Patent ID: 12209783

DETAILED DESCRIPTION

The disclosed technology can include heat pump water heater systems that are configured to operate in both cool and warm climates. For example, the disclosed technology can include heat pump water heater systems that can sufficiently heat water in warm climates as well as in climates where the ambient temperature can remain below freezing temperatures (e.g., less than 32° F.) for extended periods of time. As a non-limiting example, the heat pump water heater systems described herein can be configured to operate in ambient temperatures as low as −10° F. The heat pump water heater system can include a multi-fluid heat exchanger capable of exchanging heat between two refrigerant sources and water. The multi-fluid heat exchanger can be configured to preheat water before the water is heated by the condenser of the heat pump water heater. The multi-fluid heat exchanger can further heat refrigerant to cause the refrigerant to be a superheated vapor that can be injected into the compressor to increase the efficiency of the heat pump water heater system. The disclosed technology can also include cascading heat pump water heater systems that can be configured to efficiently heat water in both cool and warm ambient temperature conditions. Further configurations and advantages of the disclosed technology will become apparent throughout this disclosure.

Although various aspects of the disclosed technology are explained in detail herein, it is to be understood that other aspects of the disclosed technology are contemplated. Accordingly, it is not intended that the disclosed technology is limited in its scope to the details of construction and arrangement of components expressly set forth in the following description or illustrated in the drawings. The disclosed technology can be implemented and practiced or carried out in various ways. In particular, the presently disclosed subject matter is described in the context of being systems and methods for use with a heat pump water heating system. The present disclosure, however, is not so limited, and can be applicable in other contexts. The present disclosure can, for example, include devices and systems for use with air conditioning systems, refrigeration systems, pool water heater systems, and other similar systems. Furthermore, although described in the context of being a water heater, the disclosed technology can be configured to heat fluids other than water. For example, the disclosed technology can be configured to heat air, oil, glycol, refrigerants, silicones, or other fluids. Furthermore, the disclosed technology can be implemented in various commercial and industrial fluid heating systems used to heat fluids other than water. Accordingly, when the present disclosure is described in the context of a heat pump water heater system, it will be understood that other implementations can take the place of those referred to.

Although described herein as being a heat pump water heater configured to be deployed in low ambient temperature conditions, the disclosed technology can also be implemented in air conditioning systems configured to operate in high or low ambient temperature conditions. For example, the disclosed technology is described herein as having a water flow path to heat water to a high temperature using one or more heat exchangers. If the disclosed technology is deployed in an air heating context, the water flow path described herein can be and air flow path and the system can function much the same as the water heating system (e.g., the system will heat the air to a sufficient temperature even if the ambient temperature is low). If the disclosed technology is deployed in an air conditioning context (i.e., space cooling), the water flow path described herein can be an air flow path and the system can be configured to operate a first compressor in moderate ambient temperature conditions and both the first and a second compressor in high ambient temperature conditions. Thus, although described in the context of being a water heating system, one of skill in the art will appreciate that the disclosed technology can also be applicable to air conditioning systems without departing from the scope of this disclosure.

It should also 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.

The components described hereinafter as making up various elements of the disclosed technology are intended to be illustrative and not restrictive. Many suitable components that would perform the same or similar functions as the components described herein are intended to be embraced within the scope of the disclosed technology. Such other components not described herein can include, but are not limited to, similar components that are developed after development of the presently disclosed subject matter.

Referring now to the drawings, in which like numerals represent like elements, the present disclosure is herein described.FIG.2illustrates a heat pump water heater (HPWH)200that is configured to be operated in low ambient temperature conditions. The HPWH200, for example, can be operated in regions where the ambient temperature can remain below freezing for extended periods of time. The HPWH200can include a compressor202that can be configured to circulate refrigerant through a condenser204, a thermal expansion valve (TXV)206, and an evaporator208. As will be appreciated by one of skill in the art, as the refrigerant is circulated through the condenser204, the TXV206, and the evaporator208, the refrigerant can absorb heat at the evaporator208from a heat source (e.g., ambient air, a heated fluid, geothermal heat sources, etc.) and transfer the heat to water passed through the condenser204.

The HPWH200can include a vapor injection line212that can be configured to permit refrigerant in a fluid path downstream of the condenser204to pass through a supplemental TXV216and a supplemental heat exchanger210. The supplemental TXV216can cause the refrigerant to transition from a high-pressure liquid exiting the condenser204to an intermediate-pressure two-phase fluid. In other words, the vapor injection line212can be configured to facilitate refrigerant at a first pressure exiting the condenser204to transition to a refrigerant at a second pressure. Furthermore, the supplemental heat exchanger210can be configured to facilitate the intermediate-pressure two phase fluid to transition to a superheated vapor. The superheated vapor can then be directed by the vapor injection line212to the compressor202to help increase the efficiency of the compressor202.

