Multi-Temperature Level Heat Pump Water Heaters (HPWH)

Abstract

A heat pump water heater system includes a water source providing water at a water source temperature to inlet water line(s). The system includes heat pump (“HP”) circuits that involve a heat exchanger, such as an upper HP circuit and a lower HP circuit or a main HP circuit and an auxiliary refrigerant line. The heat exchanger thermally connects the HP circuits and / or auxiliary refrigerant line to facilitate heat exchange between refrigerants flowing therethrough to allow the HP circuits to operate with different pressure differentials, improving efficiency. Heat is also be exchanged to water tanks thermally coupled to the inlet water line(s) and various HP circuit components such that outlet water lines can deliver water at a first temperature, a second temperature, or at an intermediate temperature between the two by mixing water from one or more tanks and / or inlet water lines.

Description

BACKGROUND

[0001] This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the presently described embodiments to help facilitate a better understanding of various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0002] Heat pumps (“HP”) are part of a fast-growing trend within the heating, ventilation, and air conditioning (“HVAC”) industry. Heat pumps, and more specifically heat pump water heaters (“HPWH”) use electricity to move heat from one place to another (e.g., hot water supply) instead of generating heat directly. Generally, A HPWH pulls heat from the surrounding environment and transfers the heat (at a higher temperature) to heat water in a storage tank such that it can be delivered as hot or warm water.SUMMARY

[0003] Certain aspects of some embodiments of HPWH systems and devices disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.

[0004] Embodiments of the present disclosure generally relate to heat pump water heater (“HPWH”) systems and devices, and more specifically to multi-temperature level HPWH systems. The HPWH systems and arrangements described herein may include cascaded fluid circuits that allow for more efficient heating operation and application flexibility. Efficiency in heat pump systems may refer to the amount of energy required by a compressor to compress a refrigerant or gas from one pressure or P1 to a second pressure or P2 compared to theoretical ideal operating conditions, the closer the compressor is in the amount of energy it utilizes to the ideal operating conditions (and the less energy it needs) the more efficient the overall heat pump system is. In situations where the temperature and / or pressure lift is very high, especially when delivering heating in cold climates, for example anything below 14° F., where the temperature difference between heat rejection / ejection and the heat source is high, there is a large drop in heat pump efficiency since the compressor aims to reach a very high pressure, in an inherently low pressure environment.

[0005] The HPWH system(s) embodiments include a heat exchanger that thermally connects one HP circuit (e.g., a high pressure circuit or an upper circuit) to another HP circuit (e.g., a lower pressure circuit or a lower circuit) or an auxiliary refrigerant line to facilitate heat exchange between a first refrigerant or refrigerant flow flowing through the upper circuit and the second refrigerant or second refrigerant flow flowing through the lower circuit (or auxiliary refrigerant line). The refrigerants or refrigerant flows that flow through the heat exchanger allow the heat exchanger to reduce a temperature lift needed by each of the HP circuits thereby allowing the upper HP circuit to operate within a first pressure differential, and the lower HP circuit to operate within a second pressure differential, improving efficiency of the compressors of both circuits.

[0006] The disclosed cascaded systems allow a compressor for each independent circuit to operate over a lower pressure differential and therefore increase the refrigerant mass flow rate circulation for each circuit (or reduce the compressor size). Each circuit may have a different refrigerant (that may be preferably suitable for specific operating conditions), different compressor size, different compressor type, different heat exchange unit size, and the like. Each compressor may be a fixed speed or variable speed compressor, to improve system thermal capacity at low operating temperatures and to extend system operating envelope. It should be appreciated that the HPWH systems described herein may be comprised of more than two circuits, and additional circuits may be added based on the configuration of its various components described above.

[0007] In some example embodiments, the HPWH system may include a vapor injection circuit for additional efficiency improvements. Advantageously, certain disclosed embodiments may provide for independent and part-load or full-load operations based on demand and optimized control, which improves operational efficiency and reduces power consumption during low demand periods.

[0008] Various refinements of the features noted above may exist in relation to various aspects of the present embodiments. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of some embodiments without limitation to the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] These and other features, aspects, and advantages of certain embodiments will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings.

[0010] FIG. 1A is a schematic block diagram of a heat pump water heater system, and more specifically a cascaded vapor compression HPWH system, according to an example of the present disclosure.

[0011] FIG. 1B is a schematic block diagram of a heat pump water heater system, and more specifically, according to an example of the present disclosure.

[0012] FIG. 1C is a schematic block diagram of a heat pump water heater system, and more specifically a vapor injected compression HPWH system, according to an example of the present disclosure.

[0013] FIG. 2A is a schematic diagram of a pressure enthalpy chart with an example refrigeration cycle depicted therein, according to an example of the present disclosure.

[0014] FIG. 2B is a schematic diagram of a pressure enthalpy chart with an example refrigeration cycle depicted therein, according to an example of the present disclosure.

[0015] FIG. 3 is a flow chart of a method for heating water with a heat pump, according to an example of the present disclosure.DETAILED DESCRIPTION

[0016] One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation may be described. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers'specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0017] When introducing elements of various embodiments, the articles “a,”“an,”“the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0018] The present disclosure relates to heat pump water heater (“HPWH”) systems and devices, and more specifically to multi-temperature level HPWH systems. The HPWH systems may be a cascaded vapor compression system with physically separate, but thermally coupled refrigeration or heat pump (“HP”) circuits. Alternatively, the HPWH system may be a vapor injection compression system that utilizes a single vapor injected compressor or two compressors connected in series. Regardless of the configuration, the HPWH system(s) described herein advantageously allow for a variable hot temperature water supply or two or more hot water supplies at two distinct temperature levels that can also be independently controlled within a predetermined range.

[0019] The various examples described herein provide advantageously increase and improve the efficiency of heat pump systems, especially when required pressure lift of the heat pump is very high. Various heat pumps are presented that may be composed of at least two heat pump circuits that are cascaded, fluidly isolated, and thermally connected together through a heat exchanger positioned between them. The examples described herein also advantageously extend the range of applications the system may be used and designed for, while also increasing the capacity and operating range of the heat pump system at lower temperatures.

[0020] The cascaded designs described herein advantageously allows the use of two separate independent but thermally connected circuits, each at a more restricted pressure differential or ratio, allowing each circuit to pressurize its refrigerant separately from the other circuit and reducing the pressure lift on each individual circuit. Improving the efficiency of each compressor by restricting its operations within a smaller pressure differential or range, means that a larger refrigerant mass flow rate will be able to flow through the circuit, eliminating the need for supplemental heating such as by combustion or electric heating that are less efficient or rely on the burning of fossil fuels.

[0021] Turning now the figures, FIG. 1A is a schematic block diagram of a heat pump water heater system 100a, and more specifically a cascaded vapor compression HPWH system. The HPWH system 100a is configured to provide a hot water supply to an individual (e.g., user, customer, occupant, process) at two distinct temperature levels, (i) a first or high temperature level and (ii) a second or intermediate temperature level. Alternatively, the HPWH system 100a may supply water at any intermediate temperature level between the first (e.g., high) and second (e.g., intermediate) temperature levels by mixing the flows from the water supplied at the first temperature and the water supplied at the second (intermediate) temperature. Additionally, water directly from the original water source, such as a city water source or well water, may be mixed directly with either of the flows discussed above. In the HPWH system 100a, the heat pump absorbs heat and releases the heat into a desired location (e.g., a water tank, thereby increasing the temperature of the water stored within the tank) The HPWH system 100a of FIG. 1A is a cascaded vapor compression system with two physically separate, but thermally coupled, HP circuits 110a and 110b. The HP circuits 110a, 110b, may be operated at the same or different (in case of different refrigerants) pressures. For example, the upper HP circuit 110a may be operated at a high pressure, while the lower HP circuit 110b operates at a lower pressure. The different pressures for each circuit may be maintained within a specific range or envelope that is suited for different conditions. These ranges may or may not overlap between the upper and lower HP circuits 110a, 110b depending on the desired outcomes.

[0022] A HPWH system, like the one illustrated in FIG. 1A, is capable of providing heat via a compressor by supply electricity as an energy input. Essentially, a HPWH provides heat by reversing the refrigeration cycle and by “pumping” the heat from a lower energy state to a higher energy state. Both the air 50 (e.g., ambient air) and water supply (e.g., sources of water 102a-c) contain heat, which may be utilized and moved or “pumped” via the HPWH system(s) described herein. Moving or “pumping” the heat may be accomplished by lowering the pressure of the refrigerant, thereby allowing the refrigerant to absorb heat, and then raising the pressure to release or pump the heat to water to be sent out through the hot water supply 190.

[0023] The HPWH system 100a configuration of FIG. 1A advantageously allows for a variable hot temperature water supply or two hot water supplies at two distinct temperature levels that can also be independently controlled within a predetermined range. The first higher temperature level is defined by a condenser temperature of the upper HP circuit in the cascade, and the second lower temperature level is jointly defined by an evaporator of the upper HP circuit and the condenser of the lower HP circuit, for the cascaded system.

[0024] In the illustrated example, the HPWH system 100a includes one or more sources of water 102a-c, which may be generally referred to as water source(s) 102. In the illustrated example, the water source(s) 102 may be a source of city water, a source of well water, a combination thereof, or the like. Even though the water source(s) 102 are shown as three separate water sources, the water sources 102a-c may be different intermediate storage tanks or water lines that source water from a single water source. Specifically, water source(s) 102a, 102b and 102c may each be from the city water supply. Alternatively, water source(s) 102a, 102b and 102c may each be from a well water supply. In other examples, some of the water source(s) 102 may come from one water supply (e.g., city water supply) while others come from a different water supply (e.g., well water supply).

[0025] The first water source 102a is associated with a first inlet water line 104a that leads to a water tank 108a, which may be a high temperature water tank, which is thermally coupled to a condenser 120 that is associated with the upper HP circuit 110a. The upper HP circuit 110a includes the condenser 120, an upper expansion device 140a, a heat exchanger 125, and an upper compressor 150a. The upper HP circuit 110a is also thermally coupled to a second water tank 108b, which may be an intermediate temperature water tank that may be part of or thermally coupled to the heat exchanger 125. The second water tank 108b is thermally coupled to the upper HP circuit 110a, via heat exchanger 125, between the upper expansion device 140a and the compressor 150a.

[0026] As described herein, any water “line” disclosure may also be referred to herein as “flow line(s)”, “channel(s)”, “line(s)”, “flow channel(s)”, “flow line channel(s)”, “channel(s)”, “pipe(s)”, and “pipe channel(s)”, and all these may be comprised of any of pipes, tubes, channel, or other fluid, liquid, gas, or vapor delivery and circulation mechanisms that could be of various shapes and sizes and made out of various materials. Similarly, any of the “circuits” described herein may comprise various pipes, tubes, channel, or other fluid, liquid, gas, or vapor delivery and circulation mechanisms and any couplers or connectors. The components making up the “circuits” may be of various shapes and sizes and made out of various materials.

[0027] The expansion devices disclosed herein (e.g., expansion device(s) 140, upper expansion device 140a, lower expansion device 140b, vapor injection expansion device 141, etc.) may include an expansion valve, an electronic expansion valve, a capillary tube, a thermostatic expansion valve, a piston device or the like. For example, an expansion device 140 may include a capillary tube or an electronic expansion valve such as an electric expansion valve (“EEV”) or a linear expansion valve (“LEV”). The upper expansion device 140a may include a plurality of capillary tubes, for example, two capillary tubes including a first capillary tube and a second capillary tube. The first capillary tube and the second capillary tube may be different in diameter and / or in length.

[0028] In the upper HP circuit 110a, which may be referred to as a refrigerant circuit, refrigerant flows in the counterclockwise direction from the condenser 120 to the expansion device 140a, through the heat exchanger 125 thermally coupled with the second water tank 108b (e.g., intermediate temperature water tank), to the compressor 150a and back to the condenser 120, which is thermally coupled with the first water tank 108a (e.g., high temperature water tank).

[0029] The inlet water line 104a may continue after the water tank 108 and travel to a pump 160a and eventually to a valve 164a (e.g., a three-way valve). Upon exiting the water tank 108a, the water may be directed to the outlet water line 124a to the hot water supply (“HWS”) 190 or may be mixed with water from one of the other inlet water lines 104b and 104c.

[0030] As illustrated in FIG. 1A, a high-temperature water flow 101 may be provided to valve 164a after being heated through the thermal coupling with the condenser 120. The high-temperature water flow 101 may be provided at a high-temperature level that is controlled by the condenser temperature of the upper HP circuit 110a.

[0031] The second water source 102b is associated with a second inlet water line 104b that leads to a water tank 108b, which may be an intermediate temperature water tank, which is thermally coupled to the heat exchanger 125 that is associated with both the upper HP circuit 110a and lower HP circuit 110b.

[0032] The lower HP circuit 110b includes the heat exchanger 125, an expansion device 140b, an evaporator 130 (and optionally a fan 132), and a compressor 150b. The evaporator 130 may be associated with any other air movement device to direct air 50 over (e.g., across, over or through) the evaporator 130. The lower HP circuit 110b is thermally coupled to a second water tank 108b, which may be an intermediate temperature water tank that may be part of or thermally coupled to the heat exchanger 125. In other examples, the lower HP circuit may be thermally coupled to inlet water line 104c and / or a cold-water tank associated with the water supply 102c.

[0033] From the intermediate temperature water tank 108b, the inlet water line 104b continues to pump 160b and to a valve 164b (e.g., a three-way valve), where the water may be directed to the outlet water line 124b and may optionally be mixed with water from inlet water line 104c to provide intermediate temperature water (e.g., warm water) to the warm water supply (“WWS”) 192.

