exits the filter drier 116 via the second port 116b and flows towards the third heat exchanger 118. Prior to entering the third heat exchanger 118, the fluid is split into two portions. A first portion of the fluid enters the third heat exchanger 118 via the first port 118a and the second portion of the fluid is directed towards the third expansion valve 120 via the second solenoid valve 124. In this mode, the second solenoid valve 124 is open while the first solenoid valve 122 is closed. This prevents the second portion of the fluid from flowing via the first solenoid valve 122 towards the third heat exchanger 118.

The second portion of the fluid leaves the third expansion valve 120 and enters the third heat exchanger 118 via the second port 118b. The second portion of the fluid then leaves the third heat exchanger 118 via the third port 118c in the form of a slightly super-heated vapor. This vapor is then used for vapor injection into the first compressor 102, or the second compressor 104, or both the compressors.

The first portion of the fluid passes through the third heat exchanger 118 and exits the third heat exchanger 118 via the fourth port 118d. The first portion of the fluid the flows towards the second expansion valve 126. Since the first solenoid valve 122 is closed, it prevents the first portion of the fluid from flowing towards the third expansion valve 120.

As can be seen in FIG. 2, the first portion of the fluid travels along the primary refrigerant flow path 166 and the second portion of the fluid travels along the vapor injection path 167. Within the third heat exchanger 118, the first and the second portions of the fluid travel in the same direction (e.g., flow paths 166 and 167 are in the same direction) as is shown by the arrows associated with the third heat exchanger 118.

The first portion the fluid passes through the second expansion valve 126 and enters the first heat exchanger 130 via the second port 130b. In some embodiments, the first heat exchanger 130 may be located inside the premises being cooled or otherwise is in thermal communication (e.g., via one or more air ducts) with the indoor ambient environment. In the first heat exchanger 130, the first portion of the fluid absorbs heat from the warm air from inside the premises and cools that air and in the process becomes slightly super-heated. The air may be blown over the first heat exchanger 130 using a blower unit (not shown) coupled to the first heat exchanger 130.

The slightly super-heated vaporized fluid exits from the first heat exchanger 130 via the first port 130a and is directed towards the reversing valve 106. The second portion of the fluid (e.g., the slightly super-heated vaporized fluid) enters reversing valve 106 via the second port 106b and exits the reversing valve via the first port 106a. The second portion of the fluid is then directed to the common input port 136 of the first compressor 102 and the second compressor 104. The first compressor 102 and the second compressor 104 then pressurize the vaporized fluid and the cycle repeats again until the cooling mode is active.

The slightly super-heated vapor generated using the second portion of the fluid exits the third heat exchanger 118 via the third port 118c and is directed towards the first control valve 132 and the second control valve 134. The rest of the operation of the system for vapor injection is similar to what is described above with reference to FIG. 1.

FIG. 3 illustrates a heat pump system 200 according to another embodiment of the present disclosure. The difference between heat pump system 200 and heat pump system 100 of FIG. 1 is the addition of an accumulator 144 and removal of the first solenoid valve 122 and the second solenoid valve 124. Accumulator 144 is disposed between reversing valve 106 and the common input port 136. Accumulator 144 traps any fluid in a liquid form and oil and prevents any liquid or oil from entering the first compressor 102 and the second compressor 104 via the common input port 136. FIG. 3 illustrates a heating mode of operation of heat pump system 300. The functioning of heat pump system 300 in the heating mode is similar to what is described above with reference to FIG. 1, the difference being that after the portion of the fluid exits the first port 106a of the reversing valve 160, it enters the accumulator 144 via port 144a. The fluid then exits the accumulator 144 via port 144b and is then directed to the common input port 136 of the first compressor 102 and the second compressor 104. Accumulator 144 traps any oil or fluid in a liquid form and prevents any liquid from entering the first compressor 102 and the second compressor 104.

Similar to FIG. 1, in the embodiment illustrated in FIG. 3, the primary refrigerant flow path 166 and the vapor injection flow path 167 are in counter-flow directions. In other words, the primary refrigerant flow path 166 and the vapor injection flow path are in opposite directions to each other within the third heat exchanger 118.