To further increase the efficiency of the HPWH200and enable the HPWH200to effectively heat water in cooler climates, the supplemental heat exchanger210can be configured to preheat the water from a water source220prior to the water passing through the condenser204. The supplemental heat exchanger210can permit at least three fluids (e.g., a multi-fluid heat exchanger) to pass through the supplemental heat exchanger210. For example, the supplemental heat exchanger210can include a first passage configured to allow a first refrigerant to pass through the supplemental heat exchanger210, a second passage configured to allow a second refrigerant to pass through the supplemental heat exchanger210, and a third passage configured to allow water to pass through the supplemental heat exchanger210. By passing all three fluids through the supplemental heat exchanger210, heat can be exchanged between two of the fluids or between all three fluids. As will be appreciated by one of skill in the art, heat will pass from a fluid having a higher temperature to a fluid having a lower temperature. To illustrate, the high-pressure two-phase fluid from the condenser204and the intermediate-pressure two-phase fluid from the supplemental TXV216can both pass through the supplemental heat exchanger210as illustrated inFIG.2. As the high-pressure two-phase fluid or liquid refrigerant can be at a greater temperature than the intermediate-pressure two-phase fluid, heat can be transferred from the high-pressure two-phase fluid or liquid refrigerant and to the intermediate-pressure two-phase fluid or liquid refrigerant to cause the intermediate-pressure two-phase fluid to become superheated vapor. The superheated vapor can then be directed by the vapor injection line212to the compressor202to help increase the efficiency of the heat pump cycle. Similarly, as the temperature of the high pressure two-phase fluid or liquid refrigerant from the condenser204and the intermediate pressure two-phase fluid or liquid refrigerant from the supplemental TXV216are likely to both be greater than the temperature of the water, the water can be heated as it is passed through the supplemental heat exchanger210. In this way, the supplemental heat exchanger210can be configured to preheat the water before the water is passed through the condenser.

To further facilitate heat transfer between the high-pressure two-phase fluid or liquid refrigerant and the intermediate-pressure two-phase fluid or liquid refrigerant, the high-pressure two-phase fluid or liquid refrigerant and the intermediate-pressure two-phase fluid or liquid refrigerant can be in counterflow with respect to each other. Similarly, the water and the high-pressure two-phase fluid can be in counterflow with respect to each other.

The HPWH200can be configured to receive water from a water source220. For example, the water source220can be a city water supply, a well, a stream, a spring, or any other suitable water source for the particular application. The water from the water source220can be at a first temperature that is normally cooler than the rest of the water in the system prior to entering the supplemental heat exchanger210. As a non-limiting example, the water entering the HPWH200from the water source220can be approximately 58° F. As the water passes through the supplemental heat exchanger210, the water can be heated to a first target temperature. For example, the water can be heated to approximately 120° F. as it passes through the supplemental heat exchanger210. As the water passes through the condenser204, the water can be further heated to a second target temperature that is greater than the first target temperature. For example, the water can be heated to approximately 180° F. as it passes through the condenser204. As will be appreciated by one of skill in the art, the various example temperatures are offered merely for illustrative purposes and should not be construed as limiting as the HPWH200can be configured to heat the water to any suitable temperature for the application.

As the water is heated, the water can be used for various hot water uses222including, but not limited, supply heated water to a faucet, dishwashing, clothes washing, radiator space heating, floor space heating, and other suitable hot water uses222. Furthermore, as illustrated inFIG.2and depending on the application, the water can be circulated by a water pump226back through at least the condenser204to reheat the water. For example, where the water is used for space heating, the HPWH200can circulate water back through the condenser204to reheat the water and continue heating the space. As will be appreciated, the water may not need to be heated to the same temperature for space heating as would be necessary for other water uses. In some applications, for example, water at a temperature of approximately 80° F. to 100° F. would be sufficient for space heating while water at a temperature of greater than 120° F. would be necessary for other hot water uses222. In this case, the water used for space heating can be heated by just the supplemental heat exchanger210while the water used for other hot water uses222can be heated by both the supplemental heat exchanger210and the condenser204. Although not illustrated inFIG.2, the HPWH200can include a water line that can route water downstream of the supplemental heat exchanger210but upstream of the condenser204to be used for space heating.

To help control the flow of the water, the HPWH200can include a water control valve224. The water control valve224can be positioned downstream of the supplemental heat exchanger210and upstream of the condenser204. The water control valve224can be any type of valve suitable for the application. For example, the water control valve224can be a ball valve, a plug valve, a butterfly valve, a gate valve, a globe valve, a needle valve, a coaxial valve, an angle seat valve, a three-way valve, or any other type of valve that would be suitable for the particular application. Furthermore, the water control valve224can be configured to be controlled by any suitable method, including manually controlled, electronically controlled, pneumatically controlled, and/or hydraulically controlled. Similarly, the control valve214can be any type of valve suitable for the application. For example, the control valve214can be a ball valve, a plug valve, a butterfly valve, a gate valve, a globe valve, a needle valve, a coaxial valve, an angle seat valve, a three-way valve, or any other type of valve that would be suitable for the particular application. Furthermore, the control valve214can be configured to be controlled by any suitable method, including manually controlled, electronically controlled, pneumatically controlled, and/or hydraulically controlled. As a non-limiting example, the control valve214can be a normally-closed solenoid valve that is configured to open when energized.

The compressor202can be any type of compressor. For example, the compressor202can be a positive displacement compressor, a reciprocating compressor, a rotary screw compressor, a rotary vane compressor, a rolling piston compressor, a scroll compressor, an inverter compressor, a diaphragm compressor, a dynamic compressor, an axial compressor, or any other form of compressor that can be integrated into the HWPH200for the particular application. Furthermore, the compressor202can be a fixed speed or a variable speed compressor depending on the application.

The condenser204, the evaporator208, and the supplemental heat exchanger210can be or include any type of heat exchanger coil configured to facilitate heat transfer between fluids. The fluid, for example, can be refrigerant, air, water, glycol, dielectric fluids, or any other type of fluid suitable for the particular application. The condenser204, the evaporator208, and the supplemental heat exchanger210can be or include, for example, a shell and tube heat exchanger, a double pipe heat exchanger, a plate heat exchanger, or any other suitable heat exchanger for the application.

