A water heating system and method combining a heat pump and a burner for providing instantaneous and constant hot water

Abstract

A system, method, and apparatus for heating water are provided herein. A water heating system is disclosed that includes a burner, a vapor compression cycle system, and a water line in communication with the burner and the vapor compression cycle system. The water heating system can be a tankless or on-demand water heating system. Water in the water line can first be heated by the vapor compression cycle system before the water enters the burner. In this way, the water can be preheated using the vapor compression cycle system before the water is further heated by the burner.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority and benefit to U.S. Provisional Application No. 63 / 367,758, filed on July 6, 2022, which is hereby incorporated by reference in its entirety.

[0002] This application is directed to systems and methods for heating water, and more particularly, to a water heating system and method that combines a heat pump and a burner to provide instant and constant hot water.

Background Art

[0003] The most common approach for providing hot water in residential, commercial, and industrial settings involves the use of large tanks for storing hot water. Such a heated - tank system can provide hot water at a relatively high flow rate, but is inherently energy - inefficient because the water in the tank is continuously reheated even when the water is not being regularly used.

[0004] Another approach for providing warm water involves the use of a tankless water heater system that heats water only when it is being used. Such tankless water heater systems, also referred to as on-demand water heater systems, can often provide a means of heating water that is more energy efficient than storage systems that use the same type of heating (e.g., gas, electric, etc.). A typical combustion-type on-demand based water heater uses a combustible fuel gas such as methane (i.e., natural gas), and a gas burner disposed within a combustion chamber below a heat exchanger combusts the gas with ambient air, thereby heating the water by a combination of heat radiated from the burner and heat conducted from the hot gaseous products of combustion (hereinafter “combustion gas”) that travel through the walls of the combustion chamber and through the heat exchanger. The combustion gas travels from the combustion chamber through the heat exchanger and vents outside of the building or other enclosure in which the water heating system is disposed. There are also electric tankless water heaters that utilize electricity (rather than combustion gas) to heat water on demand.

[0005] Tankless water heaters eliminate the need to store large quantities of warm water by heating water on demand. These types of gas heater systems are referred to as “instantaneous” to indicate that the water is heated directly on demand rather than being pre-heated and then stored in a tank for later use.

Brief Description of the Drawings

[0006] A detailed description will be given with reference to the accompanying drawings. In some instances, the use of the same reference numeral may indicate a similar or identical item. The various embodiments may utilize elements and / or components other than those illustrated in the drawings, and some elements and / or components may not be present in the various embodiments. Throughout the present disclosure, singular and plural terms may be used interchangeably depending on the context.

[0007]

Figure 1

Figure 2

Figure 3

[0008] Disclosed herein is a water heating system. The water heating system can be implemented in a home environment, a commercial environment, and an industrial environment. The water heating system can include a burner, a vapor compression cycle system (e.g., a heat pump), and a water line in communication with the burner and the vapor compression cycle system. In some cases, the water heating system can be a tankless (or on-demand) water heating system. In other cases, the water heating system can include a tank. The water in the water line can first be heated by the vapor compression cycle system before the water enters the burner. In this way, the water can be preheated using the vapor compression cycle system before the water is further heated by the burner.

[0009] As used herein, the term "preheated" can mean heating the water by a first heating system (such as a vapor compression cycle system) before heating the water by a second heating system (such as a burner). For example, the water can be heated (i.e., preheated) from an initial temperature at the water inlet by the vapor compression cycle system before the water enters the burner, and the water can be further heated to a desired temperature of the water exiting the outlet by one or more heat exchangers of the burner. In this way, "preheating" the water means that the water is being heated prior to another heating process. Preheating the water can increase the thermal efficiency of the heating process of the system.

[0010] The burner may include a combustion chamber configured to receive fuel and air (e.g., ambient air). In some cases, the fuel may include natural gas, propane, etc. from a fuel source. In this specification, any suitable fuel and fuel source or combinations thereof may be used. The combustion chamber may also include an igniter for igniting the air / fuel mixture into combustion gas. For example, the combustion chamber may include a main igniter and a pilot igniter to which fuel and air can be supplied. In other cases, the igniter may be a flame rod or the like. In this specification, any suitable igniter or combination of igniters may be used.