FIG. 4 illustrates a heat pump system 200 according to another embodiment of the present disclosure. The difference between heat pump system 200 and heat pump system 100 of FIG. 2 is the addition of an accumulator 144 and removal of the first solenoid valve 122 and the second solenoid valve 124. Accumulator 144 is disposed between reversing valve 106 and common input port 136. Accumulator 144 traps any fluid in a liquid form and oil and prevents any liquid or oil from entering the first compressor 102 and the second compressor 104 via the common input port 136. FIG. 4 illustrates a cooling mode of operation of heat pump system 200. The functioning of heat pump system 200 in the cooling mode is similar to what is described above with reference to FIG. 2, the difference being that after the portion of the exits the first port 106a of the reversing valve 106, the portion of the fluid enters the accumulator 144 via port 144a. The portion of the fluid then exits accumulator 144 via portion 144b and is then directed towards the common input port 136 of the first compressor 102 and the second compressor 104. Accumulator 144 traps any oil or fluid in a liquid form and prevents any liquid from entering the first compressor 102 and the second compressor 104.

Similar to the embodiment illustrated in FIG. 2, in the embodiment of FIG. 4, the primary refrigerant flow path 166 and the vapor injection flow path 167 are in the same direction. In other words, the primary refrigerant flow path 166 and the vapor injection flow path are in a same direction within the third heat exchanger 118.

FIG. 5 illustrates a functional block diagram for a vapor injection control system 500 according to an embodiment of the present disclosure. Vapor injection control system 500 includes a controller 502. Controller 502 can be realized using various techniques or devices. In an embodiment, the controller 502 may be a central processing unit (CPU) specially programmed to carry out the below disclosed functions. In other embodiments, controller 502 may be an application specific integrated circuit (ASIC), or a microcontroller, or the like.

Controller 502 is communicatively coupled to compressors 510 and 512. Compressor 510 may be akin to the first compressor 102 and the compressor 512 may be akin to the second compressor 104 illustrated in FIG. 1. Controller 502 is also communicatively coupled to control valves 506 and 508. Control valve 506 is in fluid communication with the compressor 510 and the control valve 508 is in fluid communication with the compressor 512. Although two compressors are shown in FIG. 5, one skilled in the art will realize that the embodiments described in this specification are equally applicable to systems with more than two compressors and correspondingly more than two control valves.

A vapor injection source 504 is in fluid communication with both the control valves 506 and 508. Vapor injection source 504 may be any suitable source that can provide the requisite amount of vapor at a desired temperature. In an embodiment, vapor injection source 504 can be the economizer 165 described in FIG. 1, a flash tank, or other suitable structure for supplying vapor for vapor injection.

During operation of heat pump system 500, controller 502 continually monitors the operational data of the compressors 510 and 512 and ambient environment data. Based on the operational data, or the ambient environment data, or both, the controller 502 may control valves 506 and 508 to open or close to the desired level to allow the right amount of vapor to be injected into compressor 510 and 512, respectively. The control valves 506 and 508 allow precise control of the amount of vapor that is allowed to go to the compressors. For example, control valves 506 and 508 may be realized using the appropriate mass flow controllers for the fluid being used. Operational data of compressors 510 and 512 may include, but is not limited to, capacity of the compressors, compressor speed (e.g., measured in revolutions per minute (RPM)), suction temperature, suction pressure, discharge pressure, discharge temperature, compressor operating envelope, and the like. Ambient environment data may include but is not limited to outside air temperature, inside air temperature, elevation, barometric pressure, and the like.

FIG. 6 is a table 600 that illustrates the various operational modes associated with, for example, the vapor injection system 100 of FIG. 1 according to an embodiment of the present disclosure. It is to be noted that the details of operational parameters shown in table 600 are for illustrative purposes only and one skilled in the art will realize that more, or less, or different operational parameters than the ones shown in table 600 can be used to control the control valves 506 and 508 of FIG. 5. The following description of the operation of vapor injection system 500 will be explained using both FIG. 5 and FIG. 6. In order to explain the operation of control valves 506 and 508 a scale of 0%-100% is used to illustrate how open or close each of valve is. This also illustrates the precise nature of control of these valves.

In table 600, there are multiple modes of operation 602 shown. For sake of brevity and for illustration purposes only, five modes of operation are shown. However, one skilled in the art will realize that there can be less or more number of operation modes possible based on the number of operational parameters used. Column 604 illustrates some of the operational parameters of compressor 510. Column 606 illustrates some of the operational parameters of compressor 512. Column 608 illustrates the status of control valve 506 that is coupled to compressor 510. Column 610 illustrates the status of control valve 508 that is coupled to compressor 512.