[0034] An intermediate-temperature water flow 103 may be provided to valve 164b after being heated through the thermal coupling with the heat exchanger 125. The intermediate-temperature water flow 103 may be provided at an intermediate-temperature level that is jointly controlled by the various components of the heat exchanger 125, which may act as an evaporator of the upper HP circuit 110b and a condenser of the lower HP circuit 110c.

[0035] In the lower HP circuit 110a, which may be referred to as a refrigerant circuit, refrigerant flows in the counterclockwise direction from the heat exchanger 125, that is thermally coupled to the second water tank (e.g., intermediate temperature water tank) and that thermally couples the upper HP circuit 110a to the lower HP circuit 110b, to the lower expansion device 140b, through the evaporator 130 and to the lower compressor 150b, where the refrigerant is then passed back to the heat exchanger 125 to complete the circuit again.

[0036] As noted above, the heat exchanger 125 positioned between these two circuits allows the transfer of heat or facilitates heat exchange between upper HP circuit 110a carrying a first refrigerant (which may serve as a high-pressure circuit) and HP circuit 110b carrying a second refrigerant (which may serve as a low-pressure circuit). The refrigerants remain in their respective circuits but exchange heat via the heat exchanger 125 that thermally couples the two circuits together in a cascade configuration. Apart from the heat exchanger 125 that thermally couples to the two circuits 110a, and 110b, each circuit also exchanges heat at the interface between the condenser 120 and thermally coupled water tank 108a within the upper HP circuit 110a and at the interface between the heat exchanger 125 and the thermally coupled water tank 108b.

[0037] In the lower HP circuit, the evaporator 130 may absorb heat from the air, which may be effectively pumped to the water within the second water tank 109b thermally coupled to the heat exchanger 125. The heat may raise the temperature in the second water tank 109b to an intermediate temperature above the initial temperature of the water from the water source 102b. Additionally, the condenser 120 of the upper HP circuit 110a may reject heat (e.g., transmit heat to) into the water tank 108a that is thermally coupled to the condenser 120, thereby increasing the temperature of the water in the first water tank 109a to a high-temperature, above the intermediate temperature. In the heating configuration illustrated in FIG. 1A, condenser 120 rejects heat, for example into the water tank 108a while evaporator 130 in the lower HP circuit 110b absorbs heat from air running over the evaporator 130.

[0038] The system 100a illustrated in FIG. 1A advantageously allows the compressor for each independent circuit (e.g., upper compressor 150a of upper HP circuit 110a and lower compressor 150b of lower HP circuit 110b) to operate over a lower pressure differential and therefore increase the refrigerant mass flow rate circulation for each circuit, and / or allow for a reduction in the compressor size. Additionally, each circuit may have a different refrigerant (that may be preferably suitable for specific operating conditions), different compressor size, different compressor type, different heat exchange unit sizes, different configurations and the like. The compressors 150a, 150b or generally 150 described herein may be fixed speed, two-stage, tandemized, or variable speed compressor(s), to improve the system thermal performance and to extend system operating envelope. For instance, a variable speed compressor speed may be adjusted independently for each compressor to maintain a desired temperature level of the refrigerant and / or output water flows 101, 103.

[0039] The refrigerant in the upper HP circuit 110a may be pressurized by the upper compressor 150a, to a first pressure. Additionally, the refrigerant in the lower HP circuit 110b may be pressurized by the lower compressor 150b to a second pressure. In some examples, one or more of the compressors may be vapor injected (see, for example, FIG. 1C and corresponding description), or they may be variable speed compressors. The compressed and pressurized first refrigerant flow is circulated through the upper HP circuit 110a while a compressed and pressurized second refrigerant flow is circulated through the lower HP circuit 110b. The first refrigerant flow and the second refrigerant flow both run through the heat exchanger 125 and as the first refrigerant from the upper HP circuit 110a and the second refrigerant from the lower HP circuit 110b flow through the heat exchanger 125, heat is exchanged between the refrigerants in the two circuits. This exchange of heat allows each circuit to operate at a restricted pressure differential or envelope since each circuit covers one portion of an otherwise larger pressure differential of a conventional heat pump system.

[0040] The third water source 102c is associated with a third inlet water line 104c that leads to a pump 160c and valve 164c. In other examples (see FIG. 1B), the third water source 102c and / or inlet water line 104c may be thermally coupled to the evaporator 130.

[0041] It should be appreciated that water may be supplied directly to the WWS from WS 102c, which is water that is not thermally coupled to either the upper or lower HP circuits 110a, 110b. In another example, water may be supplied to the WWS from both inlet water lines 104c and inlet water lines 104b. In other examples, water may be supplied to the HWS 190 from one or more of inlet water lines 104a, 104b and 104c.

[0042] Bridge lines 114a and 114b bridge or connect the various water liens together via valves 164a-c. For example, three-way valve 164a is connected or bridged to three-way valve 164b via bridge line 114a thereby allowing water from inlet water lines 104a entering valve 164a to be mixed with water from valve 164b (e.g., water from inlet water line 104b and bridge line 114b). Bridge line 114b connects three-way valve 164b and three-way valve 164c, thereby connecting the circuits to raw or ambient water.

[0043] The valve arrangement allows water to be mixed according to control logic of controller 195. For example, control instructions may be provided that direct pumps 160 and valves 164 to adjust their flow rates, valve open and close configurations, etc. to adjust the amount of water from the various water flows 101, 103, 105 that are provided and / or combined before being supplied at one of the outlet water lines 124a, 124b. As described herein, the water flows 101 and 103, which are at different temperatures, can be combined to achieve a desired output temperature, which a more efficient approach than combining a cold-water stream with the first higher temperature water flow 101. In other examples, the cold-water stream (e.g., cold water flow 105) may be mixed with flow 101 and / or flow 103 to achieve a different desired output temperature.

[0044] It should be appreciated that each cascaded circuit (e.g., HP circuits 110a and 110b) of the HPWH system 100a can be operated independently, while the other circuit may be left deenergized or shut down. This provides another level of flexibility to operate HPWH system 100a at part-load conditions and save on energy consumption while improving system operating efficiency and reducing electric grid electricity demand. Also, it should be appreciated that more than two cascaded circuits can be implemented to further extend operational flexibility and improve performance. Furthermore, pumps 160a-c (e.g., water pumps) can be fixed or variable speed pumps and can be replaced by a single water pump 160.

[0045] Moving now to FIG. 1B, which illustrates a schematic block diagram of a heat pump water heater system 100b, and more specifically a cascaded vapor compression HPWH system. The HPWH system 100b is configured to provide a hot water supply to an individual (e.g., user, customer, occupant, process) at least two distinct temperature levels, (i) a first or high temperature level and (ii) a second or intermediate temperature level. Alternatively, the HPWH system 100a may supply water at any intermediate temperature level between the first (e.g., high) and second (e.g., intermediate) temperature levels by mixing the flows from the water supplied at the first temperature and the water supplied at the second (intermediate) temperature. Additionally, water directly from the original water source, such as a city water source or well water, may be mixed directly with either of the flows discussed above.

[0046] The HPWH system 100b of FIG. 1B may include many of the same components and perform many of the same operations and functions as HPWH system 100a. However, instead of the evaporator 130 being associated with a fan 132, the evaporator 130 of HPWH system 100b may instead be thermally coupled to the inlet water line 104c and / or another water storage tank 108c. The inlet water line 104c and / or the water tank 108c may improve the efficiency of the evaporator 130 by further assisting the evaporator 130 in cooling the refrigerant.

[0047] Instead of inlet water line 104c leading directly to the pump 160c and valve 164c as in the example illustrated in FIG. 1A, the HPWH system 100b of FIG. 1B may include a water tank 108c or otherwise thermally couple the inlet water line 104c to the lower HP circuit 110b.

[0048] FIG. 1C is a schematic block diagram of a heat pump water heater system 100c, and more specifically vapor injection HPWH system. The HPWH system 100c is configured to provide a hot water supply to an individual (e.g., user, customer, occupant, process) at two distinct temperature levels, (i) a first or high temperature level and (ii) a second or intermediate temperature level. Alternatively, the HPWH system 100c may supply water at any intermediate temperature level between the first (e.g., high) and second (e.g., intermediate) temperature levels by mixing the flows from the water supplied at the first temperature and the water supplied at the second (intermediate) temperature. Additionally, water directly from the original water source, such as a city water source or well water, may be mixed directly with either of the flows discussed above.

[0049] The HPWH system 100c of FIG. 1C includes a vapor injection system positioned along an auxiliary refrigerant line extending from and thermally coupled to a main HP circuit 110. The HPWH system 100c includes one or more sources of water 102a-c, which may be generally referred to as water source(s) 102. In the illustrated example, the water source(s) 102 may be a source of city water, a source of well water, a combination thereof, or the like. Even though the water source(s) 102 are shown as three separate water sources, the water sources 102a-c may be different intermediate storage tanks or water lines that source water from a single water source. Specifically, water source(s) 102a, 102b and 102c may each be from the city water supply. Alternatively, water source(s) 102a, 102b and 102c may each be from a well water supply. In other examples, some of the water source(s) 102 may come from one water supply (e.g., city water supply) while others come from a different water supply (e.g., well water supply).

[0050] The first water source 102a is associated with a first inlet water line 104a that leads to a water tank 108a, which may be a high temperature water tank, which is thermally coupled to a condenser 120 that is associated with the main HP circuit 110. The main HP circuit 110 includes the condenser 120, a heat exchanger 125, an expansion device 140, an evaporator 130, and a compressor 150.

[0051] As noted above, the HPWH system 100c also includes an auxiliary refrigerant line 110c that includes a secondary expansion device 141, such as a vapor injection device or vapor injection system. The auxiliary refrigerant line 110c is thermally coupled to the heat exchanger 125 (and water tank 108b) and travels from the condenser 120 to the compressor 150. The water tank 108b may be an intermediate temperature water tank or an economizer water tank that may be part of or thermally coupled to the heat exchanger 125.

[0052] In the main HP circuit 110, which may be referred to as a refrigerant circuit, refrigerant flows in the counterclockwise direction from the condenser 120, through the heat exchanger 125, to the expansion device 140, to the evaporator 130 and then to the compressor 150. The condenser 120 may be thermally coupled with the first water tank 108a (e.g., high temperature water tank), the heat exchanger 125 may be thermally coupled with a second water tank 108b (e.g., intermediate temperature water tank), and the evaporator may be thermally coupled with a third water tank (low temperature water tank).

[0053] The inlet water line 104a may continue after the water tank 108a and travel to a pump 160a and eventually to a valve 164a (e.g., a three-way valve). Upon exiting the water tank 108a, the water may be directed to the outlet water line 124a to the hot water supply (“HWS”) 190 or may be mixed with water from one of the other inlet water lines 104b and 104c.

[0054] The second water source 102b is associated with a second inlet water line 104b that is thermally coupled to a heat exchanger 125 and / or a water tank 108b, which may be an intermediate temperature water tank or an economizer tank. From the water tank 108b, the water line 104b continues to pump 160b and valve 164b (e.g., a three-way valve), where the water may be directed to the outlet water line 124b and may optionally be mixed with water from water line 104c to provide intermediate temperature water (e.g., warm water) to the warm water supply (“WWS”) 192.

[0055] The third water source 102c is associated with a third inlet water line 104c that ultimately leads to a pump 160c and valve 164c. Similar to the example illustrated in FIG. 1B, the third inlet water line 104c may lead to a third water tank 108c or may otherwise be thermally coupled to the evaporator 130.

[0056] Similar to the examples of FIGS. 1B and 1C, the HPWH system 100c of FIG. 1C includes bridge lines 114a and 114b, which are configured to bridge or connect the various water lines together via valves 164a-c.

[0057] Conversely, in the auxiliary refrigerant line 110c, a portion of the refrigerant (e.g., an auxiliary refrigerant flow) may be diverted from the condenser 120 and the main refrigerant flow to a vapor injection expansion device 141 before entering the heat exchanger 125. The refrigerant leaves the heat exchanger 125 as vapor or a vapor-liquid mixture and is injected into the compressor 150.

[0058] In an example, the nested HVAC circuit 110c may implement a flash tank or an internal heat exchanger. For example, after the refrigerant passes through condenser 120, the refrigerant may be separated into liquid and vapor phases. In an example, the liquid phase of the refrigerant may be passed through the main HP circuit 110 such that it passes through a lower-stage expansion device 140 and then into the evaporator 130. The vapor phase of the refrigerant may be passed through the nested HVAC circuit 110c may be passed through a vapor injection expansion device 141 and later injected into the compressor 150 to improve the efficiency of the condenser.

[0059] During use, a portion (e.g., auxiliary flow) of refrigerant is diverted from the main HP Circuit 110 (and the main refrigerant flow) to a vapor injection system positioned about an auxiliary refrigerant line 110c. The auxiliary flow may be cooled or chilled initially via the vapor injection expansion device 141 and then may continue to flow through the heat exchanger 125 to facilitate heat exchange between the main refrigerant flow and the cooled auxiliary flow to cool the main flow and evaporate the auxiliary flow. Furthermore, the evaporated auxiliary flow may be sent to the compressor 150 to improve the performance of the compressor 150 as compared to not using the evaporated auxiliary flow.

[0060] The vapor injection expansion device 141 is positioned between the condenser 120 and the compressor 150 along the auxiliary refrigerant line 110c without passing through the evaporator 130. By positioning the vapor injection expansion device 141 along the auxiliary refrigerant line 110c, the HPWH system 100c may provide more control on refrigerant or air volumes and flow rates and may provide additional efficiency, especially at lower temperatures. The vapor injection device or system may advantageously increase the HPWH system 100c′s heating capacity, reduce power consumption, increase refrigerant mass flow rate, and improve operational efficiency.