As described above, the supplemental heat exchanger210can be configured to facilitate heat transfer between at least three fluids (e.g., at least the high-pressure two-phase fluid refrigerant, the intermediate-pressure two-phase fluid refrigerant, and the water).FIGS.3A-3Cillustrate various examples of the supplemental heat exchanger210being a multi-fluid heat exchanger. Specifically,FIG.3Aillustrates a shell and tube heat exchanger300A having a shell302A and two tube bundles (i.e.,322A and322B),FIG.3Billustrates a tube-in-tube heat exchanger300B having three tubes (i.e.,302B,312B, and322B), andFIG.3Cillustrates a microchannel heat exchanger300C having two microchannel tubes (i.e.,312C,322C) and plates302C. As will be appreciated by one of skill in the art, the supplemental heat exchanger210can be configured such that the high pressure two-phase or liquid refrigerant coming from the condenser204can exchange heat with the incoming water only, with the low pressure two-phase or liquid refrigerant only, or both simultaneously.

Turning toFIG.3A, the supplemental heat exchanger210can be a shell and tube heat exchanger300A having a shell302A, a first tube bundle312A, and a second tube bundle322A. The shell302A can be configured to receive the high-pressure two-phase fluid refrigerant from the condenser204, the first tube bundle312A can be configured to receive the intermediate-pressure two-phase fluid refrigerant, and the second tube bundle322A can be configured to receive the water. In this way, the shell and tube heat exchanger300A can be configured to facilitate heat transfer between the three fluids. Because the high-pressure two-phase fluid refrigerant can be passed through the shell302A, the high-pressure two-phase fluid refrigerant can heat both the water and the intermediate-pressure two-phase fluid refrigerant.

The tube-in-tube heat exchanger300B illustrated inFIG.3Bcan include a first tube302B that can be positioned at least partially within a second tube312B and the second tube312B can be at least partially positioned within a third tube322B. The first tube302B can be configured to receive the water, The second tube312B can be configured to receive the high-pressure two-phase fluid refrigerant from the condenser204, and the third tube322B can be configured to receive the intermediate-pressure two-phase fluid refrigerant. In this way, the tube-in-tube heat exchanger300B can be configured to facilitate heat transfer between the three fluids. Because the high-pressure two-phase fluid refrigerant is passed through the second tube312B, the high-pressure two-phase fluid refrigerant can heat both the water and the intermediate-pressure two-phase fluid refrigerant. To further facilitate heat transfer, the high-pressure two-phase fluid refrigerant can be configured to be in counterflow with both the intermediate-pressure two-phase fluid and the water.

As illustrated inFIG.3C, the supplemental heat exchanger210can be a microchannel heat exchanger300C having a first microchannel tube312C, a second microchannel tube322C and plates302C. The plates302C can include fins that are offset to further help facilitate heat transfer. The first microchannel tube312C can be configured to receive the high-pressure two-phase fluid refrigerant from the condenser204, the second microchannel tube322C can be configured to receive the intermediate-pressure two-phase fluid refrigerant, and the plates302C can be configured to contact the water passing through the microchannel heat exchanger300C. In this way, the shell and tube heat exchanger300A can be configured to facilitate heat transfer between the three fluids. As will be appreciated, the first microchannel tube312C and the second microchannel tube322C can each be configured to pass multiple times through the microchannel heat exchanger300C to facilitate heat transfer. Furthermore, the plates302C can be configured such that the water is received through an inlet, passed through the microchannel heat exchanger300C (e.g., into and out of the page with each row of plates302C) multiple times, and exits the microchannel heat exchanger300C through an outlet. Because the high-pressure two-phase fluid refrigerant is passed through the first microchannel tube312C, the high-pressure two-phase fluid refrigerant can heat both the water and the intermediate-pressure two-phase fluid refrigerant. To further facilitate heat transfer, the high-pressure two-phase fluid refrigerant can be configured to be in counterflow with the intermediate-pressure two-phase fluid.

FIG.4illustrates a schematic diagram of a cascade heat pump water heater system (HPWH)400, in accordance with the disclosed technology. As will be appreciated, each of the components of the cascade HPWH400can be the same or similar to corresponding components of the HPWH200just described. The cascade HPWH400can include a first stage401A and a second stage401B. The first stage401A can include a first compressor402A, a first condenser404A, a first TXV406A, a first evaporator408A and the second stage401B can include a second compressor402B, a second condenser404B, a second TXV406B, and a second evaporator408B. The first stage401A and the second stage401B can be configured to operate concurrently or independently of each other. Furthermore, the components of the first stage401A and the second stage401B can each be the same type of components or different types of components (e.g., the first compressor402A can be a compressor having the same capacity or a different capacity as the second compressor402B).

As explained in relation toFIG.1B, cascading HPWH systems are generally designed to heat water to a higher temperature in cooler climates than would otherwise be achievable with a single HPWH. Existing HPWH systems, however, are generally inefficient due to both stages being required to operate simultaneously. Unlike existing HPWH systems, the cascade HPWH400can be effectively implemented in both cool and warm climates and for various uses by being able to control the first stage401A and the second stage401B independently of each other. To illustrate, in a first mode, the cascade HPWH400can be configured such that water entering the cascade HPWH400from a water source420can be heated by only the first condenser404A with only the first stage401A being in operation. In a second mode, the water entering the HPWH400from the water source420can be heated by the second condenser404B with both the first stage401A and the second stage401B being in operation. In a third mode, the water entering the HPWH400from the water source420can be heated by both the first condenser404A and the second condenser404B with both the first stage401A and the second stage401B being in operation.