Operation 1 is the first mode of operation of the system 100. In this mode, controller 502 is configured to determine or determines whether any of the two compressors 510 or 512 is OFF, such as, not working or idle. As shown in table 600, compressor 1 (510) is ON, such as, operating or running currently, and compressor 2 (512) is OFF, such as, not operating or running currently. In this instance, controller 502 sends a first signal to control valve 506 to open. ‘Open’ in this instance may be fully open (e.g., 100%) or open partially (e.g., anywhere between 0% and 100% open). Controller 502 sends a second signal to control valve 508 to close fully (e.g., 0%). In some instances, valve 508 may not close fully, but the amount of vapor passing through valve 508 may be negligible or about 0. In an embodiment, the amount of vapor may be measured in vapor volume. In an embodiment, the vapor volume may be designated in liters. Since compressor 512 is not operational, it does not need vapor injection and hence no vapor is provided to compressor 512. It is to be noted that “ON” and “OFF” in this is instance refers to the current operational status of the individual compressor. A compressor may be powered and generally functional while being “OFF” or not operating currently.

Operation 2 illustrates a second mode of operation where both compressors 510 and 512 are operational currently (e.g., running/operating). In this mode, controller 502 is configured to determine or determines based on operational data received from the compressors or other sources, that both compressors 510 and 512 are of the same capacity or substantially same capacity (e.g., 5 Tons each) and that currently they are running at a same speed. All other things being equal, controller 502 determines that both compressors are to be supplied with an equal amount of vapor. Controller 502 then sends individual signals to both control valves 506 and 508 such that they each allow substantially equal amount of vapor, from the available total vapor volume, to be directed to the respective compressor coupled to valves 506 and 508. For example, if the total amount of available vapor is 10 liters, then that may be substantially equally split between the two compressors 510 and 512 by opening both control valves 506 and 508 by approximately 50%.

Operation 3 illustrates a third mode of operation where both compressors 510 and 512 are operational currently (e.g., running/operating). In this mode, controller 502 is configured to determine or receives the operational data of the compressors and determines that compressor 1 is bigger in capacity compared to compressor 2. Since compressor 1 is bigger in capacity, it may need more vapor volume compared to compressor 2. Based on this information, and optionally additional operational parameters of the two compressors, controller 502 determines that the amount of vapor to be provided to compressor 1 is greater than the amount of vapor to be provided to compressor 2. In some embodiments, controller 502 may determine the exact amount of vapor to be supplied to each of the compressors. In other embodiments, the ratio of the relative capacities of the two compressors may be used to determine the amount of vapor to be supplied to each compressor. Controller 502 then sends the appropriate signals to the two valves 506 and 508 to open such that the determined amount of vapor is provided to each of the respective compressors. For example, consider that compressor 510 has a capacity of 6 ton and compressor 512 has a capacity of 4 ton. In this instance, the ratio associated with compressor 510 will be 0.6 (6/(6+4)) and the ratio associated with compressor 512 will be 0.4 (4/(6+4)). Based on these ratios, control valve 506 may be opened to 60% and control valve 508 may be opened to 40%. This will allow the appropriate amount of vapor to be supplied to each of the compressor 510 and compressor 512.

Operation 4 illustrates a fourth mode of operation where both compressors 510 and 512 are ‘ON’. Controller 502 determines based on the operational data that both compressors are of the same capacity or substantially of the same capacity, but they are running at diff speeds. In this instance, controller 502 may operate control valves 506 and 508 such that the compressor running at a higher speed is provided with a greater amount of vapor than the compressor that is running at a lower speed. This is because the compressor running at a higher speed is likely to have higher temperature and as a result needs more cooling vapor than the compressor that is running slower. In some instances, the relative ratios of the speeds of the compressors 510 and 512 may be used to determine the amount of vapor injection to be provided to each of the compressor 510 and compressor 512. For example, consider that compressor 510 is running at 2000 RPM and compressor 512 is running at 4000 RPM. In this instance, the speed ratio associated with compressor 510 will be 0.33 (2000/(2000+4000)) and the speed ratio associated with compressor 512 is 0.66 (4000/(2000+4000)). Based on these ratios, the control valve 506 may be opened to 33% and control valve 508 may be opened to 66%. This will allow the appropriate amount of vapor to be supplied to each of the compressor 510 and compressor 512.