[0061] It should be appreciated that although the vapor injection is shown only at one intermediate pressure level, multiple vapor injection levels can be implemented for a vapor injection expansion device 141 (e.g., a single vapor-injected compressor or compressors connected in series), allowing for greater control flexibility and improved operational efficiency. Also, it should be appreciated that one or both cascades (e.g., upper HP circuit 110a and lower HP circuit 110b) of the HWHP system 100a or 100b can be equipped with the vapor injection expansion device 141 (e.g., vapor injected compressor and auxiliary devices) to further improve system performance.Pressure-Enthalpy Diagram

[0062] Referring briefly to FIG. 2A, which illustrates a pressure enthalpy (“P-H”) diagram 200a, the pressure, enthalpy, temperature and phase transitions of the refrigerant may be described and discussed with reference to FIGS. 1A and 1B. The P-H diagram 200a describes the relationship of pressure and enthalpy for a refrigerant used in the HPWH system 100a of FIG. 1A and / or HPWH system 100b of FIG. 1B.

[0063] In the P-H diagram 200a illustrated in FIG. 2A, pressure is indicated on the y-axis and enthalpy is indicated on the x-axis. The P-H curve 205, which has a hill or upside down “U” shape, designates phase changes for the refrigerant. For example, the left portion 210 of the P-H curve 205 indicates at when pressure and enthalpy values the refrigerant is a saturated liquid (e.g., the saturated liquid curve) and the right portion 220 indicates when the refrigerant is a saturated vapor (e.g., the saturated vapor curve).

[0064] The region between the two curves is a “mixed region” that describes various refrigerant states that contain a mixture of both liquid and vapor. Outside of the curve, to the left of the saturated liquid portion of the curve, indicates a liquid region 240 that the refrigerant is in a liquid form (e.g., a sub-cooled liquid). On the opposite side, to the right of the saturated vapor portion of the curve, indicates a vapor region 250 that the refrigerant is in a vapor form (e.g., super-heated vapor). So essentially, the curve delineates the P-H diagram 200a into a liquid region 240, a vapor region 250, and a mixed region 245.

[0065] As noted above, the liquid region 240 may also be referred to as a sub-cooled liquid region. This liquid region 240 typically is characterized by vertical temperatures lines (noting constant enthalpy), which increase (e.g., temperature increases for each vertical line progressing from the left to right along the x-axis or enthalpy-axis) as the enthalpy is increased. For example, at a first enthalpy value (e.g., 1X), the temperature may be (−40° F.) and at a second enthalpy value (e.g., 2X), the temperature may be (−20° F.) and so on, progressing through 0° F., 20° F., 40° F., 60° F., etc.

[0066] In the vapor region 250, which may be referred to as a super-heated vapor region, there are vertical or nearly vertical temperature lines starting at the x-axis and extending upward along the positive y-axis. Similar to the liquid region 240, the vertical temperature lines may increase as enthalpy is increased (e.g., −40° F., −20° F., 0° F., 20° F., 40° F., 60° F., etc. and so on). The temperature lines then curve left, back towards the y-axis, as they meet the curve 205, come into close proximity to the curve 205, and / or extend near the peak or y-value of the critical point 230 of the curve 205.

[0067] In the mixed region 245, which may also be referred to as a liquid-vapor mix region, the temperature lines are horizontal thereby indicating constant temperature at each pressure while within under the curve 205. For example, As the pressure increases from the origin at the x-axis and moves upward, the horizontal temperature lines may progress upward (similar to the rungs of a ladder) and may progress from −60° F. (e.g., at 1Y), to −40° F. at 2Y, to −20° F., 0° F., 20° F., 40° F., 60° F., etc. up to the boiling point or phase transition temperature from liquid to vapor, which for water would be 212° F. As enthalpy increases (e.g., moving to the right in the mixed region) more and more liquid will vaporize, and liquid will continue to transition into vapor instead of increasing the temperature. For example, in this mixed region 245 the increased enthalpy causes liquid to phase change to a vapor while maintaining a constant temperature, whereas changes in enthalpy outside of the curve 205 typically result in changes in temperature.

[0068] The mixed region 245 may also have a plurality of upward sloping curves indicating various levels or ratios of vapor mass to total mass. For example, a level or ratio of 0.1 or ten percent (e.g., 10%), would be an upward sloping curve near the saturated liquid portion 210 of the curve 205 and would identify each of the positions on the P-H diagram 205 where the refrigerant consists of ten percent vapor by mass. On the opposite end of the ratio, an upward sloping curve near the saturated vapor portion 220 of the curve 205 may have a level or ratio value of 0.9 (e.g., ninety percent or 90%). The upward sloping curve representing a ratio of 0.9 identifies positions on the P-H diagram 204 where the refrigerant consists of ninety percent vapor by mass.

[0069] The merging location of (a) the saturated liquid portion 210 of the curve 205 and (b) the saturated vapor portion 220 of the curve 205; or the point at which (a) and (b) meet is the critical point 230. The critical point 230 designates the point on the diagram at which vapor is unable to transition or phase change into a liquid regardless of how much additional pressure is applied to the refrigerant. Example P-H diagrams for various refrigerants (e.g., R-134a) may be found in the American Society of Heating, Refrigeration and Air Conditioning Engineers (“ASHRAE”) Fundamentals book or various other sources that publish P-H diagrams 205.

[0070] Turning now to FIG. 2B, which illustrates a pressure enthalpy (“P-H”) diagram 200b, the pressure, enthalpy, temperature and phase transitions of the refrigerant may be described and discussed with reference to FIG. 1C. The P-H diagram 200b describes the relationship of pressure and enthalpy for a refrigerant used in the HPWH system 100c of FIG. 1C.Refrigeration Cycles

[0071] The refrigeration cycles for the upper circuit 110a and lower circuit 110b of FIG. 1A are described in more detail below with reference to FIG. 2A. The various stages or steps of an example refrigeration cycle include (1) evaporation from evaporator(s) 130, (2) compression from compressor(s) 150, (3) condensation from condenser(s) 120, and (4) expansion from expansion device(s) 140.

[0072] As noted above, the upper circuit 110a and lower circuit 110b may be thermally coupled with a heat exchanger 125, which may include condenser(s), evaporator(s) and the like to transfer heat between the upper circuit 110a and lower circuit 110b. For example, the heat exchanger 125 may function as an evaporator for the upper circuit 110a and may function as a condenser for the lower circuit 110b.

[0073] As refrigerant is passed through the circuit 110a, the evaporation process 282, which occurs between points “A” and “B” on the P-H diagram 200a, occurs at the heat exchanger 125. Since point “A” is within or under the curve 205 and within the mixed region 245, the refrigerant is a liquid-vapor mixture. At point “B” the refrigerant is fully saturated vapor, within vapor region 250. The phase change transitions from point “A” to “B” may occur at a constant temperature because energy (e.g., heat) transferred to the refrigerant by the evaporator 130 is used to convert the liquid into a gas or vapor.

[0074] After passing through the heat exchanger 125, which may include an evaporator or the like, the refrigerant is routed to a compressor 150a where the compression process 284 begins. As illustrated in FIG. 2A, the compression process 284 for the upper circuit 110a occurs between points “B”and “C”on the P-H diagram 200a.

[0075] At the compressor 150a, the refrigerant enters at the exit temperature of the heat exchanger 125 (e.g., evaporator) and the compressor 150a increases the pressure of the refrigerant. The compression process 284 may occur as a near-constant entropy process (e.g., isentropic compression), which is indicated by the sloped line for the compression process 284. As the compressor 150a compresses the refrigerant, the pressure of the refrigerant and enthalpy increase until reaching point “C”. Then, the higher-pressure refrigerant travels to a condenser 120 for the condensation process 286.

[0076] The condensation process 286 for the upper circuit 110a, occurs between points “C” and “D”. During the condensation process 286, the condenser 120 transforms the higher pressure, heated vapor by cooling the vapor to a saturation temperature (e.g., where the condensation process 286 intersects the saturated vapor portion 220 of the curve 205). Generally, the condenser 120 is configured to release or reject heat.

[0077] As the refrigerant cools, heat flows from the refrigerant vapor to a cooling medium associated with the condenser 120. In the example illustrated in FIG. 1A, heat from the condensation process 286 is transferred to a water tank 108a, such as a high temperature water tank. For example, the condenser 120 is configured to supply heat to the high temperature water tank 108a through the phase transition of the refrigerant from a vapor to a liquid.

[0078] Then, the saturated vapor transitions from vapor to a liquid-vapor mix in the mixed region 245. During the phase change as the vapor changes to liquid, additional heat is transferred from the refrigerant to the high temperature water tank 108a. In the example illustrated in FIG. 2A, the refrigerant may be sub-cooled, and since the refrigerant is saturated liquid at point “D”, any further heat loss decreases the temperature of the refrigerant since the phase change from vapor to liquid has completed.

[0079] In the last phase of the refrigeration cycle, the expansion process 288 occurs between points “D” and “A”. During the expansion process 288, an expansion device 140a expands the high-pressure refrigerant to a lower pressure liquid-vapor refrigerant. The expansion device is configured to reduce or lower the pressure of the refrigerant so that the refrigeration cycle can begin anew. Typically, the expansion process 288 may perform near-adiabatic expansion, which is characterized by the vertical line on the P-H diagram 200a (e.g., constant enthalpy). Once back at point “A”, the refrigeration cycle can be repeated as the refrigerant is cycled through the upper circuit 110a.

[0080] While a refrigeration cycle is occurring within the upper circuit 110a, the lower circuit 110b may perform its own refrigeration cycle. During the evaporation process 282′ in the lower circuit 110b, refrigerant is passed through the evaporator 130. Generally, an evaporator 130 is configured to absorb heat.

[0081] The evaporation process 282′ occurs between points “A′” and “B′” on the P-H diagram 200a. Similar to the refrigeration cycle for the upper circuit 110a, Point “A′” indicates that the refrigerant is a liquid-vapor mixture in the mixed region 245. At point “B′” the refrigerant is fully saturated vapor, within vapor region 250. In the example illustrated in FIG. 1A, the evaporator 130 may be associated with a fan 132 or other air-movement device that is configured to blow or pass air 50 over (e.g., across, over, or through) the evaporator 130, which may improve the efficiency of the evaporator 130.

[0082] After passing through evaporator 130, the refrigerant is routed to a compressor 150b where the compression process 284′ begins. As illustrated in FIG. 2A, the compression process 284 for the lower circuit 110b occurs between points “B′” and “C′” on the P-H diagram 200a. The compressor(s) 150 associated with the compression process 284′ are configured to raise the pressure of the refrigerant.

[0083] At the compressor 150b, the refrigerant enters at the exit temperature of the evaporator 130 and the compressor 150b increases the pressure of the refrigerant. The compression process 284′ may occur as a near-constant entropy process (e.g., near-isentropic compression), which is indicated by the sloped line for the compression process 284′. As the compressor 150b compresses the refrigerant, the pressure of the refrigerant and enthalpy increase until reaching point “C′”. Then, the higher-pressure refrigerant travels to a heat exchanger 125, which may act as a condenser for the lower circuit 110b. The condensation process 186′ for the lower circuit 110b may occur at the heat exchanger 125, which may be thermally coupled to an intermediate temperature water tank 108b.

[0084] The condensation process 286′, for the lower circuit 110b, occurs between points “C′” and “D′”. During the condensation process 286′, the heat exchanger 125 transforms the higher pressure, heated vapor by cooling the vapor to a saturation temperature (e.g., where the condensation process 286′ intersects the saturated vapor portion 220 of the curve 205. As the refrigerant cools, heat flows from the refrigerant vapor to a cooling medium associated with the heat exchanger (e.g., intermediate temperature water tank 108b). In the example illustrated in FIG. 1A, heat from the condensation process 286′ is transferred to a water tank 108b, such as an intermediate temperature water tank.

[0085] For example, as the refrigerant in the lower circuit 110b changes phase from vapor to liquid in the condensation process 286′ occurring at the heat exchanger 125, heat may be supplied to the intermediate temperature water tank 108b through the phase transition of the refrigerant from a vapor to a liquid.

[0086] Then, the saturated vapor transitions from vapor to a liquid-vapor mix in the mixed region 245. During the phase change as the vapor changes to liquid, additional heat is transferred from the refrigerant to the intermediate temperature water tank 108b. In the example illustrated in FIG. 2A, the refrigerant may be sub-cooled, and since the refrigerant is saturated liquid at point “D”, any further heat loss decreases the temperature of the refrigerant since the phase change from vapor to liquid has completed.

[0087] Lastly, the expansion process 288′ occurs between points “D′” and “A′”. For example, an expansion device 140b expands the high-pressure refrigerant to a lower pressure liquid-vapor refrigerant. The expansion process 288′ may be near-adiabatic at a near-constant enthalpy. Once back at point “A”, the refrigeration cycle for the lower circuit 110b can be repeated as the refrigerant is cycled through the upper circuit 110a.

[0088] It should be appreciated that the refrigeration cycles for the upper circuit 110a and lower circuit 110b of FIG. 1B may be similarly described, as they were for HPWH system 100a, with reference to FIG. 2A. Therefore, any common components or features between system 100a and 100b may have the same characteristics, configurations and features unless otherwise specified.

[0089] The refrigeration cycles for the main circuit 110 and nested circuit 110c of FIG. 1C are described in more detail below with reference to FIG. 2B. The nested circuit may serve as an injection circuit or an injection branch to inject refrigerant into the compressor. The various stages or steps of an example refrigeration cycle include (1) evaporation from evaporator(s) 130, (2) compression from compressor(s) 150, (3) condensation from condenser(s) 120, and (4) expansion from expansion device(s) 140.

[0090] As noted above, the main circuit 110 may be thermally coupled with a heat exchanger 125, which may include condenser(s), evaporator(s) and the like to transfer heat between the main circuit 110 and the nested circuit 110c.