To facilitate heating of the water with only a single stage or both stages in operation, the cascade HPWH400can include one or more water control valves426A-426D that can be positioned and configured to permit or prevent water from flowing through the first condenser404A, the second condenser404B, and/or the second evaporator408B. To illustrate, in the first mode just described, the water control valves426A-426D can be actuated such that the water enters the HPWH400from the water source420and passes through, and is heated by, only the first condenser404A before being used for various hot water uses422. In this mode, only the first stage401A can be operated with the second stage401B being shut down or otherwise in a standby mode. The various hot water uses422can be or include any of the hot water uses222previously described. As will be appreciated by one of skill in the art, the first mode just described can be used to heat water when the load is low (e.g., when the ambient temperature is greater than a threshold temperature, the water source420water temperature is greater than a threshold temperature, the water temperature of the hot water uses422is less than a threshold temperature the demand for heated water is low, etc.). Furthermore, although not shown inFIG.4, the cascade HPWH400can be configured to facilitate space heating similar to the HPWH200. For example, the water can be circulated through a space heating system and then back through the first condenser404A (or second condenser404B depending on the configuration) to be reheated.

In the second mode, the water control valves426A-426D can be actuated such that water entering from the water source420passes only through the second condenser404B before being used for the various hot water uses422. The water control valves426A-426D can also be actuated such that a closed fluid loop between the first condenser404A and the second evaporator408B can be formed. In other words, the control valves426A-426D can be actuated such that water can flow between control valves426A and426D but no water flows between control valves426A and426B. Similarly, water can flow between control valves426C and426B but not between control valves426C and426D to form the closed fluid loop. The water in the closed fluid loop can be circulated between the first condenser404A and the second evaporator408B by a water pump424to facilitate heat transfer between the first condenser404A and the second evaporator408B. In other words, water in the closed fluid loop can be heated by the first condenser404A and then heat can be transferred from the water in the closed fluid loop to the refrigerant in the second stage401B by the second evaporator408B. The heated refrigerant in the second stage401B can then transfer heat to water entering the cascade HPWH400from the water source420to heat the water for the various hot water uses422. To facilitate further heating of the water for the various hot water uses422, the second compressor402B can be configured to compress the refrigerant in the second stage401B to a higher pressure than the first compressor402A. Furthermore, depending on the application, the refrigerant used in the first stage401A can be the same type or a different type of refrigerant than the refrigerant used in the second stage401B. If the refrigerant in the second stage401B is a different refrigerant than the refrigerant in the first stage401A, the refrigerant in the second stage401B can be, for example, a refrigerant capable of being compressed to higher pressures. As a non-limiting example, R-32, R-290, R-410A, R-454B, R-454C, R-457A, R-468C, R-744 or other similar refrigerants can be used in the first stage401A while (CO2), R-134a, R-1234yf, R-513A, R-515B, and R-516A or other similar refrigerants can be used in the second stage401B.

As will be appreciated, both the first stage401A and the second stage401B can be operated in this second mode such that the water in the closed fluid loop can be preheated by the first stage401A. The preheated water can then act as a greater heat source for the second stage401B than would otherwise be available by the ambient air alone. For example, even in climates where traditional HPWHs would be unable to heat water to a sufficient temperature, the cascade HPWH400can be used to sufficiently heat water for various uses because of the cascading configuration. Furthermore, as will be appreciated by one of skill in the art, when the ambient air temperature rises and the cascade configuration is no longer necessary for heating the water, the cascade HPWH400can operate only the first stage401A to heat the water and conserve energy as described.

Furthermore, the cascade HPWH400can be configured to facilitate space heating in the second mode just described by circulating water from the closed fluid loop to the space heating (e.g., floor heating, radiators, etc.). For example, the cascade HPWH400can be configured such that, when the control valves426A-426D are actuated to form the closed fluid loop, the water pump424can circulate water from the closed fluid loop to various locations for space heating. The water can then be circulated back through the first condenser404A to be reheated. Alternatively, or in addition, water passing through the second stage401B (e.g., passing through the second condenser404B) can be used for space heating by being circulated back through the second condenser404B.

The cascade HPWH400can be further configured to operate in a third mode with the control valves426A-426D being actuated such that water entering from the water source420will pass through both the first condenser404A and the second condenser404B. Some of the water passing through the first condenser404A can be used for space heating or domestic water heating while the rest of the water passing through the first condenser404A can be used to heat the refrigerant in the second stage401B via the second evaporator408B. Furthermore, water passing through the second condenser404B can be used for other hot water uses422. For example, as shown inFIG.4, a control valve427and an outlet428can be positioned between water pump424and control valve426C. The outlet428and control valve427can be used to direct some of the water that has passed through the first condenser404A to hot water uses which require the water at a temperature that is less than water delivered to the hot water uses422. To illustrate, the water delivered from the first condenser404A through the outlet428between water pump424and control valve426C can be at approximately 120° F. and the water delivered from the second condenser404B to the hot water uses422can be at approximately 140° F.

FIG.5illustrates a schematic diagram of another cascade HPWH500, in accordance with the disclosed technology. As will be appreciated, unless explicitly stated otherwise, each of the components of the cascade HPWH500can be the same or similar to corresponding components of the HPWH200and the cascade HPWH400described herein. The cascade HPWH500can include a first stage501A and a second stage501B. The first stage501A can include a first compressor502A, a first TXV506A, and an evaporator508A and the second stage501B can include a second compressor502B, a condenser504, and a second TXV506B. The components of the first stage501A and the second stage501B can each be the same type of components or different types of components (e.g., the first compressor502A can be a compressor having the same capacity or a different capacity as the second compressor502B). The cascade HPWH500can further include a multi-fluid heat exchanger510that can be in place of the first condenser404A and the second evaporator408B described in relation to the cascade HPWH400. As will become apparent, by including a multi-fluid heat exchanger510, the first stage501A and the second stage501B can be configured to operate concurrently or independently of each other with the cascade HPWH500being more compact.

