Air source heat pump system for industrial steam generation and method of use

Abstract

A system for generating steam for industrial heat. The system may include a plurality of heat pump cycles in thermal communication with each other and with the steam generation cycle. The plurality of heat pump cycles may include a first and a second heat pump cycle. The first heat pump circulates a first working fluid and includes a first heat exchanger. The second heat pump cycle circulates a second working fluid and includes a second heat exchanger. The first heat exchanger transfers heat from the first working fluid to the second working fluid. The second heat exchanger transfers heat to a third working fluid within the steam generation cycle.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Application No. 63 / 211,297, filed June 16, 2021, and U.S. Provisional Application No. 63 / 290,784, filed December 17, 2021, each of which is incorporated herein by reference in its entirety.

[0002] The present disclosure is directed to industrial steam production. More specifically, the present disclosure is directed to a highly efficient air source heat pump for industrial steam production and a method of use thereof. [Background technology]

[0003] In the United States, the industrial sector accounts for 22% of greenhouse gas emissions, which equates to approximately 1.5 gigatonnes of carbon dioxide equivalent per year (GtCO2e / yr). Within the industrial sector, steam production for process heat is one of the largest energy consumers, accounting for nearly 4 quadrants of primary energy consumption in the United States, emitting over 200 MM tons of carbon dioxide (CO2) annually. The majority of these emissions are generated from the combustion of fuels for conventional boilers, combined heat and power, and process heating.

[0004] Thus, there is a need in the art for systems and methods of steam generation for industrial heat that are more efficient and produce less carbon emissions. With these considerations in mind, among others, an air source heat pump system for industrial steam generation and a method of use thereof have been developed. Summary of the Invention [Means for solving the problem]

[0005] Aspects of the disclosure include a system for generating steam. The system may include a first heat pump cycle and a second heat pump cycle. The first heat pump cycle is configured to circulate a first working fluid. The first heat pump cycle may include a first heat exchanger, a first compressor, a second heat exchanger, and a first expansion valve. The first heat exchanger is in fluid communication with the first expansion valve and configured to receive the first working fluid from the first expansion valve. The first working fluid absorbs heat in the first heat exchanger. The first compressor is in fluid communication with the first heat exchanger and configured to receive the first working fluid from the first exchanger. The first compressor is configured to increase a pressure and a temperature of the first working fluid. The second heat exchanger is in fluid communication with the first compressor and configured to receive the first working fluid from the first compressor. The second heat exchanger is configured to reject heat from the first working fluid to a second working fluid of a second heat pump cycle. The first expansion valve is in fluid communication with the second heat exchanger and configured to receive the first working fluid from the second heat exchanger. The first expansion valve is configured to expand the first working fluid to a lower pressure.

[0006] The second heat pump cycle is configured to circulate a second working fluid. The second heat pump cycle may include a second heat exchanger, a second compressor, a third heat exchanger, and a second expansion valve. The second heat exchanger is in fluid communication with the second expansion valve and configured to receive the second working fluid from the second expansion valve. The second working fluid absorbs heat from the first working fluid in the second heat exchanger. The second compressor is in fluid communication with the second heat exchanger and configured to receive the second working fluid from the second heat exchanger. The second compressor is configured to increase the pressure and temperature of the second working fluid. The third heat exchanger is in fluid communication with the second compressor and configured to receive the second working fluid from the second compressor. The third heat exchanger is in fluid communication with a third working fluid in the steam generation system. The third heat exchanger is configured to reject heat from the second working fluid to a third working fluid in the steam generation system, the third working fluid being water. The second expansion valve is in fluid communication with the third heat exchanger and configured to receive the second working fluid from the third heat exchanger. The second expansion valve is configured to expand the second working fluid to a lower pressure.

[0007] In some cases, the system may further include a first suction line heat exchanger and a second suction line heat exchanger. The first suction line heat exchanger is in fluid communication with and between the first heat exchanger and the first compressor. The first suction line heat exchanger is in fluid communication with and between the second heat exchanger and the first expansion valve. The first suction line heat exchanger is configured to preheat the first working fluid prior to compressing the first working fluid upon exit of the first working fluid from the second heat exchanger. The second suction line heat exchanger is in fluid communication with and between the second heat exchanger and the second compressor. The second suction line heat exchanger is in fluid communication with and between the third heat exchanger and the second expansion valve. The second suction line heat exchanger is configured to preheat the second working fluid prior to compressing the second working fluid upon exit of the second working fluid from the third heat exchanger.

[0008] In some cases, the first heat exchanger facilitates heat transfer from a first transfer fluid to a first working fluid, the first fluid being air.

[0009] In some cases, the steam generation system may include a steam compressor in fluid communication with the third heat exchanger, the steam compressor configured to increase a pressure and a temperature of the third working fluid to output steam. In some cases, the system may further include a steam generation system.

[0010] In some cases, the steam compressor may be configured to deliver steam from heat delivered from the first and second heat pump cycles at a temperature greater than or equal to 120 degrees Celsius.

[0011] In some cases, the system may further include a control system in electrical communication with the first and second heat pump cycles, the control system configured to control the delivery of heat from at least one or both of the first heat source and the second heat source to the third working fluid, where the first heat source includes the first and second heat pump cycles and the second heat source includes the alternative heat source.

[0012] In some cases, the first and second compressors are centrifugal compressors. In some cases, the first and second compressors are electrically powered.

[0013] In some cases, the first working fluid may be one of a fluorocarbon, a hydrofluoroolefin, a hydrofluoroether, a hydrocarbon, carbon dioxide, ammonia, or water, and the second working fluid may be one of a fluorocarbon, a hydrofluoroolefin, a hydrofluoroether, a hydrocarbon, carbon dioxide, ammonia, or water.

[0014] Aspects of the disclosure include a system for generating steam for industrial heat. The system may include a first heat pump cycle and a second heat pump cycle. The first heat pump cycle is configured to circulate a first working fluid. The first heat pump cycle may include an evaporator, a first compressor, a heat exchanger, and a first expansion valve. The evaporator is in fluid communication with the first expansion valve and configured to receive the first working fluid from the first expansion valve. The first working fluid absorbs heat in the evaporator. The first compressor is in fluid communication with the evaporator and configured to receive the first working fluid from the evaporator. The first compressor is configured to increase a pressure and a temperature of the first working fluid. The heat exchanger is in fluid communication with the first compressor and configured to receive the first working fluid from the first compressor. The heat exchanger is configured to reject heat from the first working fluid to a second working fluid of a second heat pump cycle. A first expansion valve is in fluid communication with the heat exchanger and configured to receive the first working fluid from the heat exchanger, the first expansion valve configured to expand the first working fluid to a lower pressure.

[0015] The second heat pump cycle is configured to circulate a second working fluid. The second heat pump cycle may include a heat exchanger, a suction line heat exchanger, a second compressor, a steam generator, and a second expansion valve. The heat exchanger is in fluid communication with the second expansion valve and configured to receive the second working fluid from the second expansion valve. The second working fluid absorbs heat from the first working fluid in the heat exchanger. The suction line heat exchanger is in fluid communication with the heat exchanger and configured to receive the second working fluid from the heat exchanger. The suction line heat exchanger is configured to preheat the second working fluid prior to compressing the second working fluid. The second compressor is in fluid communication with the suction line heat exchanger and configured to receive the second working fluid from the suction line heat exchanger. The second compressor is configured to increase the pressure and temperature of the second working fluid. The steam generator is in fluid communication with the second compressor and configured to receive a second working fluid from the second compressor. The steam generator is configured to dissipate heat from the second working fluid to the transfer fluid. The suction line heat exchanger is in fluid communication with the steam generator. The second expansion valve is in fluid communication with the suction line heat exchanger and configured to receive the second working fluid from the suction line heat exchanger. The second expansion valve is configured to expand the second working fluid to a lower pressure.

[0016] In some cases, the system may further include a third compressor and a fourth compressor. The third compressor is in the first heat pump cycle. The third compressor is in fluid communication with and positioned between the first compressor and the heat exchanger. The third compressor is configured to receive the first working fluid from the first compressor. The third compressor is configured to increase a pressure and a temperature of the first working fluid. The fourth compressor is in the second heat pump cycle. The fourth compressor is in fluid communication with the second compressor and configured to receive the second working fluid from the second compressor. The fourth compressor is configured to increase a pressure and a temperature of the second working fluid.

[0017] In some cases, the first compressor and the third compressor are rotatably coupled together on a shaft and electrically powered by a motor, hi some cases, the second compressor may be electrically powered by the first motor and the fourth compressor may be electrically powered by the second motor.