Operation 5 illustrates a fifth mode of operation where both compressors 510 and 512 are operational currently (e.g., running or operating). In this mode, controller 502 receives the operational data of the compressors 510 and 512 and determines that both compressors 510 and 512 are of different capacity (e.g., compressor 1 is bigger than compressor 2 or vice versa) and that both compressors are running at a different speeds (e.g., compressor 1 may be running faster than compressor 2 or vice versa). In this instance, controller 502 again determines the amount of vapor to be provided to each of the compressors based on their individual capacity and current operating speed and accordingly instructs each of control valves 506 and 508 to open proportionally to allow the determined amount of vapor to be provided to each of the compressors. In one embodiment, the compressor having the higher capacity may get more vapor injection regardless of the speed at which the compressors are operating. In another embodiment, the compressor running at the higher speed may get more vapor injection regardless of the capacity of the two compressors. One skilled in the art will realize that the amount of vapor injected into each of the compressors can be determined using other combinations of capacity and speed. In one embodiment, an effective capacity of each compressor may be determined and the control valves may be operated based on the relative ratios of the effective capacity of each of the compressors. For example, consider that compressor 510 has a capacity of 5 tons and is running at 80% of its maximum speed and compressor 512 has a capacity of 10 tons and is running at 50% of its maximum speed. In this instance the effective capacity of compressor 510 is 4 ton (5T*0.8) and the effective capacity of compressor 512 is 5 ton (10*0.5). The relative ratio of the effective capacity of compressor 510 will be 0.45 (4/(4+5)) and the relative ratio of the effective capacity of compressor 512 will be 0.55 (5/(4+5)). Based on these ratios, control valve 506 may be opened to 45% and control valve 508 may be opened to 55% to provide the appropriate amount of vapor injection to each of the compressors 510 and 512 respectively.

As used above, the term “substantially” is meant to convey that the capacity and the speeds of the two compressors are within 5%-10% of each other.

Although an air-based heat pump system is described above, it is for illustration purposes only. The vapor injection system described in this specification can be used in other application as well. For example, the above described techniques can also be used in split system, water cool system, a heat pump water heater (HPWH) system or in refrigeration systems. As such, any of the heat exchangers described herein may be a brazed plate heat exchanger configured for exchanging heat between water and refrigerant for heating the water.

It should be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. References to a composition containing “a” constituent is intended to include other constituents in addition to the one named.

Also, in describing the disclosed technology, terminology will be resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

Ranges may be expressed herein as from “about” or “approximately” or “substantially” one particular value and/or to “about” or “approximately” or substantially” another particular value. When such a range is expressed, the disclosed technology can include from the one particular value and/or to the other particular value. Further, ranges described as being between a first value and a second value are inclusive of the first and second values. Likewise, ranges described as being from a first value and to a second value are inclusive of the first and second values.

Herein, the use of terms such as “having,” “has,” “including,” or “includes” are open-ended and are intended to have the same meaning as terms such as “comprising” or “comprises” and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as “can” or “may” are intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.

It is also to be understood that the mention of one or more method steps does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Moreover, although the term “step” can be used herein to connote different aspects of methods employed, the term should not be interpreted as implying any particular order among or between various steps herein disclosed unless and except when the order of individual steps is explicitly required. Further, the disclosed technology does not necessarily require all steps included in the methods and processes described herein. That is, the disclosed technology includes methods that omit one or more steps expressly discussed with respect to the methods described herein.

It should be apparent that the foregoing relates only to certain embodiments of the present disclosure and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the disclosure.

Although specific embodiments of the disclosure have been described, numerous other modifications and alternative embodiments are within the scope of the disclosure. For example, any of the functionality described with respect to a particular device or component may be performed by another device or component. Further, while specific device characteristics have been described, embodiments of the disclosure may relate to numerous other device characteristics. Further, although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the embodiments. Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments could include, while other embodiments may not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments.

Claims

1. A heat pump system comprising:

a vapor injection source coupled to a first control valve and a second control valve;

a first vapor injection port of a first compressor coupled to the first control valve;

a second vapor injection port of a second compressor coupled to the second control valve; and

a controller coupled to the first and the second control valves and the first and second compressors,

wherein the controller is operable to: determine first operational data of the first compressor; determine second operational data of the second compressor; operate, using the controller and based on the first operational data, the first control valve to deliver a first amount of vapor to the first compressor; and operate, using the controller and based on the second operational data, the second control valve to deliver a second amount of vapor to the first compressor.

2. The heat pump system of claim 1 wherein the first amount of vapor is substantially the same as the second amount of vapor.

3. The heat pump system of claim 1, wherein the controller is further operable to:

determine, at a first time, that first operational data indicates that the first compressor is ON and the second operational data indicates that the second compressor is OFF;

open, at least partially, the first control valve to allow the vapor from the vapor injection source to flow to the first compressor; and

close the second control valve.

4. The heat pump system of claim 1, wherein the first compressor has a first capacity and the second compressor has a second capacity and the first capacity is substantially same as the second capacity and wherein the controller is further operable to:

determine, based on the first operational data, that the first compressor is ON;

determine, based on the second operational data, that the second compressor is ON;

open, at least partially, the first control valve;

open, at least partially, the second control valve; and

cause the vapor from the vapor injection source to flow to the first compressor and the second compressor, wherein the first amount of vapor and the second amount of vapor is substantially the same.