Similar to the cascade HPWH400, the cascade HPWH500can be configured such that in a first mode only the first stage501A is in operation. Control valves526A,526B can be actuated such that water entering from the water source520can bypass the condenser504and pass only through the multi-fluid heat exchanger510. With only the first stage501A being operated, the water will be heated by heat transfer from the refrigerant of the first stage501A via the multi-fluid heat exchanger510. In other words, the multi-fluid heat exchanger510can act as a condenser to heat the water before the water is delivered to the hot water uses522. The cascade HPWH500can be configured to operate in this first mode when the load is low (e.g., when the ambient temperature is greater than a threshold temperature, the water temperature is less than a threshold temperature, the demand for heated water is low, etc.).

In a second mode, the cascade HPWH500can be configured to operate with both the first stage501A and the second stage501B operating. Control valves526A,526B can be actuated such that water entering from the water source520can pass through only the condenser504before being used for the various hot water uses522. Refrigerant in the first stage501A can receive heat from the ambient air via the evaporator508and transfer the heat to the refrigerant in the second stage501B via the multi-fluid heat exchanger510. As will be appreciated, by transferring heat from the refrigerant in the first stage501A to refrigerant in the second stage501B, the cascade HPWH500can heat the water to a higher temperature than would otherwise be achievable without the cascading configuration. Furthermore, because the refrigerant in the first stage501A is capable of transferring heat directly to the refrigerant in the second stage501B, the cascade HPWH500can operate more efficiently than the cascade HPWH400since there are no heat losses associated with transferring heat to the water circulated through a closed fluid loop (as does the cascade HPWH400). The cascade HPWH500can be configured to operate in this second mode when the load is high (e.g., when the ambient temperature is less than a threshold temperature, the water source420water temperature is less than a threshold temperature, the water temperature of the hot water uses422is greater than a threshold temperature, the demand for heated water is high, etc.). Although not shown inFIG.5, the cascade HPWH500can be further configured to facilitate space heating as described herein by having at least some of the water passed through the condenser504be used for space heating.

The cascade HPWH500can be further configured to operate in a third mode with the control valves526A,526B being actuated such that water entering from the water source520will pass through both the multi-fluid heat exchanger510and the condenser504. The water passing through the multi-fluid heat exchanger510can be used to first heat the refrigerant in the multi-fluid heat exchanger510before being used for other uses such as space heating. Furthermore, water passing through the second condenser504can be used for other hot water uses522. For example, a control valve527and an outlet528can be positioned between multi-fluid heat exchanger510and control valve526CB. The outlet528and control valve527can be used to direct the water that has passed through the multi-fluid heat exchanger510to hot water uses which require the water at a temperature that is less than water delivered to the hot water uses522. To illustrate, the water delivered from the multi-fluid heat exchanger510through the outlet527can be at approximately 120° F. and the water delivered from the condenser504to the hot water uses522can be at approximately 140° F.

The multi-fluid heat exchanger510can be any of the heat exchangers shown and described in relation toFIGS.3A-3C. Specifically, the multi-fluid heat exchanger510can be a shell and tube heat exchanger300A having a shell302A and two tube bundles (e.g.,322A and322B) as illustrated inFIG.1, a tube-in-tube heat exchanger300B having three tubes (e.g.,302B,312B, and322B) as illustrated inFIG.3B, or a microchannel heat exchanger300C having two microchannel tubes (e.g.,312C,322C) and plates302C as illustrated inFIG.3C.

FIG.6. illustrates a schematic diagram of a controller640and various components of the HPWH systems described herein (i.e., HPWH200, cascade HPWH400, cascade HPWH500), in accordance with the disclosed technology. As will be appreciated, the controller640can be configured to control any of HPWHs (i.e., HPWH200, cascade HPWH400, cascade HPWH500) described herein. Thus, unless otherwise stated, when describing a HPWH in relation toFIG.6, it will be understood that the HPWH can be any of HPWH200, cascade HPWH400, or cascade HPWH500.

As illustrated inFIG.6, the disclosed technology can include a controller640that can be configured to receive data and determine actions based on the received data. For example, the controller640can be configured to monitor the temperature of ambient air via an ambient air temperature sensor650and output control signals to the various components described herein to heat the water. As another illustrative example, the controller640can be configured to monitor the temperature of the water (e.g., water entering the HPWH200, cascade HPWH400, or cascade HPWH500) via a water temperature sensor652and output control signals to the various components described herein to heat the water. As yet another illustrative example, the controller640can be configured to monitor the temperature of the refrigerant in the HPWH via a refrigerant temperature sensor654and output control signals to the various components described herein to heat the water. The controller640can receive data from, or output data to, the user interface648, the ambient air temperature sensor650, the water temperature sensor652, the refrigerant temperature sensor654, the first compressor (i.e., compressor202,402A,502A), the control valve214, the water control valve224, the water pump226, the control valves426A-426D, the water pump424, and/or the control valves526A,526B.

The ambient air temperature sensor650can be configured to detect a temperature of the ambient air proximate the HPWH. The water temperature sensor652can be configured to detect a temperature of the water supplied to the HPWH. The refrigerant temperature sensor654can be configured to detect a temperature of the refrigerant of the HPWH. Each of the temperature sensors can be any type of temperature sensor including a thermocouple, a resistance temperature detector, a thermistor, a semiconductor based integrated circuit, or any other suitable type of temperature sensor for the particular application.