[0091] As refrigerant is passed through the main circuit 110, the evaporation process 282, which occurs between points “A” and “B” on the P-H diagram 200b, occurs at evaporator 130. Since point “A” is within or under the curve 205 and within the mixed region 245, the refrigerant is a liquid-vapor mixture. At point “B” the refrigerant is fully saturated vapor, within vapor region 250. The phase change transitions from point “A” to “B” may occur at a constant temperature because energy (e.g., heat) transferred to the refrigerant by the evaporator 130 is used to convert the liquid into a gas or vapor. The evaporator 130 may be thermally coupled to the inlet water line 104c or water tank 108c to further improve the efficiency of the evaporator 130.

[0092] After passing through the evaporator 130, the refrigerant is routed to a compressor 150 where the compression process 284 begins. As illustrated in FIG. 2B, the compression process 284 for the main circuit 110 occurs between points “B” and “C′” or “C” on the P-H diagram 200b.

[0093] At the compressor 150, the refrigerant enters at the exit temperature of the evaporator 130 and the compressor 150 increases the pressure of the refrigerant. The refrigerant may also enter the compressor 150 at the exit temperature of the heat exchanger 125 and / or vapor injection expansion device 141, which is described in more detail below. The compression process 284 may occur as a near-constant entropy process (e.g., near-isentropic compression), which is indicated by the sloped line for the compression process 284. As the compressor 150a compresses the refrigerant, the pressure of the refrigerant and enthalpy increase until reaching point “C”. Then, the higher-pressure refrigerant travels to a condenser 120 for the condensation process 286.

[0094] The condensation process 286 for the main circuit 110, occurs between points “C” and “D” or “D′”. During the condensation process 286, the condenser 120 transforms the higher pressure, heated vapor by cooling the vapor to a saturation temperature (e.g., where the condensation process 286 intersects the saturated vapor portion 220 of the curve 205). Generally, the condenser 120 is configured to release or reject heat.

[0095] As the refrigerant cools, heat flows from the refrigerant vapor to a cooling medium associated with the condenser 120. In the example illustrated in FIG. 1C, heat from the condensation process 286 is transferred to a water tank 108a, such as a high temperature water tank. For example, the condenser 120 is configured to supply heat to the high temperature water tank 108a through the phase transition of the refrigerant from a vapor to a liquid.

[0096] The main difference of the HPWH system 100c from the other systems described herein, is that after exiting the condenser 120, at least some of the refrigerant may be routed through the nested circuit 110c to be used in a vapor injection refrigeration cycle. For example, the vapor injection device 141 may be used to drop the pressure of the refrigerant in an expansion process 288′ bringing that portion of the refrigerant to point “A-V” on the P-H diagram 200b before the fluid is passed through the heat exchanger 125 and is later injected into the compressor at point “B-V” where an additional compression process 284′ may occur.

[0097] For example, a portion of the condensed liquid refrigerant may be expanded through an expansion device, such as vapor injection device 141. The refrigerant may be further cooled via heat exchanger 125, and then the vapor (e.g., super-heated vapor) may be injected into the compressor 150. The additional subcooling performed during the refrigeration cycle advantageously increases the capacity of the evaporator by reducing temperature of the refrigerant and thus reducing enthalpy. Given the additional mass flow associated with the vapor injection, advantageously provides additional heat transfer at the condenser 120 and thus higher efficiency than conventional systems. For example, the subcooling achieved in the HPWH system 100c may be achieved while using less power than other methods because the incremental vapor created during subcooling is only compressed from a higher pressure instead of the lower suction pressure of the system.

[0098] Then, after being injected at the compressor, a vapor injected compression process 284′ occurs which brings the refrigerant to point “C”on the P-H diagram 200b of FIG. 2B.

[0099] The expansion processes 288 and 288′ represented in FIG. 2B occurs between points “D” and “A” in association with expansion device 140 of FIG. 1C and occurs between points “D′” and “A-V” in association with the vapor injection expansion device 141. During the expansion processes 288 and / or 288′, an expansion device 140 is configured to reduce or lower the pressure of the refrigerant. For example, the expansion device 140, 141 may expand the high-pressure refrigerant to a lower pressure liquid-vapor refrigerant so that the refrigeration cycle can begin anew.

[0100] It should be appreciated that although the vapor compression cycle is shown as operating in the sub-critical region, trans-critical or super-critical cycles can be equally employed for the entire system or one of the cascaded circuits. An example trans-critical fluid known in the heating, ventilating, air conditioning and refrigerating (“HVAC&R”) industry is CO2 or carbon dioxide. Other such trans-critical or super-critical fluids can be used as well.Methods

[0101] Turning now to FIG. 3, which is a flow chart of a method 300 for heating water with a heat pump, such as one of the HPWH systems 100a, 100b or 100c described herein. In step 310, the method 300 includes flowing water along a first inlet water line from a water source to a first water tank that is thermally coupled to a condenser of a first HP circuit of a heat pump water heater. For example, method 300 may include flowing water along a first inlet water line 104a from a water source 102 to a first water tank 108a. The water tank 108a may be a high-temperature water tank that is thermally coupled to a condenser 120 of a first HP circuit (e.g., upper HP circuit 110a or main HP circuit 110). In an example, flowing water along the first inlet water line 104a may follow the arrangement and configuration of any of the HPWH systems 100a-c illustrated in FIG. 1A-1C and may be achieved through use of the water lines, valves, pumps and other components of the HPWH system(s) 100 illustrated and described herein.

[0102] In step 320, the method 300 includes flowing water along a second inlet water line from a water source to a second water tank that is thermally coupled to a heat exchanger of the first HP circuit and a second HP circuit. For example, method 300 may include flowing water along a second inlet water line 104b from a water source 102 to a second water tank 108b. The water tank 108b may be an intermediate-temperature water tank or an economizer tank that is thermally coupled to a heat exchanger 125 of a first HP circuit (e.g., upper HP circuit 110a or main HP circuit 110). In an example, flowing water along the second inlet water line 104b may follow the arrangement and configuration of any of the HPWH systems 100a-c illustrated in FIG. 1A-1C and may be achieved through use of the water lines, valves, pumps and other components of the HPWH system(s) 100 illustrated and described herein.

[0103] Additionally, in step 330, the method 300 includes circulating a first refrigerant through the first HP circuit. In step 340, the method 300 includes circulating a second refrigerant through the second HP circuit. It should be appreciated that the first refrigerant and the second refrigerant may be the same refrigerant. Alternatively, the first refrigerant and the second refrigerant may be different based on suitability at different temperature ranges. Various refrigerants or refrigerant combinations may be used in each HP circuit, based on the desired operating condition of each circuit, including for example CO2 and R32.

[0104] Circulating refrigerant through the first and second HP circuits may follow the arrangement and configuration of the various refrigeration circuits and cycles described herein. It should be appreciated that one or more of steps 330 and 340 may be optional as the HPWH and associated HP circuits may be operated independently, at part-load, or at full-load conditions based on hot water demand and control logic. For example, it should be appreciated that upper and lower HP circuits or a main HP circuit and an auxiliary line and / or circuit can operate independently at part-load or full-load conditions (based on the conditioned space demand and environmental conditions, as well as optimized control logic), and if they integrate a variable speed compressor, the speed can be adjusted independently for each compressor.

[0105] In step 350, the method 300 includes exchanging heat between the first refrigerant flow and the second refrigerant flow via the heat exchanger to adjust the temperature of the water in one of the first water tank and / or the second water tank. For example, refrigerant may by circulated through their respective HP circuit or auxiliary refrigerant line, which is thermally coupled to the heat exchanger to exchange heat with the water tank 108b that is also thermally coupled to the heat exchanger 125. Furthermore, heat may be exchanged to the water tank 108a via the condenser 120 as described above.

[0106] In step 360, the method 300 includes controlling a valve arrangement to direct flow from at least one of the first water tank, the second water tank, or the water source. For example, method 300 may include controlling a valve arrangement (e.g., valves 160a, 160b and / or 160c) via controller 195 to direct flow from water tank 108a, water tank 108b and / or water source 102. For example, referring to FIG. 1A, water flow may be directed to an outlet water line (e.g., outlet water line 124b) by directing water from one or more of bridge line 114a, bridge line 114b and / or inlet water line 104c towards valve 164c and then opening valve 164c to direct flow towards outlet water line 124b. Similarly, water flow may be directed to outlet water line 124a by directed water from one or more of bridge line 114b, bridge line 114a and / or inlet water line 104a towards valve 164a and then opening valve 164a to direct flow towards outlet water line 124a.

[0107] It should be appreciated that the outlet water temperature may be dependent on the flow rate, quantity (e.g., mass and volume), temperature and other characteristics of the water flowing through the various water lines 104, water tanks 108, pump(s) 160 and valve(s) 164.

[0108] The method 300 may also include providing water at a desired outlet temperature at the water outlet. For example, method 300 may include providing water at a desired outlet temperature at water outlet 124. Water may be provided at water outlet 124a, which is designated for providing hot water or water outlet 124b, which is designated for providing cold or warm water.

[0109] It should be appreciated that method 300 may include more or less steps than those illustrated in FIG. 3. Furthermore, some of the steps illustrated in FIG. 3 may be repeated, rearranged to change their order, or otherwise modified according to the examples described herein and illustrated in FIG. 1A-2B. For example, method 600 may include flowing raw unprocessed debris slurry 150 and / or processed debris slurry 150′ through one or more additional chambers (e.g., additional chamber 110 or chamber(s) 120, 130) of the debris SAS apparatus 105.

[0110] Method 300 may provide two water flows at different temperatures (e.g., a high-temperature water flow 101 at high-temperature 201 or an intermediate-temperature water flow 103 at intermediate temperature 203). Method 300 may also combine water flows to achieve the desired temperature between temperatures 201 and 203, or to achieve another desired temperature between temperature 203 and the temperature of the water source. It should be appreciated that combining water flows 101 and 103 may be a more efficient approach than combining a cold-water stream (e.g., from water source 102) with the first higher temperature water flow 101.

[0111] While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims. For example, certain embodiments disclosed here envisage usage with a powered fan rather than an inducer fan, or no fan at all. Moreover, the rotating equipment (e.g., motors) and valves disclosed herein are envisaged as being operable at specified speeds or variable speeds through inverter circuitry, for example. Moreover, the internal and external communication of the furnace may be accomplished through wired and or wireless communications, including known communication protocols, Wi-Fi, 802.11(x), Bluetooth, to name just a few.

Examples

Embodiment Construction

[0016]One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation may be described. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers'specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0017]When introducing elements of various embodiments, the articles “a,”“an,”“the,” and “said” are intended to mean that there are one or more of the elements. The terms “...

BACKGROUND

[0001] This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the presently described embodiments to help facilitate a better understanding of various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0002] Heat pumps (“HP”) are part of a fast-growing trend within the heating, ventilation, and air conditioning (“HVAC”) industry. Heat pumps, and more specifically heat pump water heaters (“HPWH”) use electricity to move heat from one place to another (e.g., hot water supply) instead of generating heat directly. Generally, A HPWH pulls heat from the surrounding environment and transfers the heat (at a higher temperature) to heat water in a storage tank such that it can be delivered as hot or warm water.SUMMARY

[0003] Certain aspects of some embodiments of HPWH systems and devices disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.

[0004] Embodiments of the present disclosure generally relate to heat pump water heater (“HPWH”) systems and devices, and more specifically to multi-temperature level HPWH systems. The HPWH systems and arrangements described herein may include cascaded fluid circuits that allow for more efficient heating operation and application flexibility. Efficiency in heat pump systems may refer to the amount of energy required by a compressor to compress a refrigerant or gas from one pressure or P1 to a second pressure or P2 compared to theoretical ideal operating conditions, the closer the compressor is in the amount of energy it utilizes to the ideal operating conditions (and the less energy it needs) the more efficient the overall heat pump system is. In situations where the temperature and / or pressure lift is very high, especially when delivering heating in cold climates, for example anything below 14° F., where the temperature difference between heat rejection / ejection and the heat source is high, there is a large drop in heat pump efficiency since the compressor aims to reach a very high pressure, in an inherently low pressure environment.

[0005] The HPWH system(s) embodiments include a heat exchanger that thermally connects one HP circuit (e.g., a high pressure circuit or an upper circuit) to another HP circuit (e.g., a lower pressure circuit or a lower circuit) or an auxiliary refrigerant line to facilitate heat exchange between a first refrigerant or refrigerant flow flowing through the upper circuit and the second refrigerant or second refrigerant flow flowing through the lower circuit (or auxiliary refrigerant line). The refrigerants or refrigerant flows that flow through the heat exchanger allow the heat exchanger to reduce a temperature lift needed by each of the HP circuits thereby allowing the upper HP circuit to operate within a first pressure differential, and the lower HP circuit to operate within a second pressure differential, improving efficiency of the compressors of both circuits.

[0006] The disclosed cascaded systems allow a compressor for each independent circuit to operate over a lower pressure differential and therefore increase the refrigerant mass flow rate circulation for each circuit (or reduce the compressor size). Each circuit may have a different refrigerant (that may be preferably suitable for specific operating conditions), different compressor size, different compressor type, different heat exchange unit size, and the like. Each compressor may be a fixed speed or variable speed compressor, to improve system thermal capacity at low operating temperatures and to extend system operating envelope. It should be appreciated that the HPWH systems described herein may be comprised of more than two circuits, and additional circuits may be added based on the configuration of its various components described above.

[0007] In some example embodiments, the HPWH system may include a vapor injection circuit for additional efficiency improvements. Advantageously, certain disclosed embodiments may provide for independent and part-load or full-load operations based on demand and optimized control, which improves operational efficiency and reduces power consumption during low demand periods.

[0008] Various refinements of the features noted above may exist in relation to various aspects of the present embodiments. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of some embodiments without limitation to the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] These and other features, aspects, and advantages of certain embodiments will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings.