[0011] During operation of the water heating system, the combustion chamber may mix and ignite the air / fuel mixture to produce high-temperature combustion gas that flows upward through the burner to one or more heat exchangers within the burner. One or more heat exchangers of the burner may also communicate with a water line. In this way, the one or more heat exchangers may transfer the heat of combustion from the combustion gas to the water in the water line to maintain the water at a predetermined heating temperature. In some cases, the burner may include two heat exchangers. The burner may include any suitable number of heat exchangers. For example, the burner may include a primary heat exchanger in communication with the water line and a secondary heat exchanger in communication with the water line. The secondary heat exchanger may first preheat the water before the water is further heated by the primary heat exchanger. The combustion gas may exit the burner through a vent (or flue) after passing through the one or more heat exchangers.

[0012] A vapor compression cycle system may include refrigerant lines that direct refrigerant through a refrigerant path that includes a condenser coil, an expansion valve, an evaporator coil, and a compressor. In some cases, the condenser coil may include a portion of the refrigerant line that wraps around a water inlet line of a water line. The condenser coil can be any suitable heat exchanger configuration having a water inlet line. The refrigerant can be directed to the expansion valve following the condenser coil. The expansion valve receives a high-pressure fluid input and outputs the fluid at a lower pressure depending on the environment within the valve, enabling the pressurized refrigerant entering the expansion valve to have its pressure reduced within the evaporator coil and undergo a phase change from liquid to gas. The compressor acts as a pump to provide pressure to the refrigerant flowing through the refrigerant line, thereby maintaining the state where the refrigerant flows through the closed loop defined by the refrigerant line.

[0013] The compressor pumps the gaseous refrigerant received from the evaporator coil forward, increasing the pressure and temperature of the refrigerant, at which point the hotter refrigerant gas can flow through the condenser coil. The hot refrigerant can be separated from the water in the water inlet line by the walls of the refrigerant line and the walls of the water inlet line, both of which are metal and thus relatively highly thermally conductive. Therefore, as the refrigerant travels through the length of the condenser coil, the refrigerant can transfer heat through the walls to the cooler water in the water inlet line. Any suitable heat exchanger configuration can be used between the condenser coil and the water inlet line herein.

[0014] The heat exchanger configuration causes the refrigerant to undergo a phase change from gas to liquid as it passes through the condenser coil. However, even at this point, under the pressure provided by the compressor, the liquid refrigerant can flow from the condenser to the expansion valve, and the expansion valve can reduce its pressure as the liquid refrigerant enters the evaporator coil.

[0015] In some cases, the evaporator coil can be positioned within the burner (e.g., within the burner's vent hood and / or within the vent (or flue)). Combustion gases rising within the vent can pass through the evaporator coil and transfer heat thereto. That is, at this point, the lower-pressure refrigerant within the evaporator coil can absorb heat energy from the combustion gases flowing over the evaporator coil and transition to the vapor phase. Any suitable heat exchanger configuration can be used between the evaporator coil and the combustion gases within the burner vent. The now-warmer gaseous refrigerant can be discharged from the evaporator coil and then returned to the compressor, and this cycle can be repeated.

[0016] In certain embodiments, during operation, water (e.g., cold water) can enter the water heating system through an inlet water line. At least a segment of the inlet water line can be surrounded by a high-temperature refrigerant coil (e.g., a condenser coil) or other heat exchanger device. For example, heat exchange between the condenser coil and the inlet water line can be conserved by wrapping a high-temperature refrigerant tube around the inlet water line, or a double-tube heat exchanger arrangement can be used. The size and form of the heat exchanger arrangement can be adjusted according to the application and heat demand. That is, any suitable heat exchanger arrangement between the inlet water line and the vapor compression cycle system can be used herein.