[0018] In one case, the first heat pump cycle includes a first economizer and a third expansion valve, the first economizer configured to receive a primary fluid flow of the first working fluid from the heat exchanger and dissipate heat therefrom within the first economizer, the third expansion valve configured to receive a secondary fluid flow of the first working fluid from the heat exchanger and expand the secondary fluid flow of the first working fluid to a lower pressure prior to entering the first economizer, the secondary fluid flow of the first working fluid configured to absorb heat within the first economizer, the secondary fluid flow of the first working fluid may be directed to an inflow of the third compressor, and the primary fluid flow of the first working fluid may be directed to an inflow of the first expansion valve.

[0019] In one case, the first compressor may be configured to receive a primary fluid flow of the first working fluid, and the second compressor may be configured to receive both the primary and secondary fluid flows of the first working fluid.

[0020] In one case, the second heat pump cycle includes a second economizer and a fourth expansion valve, the second economizer configured to receive a primary fluid flow of the second working fluid from the steam generator and dissipate heat therefrom in the second economizer, the fourth expansion valve configured to receive a secondary fluid flow of the second working fluid from the steam generator and expand the secondary fluid flow of the second working fluid to a lower pressure prior to entering the second economizer, the secondary fluid flow of the second working fluid configured to absorb heat in the second economizer, the secondary fluid flow of the second working fluid may be directed to an inlet of the fourth compressor, and the primary fluid flow of the second working fluid may be directed to a suction line heat exchanger to preheat the second working fluid exiting the heat exchanger.

[0021] In some cases, the third compressor may be configured to receive a primary fluid flow of the second working fluid, and the fourth compressor may be configured to receive both the primary and secondary fluid flows of the second working fluid.

[0022] In some cases, the steam generator may be configured to deliver steam at a temperature greater than or equal to 150 degrees Celsius.

[0023] In some cases, the evaporator may be configured to receive a first transfer fluid, and the evaporator may be configured to dissipate heat from the first transfer fluid, which may be air.

[0024] Aspects of the disclosure include a method for generating steam for industrial heat, the method including the steps of rejecting heat from a first circulating fluid to a first working fluid in a first heat exchanger, preheating the first working fluid in a first suction line heat exchanger prior to compressing the first working fluid, compressing the first working fluid via a first compressor, thereby increasing the pressure of the first working fluid, rejecting heat from the first working fluid to a second working fluid in a second heat exchanger, and expanding the first working fluid to a lower pressure via a first expansion valve. The method may include preheating the second working fluid in a second suction line heat exchanger prior to compressing the second working fluid; compressing the second working fluid via a second compressor, thereby increasing a pressure of the second working fluid; rejecting heat from the second working fluid to a third working fluid in a third heat exchanger, the third working fluid being part of a steam generation system; and expanding the second working fluid to a lower pressure via a second expansion valve.

[0025] In some cases, the steam generation system includes a steam compressor configured to generate steam from a third working fluid. In some cases, the steam compressor may be configured to deliver steam at a temperature greater than or equal to 120 degrees Celsius. In some cases, the first and second compressors are centrifugal compressors. In some cases, the first and second compressors are electrically powered.

[0026] Aspects of the disclosure include a method for generating steam for industrial heat, the method including absorbing heat in a first working fluid in an evaporator, the first working fluid circulating in a first heat pump cycle, compressing the first working fluid in a first compressor, thereby increasing a pressure of the first working fluid, compressing the first working fluid in a second compressor, thereby increasing a pressure of the first working fluid, rejecting heat from the first working fluid to a second working fluid in a heat exchanger, the second working fluid circulating in a second heat pump cycle, and expanding the first working fluid to a lower pressure via a first expansion valve. the second working fluid in the fourth compressor, thereby increasing a pressure of the second working fluid; dissipating heat from the second working fluid in the steam generator; dissipating heat from the second working fluid in the suction line heat exchanger after exiting the steam generator; and expanding the second working fluid to a lower pressure via a second expansion valve.

[0027] In some cases, the system may further include splitting the first working fluid into a primary fluid stream and a secondary fluid stream; expanding the secondary fluid stream of the first working fluid to a lower pressure via a third expansion valve; absorbing heat in the secondary fluid stream of the first working fluid in the first economizer; and rejecting heat from the primary fluid stream of the first working fluid to the secondary fluid stream of the first working fluid in the first economizer.

[0028] In some cases, the system may further include directing a primary fluid flow of the first working fluid to a first expansion valve and directing a secondary fluid flow of the first working fluid to an inlet of a second compressor.

[0029] In some cases, the first and second compressors are rotatably coupled together via a shaft and powered by a motor.

[0030] In some cases, heat may be absorbed from ambient air in the evaporator, and the steam generator may be configured to deliver steam at temperatures of 150 degrees Celsius or greater.

[0031] Aspects of the disclosure include a system for generating steam for industrial heat. The system may include a plurality of heat pump cycles in thermal communication with each other and with the steam generating cycle. The plurality of heat pump cycles may include a first heat pump cycle and a second heat pump cycle. The first heat pump is configured to circulate a first working fluid and includes a first heat exchanger and a first suction line heat exchanger. The second heat pump cycle is configured to circulate a second working fluid and includes a second heat exchanger and a second suction line heat exchanger. The first suction line heat exchanger is configured to preheat the first working fluid prior to compressing the first working fluid. The first heat exchanger is configured to transfer heat from the first working fluid to the second working fluid. The second suction line heat exchanger is configured to preheat the second working fluid prior to compressing the second working fluid. The second heat exchanger is configured to transfer heat from the second working fluid to a third working fluid in a steam generating cycle.

[0032] Aspects of the disclosure include an energy arbitrage system including a hierarchical heat pump system generating steam. The energy arbitrage system further includes a computing device in communication with the hierarchical heat pump system for generating steam and a boiler configured to generate steam. The computing device includes a processing device and a computer readable medium with one or more executable instructions stored thereon, the processing device of the computing device executes the one or more instructions to perform operations of receiving steam demand from a facility, sending instructions to the hierarchical heat pump system for generating steam to provide the steam demand from the facility, and if the hierarchical heat pump system for generating steam cannot fulfill all of the steam demand, sending instructions to the boiler to provide a remaining portion of the steam demand from the facility.

[0033] In some instances, the computing device is further in communication with a renewable energy source configured to provide electricity to the electrical grid and to the hierarchical heat pump system. A processing device of the computing device executes one or more instructions and performs further operations of receiving information associated with an amount of electricity produced by the renewable energy source, sending instructions to the renewable energy source to supply the electricity to the system for generating steam, sending instructions to the renewable energy source to supply excess electricity not required by the hierarchical heat pump system for generating steam to the electrical grid, and if the renewable energy source provides an insufficient amount of electricity, sending instructions to the hierarchical heat pump system for generating steam to draw electricity from the electrical grid.

[0034] Aspects of the disclosure include an energy arbitrage system including a hierarchical heat pump system for generating steam. The energy arbitrage system further includes a computing device in communication with the hierarchical heat pump system for generating steam and a renewable energy source configured to provide electricity to an electric grid and to the system for generating steam. The computing device includes a processing device and a computer-readable medium with one or more executable instructions stored thereon, the processing device of the computing device executes one or more instructions to perform the following operations: receive information associated with an amount of electricity produced by the renewable energy source, send instructions to the renewable energy source to supply electricity to the system for generating steam, send instructions to the renewable energy source to supply excess electricity not required by the hierarchical heat pump system for generating steam to the electric grid, and if the renewable energy source provides an insufficient amount of electricity, send instructions to the hierarchical heat pump system for generating steam to draw electricity from the electric grid.

[0035] Aspects of the disclosure include an energy arbitrage system including a hierarchical heat pump system that generates steam. The energy arbitrage system further includes a computing device in communication with the system for generating steam, a thermal storage unit configured to deliver the steam, and a renewable energy source configured to provide electricity to the thermal storage unit and the system for generating steam. The computing device includes a processing device and a computer-readable medium with one or more executable instructions stored thereon, the processing device of the computing device executes one or more instructions to perform operations of receiving information associated with an amount of electricity produced by the renewable energy source, transmitting instructions to the renewable energy source, supplying the electricity to the system for generating steam, transmitting instructions to the renewable energy source, and supplying excess electricity not required by the hierarchical heat pump system for generating steam to the thermal storage unit.