[0010] FIG. 1A is a schematic block diagram of a heat pump water heater system, and more specifically a cascaded vapor compression HPWH system, according to an example of the present disclosure.

[0011] FIG. 1B is a schematic block diagram of a heat pump water heater system, and more specifically, according to an example of the present disclosure.

[0012] FIG. 1C is a schematic block diagram of a heat pump water heater system, and more specifically a vapor injected compression HPWH system, according to an example of the present disclosure.

[0013] FIG. 2A is a schematic diagram of a pressure enthalpy chart with an example refrigeration cycle depicted therein, according to an example of the present disclosure.

[0014] FIG. 2B is a schematic diagram of a pressure enthalpy chart with an example refrigeration cycle depicted therein, according to an example of the present disclosure.

[0015] FIG. 3 is a flow chart of a method for heating water with a heat pump, according to an example of the present disclosure.DETAILED DESCRIPTION

[0016] One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation may be described. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers'specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0017] When introducing elements of various embodiments, the articles “a,”“an,”“the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0018] The present disclosure relates to heat pump water heater (“HPWH”) systems and devices, and more specifically to multi-temperature level HPWH systems. The HPWH systems may be a cascaded vapor compression system with physically separate, but thermally coupled refrigeration or heat pump (“HP”) circuits. Alternatively, the HPWH system may be a vapor injection compression system that utilizes a single vapor injected compressor or two compressors connected in series. Regardless of the configuration, the HPWH system(s) described herein advantageously allow for a variable hot temperature water supply or two or more hot water supplies at two distinct temperature levels that can also be independently controlled within a predetermined range.

[0019] The various examples described herein provide advantageously increase and improve the efficiency of heat pump systems, especially when required pressure lift of the heat pump is very high. Various heat pumps are presented that may be composed of at least two heat pump circuits that are cascaded, fluidly isolated, and thermally connected together through a heat exchanger positioned between them. The examples described herein also advantageously extend the range of applications the system may be used and designed for, while also increasing the capacity and operating range of the heat pump system at lower temperatures.

[0020] The cascaded designs described herein advantageously allows the use of two separate independent but thermally connected circuits, each at a more restricted pressure differential or ratio, allowing each circuit to pressurize its refrigerant separately from the other circuit and reducing the pressure lift on each individual circuit. Improving the efficiency of each compressor by restricting its operations within a smaller pressure differential or range, means that a larger refrigerant mass flow rate will be able to flow through the circuit, eliminating the need for supplemental heating such as by combustion or electric heating that are less efficient or rely on the burning of fossil fuels.

[0021] Turning now the figures, FIG. 1A is a schematic block diagram of a heat pump water heater system 100a, and more specifically a cascaded vapor compression HPWH system. The HPWH system 100a is configured to provide a hot water supply to an individual (e.g., user, customer, occupant, process) at two distinct temperature levels, (i) a first or high temperature level and (ii) a second or intermediate temperature level. Alternatively, the HPWH system 100a may supply water at any intermediate temperature level between the first (e.g., high) and second (e.g., intermediate) temperature levels by mixing the flows from the water supplied at the first temperature and the water supplied at the second (intermediate) temperature. Additionally, water directly from the original water source, such as a city water source or well water, may be mixed directly with either of the flows discussed above. In the HPWH system 100a, the heat pump absorbs heat and releases the heat into a desired location (e.g., a water tank, thereby increasing the temperature of the water stored within the tank) The HPWH system 100a of FIG. 1A is a cascaded vapor compression system with two physically separate, but thermally coupled, HP circuits 110a and 110b. The HP circuits 110a, 110b, may be operated at the same or different (in case of different refrigerants) pressures. For example, the upper HP circuit 110a may be operated at a high pressure, while the lower HP circuit 110b operates at a lower pressure. The different pressures for each circuit may be maintained within a specific range or envelope that is suited for different conditions. These ranges may or may not overlap between the upper and lower HP circuits 110a, 110b depending on the desired outcomes.

[0022] A HPWH system, like the one illustrated in FIG. 1A, is capable of providing heat via a compressor by supply electricity as an energy input. Essentially, a HPWH provides heat by reversing the refrigeration cycle and by “pumping” the heat from a lower energy state to a higher energy state. Both the air 50 (e.g., ambient air) and water supply (e.g., sources of water 102a-c) contain heat, which may be utilized and moved or “pumped” via the HPWH system(s) described herein. Moving or “pumping” the heat may be accomplished by lowering the pressure of the refrigerant, thereby allowing the refrigerant to absorb heat, and then raising the pressure to release or pump the heat to water to be sent out through the hot water supply 190.

[0023] The HPWH system 100a configuration of FIG. 1A advantageously allows for a variable hot temperature water supply or two hot water supplies at two distinct temperature levels that can also be independently controlled within a predetermined range. The first higher temperature level is defined by a condenser temperature of the upper HP circuit in the cascade, and the second lower temperature level is jointly defined by an evaporator of the upper HP circuit and the condenser of the lower HP circuit, for the cascaded system.

[0024] In the illustrated example, the HPWH system 100a includes one or more sources of water 102a-c, which may be generally referred to as water source(s) 102. In the illustrated example, the water source(s) 102 may be a source of city water, a source of well water, a combination thereof, or the like. Even though the water source(s) 102 are shown as three separate water sources, the water sources 102a-c may be different intermediate storage tanks or water lines that source water from a single water source. Specifically, water source(s) 102a, 102b and 102c may each be from the city water supply. Alternatively, water source(s) 102a, 102b and 102c may each be from a well water supply. In other examples, some of the water source(s) 102 may come from one water supply (e.g., city water supply) while others come from a different water supply (e.g., well water supply).

[0025] The first water source 102a is associated with a first inlet water line 104a that leads to a water tank 108a, which may be a high temperature water tank, which is thermally coupled to a condenser 120 that is associated with the upper HP circuit 110a. The upper HP circuit 110a includes the condenser 120, an upper expansion device 140a, a heat exchanger 125, and an upper compressor 150a. The upper HP circuit 110a is also thermally coupled to a second water tank 108b, which may be an intermediate temperature water tank that may be part of or thermally coupled to the heat exchanger 125. The second water tank 108b is thermally coupled to the upper HP circuit 110a, via heat exchanger 125, between the upper expansion device 140a and the compressor 150a.

[0026] As described herein, any water “line” disclosure may also be referred to herein as “flow line(s)”, “channel(s)”, “line(s)”, “flow channel(s)”, “flow line channel(s)”, “channel(s)”, “pipe(s)”, and “pipe channel(s)”, and all these may be comprised of any of pipes, tubes, channel, or other fluid, liquid, gas, or vapor delivery and circulation mechanisms that could be of various shapes and sizes and made out of various materials. Similarly, any of the “circuits” described herein may comprise various pipes, tubes, channel, or other fluid, liquid, gas, or vapor delivery and circulation mechanisms and any couplers or connectors. The components making up the “circuits” may be of various shapes and sizes and made out of various materials.

[0027] The expansion devices disclosed herein (e.g., expansion device(s) 140, upper expansion device 140a, lower expansion device 140b, vapor injection expansion device 141, etc.) may include an expansion valve, an electronic expansion valve, a capillary tube, a thermostatic expansion valve, a piston device or the like. For example, an expansion device 140 may include a capillary tube or an electronic expansion valve such as an electric expansion valve (“EEV”) or a linear expansion valve (“LEV”). The upper expansion device 140a may include a plurality of capillary tubes, for example, two capillary tubes including a first capillary tube and a second capillary tube. The first capillary tube and the second capillary tube may be different in diameter and / or in length.

[0028] In the upper HP circuit 110a, which may be referred to as a refrigerant circuit, refrigerant flows in the counterclockwise direction from the condenser 120 to the expansion device 140a, through the heat exchanger 125 thermally coupled with the second water tank 108b (e.g., intermediate temperature water tank), to the compressor 150a and back to the condenser 120, which is thermally coupled with the first water tank 108a (e.g., high temperature water tank).

[0029] The inlet water line 104a may continue after the water tank 108 and travel to a pump 160a and eventually to a valve 164a (e.g., a three-way valve). Upon exiting the water tank 108a, the water may be directed to the outlet water line 124a to the hot water supply (“HWS”) 190 or may be mixed with water from one of the other inlet water lines 104b and 104c.

[0030] As illustrated in FIG. 1A, a high-temperature water flow 101 may be provided to valve 164a after being heated through the thermal coupling with the condenser 120. The high-temperature water flow 101 may be provided at a high-temperature level that is controlled by the condenser temperature of the upper HP circuit 110a.

[0031] The second water source 102b is associated with a second inlet water line 104b that leads to a water tank 108b, which may be an intermediate temperature water tank, which is thermally coupled to the heat exchanger 125 that is associated with both the upper HP circuit 110a and lower HP circuit 110b.

[0032] The lower HP circuit 110b includes the heat exchanger 125, an expansion device 140b, an evaporator 130 (and optionally a fan 132), and a compressor 150b. The evaporator 130 may be associated with any other air movement device to direct air 50 over (e.g., across, over or through) the evaporator 130. The lower HP circuit 110b is thermally coupled to a second water tank 108b, which may be an intermediate temperature water tank that may be part of or thermally coupled to the heat exchanger 125. In other examples, the lower HP circuit may be thermally coupled to inlet water line 104c and / or a cold-water tank associated with the water supply 102c.

[0033] From the intermediate temperature water tank 108b, the inlet water line 104b continues to pump 160b and to a valve 164b (e.g., a three-way valve), where the water may be directed to the outlet water line 124b and may optionally be mixed with water from inlet water line 104c to provide intermediate temperature water (e.g., warm water) to the warm water supply (“WWS”) 192.

[0034] An intermediate-temperature water flow 103 may be provided to valve 164b after being heated through the thermal coupling with the heat exchanger 125. The intermediate-temperature water flow 103 may be provided at an intermediate-temperature level that is jointly controlled by the various components of the heat exchanger 125, which may act as an evaporator of the upper HP circuit 110b and a condenser of the lower HP circuit 110c.

[0035] In the lower HP circuit 110a, which may be referred to as a refrigerant circuit, refrigerant flows in the counterclockwise direction from the heat exchanger 125, that is thermally coupled to the second water tank (e.g., intermediate temperature water tank) and that thermally couples the upper HP circuit 110a to the lower HP circuit 110b, to the lower expansion device 140b, through the evaporator 130 and to the lower compressor 150b, where the refrigerant is then passed back to the heat exchanger 125 to complete the circuit again.

[0036] As noted above, the heat exchanger 125 positioned between these two circuits allows the transfer of heat or facilitates heat exchange between upper HP circuit 110a carrying a first refrigerant (which may serve as a high-pressure circuit) and HP circuit 110b carrying a second refrigerant (which may serve as a low-pressure circuit). The refrigerants remain in their respective circuits but exchange heat via the heat exchanger 125 that thermally couples the two circuits together in a cascade configuration. Apart from the heat exchanger 125 that thermally couples to the two circuits 110a, and 110b, each circuit also exchanges heat at the interface between the condenser 120 and thermally coupled water tank 108a within the upper HP circuit 110a and at the interface between the heat exchanger 125 and the thermally coupled water tank 108b.

[0037] In the lower HP circuit, the evaporator 130 may absorb heat from the air, which may be effectively pumped to the water within the second water tank 109b thermally coupled to the heat exchanger 125. The heat may raise the temperature in the second water tank 109b to an intermediate temperature above the initial temperature of the water from the water source 102b. Additionally, the condenser 120 of the upper HP circuit 110a may reject heat (e.g., transmit heat to) into the water tank 108a that is thermally coupled to the condenser 120, thereby increasing the temperature of the water in the first water tank 109a to a high-temperature, above the intermediate temperature. In the heating configuration illustrated in FIG. 1A, condenser 120 rejects heat, for example into the water tank 108a while evaporator 130 in the lower HP circuit 110b absorbs heat from air running over the evaporator 130.

[0038] The system 100a illustrated in FIG. 1A advantageously allows the compressor for each independent circuit (e.g., upper compressor 150a of upper HP circuit 110a and lower compressor 150b of lower HP circuit 110b) to operate over a lower pressure differential and therefore increase the refrigerant mass flow rate circulation for each circuit, and / or allow for a reduction in the compressor size. Additionally, each circuit may have a different refrigerant (that may be preferably suitable for specific operating conditions), different compressor size, different compressor type, different heat exchange unit sizes, different configurations and the like. The compressors 150a, 150b or generally 150 described herein may be fixed speed, two-stage, tandemized, or variable speed compressor(s), to improve the system thermal performance and to extend system operating envelope. For instance, a variable speed compressor speed may be adjusted independently for each compressor to maintain a desired temperature level of the refrigerant and / or output water flows 101, 103.

[0039] The refrigerant in the upper HP circuit 110a may be pressurized by the upper compressor 150a, to a first pressure. Additionally, the refrigerant in the lower HP circuit 110b may be pressurized by the lower compressor 150b to a second pressure. In some examples, one or more of the compressors may be vapor injected (see, for example, FIG. 1C and corresponding description), or they may be variable speed compressors. The compressed and pressurized first refrigerant flow is circulated through the upper HP circuit 110a while a compressed and pressurized second refrigerant flow is circulated through the lower HP circuit 110b. The first refrigerant flow and the second refrigerant flow both run through the heat exchanger 125 and as the first refrigerant from the upper HP circuit 110a and the second refrigerant from the lower HP circuit 110b flow through the heat exchanger 125, heat is exchanged between the refrigerants in the two circuits. This exchange of heat allows each circuit to operate at a restricted pressure differential or envelope since each circuit covers one portion of an otherwise larger pressure differential of a conventional heat pump system.

[0040] The third water source 102c is associated with a third inlet water line 104c that leads to a pump 160c and valve 164c. In other examples (see FIG. 1B), the third water source 102c and / or inlet water line 104c may be thermally coupled to the evaporator 130.