[0017] In this way, the water within the inlet water line is preheated by the vapor compression cycle system before the water line enters the burner's condensate heat exchanger, which can be referred to as a secondary heat exchanger. The water can absorb heat from the flue gases passing through the secondary heat exchanger and can be further preheated by the burner's secondary heat exchanger. The preheated water then enters the burner's primary heat exchanger and raises its temperature to its desired set point.

[0018] The refrigerant of the secondary heat exchanger can transfer its heat to the water in the inlet water line, and then the refrigerant can then enter the expansion valve. The refrigerant can undergo an expansion process in the expansion valve and become a low-pressure and low-temperature fluid. The refrigerant can then enter the evaporator coil, which can be an integral part of the secondary heat exchanger, or can be disposed in the vent hood and / or vent, or in other parts of the burner. The evaporator coil can be any suitable heat exchanger. The refrigerant can extract heat from the flue gas of the evaporator coil, and thus further cool the flue gas. After the evaporator coil, the refrigerant can be converted into steam and then enter the compressor to become a high-pressure and high-temperature refrigerant. Then, the vapor compression cycle can be repeated.

[0019] These and other embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. This brief introduction, including section titles and corresponding summaries, is provided for the convenience of the reader and is not intended to limit the scope of the claims or the procedural sections. Further, the techniques described above and below can be implemented in numerous ways and in numerous situations. Some exemplary implementations and situations are provided below with reference to the following figures, as described in more detail below. However, the following implementations and situations are only a part of many.

[0020] Returning now to the drawings, FIG. 1 schematically depicts an exemplary water heating system 100 according to one or more embodiments of the present disclosure. In some cases, the water heating system 100 can be a tankless water heating system. That is, the water heating system 100 can be configured to continuously provide hot water on demand. In other cases, the water heating system 100 can include a tank.

[0021] The water heating system 100 may include a burner 102, a vapor compression cycle system 104, and a water line 106 that communicates with the burner 102 and the vapor compression cycle system 104. In some cases, the vapor compression cycle system 104 may be referred to as a heat pump or the like. The water in the water line 106 may first be heated by the vapor compression cycle system 104 before the water enters the burner 102. In this way, the water can be preheated using the vapor compression cycle system 104 before the water is further heated by the burner 102.

[0022] In some cases, the water line 106 may include a water inlet line 108 and a water outlet line 110. The water line 106, the water inlet line 108, and the water outlet line 110 may form a single water line from a water source to a water outlet. The water inlet line 108 may communicate with the vapor compression cycle system 104 in front of the burner 102 so as to preheat the water in the water inlet line 108 before the water line enters the burner 102.

[0023] The vapor compression cycle system 104 may include a refrigerant line 112, a compressor 114, a condenser 116 including a condenser coil 118, an expansion valve 120, and an evaporator 122 including an evaporator coil 124. The refrigerant line 112 may be a closed loop having refrigerant therein. As the refrigerant circulates through the closed loop of the vapor compression cycle system 104, the refrigerant is alternately compressed and expanded to change the state of the refrigerant from a liquid to a vapor. When the state of the refrigerant changes, heat is absorbed and released by the vapor compression cycle system 104.

[0024] The condenser coil 118 can be disposed around the water inlet line 108 so as to preheat the water in the water inlet line 108 before the water enters the burner 102. For example, the compressor 114 can pump the refrigerant to increase the pressure and temperature of the refrigerant. In some cases, the compressor 114 can be a rotary compressor or the like. Any suitable compressor can be used herein. The refrigerant gas can flow through the condenser coil 118. The refrigerant can be separated from the water in the water inlet line 108 by the wall of the refrigerant line and the wall of the water inlet line 108. For example, the condenser coil 118 can be wound around the water inlet line 108. The condenser coil 118 and the water line can be made of a metal material and thus have relatively high thermal conductivity. Therefore, when the refrigerant travels through the length of the condenser coil 118, the refrigerant can transfer heat to the cooler water in the water inlet line 108 through the wall. Any suitable heat exchanger configuration can be used between the condenser 118 and the water inlet line 108 herein. For example, the water inlet line 108 can include a heat exchanger tank or the like that is disposed around it and communicates with the vapor compression cycle system 104 and is a part thereof.