[0036] In some cases, the processing device of the computing device executes the one or more instructions and performs a further operation of sending instructions to a thermal storage unit to supply steam to a facility when the amount of electricity produced by the renewable energy source is insufficient to operate the system to generate steam. [Brief description of the drawings]

[0037] [Figure 1] FIG. 1 is a schematic diagram of a modular, electrically powered, hierarchical air-source heat pump system in conjunction with a steam compressor for use in industrial applications.

[0038] [Diagram 2] FIG. 2 is a schematic diagram of a hierarchical heat pump system including a low temperature air source heat pump and a high temperature vapor coupled heat pump, and a vapor compressor.

[0039] [Diagram 3]FIG. 3 is a schematic diagram of a steam generation system including a bottoming heat pump cycle, a topping heat pump cycle, and a steam compressor.

[0040] [Figure 4] FIG. 4 is a schematic diagram of a modular, hierarchical air source heat pump system.

[0041] [Diagram 5] FIG. 5 is a schematic diagram of a hierarchical heat pump system including a low temperature air source heat pump and a high temperature stream coupled heat pump.

[0042] [Figure 6] FIG. 6 is a table containing exemplary design specifications for a two-stage compressor for the bottoming cycle.

[0043] [Figure 7] FIG. 7 is a schematic diagram of a design for a two-stage compressor for the topping cycle.

[0044] [Figure 8] FIG. 8 is a table containing exemplary design specifications for a two-stage compressor for the topping cycle.

[0045] [Figure 9] FIG. 9 is a schematic diagram of the electrical power input and thermal power output.

[0046] [Figure 10] FIG. 10 is a schematic diagram of a steam generation system including bottoming and topping heat pump cycles with an economizer and a suction line heat exchanger.

[0047] [Figure 11] FIG. 11 is a schematic diagram of an energy arbitrage system.

[0048] [Figure 12]FIG. 12 is an exemplary diagram of a computing device capable of operating as a control system in an energy arbitrage system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] Detailed Description It should be understood that, for convenience and clarity of illustration, reference numerals may be repeated among different figures to indicate corresponding or similar elements, where necessary. In addition, numerous specific details are described to provide a thorough understanding of the embodiments described herein. However, it will be understood by those skilled in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the relevant associated features being described. The drawings are not necessarily to scale, and the proportions of certain parts may be exaggerated to more closely illustrate details and features. The description should not be considered as a limitation on the scope of the embodiments described herein. Thus, elements of one system can be incorporated into any of the systems described herein. Also, elements can be removed from any of the systems described herein, without limitation.

[0050] Several definitions that apply throughout this disclosure will now be presented.

[0051] The term "conduit" is defined as a tube, pipe, or channel for conveying, distributing, or otherwise flowing a fluid. A conduit may be a system conduit or may connect two elements in a system, thereby establishing fluid communication between the two elements.

[0052] The term "coupled" is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to a physical connection. A connection may be such that objects are permanently or releasably connected.

[0053] FIG. 1 illustrates an exemplary steam generation system 100 in an industrial application. A specific example of components of such a system will be illustrated and described in more detail with reference to FIG. 3. FIG. 1 provides an overview of the system 100, which includes a two-stage air-source heat pump with a bottoming heat pump 102 (i.e., a first heat pump) and a topping heat pump 104 (i.e., a second heat pump) that are thermally coupled together by an intermediate heat exchanger (i.e., a heat exchanger). The steam generation system 100 may also include a steam compressor 106. In the intermediate heat exchanger, a working fluid in the bottoming heat pump 102 rejects heat to a working fluid in the topping heat pump 104. In the steam generator (i.e., a heat exchanger), the working fluid of the topping heat pump 104 then rejects heat to a third working fluid 108. In some cases, the third working fluid 108 may pass through the steam compressor 106 after absorbing heat from the steam generator.

[0054] Each of the heat pumps 102, 104 is used to "pump" lower temperature heat to a higher temperature by using an electrical energy source. Currently available heat pumps either do not generate a large enough temperature lift to produce steam or they require the use of a higher temperature waste heat stream as an energy source. As described herein, the system 100 utilizes a "cascade" or series of heat pump cycles, thermally connected with each other, that gradually increase the temperature and deliver decarbonized steam at a lower cost than alternative sources. The system 100 does not require waste heat to deliver high temperature steam.

[0055] The steam generation system 100 of FIG. 1 may be generally applicable to various industrial processes and / or manufacturing environments. For example, the steam generation system 100 may be used to generate industrial steam. In one case, the bottoming heat pump 102 and the topping heat pump 104 may be modular, electrically powered, air-source heat pumps that are thermally arranged in a hierarchical fashion. This modularity may allow for industry-specific needs such as different steam pressures and capacities. Although the system in this application illustrates two heat pump cycles (i.e., a topping heat pump and a bottoming heat pump), the system is scalable and can be modified to include additional heat pumps. In some cases, the system may include three heat pump cycles. In some cases, the system may include four heat pump cycles. In some cases, the system may include five heat pump cycles. In one case, the steam generation system 100 may generate steam at a temperature of about 150 degrees Celsius and a pressure of about 4.5 bar, which may meet the majority of industrial steam production needs, including the food, paper, and chemical industries.

[0056] 1, the bottoming heat pump 102 may utilize ambient air as a heat source (i.e., air-fed). An evaporator (i.e., heat exchanger) of the bottoming heat pump 102 captures heat from the ambient air. The heat is absorbed by the evaporator of the bottoming heat pump 102, thereby evaporating a working fluid within the bottoming heat pump 102.

[0057] The topping heat pump 104 is thermally coupled to the bottoming heat pump 102 by an intermediate heat exchanger. In one case, the intermediate heat exchanger comprises a condenser of the bottoming heat pump 102 and an evaporator of the topping heat pump 104. Thus, in the intermediate heat exchanger, the condenser of the bottoming heat pump 102 dissipates heat and the evaporator of the topping heat pump 104 absorbs heat.

[0058] A conduit (i.e., a fluid flow path) for the third working fluid 108 is coupled to the topping heat pump 104 by a steam generator (i.e., a heat exchanger). In one case, the steam generator comprises a condenser of the topping heat pump 104 and a conduit for the third working fluid 108. Thus, within the steam generator, the condenser of the topping heat pump 104 dissipates heat and the third working fluid 108 absorbs heat.

[0059] A mechanical pump may be used to increase the pressure of the third working fluid 108 before it enters the steam generator. After the third working fluid 108 exits the steam generator, a steam compressor 106 may be used to increase the pressure and temperature of the third working fluid 108. Thus, the mechanical pump may be disposed before the steam generator, the steam compressor 106 may be disposed after the steam generator, or both.

[0060] In one case, the third working fluid 108 is water. In the steam generator, the water absorbs heat from the working fluid of the topping heat pump 104. In one embodiment, the pressure of the water may be above or equal to the target steam saturation temperature. In other words, the water may absorb enough heat from the topping heat pump 104 to evaporate into steam 110. After the steam generator, the steam compressor 106 may be used to directly increase the pressure and temperature of the steam 110. In one embodiment, the pressure of the water may be below the target steam saturation temperature after exiting the steam generator, and therefore the steam compressor 106 may be used to increase the pressure of the water to the required saturation temperature. The system 100 may be retrofitted to an existing steam generation system in a facility. Alternatively, the system 100 may include a steam generation system as part of the overall system 100.

[0061] The steam generation system 100 may be powered by electricity 112. In other words, the electricity 112 is input into the steam generation system 100 to generate steam 110. For example, the steam generation system 100 may be powered through grid electricity, on-site renewable energy, or a combination thereof. The steam generation system 100 may enable the economic decarbonization of industrial steam production, as steam energy in the industrial sector 114 accounts for nearly 4 quads of primary energy consumption in the United States and emits over 200 MM tons of CO2 annually.

[0062] In some cases, the steam generation system 100 may incorporate energy arbitrage. In other words, energy arbitrage may be used in conjunction with the steam generation system 100 by incorporating additional systems that may provide heat to the steam generation system 100 and / or electricity to the heat pump system described herein. The additional systems may include solar arrays, thermal storage systems, and fuel boilers (e.g., natural gas, coal, waste, or biomass), among other systems. These systems may be coupled to the steam generation system 100 and / or heat pump system and selectively activated to provide heat to the system 100 and / or electricity to the heat pump system. The specific system that provides heat to the steam generation system 100 and / or electricity to the heat pump system may be determined by other factors, including the availability and price of the energy source of the system that applies the heat or electricity, and the requirements of the steam generation system 100. By incorporating energy arbitrage, the steam generation system 100 is capable of generating consistent steam delivery while significantly reducing carbon emissions.