[0041] It should be appreciated that water may be supplied directly to the WWS from WS 102c, which is water that is not thermally coupled to either the upper or lower HP circuits 110a, 110b. In another example, water may be supplied to the WWS from both inlet water lines 104c and inlet water lines 104b. In other examples, water may be supplied to the HWS 190 from one or more of inlet water lines 104a, 104b and 104c.

[0042] Bridge lines 114a and 114b bridge or connect the various water liens together via valves 164a-c. For example, three-way valve 164a is connected or bridged to three-way valve 164b via bridge line 114a thereby allowing water from inlet water lines 104a entering valve 164a to be mixed with water from valve 164b (e.g., water from inlet water line 104b and bridge line 114b). Bridge line 114b connects three-way valve 164b and three-way valve 164c, thereby connecting the circuits to raw or ambient water.

[0043] The valve arrangement allows water to be mixed according to control logic of controller 195. For example, control instructions may be provided that direct pumps 160 and valves 164 to adjust their flow rates, valve open and close configurations, etc. to adjust the amount of water from the various water flows 101, 103, 105 that are provided and / or combined before being supplied at one of the outlet water lines 124a, 124b. As described herein, the water flows 101 and 103, which are at different temperatures, can be combined to achieve a desired output temperature, which a more efficient approach than combining a cold-water stream with the first higher temperature water flow 101. In other examples, the cold-water stream (e.g., cold water flow 105) may be mixed with flow 101 and / or flow 103 to achieve a different desired output temperature.

[0044] It should be appreciated that each cascaded circuit (e.g., HP circuits 110a and 110b) of the HPWH system 100a can be operated independently, while the other circuit may be left deenergized or shut down. This provides another level of flexibility to operate HPWH system 100a at part-load conditions and save on energy consumption while improving system operating efficiency and reducing electric grid electricity demand. Also, it should be appreciated that more than two cascaded circuits can be implemented to further extend operational flexibility and improve performance. Furthermore, pumps 160a-c (e.g., water pumps) can be fixed or variable speed pumps and can be replaced by a single water pump 160.

[0045] Moving now to FIG. 1B, which illustrates a schematic block diagram of a heat pump water heater system 100b, and more specifically a cascaded vapor compression HPWH system. The HPWH system 100b is configured to provide a hot water supply to an individual (e.g., user, customer, occupant, process) at least two distinct temperature levels, (i) a first or high temperature level and (ii) a second or intermediate temperature level. Alternatively, the HPWH system 100a may supply water at any intermediate temperature level between the first (e.g., high) and second (e.g., intermediate) temperature levels by mixing the flows from the water supplied at the first temperature and the water supplied at the second (intermediate) temperature. Additionally, water directly from the original water source, such as a city water source or well water, may be mixed directly with either of the flows discussed above.

[0046] The HPWH system 100b of FIG. 1B may include many of the same components and perform many of the same operations and functions as HPWH system 100a. However, instead of the evaporator 130 being associated with a fan 132, the evaporator 130 of HPWH system 100b may instead be thermally coupled to the inlet water line 104c and / or another water storage tank 108c. The inlet water line 104c and / or the water tank 108c may improve the efficiency of the evaporator 130 by further assisting the evaporator 130 in cooling the refrigerant.

[0047] Instead of inlet water line 104c leading directly to the pump 160c and valve 164c as in the example illustrated in FIG. 1A, the HPWH system 100b of FIG. 1B may include a water tank 108c or otherwise thermally couple the inlet water line 104c to the lower HP circuit 110b.

[0048] FIG. 1C is a schematic block diagram of a heat pump water heater system 100c, and more specifically vapor injection HPWH system. The HPWH system 100c is configured to provide a hot water supply to an individual (e.g., user, customer, occupant, process) at two distinct temperature levels, (i) a first or high temperature level and (ii) a second or intermediate temperature level. Alternatively, the HPWH system 100c may supply water at any intermediate temperature level between the first (e.g., high) and second (e.g., intermediate) temperature levels by mixing the flows from the water supplied at the first temperature and the water supplied at the second (intermediate) temperature. Additionally, water directly from the original water source, such as a city water source or well water, may be mixed directly with either of the flows discussed above.

[0049] The HPWH system 100c of FIG. 1C includes a vapor injection system positioned along an auxiliary refrigerant line extending from and thermally coupled to a main HP circuit 110. The HPWH system 100c includes one or more sources of water 102a-c, which may be generally referred to as water source(s) 102. In the illustrated example, the water source(s) 102 may be a source of city water, a source of well water, a combination thereof, or the like. Even though the water source(s) 102 are shown as three separate water sources, the water sources 102a-c may be different intermediate storage tanks or water lines that source water from a single water source. Specifically, water source(s) 102a, 102b and 102c may each be from the city water supply. Alternatively, water source(s) 102a, 102b and 102c may each be from a well water supply. In other examples, some of the water source(s) 102 may come from one water supply (e.g., city water supply) while others come from a different water supply (e.g., well water supply).

[0050] The first water source 102a is associated with a first inlet water line 104a that leads to a water tank 108a, which may be a high temperature water tank, which is thermally coupled to a condenser 120 that is associated with the main HP circuit 110. The main HP circuit 110 includes the condenser 120, a heat exchanger 125, an expansion device 140, an evaporator 130, and a compressor 150.

[0051] As noted above, the HPWH system 100c also includes an auxiliary refrigerant line 110c that includes a secondary expansion device 141, such as a vapor injection device or vapor injection system. The auxiliary refrigerant line 110c is thermally coupled to the heat exchanger 125 (and water tank 108b) and travels from the condenser 120 to the compressor 150. The water tank 108b may be an intermediate temperature water tank or an economizer water tank that may be part of or thermally coupled to the heat exchanger 125.

[0052] In the main HP circuit 110, which may be referred to as a refrigerant circuit, refrigerant flows in the counterclockwise direction from the condenser 120, through the heat exchanger 125, to the expansion device 140, to the evaporator 130 and then to the compressor 150. The condenser 120 may be thermally coupled with the first water tank 108a (e.g., high temperature water tank), the heat exchanger 125 may be thermally coupled with a second water tank 108b (e.g., intermediate temperature water tank), and the evaporator may be thermally coupled with a third water tank (low temperature water tank).

[0053] The inlet water line 104a may continue after the water tank 108a and travel to a pump 160a and eventually to a valve 164a (e.g., a three-way valve). Upon exiting the water tank 108a, the water may be directed to the outlet water line 124a to the hot water supply (“HWS”) 190 or may be mixed with water from one of the other inlet water lines 104b and 104c.

[0054] The second water source 102b is associated with a second inlet water line 104b that is thermally coupled to a heat exchanger 125 and / or a water tank 108b, which may be an intermediate temperature water tank or an economizer tank. From the water tank 108b, the water line 104b continues to pump 160b and valve 164b (e.g., a three-way valve), where the water may be directed to the outlet water line 124b and may optionally be mixed with water from water line 104c to provide intermediate temperature water (e.g., warm water) to the warm water supply (“WWS”) 192.

[0055] The third water source 102c is associated with a third inlet water line 104c that ultimately leads to a pump 160c and valve 164c. Similar to the example illustrated in FIG. 1B, the third inlet water line 104c may lead to a third water tank 108c or may otherwise be thermally coupled to the evaporator 130.

[0056] Similar to the examples of FIGS. 1B and 1C, the HPWH system 100c of FIG. 1C includes bridge lines 114a and 114b, which are configured to bridge or connect the various water lines together via valves 164a-c.

[0057] Conversely, in the auxiliary refrigerant line 110c, a portion of the refrigerant (e.g., an auxiliary refrigerant flow) may be diverted from the condenser 120 and the main refrigerant flow to a vapor injection expansion device 141 before entering the heat exchanger 125. The refrigerant leaves the heat exchanger 125 as vapor or a vapor-liquid mixture and is injected into the compressor 150.

[0058] In an example, the nested HVAC circuit 110c may implement a flash tank or an internal heat exchanger. For example, after the refrigerant passes through condenser 120, the refrigerant may be separated into liquid and vapor phases. In an example, the liquid phase of the refrigerant may be passed through the main HP circuit 110 such that it passes through a lower-stage expansion device 140 and then into the evaporator 130. The vapor phase of the refrigerant may be passed through the nested HVAC circuit 110c may be passed through a vapor injection expansion device 141 and later injected into the compressor 150 to improve the efficiency of the condenser.

[0059] During use, a portion (e.g., auxiliary flow) of refrigerant is diverted from the main HP Circuit 110 (and the main refrigerant flow) to a vapor injection system positioned about an auxiliary refrigerant line 110c. The auxiliary flow may be cooled or chilled initially via the vapor injection expansion device 141 and then may continue to flow through the heat exchanger 125 to facilitate heat exchange between the main refrigerant flow and the cooled auxiliary flow to cool the main flow and evaporate the auxiliary flow. Furthermore, the evaporated auxiliary flow may be sent to the compressor 150 to improve the performance of the compressor 150 as compared to not using the evaporated auxiliary flow.

[0060] The vapor injection expansion device 141 is positioned between the condenser 120 and the compressor 150 along the auxiliary refrigerant line 110c without passing through the evaporator 130. By positioning the vapor injection expansion device 141 along the auxiliary refrigerant line 110c, the HPWH system 100c may provide more control on refrigerant or air volumes and flow rates and may provide additional efficiency, especially at lower temperatures. The vapor injection device or system may advantageously increase the HPWH system 100c′s heating capacity, reduce power consumption, increase refrigerant mass flow rate, and improve operational efficiency.

[0061] It should be appreciated that although the vapor injection is shown only at one intermediate pressure level, multiple vapor injection levels can be implemented for a vapor injection expansion device 141 (e.g., a single vapor-injected compressor or compressors connected in series), allowing for greater control flexibility and improved operational efficiency. Also, it should be appreciated that one or both cascades (e.g., upper HP circuit 110a and lower HP circuit 110b) of the HWHP system 100a or 100b can be equipped with the vapor injection expansion device 141 (e.g., vapor injected compressor and auxiliary devices) to further improve system performance.Pressure-Enthalpy Diagram

[0062] Referring briefly to FIG. 2A, which illustrates a pressure enthalpy (“P-H”) diagram 200a, the pressure, enthalpy, temperature and phase transitions of the refrigerant may be described and discussed with reference to FIGS. 1A and 1B. The P-H diagram 200a describes the relationship of pressure and enthalpy for a refrigerant used in the HPWH system 100a of FIG. 1A and / or HPWH system 100b of FIG. 1B.

[0063] In the P-H diagram 200a illustrated in FIG. 2A, pressure is indicated on the y-axis and enthalpy is indicated on the x-axis. The P-H curve 205, which has a hill or upside down “U” shape, designates phase changes for the refrigerant. For example, the left portion 210 of the P-H curve 205 indicates at when pressure and enthalpy values the refrigerant is a saturated liquid (e.g., the saturated liquid curve) and the right portion 220 indicates when the refrigerant is a saturated vapor (e.g., the saturated vapor curve).

[0064] The region between the two curves is a “mixed region” that describes various refrigerant states that contain a mixture of both liquid and vapor. Outside of the curve, to the left of the saturated liquid portion of the curve, indicates a liquid region 240 that the refrigerant is in a liquid form (e.g., a sub-cooled liquid). On the opposite side, to the right of the saturated vapor portion of the curve, indicates a vapor region 250 that the refrigerant is in a vapor form (e.g., super-heated vapor). So essentially, the curve delineates the P-H diagram 200a into a liquid region 240, a vapor region 250, and a mixed region 245.

[0065] As noted above, the liquid region 240 may also be referred to as a sub-cooled liquid region. This liquid region 240 typically is characterized by vertical temperatures lines (noting constant enthalpy), which increase (e.g., temperature increases for each vertical line progressing from the left to right along the x-axis or enthalpy-axis) as the enthalpy is increased. For example, at a first enthalpy value (e.g., 1X), the temperature may be (−40° F.) and at a second enthalpy value (e.g., 2X), the temperature may be (−20° F.) and so on, progressing through 0° F., 20° F., 40° F., 60° F., etc.

[0066] In the vapor region 250, which may be referred to as a super-heated vapor region, there are vertical or nearly vertical temperature lines starting at the x-axis and extending upward along the positive y-axis. Similar to the liquid region 240, the vertical temperature lines may increase as enthalpy is increased (e.g., −40° F., −20° F., 0° F., 20° F., 40° F., 60° F., etc. and so on). The temperature lines then curve left, back towards the y-axis, as they meet the curve 205, come into close proximity to the curve 205, and / or extend near the peak or y-value of the critical point 230 of the curve 205.

[0067] In the mixed region 245, which may also be referred to as a liquid-vapor mix region, the temperature lines are horizontal thereby indicating constant temperature at each pressure while within under the curve 205. For example, As the pressure increases from the origin at the x-axis and moves upward, the horizontal temperature lines may progress upward (similar to the rungs of a ladder) and may progress from −60° F. (e.g., at 1Y), to −40° F. at 2Y, to −20° F., 0° F., 20° F., 40° F., 60° F., etc. up to the boiling point or phase transition temperature from liquid to vapor, which for water would be 212° F. As enthalpy increases (e.g., moving to the right in the mixed region) more and more liquid will vaporize, and liquid will continue to transition into vapor instead of increasing the temperature. For example, in this mixed region 245 the increased enthalpy causes liquid to phase change to a vapor while maintaining a constant temperature, whereas changes in enthalpy outside of the curve 205 typically result in changes in temperature.