[0025] After the refrigerant exchanges heat with the water in the inlet water line 108, the refrigerant can be expanded by the expansion valve 120. The refrigerant can undergo an expansion process in the expansion valve 120 to become a low-pressure and low-temperature fluid.

[0026] The refrigerant can then enter the evaporator coil 124 after the expansion valve 120. In some cases, the evaporator coil 124 can be disposed in the vent (or flue) of the burner 102 so as to exchange heat with the combustion gas of the burner. For example, the burner 102 can include a combustion chamber 126, a fuel source 128 communicating with the combustion chamber 126, a primary heat exchanger 130, a secondary heat exchanger 132, a vent 134, and a vent hood 136.

[0027] The combustion chamber 126 may be configured to receive fuel from a fuel source 128. The combustion chamber 126 may be configured to receive air from any suitable air source. The fuel and air may be mixed and ignited within the combustion chamber 126. Ignition of the air / fuel mixture may cause hot combustion gases to flow upward through the burner 102, through the primary heat exchanger 130, through the secondary heat exchanger 132, and to the vent hood 136 that may direct the gases toward the vent 134 of the combustion case.

[0028] In certain embodiments, the primary heat exchanger 130 may communicate with the water line 106. Combustion gases rising within the burner may pass through the primary heat exchanger 130 and transfer heat between the water in the water line and the combustion gases. Similarly, in certain embodiments, the secondary heat exchanger 132 may communicate with the water line 106. Combustion gases rising within the burner may pass through the secondary heat exchanger 132 and transfer heat between the water in the water line and the combustion gases. In some cases, the secondary heat exchanger 132 may be positioned downstream (with respect to the combustion gases) of the primary heat exchanger 130. In this way, the combustion gases may first pass through the primary heat exchanger 130 and then through the secondary heat exchanger 132.

[0029] The secondary heat exchanger 132 may further preheat the water in the water line 106 after the water in the water inlet line 108 has been preheated by the vapor compression cycle system 104. For example, in certain embodiments, the water line 106 may first enter the burner 102 and pass through the secondary heat exchanger 132 in order to preheat the water in the water line 106 before the water is further heated by the primary heat exchanger 130. After the primary heat exchanger 130 exchanges heat with the water, the water line 106 may exit the primary heat exchanger to the water outlet line 138.

[0030] After passing through the secondary heat exchanger 132 and the primary heat exchanger 132, the combustion gas can enter a vent hood 136 that can direct the combustion gas toward the vent 134. The evaporator coil 124 can be disposed within the vent hood 136 or the vent 134 so as to exchange heat with the combustion gas of the burner 102. The evaporator coil 124 can be positioned downstream (with respect to the combustion gas) of the primary heat exchanger 130 and the secondary heat exchanger 132. The combustion gas rising within the burner can pass through the evaporator coil to transfer heat between the combustion gas and the refrigerant within the evaporator coil 124. For example, the refrigerant can extract thermal energy from the combustion gas flowing over the evaporator coil 124 within the evaporator coil 124 and transition to the gas phase. The evaporator 122 can be positioned at any suitable location within the burner 102.

[0031] The water heating system 100 can include a bypass line 138 for bypassing the burner 102 and the vapor compression cycle system 104. For example, the bypass line 138 can be disposed between the water inlet line 108 and the water outlet line 110. In some cases, a bypass valve 140 can be disposed on the bypass line 138. When the bypass valve 140 is open, water can flow directly from the water inlet line 108 to the water outlet line 110, thereby bypassing the burner 102 and the vapor compression cycle system 104. In other cases, when the bypass valve 140 is closed, the water in the water inlet line 108 can flow through the water line 106 and exchange heat with the vapor compression cycle system 104 and the burner 102.