[0063] In some cases, the steam generation system 100 may include more than two heat pumps arranged in a thermal tiered fashion to heat and pump air and generate steam. In one case, the steam generation system 100 may include three heat pumps. For example, the steam generation system 100 may include a bottoming heat pump (i.e., the first heat pump), an intermediate heat pump (i.e., the second heat pump), and a topping heat pump (i.e., the third heat pump). In another case, the steam generation system 100 may include four heat pumps. For example, the steam generation system 100 may include a bottoming heat pump (i.e., the first heat pump), a first intermediate heat pump (i.e., the second heat pump), a second intermediate heat pump (i.e., the third heat pump), and a topping heat pump (i.e., the fourth heat pump). In another case, the steam generation system 100 may include five heat pumps.

[0064] In one case, the bottoming heat pump 102 is coupled to ambient air (i.e., air-fed). However, in other cases, the bottoming heat pump 102 may be coupled to another low temperature heat source. For example, the low temperature heat source may be a liquid loop that dissipates heat to the air, the ground, or another co-located cooling load. In one example, the liquid loop may contain water.

[0065] 2 illustrates a partial schematic diagram of a steam generation system 200, which is a partial embodiment of the steam generation system 100 illustrated in FIG. 1. Steam generation system 200 includes a bottoming heat pump 202 (i.e., a first heat pump) and a topping heat pump 204 (i.e., a second heat pump) that are thermally arranged in a hierarchical manner. Bottoming heat pump 202 may be a low temperature air source heat pump and topping heat pump 204 may be a high temperature steam coupled heat pump. Steam generation system 200 may also include a steam compressor 206.

[0066] The steam generation system 200 may include a hierarchical heat pump that incorporates high efficiency components to achieve a coefficient of performance greater than 2 without using waste heat. For example, the high efficiency components may include a high efficiency refrigerant compressor and a motor. In one case, the compressor may be equal to or greater than 85% efficient and the motor may be equal to or greater than 93% efficient.

[0067] For example, a 1 megawatt thermal power (MWth) steam generation system 200 may produce 150 degree Celsius steam at a nominal ambient temperature of 20 degrees Celsius. In other words, the steam generation system 200 may provide a temperature lift of 20 degrees Celsius to 150 degrees Celsius at a coefficient of performance greater than 2 without requiring waste heat.

[0068] Heat transfer 216a involves bottoming heat pump 202 capturing heat from ambient air by evaporating a working fluid, which may be a refrigerant. In one case, the ambient air may be at about 20 degrees Celsius and the working fluid may be evaporated at 0 degrees Celsius. Electricity 212a may be applied to bottoming heat pump 202, which may include a 144 kilowatt electric (kWe) high efficiency compressor and motor. In one case, the compressor may operate at about 85% efficiency and the motor may operate at about 93% efficiency.

[0069] Heat transfer 216b involves a condenser rejecting heat from the bottoming heat pump 202 to an evaporator in the topping heat pump 204, thereby evaporating a working fluid in the topping heat pump 204. The working fluid in the topping heat pump 204 may be a refrigerant. In one case, the working fluid in the topping heat pump 204 may be evaporated at 50 degrees Celsius. Electricity 212b may be applied to the topping heat pump 204, which may include a 170 kWe high efficiency compressor and motor. In one case, the compressor may operate at about 85% efficiency and the motor may operate at about 93% efficiency.

[0070] Heat transfer 216c involves the condenser rejecting heat from the topping heat pump 204 to the evaporating water stream. Within the evaporating water stream, electricity 212c may be applied to the steam compressor 206, which may consume an additional 122 kWe. Thus, 1 MWth of steam 210 is delivered at 150 degrees Celsius saturation temperature.

[0071] In colder environments, the steam generation system 200 coefficient of performance may decrease due to the higher pressure lift required by the refrigerant compressor. However, the steam generation system 200 may achieve high performance even in low temperature environments through system design and high efficiency compressors. The steam generation system 200 may use two different working fluids for the topping and bottoming cycle and the final stage steam compressor. In one case, reduced auxiliary loads, increased motor efficiency, and an improved air-coupled heat exchanger may be optimized to reduce the refrigerant to ambient air temperature difference. For example, increasing the compressor efficiency to 90%, reducing the evaporator to air temperature difference from 20 degrees Celsius to 8.5 degrees Celsius, and increasing the motor efficiency to 96% allows the steam generation system 200 to maintain a coefficient of performance above 2 when the ambient air is below -6.5 degrees Celsius.

[0072] Figure 3 illustrates a steam generation system 300 that includes many of the elements described with reference to Figures 1 and 2. Figure 3 is a schematic diagram of steam generation system 300, which includes a first heat pump cycle 302 (i.e., a bottoming heat pump cycle) and a second heat pump cycle 304 (i.e., a topping heat pump cycle) in thermal communication with each other. Steam generation system 300 is in thermal communication with second heat pump cycle 304 and may also include a steam compressor 306.

[0073] The first heat pump cycle 302 circulates a first working fluid 318 through a conduit 320 of the first heat pump cycle 302 as illustrated in FIG. 3. In one case, the first working fluid 318 may be a fluorocarbon. As a non-limiting example, the fluorocarbon may be R1234ze(z) or R1234ze(E). In one case, the first working fluid 318 may be a hydrofluoroolefin. As a non-limiting example, the hydrofluoroolefin may be R514a. In one case, the first working fluid 318 may be a hydrofluoroether. In one case, the first working fluid 318 may be a hydrocarbon. In one case, the first working fluid 318 may be carbon dioxide. In one case, the first working fluid 318 may be ammonia. In one case, the first working fluid 318 may be water. In one instance, the first working fluid 318 may be an engineered fluid. As a non-limiting example, the engineered fluid may be Novec649.

[0074] In the first heat pump cycle 302, the heat exchanger 322 receives a first working fluid 318 from an expansion valve 324. In other words, the first working fluid 318 exits the expansion valve 324 at an expansion valve outlet 326 and enters the heat exchanger 322 at a heat exchanger inlet 328. A conduit 320 connects the expansion valve outlet 326 to the heat exchanger inlet 328, thereby establishing fluid communication between the expansion valve 324 and the heat exchanger 322. Within the heat exchanger 322, the first working fluid 318 absorbs heat. This heat absorption may vaporize the first working fluid 318, such that the first working fluid 318 becomes low pressure steam when it exits the heat exchanger 322 at a heat exchanger outlet 330. In one case, the heat exchanger 322 may include an evaporator of the first heat pump cycle 302, whereby the evaporator absorbs heat and the first working fluid 318 is evaporated within the evaporator. In one case, the heat exchanger 322 may be a low temperature evaporator.

[0075] In one case, a suction line heat exchanger ("SLHX") 332 may be incorporated into the first heat pump cycle 302. The SLHX 332 receives a first working fluid 318 from a heat exchanger 322 in a first passage of the SLHX 332. In other words, the first working fluid 318 exits the heat exchanger 322 at a heat exchanger outlet 330 and enters the SLHX 332 at a SLHX inlet 334. A conduit 320 connects the heat exchanger outlet 330 to the SLHX inlet 334, thereby establishing fluid communication between the heat exchanger 322 and the SLHX 332. Within the first passage of the SLHX 332 , the first working fluid 318 absorbs heat, thereby further heating (ie, pre-heating) the first working fluid 318 before exiting the SLHX 332 at the SLHX outlet 336 .

[0076] In other cases, the first heat pump cycle 302 does not include a SLHX 332. In other words, the first working fluid 318 exits the heat exchanger 322 at a heat exchanger outlet 330 and enters the compressor 338 at a compressor inlet 340. A conduit 320 connects the heat exchanger outlet 330 to the compressor inlet 340, thereby establishing fluid communication between the heat exchanger 322 and the compressor 338.

[0077] The compressor 338 receives the first working fluid 318 from the SLHX 332. In other words, the first working fluid 318 exits the SLHX 332 at an SLHX outlet 336 and enters the compressor 338 at a compressor inlet 340. A conduit 320 connects the SLHX outlet 336 to the compressor inlet 340, thereby establishing fluid communication between the SLHX 332 and the compressor 338. Within the compressor 338, the first working fluid 318 is compressed to a higher pressure, which increases the temperature before the first working fluid 318 exits the compressor 338 at a compressor outlet 342. In one case, the compressor 338 is a high efficiency compressor. In one case, the compressor 338 may be a centrifugal compressor. In one case, the compressor 338 may be a two-stage centrifugal compressor. In one case, the compressor 338 may be electrically powered. In one case, a high speed and / or high efficiency motor may drive the compressor 338.