The controller640can have a memory642, a processor644, and a communication interface646. The controller640can be a computing device configured to receive data, determine actions based on the received data, and output a control signal instructing one or more components of the HPWH200, cascade HPWH400, or cascade HPWH500, to perform one or more actions. One of skill in the art will appreciate that the controller640can be installed in any location, provided the controller640is in communication with at least some of the components of the system. Furthermore, the controller640can be configured to send and receive wireless or wired signals and the signals can be analog or digital signals. The wireless signals can include Bluetooth™, BLE, WiFi™, ZigBee™, infrared, microwave radio, or any other type of wireless communication as may be suitable for the particular application. The hard-wired signal can include any directly wired connection between the controller and the other components described herein. Alternatively, the components can be powered directly from a power source and receive control instructions from the controller640via a digital connection. The digital connection can include a connection such as an Ethernet or a serial connection and can utilize any suitable communication protocol for the application such as Modbus, fieldbus, PROFIBUS, SafetyBus p, Ethernet/IP, or any other suitable communication protocol for the application. Furthermore, the controller640can utilize a combination of wireless, hard-wired, and analog or digital communication signals to communicate with and control the various components. One of skill in the art will appreciate that the above modes and configurations are given merely as non-limiting examples and the actual configuration can vary depending on the particular application.

The controller640can include a memory642that can store a program and/or instructions associated with the functions and methods described herein and can include one or more processors644configured to execute the program and/or instructions. The memory642can include one or more suitable types of memory (e.g., volatile or non-volatile memory, random access memory (RAM), read only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, floppy disks, hard disks, removable cartridges, flash memory, a redundant array of independent disks (RAID), and the like) for storing files including the operating system, application programs (including, for example, a web browser application, a widget or gadget engine, and or other applications, as necessary), executable instructions and data. One, some, or all of the processing techniques or methods described herein can be implemented as a combination of executable instructions and data within the memory.

The controller640can also have a communication interface646for sending and receiving communication signals between the various components. Communication interface646can include hardware, firmware, and/or software that allows the processor(s)644to communicate with the other components via wired or wireless networks or connections, whether local or wide area, private or public, as known in the art. Communication interface646can also provide access to a cellular network, the Internet, a local area network, or another wide-area network as suitable for the particular application.

Additionally, the controller640can have or be in communication with a user interface648for displaying system information and receiving inputs from a user. The user interface648can be installed locally or be a remotely controlled device such as a mobile device. The user, for example, can view system data on the user interface648and input data or commands to the controller640via the user interface648. For example, the user can view temperature threshold settings on the user interface648and provide inputs to the controller640via the user interface648to change a temperature threshold setting. The temperature threshold settings can be, for example, an ambient air temperature threshold, a water temperature threshold, and/or a refrigerant temperature threshold.

FIG.7illustrates a flow chart of a method700of operating a heat pump water heater system (e.g., HPWH200), in accordance with the disclosed technology. The method700can include starting702a logic sequence by receiving a start signal or by initiating the method700(e.g., as power is received to the controller640). The method700can include receiving704sensor data from one or more sensors in the heat pump system (e.g., ambient temperature data from the ambient air temperature sensor650, water temperature data from the water temperature sensor652, refrigerant temperature data from the refrigerant temperature sensor654, humidity data from a humidity sensor, flow data from a flow sensor, or any other data from a connected sensor).

The method700can include determining706whether the ambient temperature is less than or equal to a low ambient temperature threshold or whether the water temperature is greater than or equal to a high water temperature threshold. The low ambient temperature threshold can be, for example, a temperature of the ambient air wherein the HPWH begins to be unable to sufficiently heat the water to a water temperature threshold. For example, as will be appreciated by one of skill in the art, as the temperature of the ambient air begins to decrease to a low temperature (e.g., below a freezing temperature (32° F.)), the HPWH will begin to be unable to sufficiently heat the water for the various hot water uses (222,422, or522). In this scenario, the load on the HPWH will be high. Similarly, as the temperature of the water increases above a high water temperature threshold, the HPWH is less able to transfer heat from the refrigerant to the water because the temperature differential between the refrigerant and the water decreases. As the temperature of the water increases, the load on the HPWH will also begin to increase.

If the ambient temperature is greater than the low ambient temperature threshold or the water temperature is less than the high water temperature threshold, the method700can include outputting708a control signal to close control valve214to thereby cause refrigerant to bypass the vapor injection line212and pass only through the evaporator208. The method700can further include outputting710a control signal to turn on compressor202to cause the refrigerant to circulate through the evaporator208and the condenser204to heat the water. The method700can include determining716whether the heating cycle is complete. The heating cycle can be complete, for example, when the water temperature has reached a threshold temperature (e.g., a target temperature), after the water has been heated for a predetermined length of time, when a demand for heated water is no longer present, when a temperature of a building is sufficiently heated by the space heating, and/or other conditions which would indicate that the water no longer needs to be heated. If the heating cycle is determined716to be complete, the method700can end718by shutting down the HPWH, placing the HPWH on standby mode, turning off the compressor202, or other similar actions which would cause the HPWH to no longer heat the water. If the heating cycle is not complete, the method700can include once again receiving704the sensor data and continuing the method700.