[0032] The water heating system 100 may include one or more controllers 142 for controlling various operations and functions of the water heating system 100 and its components. The controller 142 can be an independent controller or can be integrated with the components of the water heating system 100. To control the operation of the water heating system 100, a single controller can be used or multiple controllers can be used. For example, each component of the water heating system 100 can include a controller or one or more controllers can be used to control the operation of the various components of the water heating system 100. The controller 142 can communicate wirelessly with the water heating system 100 and its components and / or can be wired-connected. The controller 142 can include at least a memory and one or more processing units (or processors). The processor can be implemented in hardware, software, firmware, or a combination thereof as needed. The software or firmware implementation of the processor can include computer-executable instructions or machine-executable instructions written in any suitable programming language to perform the various functions described herein. Further, the processor can be associated with a network, server, computer, or mobile device.

[0033] FIG. 2 is a flow diagram representing an exemplary method 200 for heating water according to one or more embodiments of the present disclosure. At block 202 of method 200, heat can be exchanged between the water in the water line 106 by the vapor compression cycle system 104. For example, the condenser coil 118 can be disposed around the water inlet line 108 to preheat the water in the water inlet line 108 before the water enters the burner 102. The refrigerant gas can flow through the condenser coil 118. In some cases, as the refrigerant travels through the length of the condenser coil 118, the refrigerant can transfer heat through the wall to the cooler water in the water inlet line 108. Any suitable heat exchanger configuration can be used between the condenser 118 and the water inlet line 108 herein. For example, the water inlet line 108 can include a heat exchanger tank or the like that is disposed around it and is in communication with the vapor compression cycle system 104 and is a part thereof.

[0034] After the water is preheated by the vapor compression cycle system 104, in block 204 of method 200, heat can be exchanged between the water in the water line 106 and the burner 102. For example, the combustion gas rising within the burner 102 can pass through the primary heat exchanger 130 to transfer heat between the water in the water line and the combustion gas. Similarly, the combustion gas rising within the burner 102 can pass through the secondary heat exchanger 132 to transfer heat between the water in the water line and the combustion gas. In certain embodiments, the water line 106 can first enter the burner 102 and pass through the secondary heat exchanger 132 in order to preheat the water in the water line 106 before the water is further heated by the primary heat exchanger 130.

[0035] In block 206 of method 200, heat can be exchanged between the evaporator 122 of the vapor compression cycle system 104 and the gas within the burner 102. For example, the evaporator coil 124 can be disposed within the vent hood 136 or the vent 134 so as to exchange heat with the combustion gas of the burner 102. The evaporator 122 can be positioned at any suitable location within the burner 102. The combustion gas rising within the burner 102 can pass through the evaporator coil 124 to transfer heat between the combustion gas and the refrigerant within the evaporator coil 124. For example, the refrigerant can take heat energy from the combustion gas flowing over the evaporator coil 124 within the evaporator coil 124 and transition to the gas phase.

[0036] FIG. 3 is a flow diagram depicting an exemplary method 300 for bypassing a water heating system according to one or more embodiments of the present disclosure. In block 302 of method 300, water can be directed from the water inlet line 108 to the water line 106, and the water can be preheated by exchanging heat with the vapor compression cycle system 104. In block 304 of method 300, the water can be further heated within the burner 102.

[0037] In block 306 of method 300, the vapor compression cycle system 104 and the burner 102 can be bypassed. This step can be optional. For example, the water heating system 100 can include a bypass line 138 for bypassing the burner 102 and the vapor compression cycle system 104. In some cases, the bypass line 138 can be disposed between the water inlet line 108 and the water outlet line 110. A bypass valve 140 can be disposed on the bypass line 138. When the bypass valve 140 opens, water can flow directly from the water inlet line 108 to the water outlet line 110, thereby bypassing the burner 102 and the vapor compression cycle system 104. In other cases, when the bypass valve 140 closes, the water in the water inlet line 108 can flow through the water line 106 and exchange heat with the vapor compression cycle system 104 and the burner 102.