[0078] A heat exchanger 344 (i.e., an intermediate heat exchanger) thermally couples the first heat pump cycle 302 and the second heat pump cycle 304. The heat exchanger 344 receives the first working fluid 318 from the compressor 338. In other words, the first working fluid 318 exits the compressor 338 at a compressor outlet 342 and enters the heat exchanger 344 at a heat exchanger inlet 346. A conduit 320 connects the compressor outlet 342 to the heat exchanger inlet 346, thereby establishing fluid communication between the compressor 338 and the heat exchanger 344. Within the heat exchanger 344, the first working fluid 318 releases heat. This release of heat may cause the first working fluid 318 to condense before exiting the heat exchanger 344 at the heat exchanger outlet 348. In one case, the heat exchanger 344 comprises a condenser of the first heat pump cycle 302 and an evaporator of the second heat pump cycle 304. Thus, in the heat exchanger 344, the condenser of the first heat pump cycle 302 gives off heat and the evaporator of the second heat pump cycle 304 absorbs heat. In the heat exchanger 344, a second working fluid 350, which may circulate in a conduit 352 in the second heat pump cycle 304, absorbs heat. This heat absorption may vaporize the second working fluid 350, such that the second working fluid 350 is low pressure steam when it exits the heat exchanger 344.

[0079] In one case, when the SLHX 332 is incorporated into the first heat pump cycle 302, the SLHX 332 receives the first working fluid 318 from the heat exchanger 344 in a second passage of the SLHX 332. In other words, the first working fluid 318 exits the heat exchanger 344 at a heat exchanger outlet 348 and enters the SLHX 332 at a SLHX inlet 354. A conduit 320 connects the heat exchanger outlet 348 to the SLHX inlet 354, thereby establishing fluid communication between the heat exchanger 344 and the SLHX 332. Within the second passage of the SLHX 332, the first working fluid 318 releases heat, thereby cooling (i.e., pre-cooling) the first working fluid 318 before exiting the SLHX 332 at the SLHX outlet 356.

[0080] In other cases, the first heat pump cycle 302 does not include a SLHX 332. In other words, the first working fluid 318 exits the heat exchanger 344 at a heat exchanger outlet 348 and enters the expansion valve 324 at an expansion valve inlet 358. A conduit 320 connects the heat exchanger outlet 348 to the expansion valve inlet 358, thereby establishing fluid communication between the heat exchanger 344 and the expansion valve 324.

[0081] An expansion valve 324 receives the first working fluid 318 from the SLHX 332. In other words, the first working fluid 318 exits the SLHX 332 at an SLHX outlet 356 and enters the expansion valve 324 at an expansion valve inlet 358. A conduit 320 connects the SLHX outlet 356 to the expansion valve inlet 358, thereby establishing fluid communication between the SLHX 332 and the expansion valve 324. Within the expansion valve 324, the first working fluid 318 is expanded to a lower pressure, which reduces the temperature before the first working fluid 318 exits the expansion valve 324 at an expansion valve outlet 326.

[0082] The second heat pump cycle 304 circulates a second working fluid 350 as illustrated in FIG. 3. In one case, the second working fluid 350 may be a fluorocarbon. As a non-limiting example, the fluorocarbon may be R1234ze(z) or R1234ze(E). In one case, the second working fluid 350 may be a hydrofluoroolefin. As a non-limiting example, the hydrofluoroolefin may be R514a. In one case, the second working fluid 350 may be a hydrofluoroether. In one case, the second working fluid 350 may be a hydrocarbon. In one case, the second working fluid 350 may be carbon dioxide. In one case, the second working fluid 350 may be ammonia. In one case, the second working fluid 350 may be water. In one case, the second working fluid 350 may be an engineered fluid. As a non-limiting example, the engineered fluid may be Novec649.

[0083] In one case, the same fluid may be used for both the first working fluid 318 and the second working fluid 350. In other cases, different fluids may be used for the first working fluid 318 and the second working fluid 350.

[0084] In one case, the second heat pump cycle 304 may contain the same components as the first heat pump cycle 302. The components of the second heat pump cycle 304 may be arranged in the same configuration as the components of the first heat pump cycle 302. The components of the second heat pump cycle 304 may be arranged in a different configuration than the components of the first heat pump cycle 302. In other cases, the second heat pump cycle 304 may contain different components than the first heat pump cycle 302.

[0085] In the second heat pump cycle 304, the heat exchanger 344 receives the second working fluid 350 from the expansion valve 360. In other words, the second working fluid 350 exits the expansion valve 360 ​​at the expansion valve outlet 362 and enters the heat exchanger 344 at the heat exchanger inlet 364. A conduit 352 connects the expansion valve outlet 362 to the heat exchanger inlet 364, thereby establishing fluid communication between the expansion valve 360 ​​and the heat exchanger 344. Within the heat exchanger 344, the second working fluid 350 absorbs heat. This heat absorption may vaporize the second working fluid 350, such that the second working fluid 350 becomes low pressure steam when it exits the heat exchanger 344 at the heat exchanger outlet 366. In one case, the heat exchanger 344 includes a condenser of the first heat pump cycle 302 and an evaporator of the second heat pump cycle 304. Thus, in the heat exchanger 344, the condenser of the first heat pump cycle 302 dissipates heat and the evaporator of the second heat pump cycle 304 absorbs heat.

[0086] In one case, a suction line heat exchanger ("SLHX") 368 may be incorporated into the second heat pump cycle 304. The SLHX 368 receives a second working fluid 350 from a heat exchanger 344 in a first passage of the SLHX 368. In other words, the second working fluid 350 exits the heat exchanger 344 at a heat exchanger outlet 366 and enters the SLHX 368 at a SLHX inlet 370. A conduit 352 connects the heat exchanger outlet 366 to the SLHX inlet 370, thereby establishing fluid communication between the heat exchanger 344 and the SLHX 368. Within the first passage of the SLHX 368, the second working fluid 350 absorbs heat, thereby further heating (ie, pre-heating) the second working fluid 350 before exiting the SLHX 368 at the SLHX outlet 372.

[0087] In other cases, the second heat pump cycle 304 does not include a SLHX 368. In other words, the second working fluid 350 exits the heat exchanger 344 at a heat exchanger outlet 366 and enters the compressor 374 at a compressor inlet 376. A conduit 352 connects the heat exchanger outlet 366 to the compressor inlet 376, thereby establishing fluid communication between the heat exchanger 344 and the compressor 374.

[0088] The compressor 374 receives the second working fluid 350 from the SLHX 368. In other words, the second working fluid 350 exits the SLHX 368 at an SLHX outlet 372 and enters the compressor 374 at a compressor inlet 376. A conduit 352 connects the SLHX outlet 372 to the compressor inlet 376, thereby establishing fluid communication between the SLHX 368 and the compressor 374. Within the compressor 374, the second working fluid 350 is compressed to a higher pressure, which increases the temperature before the second working fluid 350 exits the compressor 374 at a compressor outlet 378. In one case, the compressor 374 is a high efficiency compressor. In one case, the compressor 374 may be a centrifugal compressor. In one case, the compressor 374 may be electrically powered. In one case, a high speed and / or high efficiency motor may drive the compressor 374.

[0089] A heat exchanger 380 thermally couples the second heat pump cycle 304 and the third working fluid 308 system. The heat exchanger 380 receives the second working fluid 350 from the compressor 374. In other words, the second working fluid 350 exits the compressor 374 at a compressor outlet 378 and enters the heat exchanger 380 at a heat exchanger inlet 382. A conduit 352 connects the compressor outlet 378 to the heat exchanger inlet 382, ​​thereby establishing fluid communication between the compressor 374 and the heat exchanger 380. Within the heat exchanger 380, the second working fluid 350 releases heat. This release of heat may cause the second working fluid 350 to condense before exiting the heat exchanger 380 at a heat exchanger outlet 384. In one case, the heat exchanger 380 may include a condenser of the second heat pump cycle 304, whereby the condenser gives off heat and the second working fluid 350 condenses in the condenser. Within the heat exchanger 380, the third working fluid 308, which may flow in a conduit 386, absorbs heat. This heat absorption may vaporize the third working fluid 308, whereby the third working fluid 308 is a vapor when it exits the heat exchanger 380.