If the ambient air temperature is less than or equal to the low ambient temperature threshold or if the water temperature is greater than or equal to the high water temperature threshold, the method700can include outputting712a control signal to open control valve214to cause refrigerant to pass through the vapor injection line212and provide vapor injection to the compressor202. The method700can further include outputting714a control signal to turn on compressor202to cause refrigerant to circulate through the condenser204and the evaporator208. As will be appreciated by one of skill in the art, by injecting vapor refrigerant into the compressor202, the compressor202can operate more efficiently to heat the water as described herein.

The method700can further include determining716whether the heating cycle is complete. If the heating cycle is determined716to be complete, the method700can end718by shutting down the HPWH, placing the HPWH on standby mode, turning off the compressor202, or other similar actions which would cause the HPWH to no longer heat the water. If the heating cycle is not complete, the method700can include once again receiving704the sensor data and continuing the method700.

FIG.8illustrates a flow chart of a method800of operating a cascade heat pump water heater system (e.g., cascade HPWH400), in accordance with the disclosed technology. The method800can include starting802a logic sequence by receiving a start signal or by initiating the method800(e.g., as power is received to the controller640). The method800can include receiving804sensor data from one or more sensors in the heat pump system (e.g., ambient temperature data from the ambient air temperature sensor650, water temperature data from the water temperature sensor652, refrigerant temperature data from the refrigerant temperature sensor654, humidity data from a humidity sensor, flow data from a flow sensor, or any other data from a connected sensor).

The method800can include determining806whether there is a demand for space heating. If there is a demand for space heating, the method can include performing actions to facilitate space heating as described herein with respect toFIG.4. For example, and not limitation, the method800can include actuating808control valves426A-426D to cause the water to flow through both the first condenser404A and the second condenser404B. The method800can further include outputting810a control signal to turn on the first compressor402A and the second compressor402B. As described with respect toFIG.4, the cascade HPWH400can be configured to circulate at least a portion of the heated water through a space heating system (e.g., radiators, floor heating, etc.) to provide heat to a building.

If a demand for space heating is not present, the method800can include determining812whether the ambient temperature is less than or equal to a low ambient temperature threshold or whether the water temperature is greater than or equal to a high water temperature threshold. The low ambient temperature threshold can be, for example, a temperature of the ambient air wherein the HPWH begins to be unable to sufficiently heat the water to a water temperature threshold. For example, as will be appreciated by one of skill in the art, as the temperature of the ambient air begins to decrease to a low temperature (e.g., below a freezing temperature (32° F.)), the HPWH will begin to be unable to sufficiently heat the water for the various hot water uses (222,422, or522). In this scenario, the load on the HPWH will be high. Similarly, as the temperature of the water increases above a high water temperature threshold, the HPWH is less able to transfer heat from the refrigerant to the water because the temperature differential between the refrigerant and the water decreases. As the temperature of the water increases, the load on the HPWH will also begin to increase.

If the ambient temperature is greater than the low ambient temperature threshold or the water temperature is less than the high water temperature threshold, the method800can include outputting814a control signal to actuate control valves426A-426D to cause the water entering the HPWH from the water source420to pass only through the first condenser404A. The method800can further include outputting816a control signal to turn on the first compressor402A to cause the refrigerant to circulate through the first evaporator408A and the first condenser404A to heat the water. The method can include determining822whether the heating cycle is complete. The heating cycle can be complete, for example, when the water temperature has reached a threshold temperature (e.g., a target temperature), after the water has been heated for a predetermined length of time, when a demand for heated water is no longer present, when a temperature of a building is sufficiently heated by the space heating, and/or other conditions which would indicate that the water no longer needs to be heated. If the heating cycle is determined822to be complete, the method800can end824by shutting down the HPWH, placing the HPWH on standby mode, turning off the compressor202, or other similar actions which would cause the HPWH to no longer heat the water. If the heating cycle is not complete, the method800can include once again receiving804the sensor data and continuing the method800.

If the ambient air temperature is less than or equal to the low ambient temperature threshold or if the water temperature is greater than or equal to the high water temperature threshold, the method800can include outputting818a control signal to actuate control valves426A-426D to cause the water to flow from the water source420directly to the second condenser404B. Outputting818the control signal to actuate the control valves426A-426D can also cause the control valves426A-426D to actuate and create a closed fluid loop where water can be circulated between the first condenser404A and the second evaporator408B. The method800can include outputting819a control signal to cause the water pump424to begin circulating water in the closed fluid loop. The method800can further include outputting820a control signal to turn on the first compressor402A and the second compressor402B to cause refrigerant to circulate in both the first stage401A and the second stage401B.

The method800can further include determining822whether the heating cycle is complete. If the heating cycle is determined822to be complete, the method800can end824by shutting down the HPWH, placing the HPWH on standby mode, turning off the compressor202, or other similar actions which would cause the HPWH to no longer heat the water. If the heating cycle is not complete, the method800can include once again receiving804the sensor data and continuing the method800.

FIG.9illustrates a flow chart of a method900of operating a cascade heat pump water heater system (e.g., cascade HPWH500), in accordance with the disclosed technology. The method900can include starting902a logic sequence by receiving a start signal or by initiating the method900(e.g., as power is received to the controller640). The method900can include receiving904sensor data from one or more sensors in the heat pump system (e.g., ambient temperature data from the ambient air temperature sensor650, water temperature data from the water temperature sensor652, refrigerant temperature data from the refrigerant temperature sensor654, humidity data from a humidity sensor, flow data from a flow sensor, or any other data from a connected sensor).