[0038] It should be apparent that the above relates only to particular embodiments of the present application and that numerous changes and modifications can be made by those skilled in the art herein without departing from the general spirit and scope of the disclosure.

[0039] While particular embodiments of the present disclosure have been described, numerous other modifications and alternative embodiments are within the scope of the present disclosure. For example, any of the functions described with respect to a particular device or component may be performed by another device or component. Further, while particular device characteristics have been described, embodiments of the present disclosure may relate to numerous other device characteristics. Additionally, while embodiments have been described in specific language with respect to structural features and / or methodological acts, it should be understood that the present disclosure is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing embodiments. In particular, conditional language such as "can," "could," "might," or "may," unless specifically stated otherwise or otherwise understood within the context in which it is used, generally intends to convey that while a particular embodiment may include a particular feature, element, and / or step, other embodiments may not include it. Thus, such conditional language generally does not imply that a feature, element, and / or step is necessarily required for at least one or more embodiments.

Claims

1. A water heating system comprising: a burner; a vapor compression cycle system; and a water line in communication with the burner and the vapor compression cycle system.

2. The water heating system according to claim 1, wherein the water line comprises a water inlet line and a water outlet line, and the water inlet line is in communication with the vapor compression cycle system upstream of the burner.

3. The water heating system according to claim 2, further comprising a bypass line connecting the water inlet line and the water outlet line.

4. The water heating system according to claim 3, further comprising a bypass valve disposed on the bypass line.

5. The water heating system according to claim 2, wherein the vapor compression cycle system comprises a condenser and an evaporator.

6. The water heating system according to claim 5, wherein the condenser is in communication with the water inlet line so as to exchange heat with the water in the water line.

7. The water heating system according to claim 5, wherein the burner comprises a primary heat exchanger, a secondary heat exchanger, and a vent.

8. The water heating system according to claim 7, wherein the evaporator is in communication with the burner so as to exchange heat with the gas in the burner.

9. The water heating system according to claim 7, wherein the water inlet line is in communication with the secondary heat exchanger so that the water exchanges heat with the water in the water line after the water exchanges heat with the condenser.

10. The water heating system according to claim 9, wherein the water line is in communication with the primary heat exchanger so that the water exchanges heat with the water in the water line after the water exchanges heat with the secondary heat exchanger.

11. The water heating system according to claim 7, wherein the water outlet line exits from the primary heat exchanger.

12. A method for heating water, comprising: exchanging heat between water in a water line by a vapor compression cycle system; and then exchanging heat between the water in the water line by a burner.

13. The method according to claim 12, further comprising bypassing the vapor compression cycle system and the burner by a bypass line connecting a water inlet line and a water outlet line of the water line.

14. The method according to claim 12, further comprising exchanging heat between a condenser of the vapor compression cycle system and an inlet water line of the water line.

15. The method according to claim 14, further comprising exchanging heat between the water and a secondary heat exchanger of the burner after the water exchanges heat with the condenser.

16. The method according to claim 15, further comprising exchanging heat between the water and a primary heat exchanger of the burner after the water exchanges heat with the secondary heat exchanger.

17. The method according to claim 12, further comprising exchanging heat between an evaporator of the vapor compression cycle system and a gas in the burner.

18. A water heating system comprising: A burner having at least one heat exchanger; A vapor compression cycle system having at least one heat exchanger; A water line communicating with the at least one heat exchanger of the vapor compression cycle system and the at least one heat exchanger of the burner, Wherein the at least one heat exchanger of the vapor compression cycle system communicates with the water line, and before exchanging heat between water in the water line and gas in the at least one heat exchanger of the burner, heat is exchanged between the water in the water line and a refrigerant of the vapor compression cycle system. A water heating system.

19. The water heating system according to claim 18, further comprising a bypass line connecting a water inlet line and a water outlet line of the water line.

20. The water heating system according to claim 19, further comprising a bypass valve disposed on the bypass line.

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