5. The heat pump system of claim 4, wherein the controller is further operable to:

determine, based on the first operational data, that the first compressor is operating at a first speed; and

determine, based on the second operational data, that the second compressor is operating at a second speed, wherein the first speed is about equal to the second speed.

6. The heat pump system of claim 1, wherein the controller is further operable to:

determine, based on the first operational data, that the first compressor is operating at a first speed; and

determine, based on the second operational data, that the second compressor is operating at a second speed, wherein the first speed is greater the second speed, wherein the first amount of vapor is greater than the second amount of vapor.

7. The heat pump system of claim 6, wherein the first compressor has a first capacity and the second compressor has a second capacity and the first capacity is substantially equal to the second capacity.

8. The heat pump system of claim 1, wherein the first compressor has a first capacity and the second compressor has a second capacity and the first capacity is greater than the second capacity and wherein the controller is further operable to:

determine, based on the first operational data that the first compressor is ON;

determine, based on the second operational data, that the second compressor is ON;

open, at least partially, the first control valve;

open, at least partially, the second control valve; and

cause the vapor from the vapor injection source to flow to the first compressor and the second compressor, wherein the first amount of vapor is greater than the second amount of vapor is substantially the same.

9. The heat pump system of claim 7, wherein the first compressor is operating at a first speed and the second compressor is operating at a second speed and wherein the first speed is equal to the second speed.

10. The heat pump system of claim 7, wherein the first compressor has a first capacity and the second compressor has a second capacity and the first capacity is different than the second capacity, and wherein the controller is further operable to:

determine, based on the first operation data, that the first compressor is operating at a first speed;

determine, based on the second operational data, that the second compressor is operating a second speed, wherein the first speed is different than the second speed;

operate the first control valve based on the first capacity and the first speed; and

operate the second control valve based on the second capacity and the second speed.

11. A method of operating a heat pump system, the method comprising:

determining first operational data of a first compressor;

determining second operational data of a second compressor;

operating, using a controller and based on the first operational data, a first control valve to deliver a first amount of vapor to the first compressor; and

operating, using the controller and based on the second operational data, a second control valve to deliver a second amount of vapor to the first compressor, wherein the controller is coupled to the first compressor, the second compressor, the first control valve, and the second control valve.

12. The method of claim 11, further comprising:

determining that the first compressor is ON;

determining that the second compressor is OFF;

opening, at least partially, the first control valve;

closing the second control valve; and

causing the first amount of vapor to travel to the first compressor; and

wherein the second amount of vapor is zero.

13. The method claim 11, further comprising:

determining that the first compressor is ON;

determining that the second compressor is ON;

opening, at least partially, the first control valve; and

opening, at least partially, the second control valve; and

wherein the first amount of vapor and the second amount of vapor are substantially the same.

14. The method of claim 13, further comprising:

determining that the first compressor is operating at a first speed; and

determining that the second compressor is operating at a second speed, wherein the first speed is substantially equal to the second speed.

15. The method of claim 13, further comprising:

determining that the first compressor has a first capacity; and

determining that the second compressor has a second capacity, wherein the first capacity is equal to the second capacity.

16. The method of claim 11, further comprising:

determining that the first compressor has a first capacity;

determining that the second compressor has a second capacity, wherein the first capacity is different than the second capacity;

determining that the first compressor is operating at a first speed;

determining that the second compressor is operating a second speed, wherein the first speed is different than the second speed;

operating the first control valve based on the first capacity and the first speed; and

operating the second control valve based on the second capacity and the second speed.

17. The method of claim 11, further comprising:

determining that first compressor has a first capacity;

determining that and the second compressor has a second capacity, wherein the first capacity is substantially same as the second capacity;

determining that the first compressor is ON;

determining that the second compressor is ON;

opening, at least partially, the first control valve; and

opening, at least partially, the second control valve; and

wherein the first amount of vapor and the second amount of vapor is substantially the same.

18. The method of claim 11, further comprising:

determining that the first compressor is operating at a first speed;

determining that the second compressor is operating at a second speed that is lower than the first speed;

determining that the first compressor is ON;

determining that the second compressor is ON;

opening, at least partially, the first control valve; and

opening, at least partially, the second control valve,

wherein the first amount of vapor is greater than the second amount of vapor.

19. The method of claim 18, further comprising:

determining that the first compressor has a first capacity; and

determining that the second compressor has a second capacity that is substantially equal to the first capacity.

20. The method of claim 11, wherein the first amount of vapor and the second amount of vapor is substantially the same.