The method900can include determining906whether the ambient temperature is less than or equal to a low ambient temperature threshold or whether the water temperature is greater than or equal to a high water temperature threshold. The low ambient temperature threshold can be, for example, a temperature of the ambient air wherein the HPWH begins to be unable to sufficiently heat the water to a water temperature threshold. For example, as will be appreciated by one of skill in the art, as the temperature of the ambient air begins to decrease to a low temperature (e.g., below a freezing temperature (32° F.)), the HPWH will begin to be unable to sufficiently heat the water for the various hot water uses (222,422, or522). In this scenario, the load on the HPWH will be high. Similarly, as the temperature of the water increases above a high water temperature threshold, the HPWH is less able to transfer heat from the refrigerant to the water because the temperature differential between the refrigerant and the water decreases. As the temperature of the water increases, the load on the HPWH will also begin to increase.

If the ambient temperature is greater than the low ambient temperature threshold or the water temperature is less than the high water temperature threshold, the method900can include outputting908a control signal to actuate control valves526A,526B to cause the water to pass only through the multi-fluid heat exchanger510when entering the cascade HPWH500from the water source520. The method900can further include outputting910a control signal to turn on the first compressor502A to cause the refrigerant to circulate through the evaporator508and the multi-fluid heat exchanger510to heat the water. The method900can include determining916whether the heating cycle is complete. The heating cycle can be complete, for example, when the water temperature has reached a threshold temperature (e.g., a target temperature), after the water has been heated for a predetermined length of time, when a demand for heated water is no longer present, when a temperature of a building is sufficiently heated by the space heating, and/or other conditions which would indicate that the water no longer needs to be heated. If the heating cycle is determined916to be complete, the method900can end918by shutting down the HPWH, placing the HPWH on standby mode, turning off the compressor202, or other similar actions which would cause the HPWH to no longer heat the water. If the heating cycle is not complete, the method900can include once again receiving904the sensor data and continuing the method900.

If the ambient air temperature is less than or equal to the low ambient temperature threshold or if the water temperature is greater than or equal to the high water temperature threshold, the method900can include outputting912one or more control signals to actuate control valves526A,526B to cause the water to pass only through the condenser504to heat the water. The method900can further include outputting914a control signal to turn on the first compressor502A and the second compressor502B. As will be appreciated by one of skill in the art, by turning on the first compressor502A and the second compressor502B, the refrigerant in the first stage501A can provide heat to the refrigerant in the second stage501B and the refrigerant in the second stage501B can provide heat to the water in the condenser504, as previously described in relation toFIG.5.

The method900can further include determining916whether the heating cycle is complete. If the heating cycle is determined916to be complete, the method900can end918by shutting down the HPWH, placing the HPWH on standby mode, turning off the compressor202, or other similar actions which would cause the HPWH to no longer heat the water. If the heating cycle is not complete, the method900can include once again receiving904the sensor data and continuing the method900.

As will be appreciated, the methods700,800, and900just described can be varied in accordance with the various elements and implementations described herein. That is, methods in accordance with the disclosed technology can include all or some of the steps or components described above and/or can include additional steps or components not expressly disclosed above. Further, methods in accordance with the disclosed technology can include some, but not all, of a particular step described above. Further still, various methods described herein can be combined in full or in part. That is, methods in accordance with the disclosed technology can include at least some elements or steps of a first method and at least some elements or steps of a second method.

The disclosed technology, although described in the context of being a heat pump water heating system, can be applicable to water cooling systems or other fluid cooling systems. For example, the HPWH200can be configured to circulate the refrigerant in a reverse direction such that the condenser204acts as an evaporator and the evaporator208acts as a condenser. In this way, the HPWH200can remove heat from water to sufficiently cool the water for end uses. This can be useful in applications where source water may be at temperature that is greater than the temperature of water necessary for the end use.

As mentioned previously, although described herein as being a heat pump water heating system, the disclosed technology can also be applicable to air heating and cooling systems (i.e., a heating ventilation and air conditioning (HVAC) system). For example, the HVAC system can be a system including all of the same components as those discussed in relations to the HPWH systems described herein. Furthermore, when in a heating mode, the HVAC system can operate similar to the HPWH system in that the compressor202(or first compressor402A and second compressor402B) and the control valves can circulate the refrigerant through the condenser204(or first condenser404A and second condenser404B, condenser504), the evaporator208(or first evaporator408A and second evaporator408B, condenser508), the supplemental heat exchanger210, and/or the multi-fluid heat exchanger510, to heat the air to a sufficient temperature in accordance with the methods and systems described herein.

When in a heating mode, the HVAC system can be configured to circulate the refrigerant in a reverse direction such that the condenser acts as an evaporator and the evaporator acts as a condenser. In this way, the HVAC system can remove heat from air circulated through a ventilated space to provide cooling to the ventilated space. As will be appreciated, the disclosed technology can be particularly helpful in areas having high ambient temperatures because the disclosed technology can be configured to cool air sufficiently even when ambient temperatures are high. Furthermore, as will be appreciated, rather than activating the first compressor(s) based on the ambient temperature being below a low ambient temperature, the HVAC system can be configured to activate the first compressors(s) based on the ambient temperature being greater than a high ambient temperature. Thus, one of skill in the art will understand that the disclosed technology can be applicable to HVAC systems while remaining within the scope of this disclosure.

While the present disclosure has been described in connection with a plurality of exemplary aspects, as illustrated in the various figures and discussed above, it is understood that other similar aspects can be used, or modifications and additions can be made to the described subject matter for performing the same function of the present disclosure without deviating therefrom. In this disclosure, methods and compositions were described according to aspects of the presently disclosed subject matter. But other equivalent methods or compositions to these described aspects are also contemplated by the teachings herein. Therefore, the present disclosure should not be limited to any single aspect, but rather construed in breadth and scope in accordance with the appended claims.