[0090] In one case, when the SLHX 368 is incorporated into the second heat pump cycle 304, the SLHX 368 receives the second working fluid 350 from the heat exchanger 380 in a second passage of the SLHX 368. In other words, the second working fluid 350 exits the heat exchanger 380 at a heat exchanger outlet 384 and enters the SLHX 368 at a SLHX inlet 388. A conduit 352 connects the heat exchanger outlet 384 to the SLHX inlet 388, thereby establishing fluid communication between the heat exchanger 380 and the SLHX 368. Within the second passage of the SLHX 368, the second working fluid 350 dissipates heat, thereby cooling (i.e., pre-cooling) the second working fluid 350 before exiting the SLHX 368 at the SLHX outlet 390.

[0091] In other cases, the second heat pump cycle 304 does not include the SLHX 368. In other words, the second working fluid 350 exits the heat exchanger 380 at a heat exchanger outlet 384 and enters the expansion valve 360 ​​at an expansion valve inlet 392. A conduit 352 connects the heat exchanger outlet 384 to the expansion valve inlet 392, thereby establishing fluid communication between the heat exchanger 380 and the expansion valve 360.

[0092] Expansion valve 360 ​​receives second working fluid 350 from SLHX 368. In other words, second working fluid 350 exits SLHX 368 at SLHX outlet 390 and enters expansion valve 360 ​​at expansion valve inlet 392. Conduit 352 connects SLHX outlet 390 to expansion valve inlet 392, thereby establishing fluid communication between SLHX 368 and expansion valve 360. Within expansion valve 360, second working fluid 350 is expanded to a lower pressure, which reduces the temperature before second working fluid 350 exits expansion valve 360 ​​at expansion valve outlet 362.

[0093] The third working fluid 308 may absorb heat from the heat exchanger 380 as illustrated in FIG. 3 . In other words, the heat exchanger 380 may receive the third working fluid 308. In the heat exchanger 380, the second working fluid 350 releases heat and the third working fluid 308 absorbs heat. In one case, the heat exchanger 380 may include a condenser of the second heat pump cycle 304, whereby the condenser releases heat and the third working fluid 308 absorbs heat. The second working fluid 350 is condensed as it releases heat in the condenser. In one case, the heat exchanger 380 may be a steam generator. In the steam generator, the third working fluid 308 may absorb enough heat to become water vapor.

[0094] In one case, the third working fluid 308 may be supplied to the heat exchanger 380 via a conduit 386. In other words, the conduit 386 for the third working fluid 308 is thermally coupled to the second heat pump cycle 304 by the heat exchanger 380.

[0095] In one case, the mechanical pump 301 may increase the pressure of the third working fluid 308. The mechanical pump 301 may be upstream of the heat exchanger 380, such that the heat exchanger 380 receives the third working fluid 308 from the mechanical pump 301. In other words, the third working fluid 308 exits the mechanical pump 301 at a mechanical pump outlet 303 and enters the heat exchanger 380 at a heat exchanger inlet 305. A conduit 386 connects the mechanical pump outlet 303 to the heat exchanger inlet 305, thereby establishing fluid communication between the mechanical pump 301 and the heat exchanger 380. The third working fluid 308 may exit the heat exchanger 380 at a heat exchanger outlet 307 and enter the conduit 386.

[0096] In one case, steam compressor 306 may increase the pressure and temperature of third working fluid 308. Steam compressor 306 may be downstream of heat exchanger 380, whereby steam compressor 306 receives third working fluid 308 from heat exchanger 380. In other words, third working fluid 308 exits heat exchanger 380 at heat exchanger outlet 307 and enters steam compressor 306 at steam compressor inlet 309. Conduit 386 connects heat exchanger outlet 307 to steam compressor inlet 309, thereby establishing fluid communication between heat exchanger 380 and steam compressor 306.

[0097] In the steam compressor 306, the third working fluid 308 is compressed to a higher pressure and temperature. In one case, the steam compressor 306 increases the pressure and temperature of the third working fluid 308 and converts the third working fluid 308 to steam before it exits the steam compressor 306 at a steam compressor outlet 311. The steam may enter a conduit 386, which is connected to the steam compressor outlet 311. In one case, the steam compressor 306 delivers steam at a temperature equal to or greater than 120 degrees Celsius. In one case, the steam compressor 306 is a high efficiency compressor. In one case, the steam compressor 306 may be a centrifugal compressor. In one case, the steam compressor 306 may be electrically powered.

[0098] In one case, the third working fluid 308 is water. In the heat exchanger 380, the water absorbs heat from the second working fluid 350 of the second heat pump cycle 304. In one embodiment, the pressure of the water may be above or equal to the target vapor saturation temperature when the water exits the heat exchanger 380 at the heat exchanger outlet 307. In other words, the water may absorb enough heat from the second heat pump cycle 304 to evaporate into vapor. After the heat exchanger 380, the steam compressor 306 may be used to directly increase the pressure and temperature of the vapor. In one embodiment, the pressure of the water may be below the target vapor saturation temperature when the water exits the heat exchanger 380 at the heat exchanger outlet 307. Thus, the steam compressor 306 may be used to increase the pressure of the water to the required saturation temperature.

[0099] Turning back to the first heat pump cycle 302 and the heating therefor, the transfer fluid 313 may dissipate heat to the heat exchanger 322 as illustrated in FIG. 3 . In other words, the heat exchanger 322 receives the transfer fluid 313. In the heat exchanger 322, the transfer fluid 313 dissipates heat and the first working fluid 318 absorbs heat. In one case, the heat exchanger 322 may include an evaporator of the first heat pump cycle 302, whereby the transfer fluid 313 dissipates heat and the evaporator absorbs heat. The first working fluid 318 is evaporated as it absorbs heat in the evaporator. In one case, the heat exchanger 322 may be a low-temperature evaporator.

[0100] In one case, the transfer fluid 313 may be provided to the heat exchanger 322 via a conduit 315. In other words, the conduit 315 for the transfer fluid 313 is coupled to the first heat pump cycle 302 by the heat exchanger 322.

[0101] In one case, the mechanical pump 317 may increase the pressure of the transfer fluid 313. The mechanical pump 317 may be upstream of the heat exchanger 322, such that the heat exchanger 322 receives the transfer fluid 313 from the mechanical pump 317. In other words, the transfer fluid 313 exits the mechanical pump 317 at a mechanical pump outlet 319 and enters the heat exchanger 322 at a heat exchanger inlet 321. A conduit 315 connects the mechanical pump outlet 319 to the heat exchanger inlet 321, thereby establishing fluid communication between the mechanical pump 317 and the heat exchanger 322. The transfer fluid 313 may exit the heat exchanger 322 at a heat exchanger outlet 323 and enter the conduit 315.

[0102] In one case, the transfer fluid 313 is ambient air, whereby the heat exchanger 322 of the first heat pump cycle 302 utilizes the ambient air as a heat source (i.e., air-fed). The heat exchanger 322 of the first heat pump cycle 302 may capture heat from the ambient air. The heat is absorbed by the heat exchanger 322 of the first heat pump cycle 302, thereby evaporating the first working fluid 318 in the first heat pump cycle 302.

[0103] In other cases, the transfer fluid 313 may be a liquid that is connected to a low temperature heat source. In one case, the low temperature heat source may be ambient air. In other cases, the first heat pump cycle 302 may be coupled to another low temperature heat source. For example, the low temperature heat source may be a liquid loop that dissipates heat to the air, ground, or another co-located cooling load. In one example, the liquid loop may contain water.

[0104] A control system may be in electrical communication with the first heat pump cycle 302 and the second heat pump cycle 304. The control system may control the delivery of heat from the first heat source and / or the second heat source to the third working fluid 308. The first heat source may include the first heat pump cycle 302 and the second heat pump cycle 304. The second heat source may include alternative heat sources such as thermal storage steam systems, fuel-fired boilers (e.g., natural gas, coal, biomass), among other possible heat sources. The control system may also control the source of electrical power supplied to the first and second heat pump cycles 302, 304. For example, the first and second heat pump cycles 302, 304 may be electrically coupled to an electrical grid and a solar thermal grid. When conditions are favorable based on availability, price, and power requirements, the first and second heat pump cycles 302, 304 may be powered from one or both of the electric grid and the solar thermal grid.