[0068] The mixed region 245 may also have a plurality of upward sloping curves indicating various levels or ratios of vapor mass to total mass. For example, a level or ratio of 0.1 or ten percent (e.g., 10%), would be an upward sloping curve near the saturated liquid portion 210 of the curve 205 and would identify each of the positions on the P-H diagram 205 where the refrigerant consists of ten percent vapor by mass. On the opposite end of the ratio, an upward sloping curve near the saturated vapor portion 220 of the curve 205 may have a level or ratio value of 0.9 (e.g., ninety percent or 90%). The upward sloping curve representing a ratio of 0.9 identifies positions on the P-H diagram 204 where the refrigerant consists of ninety percent vapor by mass.

[0069] The merging location of (a) the saturated liquid portion 210 of the curve 205 and (b) the saturated vapor portion 220 of the curve 205; or the point at which (a) and (b) meet is the critical point 230. The critical point 230 designates the point on the diagram at which vapor is unable to transition or phase change into a liquid regardless of how much additional pressure is applied to the refrigerant. Example P-H diagrams for various refrigerants (e.g., R-134a) may be found in the American Society of Heating, Refrigeration and Air Conditioning Engineers (“ASHRAE”) Fundamentals book or various other sources that publish P-H diagrams 205.

[0070] Turning now to FIG. 2B, which illustrates a pressure enthalpy (“P-H”) diagram 200b, the pressure, enthalpy, temperature and phase transitions of the refrigerant may be described and discussed with reference to FIG. 1C. The P-H diagram 200b describes the relationship of pressure and enthalpy for a refrigerant used in the HPWH system 100c of FIG. 1C.Refrigeration Cycles

[0071] The refrigeration cycles for the upper circuit 110a and lower circuit 110b of FIG. 1A are described in more detail below with reference to FIG. 2A. The various stages or steps of an example refrigeration cycle include (1) evaporation from evaporator(s) 130, (2) compression from compressor(s) 150, (3) condensation from condenser(s) 120, and (4) expansion from expansion device(s) 140.

[0072] As noted above, the upper circuit 110a and lower circuit 110b may be thermally coupled with a heat exchanger 125, which may include condenser(s), evaporator(s) and the like to transfer heat between the upper circuit 110a and lower circuit 110b. For example, the heat exchanger 125 may function as an evaporator for the upper circuit 110a and may function as a condenser for the lower circuit 110b.

[0073] As refrigerant is passed through the circuit 110a, the evaporation process 282, which occurs between points “A” and “B” on the P-H diagram 200a, occurs at the heat exchanger 125. Since point “A” is within or under the curve 205 and within the mixed region 245, the refrigerant is a liquid-vapor mixture. At point “B” the refrigerant is fully saturated vapor, within vapor region 250. The phase change transitions from point “A” to “B” may occur at a constant temperature because energy (e.g., heat) transferred to the refrigerant by the evaporator 130 is used to convert the liquid into a gas or vapor.

[0074] After passing through the heat exchanger 125, which may include an evaporator or the like, the refrigerant is routed to a compressor 150a where the compression process 284 begins. As illustrated in FIG. 2A, the compression process 284 for the upper circuit 110a occurs between points “B”and “C”on the P-H diagram 200a.

[0075] At the compressor 150a, the refrigerant enters at the exit temperature of the heat exchanger 125 (e.g., evaporator) and the compressor 150a increases the pressure of the refrigerant. The compression process 284 may occur as a near-constant entropy process (e.g., isentropic compression), which is indicated by the sloped line for the compression process 284. As the compressor 150a compresses the refrigerant, the pressure of the refrigerant and enthalpy increase until reaching point “C”. Then, the higher-pressure refrigerant travels to a condenser 120 for the condensation process 286.

[0076] The condensation process 286 for the upper circuit 110a, occurs between points “C” and “D”. During the condensation process 286, the condenser 120 transforms the higher pressure, heated vapor by cooling the vapor to a saturation temperature (e.g., where the condensation process 286 intersects the saturated vapor portion 220 of the curve 205). Generally, the condenser 120 is configured to release or reject heat.

[0077] As the refrigerant cools, heat flows from the refrigerant vapor to a cooling medium associated with the condenser 120. In the example illustrated in FIG. 1A, heat from the condensation process 286 is transferred to a water tank 108a, such as a high temperature water tank. For example, the condenser 120 is configured to supply heat to the high temperature water tank 108a through the phase transition of the refrigerant from a vapor to a liquid.

[0078] Then, the saturated vapor transitions from vapor to a liquid-vapor mix in the mixed region 245. During the phase change as the vapor changes to liquid, additional heat is transferred from the refrigerant to the high temperature water tank 108a. In the example illustrated in FIG. 2A, the refrigerant may be sub-cooled, and since the refrigerant is saturated liquid at point “D”, any further heat loss decreases the temperature of the refrigerant since the phase change from vapor to liquid has completed.

[0079] In the last phase of the refrigeration cycle, the expansion process 288 occurs between points “D” and “A”. During the expansion process 288, an expansion device 140a expands the high-pressure refrigerant to a lower pressure liquid-vapor refrigerant. The expansion device is configured to reduce or lower the pressure of the refrigerant so that the refrigeration cycle can begin anew. Typically, the expansion process 288 may perform near-adiabatic expansion, which is characterized by the vertical line on the P-H diagram 200a (e.g., constant enthalpy). Once back at point “A”, the refrigeration cycle can be repeated as the refrigerant is cycled through the upper circuit 110a.

[0080] While a refrigeration cycle is occurring within the upper circuit 110a, the lower circuit 110b may perform its own refrigeration cycle. During the evaporation process 282′ in the lower circuit 110b, refrigerant is passed through the evaporator 130. Generally, an evaporator 130 is configured to absorb heat.

[0081] The evaporation process 282′ occurs between points “A′” and “B′” on the P-H diagram 200a. Similar to the refrigeration cycle for the upper circuit 110a, Point “A′” indicates that the refrigerant is a liquid-vapor mixture in the mixed region 245. At point “B′” the refrigerant is fully saturated vapor, within vapor region 250. In the example illustrated in FIG. 1A, the evaporator 130 may be associated with a fan 132 or other air-movement device that is configured to blow or pass air 50 over (e.g., across, over, or through) the evaporator 130, which may improve the efficiency of the evaporator 130.

[0082] After passing through evaporator 130, the refrigerant is routed to a compressor 150b where the compression process 284′ begins. As illustrated in FIG. 2A, the compression process 284 for the lower circuit 110b occurs between points “B′” and “C′” on the P-H diagram 200a. The compressor(s) 150 associated with the compression process 284′ are configured to raise the pressure of the refrigerant.

[0083] At the compressor 150b, the refrigerant enters at the exit temperature of the evaporator 130 and the compressor 150b increases the pressure of the refrigerant. The compression process 284′ may occur as a near-constant entropy process (e.g., near-isentropic compression), which is indicated by the sloped line for the compression process 284′. As the compressor 150b compresses the refrigerant, the pressure of the refrigerant and enthalpy increase until reaching point “C′”. Then, the higher-pressure refrigerant travels to a heat exchanger 125, which may act as a condenser for the lower circuit 110b. The condensation process 186′ for the lower circuit 110b may occur at the heat exchanger 125, which may be thermally coupled to an intermediate temperature water tank 108b.

[0084] The condensation process 286′, for the lower circuit 110b, occurs between points “C′” and “D′”. During the condensation process 286′, the heat exchanger 125 transforms the higher pressure, heated vapor by cooling the vapor to a saturation temperature (e.g., where the condensation process 286′ intersects the saturated vapor portion 220 of the curve 205. As the refrigerant cools, heat flows from the refrigerant vapor to a cooling medium associated with the heat exchanger (e.g., intermediate temperature water tank 108b). In the example illustrated in FIG. 1A, heat from the condensation process 286′ is transferred to a water tank 108b, such as an intermediate temperature water tank.

[0085] For example, as the refrigerant in the lower circuit 110b changes phase from vapor to liquid in the condensation process 286′ occurring at the heat exchanger 125, heat may be supplied to the intermediate temperature water tank 108b through the phase transition of the refrigerant from a vapor to a liquid.

[0086] Then, the saturated vapor transitions from vapor to a liquid-vapor mix in the mixed region 245. During the phase change as the vapor changes to liquid, additional heat is transferred from the refrigerant to the intermediate temperature water tank 108b. In the example illustrated in FIG. 2A, the refrigerant may be sub-cooled, and since the refrigerant is saturated liquid at point “D”, any further heat loss decreases the temperature of the refrigerant since the phase change from vapor to liquid has completed.

[0087] Lastly, the expansion process 288′ occurs between points “D′” and “A′”. For example, an expansion device 140b expands the high-pressure refrigerant to a lower pressure liquid-vapor refrigerant. The expansion process 288′ may be near-adiabatic at a near-constant enthalpy. Once back at point “A”, the refrigeration cycle for the lower circuit 110b can be repeated as the refrigerant is cycled through the upper circuit 110a.

[0088] It should be appreciated that the refrigeration cycles for the upper circuit 110a and lower circuit 110b of FIG. 1B may be similarly described, as they were for HPWH system 100a, with reference to FIG. 2A. Therefore, any common components or features between system 100a and 100b may have the same characteristics, configurations and features unless otherwise specified.

[0089] The refrigeration cycles for the main circuit 110 and nested circuit 110c of FIG. 1C are described in more detail below with reference to FIG. 2B. The nested circuit may serve as an injection circuit or an injection branch to inject refrigerant into the compressor. The various stages or steps of an example refrigeration cycle include (1) evaporation from evaporator(s) 130, (2) compression from compressor(s) 150, (3) condensation from condenser(s) 120, and (4) expansion from expansion device(s) 140.

[0090] As noted above, the main circuit 110 may be thermally coupled with a heat exchanger 125, which may include condenser(s), evaporator(s) and the like to transfer heat between the main circuit 110 and the nested circuit 110c.

[0091] As refrigerant is passed through the main circuit 110, the evaporation process 282, which occurs between points “A” and “B” on the P-H diagram 200b, occurs at evaporator 130. Since point “A” is within or under the curve 205 and within the mixed region 245, the refrigerant is a liquid-vapor mixture. At point “B” the refrigerant is fully saturated vapor, within vapor region 250. The phase change transitions from point “A” to “B” may occur at a constant temperature because energy (e.g., heat) transferred to the refrigerant by the evaporator 130 is used to convert the liquid into a gas or vapor. The evaporator 130 may be thermally coupled to the inlet water line 104c or water tank 108c to further improve the efficiency of the evaporator 130.

[0092] After passing through the evaporator 130, the refrigerant is routed to a compressor 150 where the compression process 284 begins. As illustrated in FIG. 2B, the compression process 284 for the main circuit 110 occurs between points “B” and “C′” or “C” on the P-H diagram 200b.

[0093] At the compressor 150, the refrigerant enters at the exit temperature of the evaporator 130 and the compressor 150 increases the pressure of the refrigerant. The refrigerant may also enter the compressor 150 at the exit temperature of the heat exchanger 125 and / or vapor injection expansion device 141, which is described in more detail below. The compression process 284 may occur as a near-constant entropy process (e.g., near-isentropic compression), which is indicated by the sloped line for the compression process 284. As the compressor 150a compresses the refrigerant, the pressure of the refrigerant and enthalpy increase until reaching point “C”. Then, the higher-pressure refrigerant travels to a condenser 120 for the condensation process 286.

[0094] The condensation process 286 for the main circuit 110, occurs between points “C” and “D” or “D′”. During the condensation process 286, the condenser 120 transforms the higher pressure, heated vapor by cooling the vapor to a saturation temperature (e.g., where the condensation process 286 intersects the saturated vapor portion 220 of the curve 205). Generally, the condenser 120 is configured to release or reject heat.

[0095] As the refrigerant cools, heat flows from the refrigerant vapor to a cooling medium associated with the condenser 120. In the example illustrated in FIG. 1C, heat from the condensation process 286 is transferred to a water tank 108a, such as a high temperature water tank. For example, the condenser 120 is configured to supply heat to the high temperature water tank 108a through the phase transition of the refrigerant from a vapor to a liquid.

[0096] The main difference of the HPWH system 100c from the other systems described herein, is that after exiting the condenser 120, at least some of the refrigerant may be routed through the nested circuit 110c to be used in a vapor injection refrigeration cycle. For example, the vapor injection device 141 may be used to drop the pressure of the refrigerant in an expansion process 288′ bringing that portion of the refrigerant to point “A-V” on the P-H diagram 200b before the fluid is passed through the heat exchanger 125 and is later injected into the compressor at point “B-V” where an additional compression process 284′ may occur.

[0097] For example, a portion of the condensed liquid refrigerant may be expanded through an expansion device, such as vapor injection device 141. The refrigerant may be further cooled via heat exchanger 125, and then the vapor (e.g., super-heated vapor) may be injected into the compressor 150. The additional subcooling performed during the refrigeration cycle advantageously increases the capacity of the evaporator by reducing temperature of the refrigerant and thus reducing enthalpy. Given the additional mass flow associated with the vapor injection, advantageously provides additional heat transfer at the condenser 120 and thus higher efficiency than conventional systems. For example, the subcooling achieved in the HPWH system 100c may be achieved while using less power than other methods because the incremental vapor created during subcooling is only compressed from a higher pressure instead of the lower suction pressure of the system.

[0098] Then, after being injected at the compressor, a vapor injected compression process 284′ occurs which brings the refrigerant to point “C”on the P-H diagram 200b of FIG. 2B.

[0099] The expansion processes 288 and 288′ represented in FIG. 2B occurs between points “D” and “A” in association with expansion device 140 of FIG. 1C and occurs between points “D′” and “A-V” in association with the vapor injection expansion device 141. During the expansion processes 288 and / or 288′, an expansion device 140 is configured to reduce or lower the pressure of the refrigerant. For example, the expansion device 140, 141 may expand the high-pressure refrigerant to a lower pressure liquid-vapor refrigerant so that the refrigeration cycle can begin anew.

[0100] It should be appreciated that although the vapor compression cycle is shown as operating in the sub-critical region, trans-critical or super-critical cycles can be equally employed for the entire system or one of the cascaded circuits. An example trans-critical fluid known in the heating, ventilating, air conditioning and refrigerating (“HVAC&R”) industry is CO2 or carbon dioxide. Other such trans-critical or super-critical fluids can be used as well.Methods

[0101] Turning now to FIG. 3, which is a flow chart of a method 300 for heating water with a heat pump, such as one of the HPWH systems 100a, 100b or 100c described herein. In step 310, the method 300 includes flowing water along a first inlet water line from a water source to a first water tank that is thermally coupled to a condenser of a first HP circuit of a heat pump water heater. For example, method 300 may include flowing water along a first inlet water line 104a from a water source 102 to a first water tank 108a. The water tank 108a may be a high-temperature water tank that is thermally coupled to a condenser 120 of a first HP circuit (e.g., upper HP circuit 110a or main HP circuit 110). In an example, flowing water along the first inlet water line 104a may follow the arrangement and configuration of any of the HPWH systems 100a-c illustrated in FIG. 1A-1C and may be achieved through use of the water lines, valves, pumps and other components of the HPWH system(s) 100 illustrated and described herein.

[0102] In step 320, the method 300 includes flowing water along a second inlet water line from a water source to a second water tank that is thermally coupled to a heat exchanger of the first HP circuit and a second HP circuit. For example, method 300 may include flowing water along a second inlet water line 104b from a water source 102 to a second water tank 108b. The water tank 108b may be an intermediate-temperature water tank or an economizer tank that is thermally coupled to a heat exchanger 125 of a first HP circuit (e.g., upper HP circuit 110a or main HP circuit 110). In an example, flowing water along the second inlet water line 104b may follow the arrangement and configuration of any of the HPWH systems 100a-c illustrated in FIG. 1A-1C and may be achieved through use of the water lines, valves, pumps and other components of the HPWH system(s) 100 illustrated and described herein.

[0103] Additionally, in step 330, the method 300 includes circulating a first refrigerant through the first HP circuit. In step 340, the method 300 includes circulating a second refrigerant through the second HP circuit. It should be appreciated that the first refrigerant and the second refrigerant may be the same refrigerant. Alternatively, the first refrigerant and the second refrigerant may be different based on suitability at different temperature ranges. Various refrigerants or refrigerant combinations may be used in each HP circuit, based on the desired operating condition of each circuit, including for example CO2 and R32.

[0104] Circulating refrigerant through the first and second HP circuits may follow the arrangement and configuration of the various refrigeration circuits and cycles described herein. It should be appreciated that one or more of steps 330 and 340 may be optional as the HPWH and associated HP circuits may be operated independently, at part-load, or at full-load conditions based on hot water demand and control logic. For example, it should be appreciated that upper and lower HP circuits or a main HP circuit and an auxiliary line and / or circuit can operate independently at part-load or full-load conditions (based on the conditioned space demand and environmental conditions, as well as optimized control logic), and if they integrate a variable speed compressor, the speed can be adjusted independently for each compressor.

[0105] In step 350, the method 300 includes exchanging heat between the first refrigerant flow and the second refrigerant flow via the heat exchanger to adjust the temperature of the water in one of the first water tank and / or the second water tank. For example, refrigerant may by circulated through their respective HP circuit or auxiliary refrigerant line, which is thermally coupled to the heat exchanger to exchange heat with the water tank 108b that is also thermally coupled to the heat exchanger 125. Furthermore, heat may be exchanged to the water tank 108a via the condenser 120 as described above.

[0106] In step 360, the method 300 includes controlling a valve arrangement to direct flow from at least one of the first water tank, the second water tank, or the water source. For example, method 300 may include controlling a valve arrangement (e.g., valves 160a, 160b and / or 160c) via controller 195 to direct flow from water tank 108a, water tank 108b and / or water source 102. For example, referring to FIG. 1A, water flow may be directed to an outlet water line (e.g., outlet water line 124b) by directing water from one or more of bridge line 114a, bridge line 114b and / or inlet water line 104c towards valve 164c and then opening valve 164c to direct flow towards outlet water line 124b. Similarly, water flow may be directed to outlet water line 124a by directed water from one or more of bridge line 114b, bridge line 114a and / or inlet water line 104a towards valve 164a and then opening valve 164a to direct flow towards outlet water line 124a.

[0107] It should be appreciated that the outlet water temperature may be dependent on the flow rate, quantity (e.g., mass and volume), temperature and other characteristics of the water flowing through the various water lines 104, water tanks 108, pump(s) 160 and valve(s) 164.

[0108] The method 300 may also include providing water at a desired outlet temperature at the water outlet. For example, method 300 may include providing water at a desired outlet temperature at water outlet 124. Water may be provided at water outlet 124a, which is designated for providing hot water or water outlet 124b, which is designated for providing cold or warm water.

[0109] It should be appreciated that method 300 may include more or less steps than those illustrated in FIG. 3. Furthermore, some of the steps illustrated in FIG. 3 may be repeated, rearranged to change their order, or otherwise modified according to the examples described herein and illustrated in FIG. 1A-2B. For example, method 600 may include flowing raw unprocessed debris slurry 150 and / or processed debris slurry 150′ through one or more additional chambers (e.g., additional chamber 110 or chamber(s) 120, 130) of the debris SAS apparatus 105.

[0110] Method 300 may provide two water flows at different temperatures (e.g., a high-temperature water flow 101 at high-temperature 201 or an intermediate-temperature water flow 103 at intermediate temperature 203). Method 300 may also combine water flows to achieve the desired temperature between temperatures 201 and 203, or to achieve another desired temperature between temperature 203 and the temperature of the water source. It should be appreciated that combining water flows 101 and 103 may be a more efficient approach than combining a cold-water stream (e.g., from water source 102) with the first higher temperature water flow 101.

[0111] While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims. For example, certain embodiments disclosed here envisage usage with a powered fan rather than an inducer fan, or no fan at all. Moreover, the rotating equipment (e.g., motors) and valves disclosed herein are envisaged as being operable at specified speeds or variable speeds through inverter circuitry, for example. Moreover, the internal and external communication of the furnace may be accomplished through wired and or wireless communications, including known communication protocols, Wi-Fi, 802.11(x), Bluetooth, to name just a few.

Examples

Embodiment Construction

[0016]One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation may be described. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers'specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0017]When introducing elements of various embodiments, the articles “a,”“an,”“the,” and “said” are intended to mean that there are one or more of the elements. The terms “...

Claims

1. A heat pump water heater (“HPWH”) system comprising:at least one water source providing water at a water source temperature to a first inlet water line, a second inlet water line, and a third inlet water line;an upper HP circuit comprising a condenser thermally coupled to a first water tank in fluid communication with the first inlet water line, an upper expansion device, a heat exchanger, an upper compressor, and a first refrigerant flowing therethrough;a lower HP circuit, fluidly isolated from the upper HP circuit, comprising the heat exchanger thermally coupled to a second water tank in fluid communication with the second inlet water line, a lower expansion device, an evaporator, a lower compressor, and a second refrigerant flowing therethrough, wherein the heat exchanger thermally couples the fluidly isolated upper HP circuit to the lower HP circuit to facilitate heat exchange between the first refrigerant and the second refrigerant within the heat exchanger such that the heat exchange reduces a temperature lift needed by each of the upper HP circuit and the lower HP circuit thereby allowing the upper HP circuit and the lower HP circuit to operate at different pressure differentials; andat least two outlet water lines configured to deliver at least one of (i) water at a first temperature level from the first water tank, (ii) water at a second temperature level from the second water tank, and (iii) water at an intermediate temperature between the first temperature level and the second temperature level by mixing water from at least two of the first water tank, the second water tank, and the third inlet water line.

2. The HPWH system of claim 1, wherein the first water tank is configured to store water at the first temperature level, and wherein the first temperature level is a higher temperature level than both the second temperature level and the water source temperature.

3. The HPWH system of claim 2, wherein the second water tank is configured to store water at the second temperature level, and wherein the second temperature level a lower temperature level than the first temperature level and a higher temperature than the water source temperature.

4. The HPWH system of claim 1, further comprising a fan that is associated with the evaporator and is operable to move air over the evaporator.

5. The HPWH system of claim 1, wherein the third water inlet line is thermally coupled to the evaporator.

6. The HPWH system of claim 1, further comprising a third water tank in fluid communication with the third water inlet line, wherein the third water tank is thermally coupled to the evaporator and configured to store water at the water source temperature.

7. The HPWH system of claim 1, wherein the first refrigerant and the second refrigerant are different refrigerants.

8. The HPWH system of claim 1, wherein the first refrigerant and the second refrigerant are the same refrigerant.

9. The HPWH system of claim 1, wherein at least one of the upper compressor and the lower compressor is one of a fixed speed compressor, two-stage compressor, tandemized compressor, or a variable speed compressor.

10. The HPWH system of claim 1, wherein the upper compressor is a variable speed compressor that is configured to maintain the first refrigerant in the upper HP circuit at a first refrigerant temperature.

11. The HPWH system of claim 1, wherein at least one of an upper pump of the upper HP circuit and a lower pump of the lower HP circuit is a variable speed water pump.

12. A heat pump water heater (“HPWH”) system comprising:at least one water source providing water at a water source temperature to a first inlet water line, a second inlet water line, and a third inlet water line;a main HP circuit comprising a condenser thermally coupled to a first water tank in fluid communication with the first inlet water line, a heat exchanger thermally coupled to a second water tank in fluid communication with the second inlet water line, an expansion device, an evaporator, a compressor, and a refrigerant flowing therethrough;a vapor injection system extending along an auxiliary refrigerant line that extends between the condenser and the compressor and passes through the heat exchanger of the main HP circuit, the vapor injection system comprising a vapor injection device, wherein the heat exchanger thermally couples the main HP circuit to the vapor injection system extending along an auxiliary refrigerant line, the vapor injection system is configured to receive a portion of refrigerant diverted from the main HP circuit to the auxiliary refrigerant line as auxiliary flow while the remaining portion of refrigerant continues through the main HP circuit as a main flow thereby cooling the auxiliary flow more than the main flow to facilitate heat exchange between the main flow and the auxiliary flow within the heat exchanger; andat least two outlet water lines configured to deliver at least one of (i) water at a first temperature level from the first water tank, (ii) water at a second temperature level from the second water tank, and (iii) water at an intermediate temperature between the first temperature level and the second temperature level by mixing water from at least two of the first water tank, the second water tank, and the third inlet water line.

13. The HPWH system of claim 12, wherein the heat exchanger thermally connected the main flow and the auxiliary flow is configured to exchange heat between the main flow and the auxiliary flow to cool the main flow and evaporate the auxiliary flow, and wherein the evaporated auxiliary flow is directable into the compressor to improve the performance of the compressor as compared to not using the auxiliary flow and the vapor injection system.

14. The HPWH system of claim 12, wherein the third inlet water line is thermally coupled to the evaporator 130.

15. The HPWH system of claim 12, further comprising a third water tank in fluid communication with the third inlet water line, the third water tank is thermally coupled to the evaporator and is configured to store water at the water source temperature.

16. The HPWH system of claim 12, wherein the vapor injection device is one of (i) a single vapor injected compressor, (ii) a variable speed compressor, and (iii) two compressors connected in series.

17. The HPWH system of claim 12, wherein the heat exchanger is one of a flash tank or an economizer heat exchanger.

18. A method of heating water comprising:flowing water along a fist inlet water line from a water source to a first water tank that is thermally coupled to a condenser of a first HP circuit of a heat pump water heater;flowing water from a second inlet water line from the water source to a second water tank that is thermally coupled to a heat exchanger of the first HP circuit and at least one of a second HP circuit or an auxiliary refrigerant line of the HPWH;circulating a first refrigerant flow through the first HP circuit;circulating a second refrigerant flow through at least one of the second HP circuit or the auxiliary refrigerant line;exchanging heat between the first refrigerant flow and the second refrigerant flow via the heat exchanger to adjust the temperature of the water in one or more of the second water tank and the first water tank;controlling a valve arrangement associated with the first water tank, the second water tank, and the water source to direct flow from at least one of the first water tank, the second water tank, or the water source towards a water outlet at a desired outlet temperature.

19. The method of claim 18, wherein the first HP circuit includes a condenser, an upper expansion device, a heat exchanger, and an upper compressor, wherein the second HP circuit includes the heat exchanger, a lower expansion device, an evaporator, and a lower compressor, and wherein the heat exchanger thermally couples the first HP circuit to the second HP circuit.

20. The method of claim 18, wherein the first HP circuit includes a condenser, a heat exchanger, an expansion device, an evaporator, and a compressor, and wherein the auxiliary refrigerant line extends between the condenser and the compressor of the first HP circuit and includes a vapor injection system positioned along the auxiliary refrigerant line between the condenser and the compressor.

21. The method of claim 20, wherein the auxiliary refrigerant line, which is thermally coupled to the heat exchanger and the second water tank, is in fluid communication with the vapor injection system and the compressor, and is configured to receive the second refrigerant flow as an auxiliary flow such that (i) the auxiliary flow is cooled by the vapor injection system positioned along the auxiliary refrigerant line, (ii) the auxiliary flow is evaporated at the heat exchanger while exchanging heat with the first refrigerant flow, and (iii) the evaporated auxiliary flow is provided to the compressor to improve performance of the compressor as compared to not using the evaporated auxiliary flow.

22. The method of claim 18, wherein providing water at a desired outlet temperature includes at least one of (i) providing water solely from the first water tank at a first temperature, (ii) providing water solely from the second water tank at a second temperature, lower than the first temperature, (iii) providing water solely from the water source at a water source temperature, lower than the second temperature (iv) providing water at a first intermediate temperature by mixing water from the water source and at least one of the first water tank or the second water tank (v) providing water a second intermediate temperature by mixing water from the first water tank and the second water tank.

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