[0105] FIG. 4 illustrates an exemplary steam generation system 400 in an industrial application. A specific example of components of such a system will be illustrated and described in more detail with reference to FIG. 10. FIG. 4 provides an overview of the system 400, which includes a two-stage air-source heat pump with a bottoming heat pump 402 (i.e., a first heat pump) and a topping heat pump 404 (i.e., a second heat pump) that are thermally coupled together by an intermediate heat exchanger (i.e., a heat exchanger). In the intermediate heat exchanger, the working fluid in the bottoming heat pump 402 rejects heat to a working fluid in the topping heat pump 404. In the steam generator (i.e., a heat exchanger), the working fluid of the topping heat pump 404 then rejects heat to a third working fluid 408. In some cases, the steam generation system 400 may also include a steam compressor (not shown in FIG. 4) configured to increase the temperature and pressure of the third working fluid 408 after the third working fluid 408 absorbs heat from the steam generator.

[0106] Heat pumps 402, 404 are each used to "pump" lower temperature heat to a higher temperature by using an electrical energy source. Currently available heat pumps either do not generate a large enough temperature lift to produce steam or they require the use of a higher temperature waste heat stream as an energy source. As described herein, system 400 utilizes a "cascade" or series of heat pump cycles, thermally connected with each other, that gradually increase the temperature and deliver decarbonized steam at a lower cost than alternative sources. System 400 does not require waste heat to deliver high temperature steam.

[0107] The steam generation system 400 of FIG. 4 may be generally applicable to various industrial processes and / or manufacturing environments. For example, the steam generation system 400 may be used to generate industrial steam. In one case, the bottoming heat pump 402 and the topping heat pump 404 may be modular, electrically powered, air-source heat pumps that are thermally arranged in a hierarchical fashion. This modularity may allow for industry-specific needs such as different steam pressures and capacities. Although the system in this application illustrates two heat pump cycles (i.e., a topping heat pump and a bottoming heat pump), the system is scalable and can be modified to include additional heat pumps. In some cases, the system may include three heat pump cycles. In some cases, the system may include four heat pump cycles. In some cases, the system may include five heat pump cycles. In one case, the steam generation system 400 may generate steam at a temperature of about 150 degrees Celsius and a pressure of about 4.5 bar, which may meet the majority of industrial steam production needs, including the food, paper, and chemical industries.

[0108] In the steam generation system 400 of Figure 4, the bottoming heat pump 402 may utilize ambient air as a heat source (i.e., air-fed). An evaporator (i.e., heat exchanger) of the bottoming heat pump 402 captures heat from the ambient air. The heat is absorbed by the evaporator of the bottoming heat pump 402, thereby evaporating a working fluid within the bottoming heat pump 402.

[0109] The topping heat pump 404 is thermally coupled to the bottoming heat pump 402 by an intermediate heat exchanger. In one case, the intermediate heat exchanger comprises a condenser of the bottoming heat pump 402 and an evaporator of the topping heat pump 404. Thus, in the intermediate heat exchanger, the condenser of the bottoming heat pump 402 dissipates heat and the evaporator of the topping heat pump 404 absorbs heat.

[0110] A conduit (i.e., a pipe providing a fluid flow path) for the third working fluid 408 is coupled to the topping heat pump 404 by a steam generator (i.e., a heat exchanger). In one case, the steam generator comprises a condenser of the topping heat pump 404 and a conduit for the third working fluid 408. Thus, within the steam generator, the condenser of the topping heat pump 404 dissipates heat and the third working fluid 408 absorbs heat.

[0111] A mechanical pump may be used to increase the pressure of third working fluid 408 before it enters the steam generator. After third working fluid 408 exits the steam generator, a steam compressor may be used to increase the pressure and temperature of third working fluid 408. Thus, the mechanical pump may be disposed before the steam generator, the steam compressor may be disposed after the steam generator, or both.

[0112] In one case, the third working fluid 408 is water. In the steam generator, the water absorbs heat from the working fluid of the topping heat pump 404. In one embodiment, the pressure of the water may be above or equal to the target steam saturation temperature. In other words, the water may absorb enough heat from the topping heat pump 404 to evaporate into steam 410. After the steam generator, a steam compressor may be used to directly increase the pressure and temperature of the steam 410. In one embodiment, the pressure of the water may be below the target steam saturation temperature after exiting the steam generator, and therefore a steam compressor may be used to increase the pressure of the water to the required saturation temperature. The system 400 may be retrofitted to an existing steam generation system in a facility. Alternatively, the system 400 may include a steam generation system as part of the overall system 400.

[0113] The steam generation system 400 may be powered by electricity 412. In other words, electricity 412 is input into the steam generation system 400 to generate steam 410. For example, the steam generation system 400 may be powered through grid electricity, on-site renewable energy, or a combination thereof. The steam generation system 400 may enable the economic decarbonization of industrial steam production, as steam energy in the industrial sector accounts for nearly 4 quads of primary energy consumption in the United States and emits over 200 MM tons of CO2 annually.

[0114] In some cases, the steam generation system 400 may incorporate energy arbitrage, as described with reference to FIG. 1. In other words, energy arbitrage may be used in conjunction with the steam generation system 400 by incorporating additional systems that may provide heat to the steam generation system 400 and / or electricity to the heat pump system described herein. The additional systems may include solar arrays, thermal storage systems, and fuel boilers (e.g., natural gas, coal, waste, or biomass), among other systems. These systems may be coupled to the steam generation system 400 and / or the heat pump system and selectively activated to provide heat to the system 400 and / or electricity to the heat pump system. The specific systems that provide heat to the steam generation system 400 and / or electricity to the heat pump system may be determined by other factors, including the availability and price of the energy sources of the systems that apply the heat or electricity, as well as the requirements of the steam generation system 400. By incorporating energy arbitrage, the steam generation system 400 is capable of generating a consistent steam delivery while significantly reducing carbon emissions.

[0115] In some cases, the steam generation system 400 may include more than two heat pumps arranged in a thermal tiered fashion to heat and pump air and generate steam. In one case, the steam generation system 400 may include three heat pumps. For example, the steam generation system 400 may include a bottoming heat pump (i.e., the first heat pump), a middle heat pump (i.e., the second heat pump), and a topping heat pump (i.e., the third heat pump). In another case, the steam generation system 400 may include four heat pumps. For example, the steam generation system 400 may include a bottoming heat pump (i.e., the first heat pump), a first middle heat pump (i.e., the second heat pump), a second middle heat pump (i.e., the third heat pump), and a topping heat pump (i.e., the fourth heat pump). In another case, the steam generation system 400 may include five heat pumps.

[0116] In one case, the bottoming heat pump 402 is coupled to ambient air (i.e., air-fed). However, in other cases, the bottoming heat pump 402 may be coupled to another low temperature heat source. For example, the low temperature heat source may be a liquid loop that dissipates heat to the air, ground, or another co-located cooling load. In one example, the liquid loop may contain water.

[0117] 5 illustrates a partial schematic diagram of a steam generation system 500, which is a partial embodiment of the steam generation system 400 illustrated in FIG. 4. The steam generation system 500 includes a bottoming heat pump 502 (i.e., a first heat pump) and a topping heat pump 504 (i.e., a second heat pump) that are thermally arranged in a hierarchical manner. The bottoming heat pump 502 may be a low temperature air source heat pump and the topping heat pump 504 may be a high temperature steam coupled heat pump. The steam generation system 500 may also include a steam compressor (not shown in FIG. 5).

[0118] The steam generation system 500 may include a hierarchical heat pump that incorporates high efficiency components to achieve a coefficient of performance greater than 2 without using waste heat. For example, the high efficiency components may include a high efficiency refrigerant compressor and motor. In one case, the compressor may be equal to or greater than 85% efficient and the motor may be equal to or greater than 93% efficient.

[0119] For example, a 1 megawatt thermal power (MWth) steam generation system 500 may produce 150 degree Celsius steam at a nominal ambient temperature of 20 degrees Celsius. In other words, the steam generation system 500 may provide a temperature lift of 20 degrees Celsius to 150 degrees Celsius at a coefficient of performance greater than 2 without requiring waste heat.

[0120] Heat transfer 516a involves bottoming heat pump 502 capturing heat from ambient air by evaporating a working fluid, which may be a refrigerant. In one case, the ambient air may be about 20 degrees Celsius and the working fluid may be evaporated at 15 degrees Celsius. Electricity 212a may be applied to bottoming heat pump 502, which may include an 88.5 kWe high efficiency compressor and motor. In one case, compressor power 297a may consume 75.5 kilowatts (kw). In one case, fan power and losses 299a may be 13 kWe.

[0121] The heat transfer 516b involves the condenser rejecting heat from the bottoming heat pump 502 to an evaporator in the topping heat pump 504, thereby evaporating a working fluid in the topping heat pump 504. The working fluid in the topping heat pump 504 may be a refrigerant. In one case, the working fluid in the topping heat pump 504 may be evaporated at 60 degrees Celsius. Electricity 512b may be applied to the topping heat pump 504, which may include a 159.2 kWe high efficiency compressor and motor. In one case, the compressor power 297b may consume 146 kw. In one case, the fan power and losses 299b may be 13.2 kWe.

[0122] Heat transfer 516c involves the condenser rejecting heat from the topping heat pump 504 to the evaporating water stream. Thus, 1 MWth of steam is delivered at 150 degrees Celsius saturation temperature.

[0123] FIG. 6 is a table outlining an example design specification for a two-stage compressor for the bottoming cycle 602 of the steam generating system 600, which is a partial embodiment of the steam generating system 500 illustrated in FIG. 5. This compressor will be further shown and described with reference to the first heat pump cycle 1002 of the steam generating system 100 in FIG. 10. In one case, the compressor in the bottoming cycle 602 may comprise two-stage compression with a single shaft and motor. In other words, the first stage of the compressor may comprise the first compressor 638 and the second stage of the compressor may comprise the second compressor 629. In one case, the motor may orbit a shaft that drives both the first compressor 638 and the second compressor 629 (i.e., the compressors are both rotatably coupled on a shaft and powered by the same motor) (shown subsequently in FIG. 10). The specific speed (N s ) vs. the specific diameter of the compressor (D s) may result in an efficiency equal to or greater than 80%. The total electrical efficiency may be approximately 94.1% efficient.

[0124] FIG. 7 is a schematic diagram of a design for a two-stage compressor for the topping cycle 704 of a steam generating system 700, which is a partial embodiment of the steam generating system 400 illustrated in FIG. 4. In one case, the compressor may have two-stage compression with two shafts and motors. In other words, the first stage of the compressor may include a first compressor 774, and the second stage of the compressor may include a second compressor 763. In one case, the first motor may turn a shaft that drives the first compressor 774, and the second motor may turn a separate shaft that drives the second compressor 763 (i.e., the compressors are on separate shafts powered by separate motors). This type of compressor is illustrated and described with reference to FIG. 10.

[0125] Separate stages may reduce windage losses in the compressor motor. Additionally, separate stages may isolate higher risk components. For example, second compressor 763 is a higher temperature compressor, which may create increased risk. Thus, isolating second compressor 763 by providing a separate motor and shaft from first compressor 774 may isolate the rest of steam generation system 700 from these issues.

[0126] In one case, the working fluid in the topping cycle 704 may enter the first compressor 774 (i.e., at the inlet) at a temperature 716d of about 103 degrees Celsius. The first compressor 774 compresses the working fluid, which increases the temperature and pressure of the working fluid. The working fluid may exit the first compressor 774 (i.e., at the outlet) at a temperature 716e of about 144 degrees Celsius. The temperature 716f of the working fluid from the economizer (shown and described with reference to FIG. 10 ) may be about 104 degrees Celsius. The two working fluid streams (at different temperatures) mix together such that the temperature of the working fluid may enter the second compressor 763 (i.e., at the inlet) at a temperature 716g of about 132 degrees Celsius. The second compressor 763 compresses the working fluid, which increases the temperature and pressure of the working fluid. The working fluid may exit the second compressor 763 (ie, at the outlet) at a temperature 716h of approximately 174 degrees Celsius.

[0127] FIG. 8 is a table outlining example design specifications for a two-stage compressor for the topping cycle 804 of steam generation system 800, which is a partial embodiment of steam generation system 700 illustrated in FIG. 7. Such a compressor design may be seen and implemented in system 1000 of FIG. 10 in topping heat pump cycle 1004. Continuing with FIG. 8, in one case, the compressor in topping cycle 804 may comprise two-stage compression with two shafts and motors. In other words, the first stage of the compressor may comprise first compressor 874 and the second stage of the compressor may comprise second compressor 863. In one case, the first motor may orbit a shaft that drives first compressor 874 and the second motor may orbit a separate shaft that drives second compressor 863 (i.e., the compressors use different shafts and motors). Specific speed of compressor (N s ) vs. the specific diameter of the compressor (D s ) can result in efficiencies equal to or greater than 80% efficiency.

[0128] Figure 9 is a schematic diagram of an electric power input and a thermal power output of a steam generation system 900, which is a partial embodiment of the steam generation system 400 illustrated in Figure 4. The steam generation system 900 includes a bottoming heat pump 902 and a topping heat pump 904. The electric power input may include electricity 912, which may be approximately 0.5 megawatts of electricity (MWe). The thermal power output may include steam 910, which may be approximately 1.0 megawatts of thermal power (MWth) of steam 910 delivered at a saturation temperature of 150 degrees Celsius.

[0129] Figure 10 illustrates a steam generation system 1000 that includes many of the elements described with reference to Figures 4-9. Figure 10 is a schematic diagram of the steam generation system 1000, which includes a first heat pump cycle 1002 (i.e., a bottoming heat pump cycle) and a second heat pump cycle 1004 (i.e., a topping heat pump cycle) in thermal communication with each other. The steam generation system 1000 may also include a steam compressor (not shown in Figure 10) in thermal communication with the second heat pump cycle 1004.

[0130] The first heat pump cycle 1002 circulates a first working fluid 1018 through a conduit 1020 of the first heat pump cycle 1002 as illustrated in FIG. 10. In one case, the first working fluid 1018 may be a fluorocarbon. As a non-limiting example, the fluorocarbon may be R1234ze(z) or R1234ze(E). In one case, the first working fluid 1018 may be a hydrofluoroolefin. As a non-limiting example, the hydrofluoroolefin may be R514a. In one case, the first working fluid 1018 may be a hydrofluoroether. In one case, the first working fluid 1018 may be a hydrocarbon. In one case, the first working fluid 1018 may be carbon dioxide. In one case, the first working fluid 1018 may be ammonia. In one case, the first working fluid 1018 may be water. In one case, the first working fluid 1018 may be an engineered fluid. As a non-limiting example, the engineered fluid may be Novec 649.

[0131] In the first heat pump cycle 1002, the heat exchanger 1022 receives a first working fluid 1018 from an expansion valve 1024. In other words, the first working fluid 1018 exits the expansion valve 1024 at an expansion valve outlet 1026 and enters the heat exchanger 1022 at a heat exchanger inlet 1028. A conduit 1020 connects the expansion valve outlet 1026 to the heat exchanger inlet 1028, thereby establishing fluid communication between the expansion valve 1024 and the heat exchanger 1022. Within the heat exchanger 1022, the first working fluid 1018 absorbs heat. This heat absorption may vaporize the first working fluid 1018, such that when the first working fluid 1018 exits the heat exchanger 1022 at a heat exchanger outlet 1030, it becomes low pressure steam. In one case, the heat exchanger 1022 may include an evaporator of the first heat pump cycle 1002, whereby the evaporator absorbs heat and the first working fluid 1018 is evaporated in the evaporator. In one case, the heat exchanger 1022 may be a low temperature evaporator. In one case, the heat exchanger 1022 may operate at an efficiency greater than or equal to 90%.

[0132] The compressor 1038 receives the first working fluid 1018 from the heat exchanger 1022. In other words, the first working fluid 1018 exits the heat exchanger 1022 at a heat exchanger outlet 1030 and enters the compressor 1038 at a compressor inlet 1040. A conduit 1020 connects the heat exchanger outlet 1030 to the compressor inlet 1040, thereby establishing fluid communication between the heat exchanger 1022 and the compressor 1038. Within the compressor 1038, the first working fluid 1018 is compressed to a higher pressure, which increases the temperature before the first working fluid 1018 exits the compressor 1038 at a compressor outlet 1042. Thus, the low pressure water vapor is compressed to a higher pressure. In one case, the first working fluid 1018 becomes a medium pressure fluid as it exits the compressor 1038 at compressor outlet 1042. In one case, the compressor 1038 is a high efficiency compressor. In one case, the compressor 1038 may be a centrifugal compressor. In one case, the compressor 1038 may be a two-stage centrifugal compressor. In one case, the compressor 1038 may be electrically powered. The motor 1027 may orbit a shaft that drives the compressor 1038. In one case, the motor 1027 may be a high speed and / or high efficiency motor. In one case, the motor 1027 may be electrically powered.

[0133] In one case, the first heat pump cycle 1002 does not include a suction line heat exchanger ("SLHX"). However, in other cases, an SLHX (not shown in the first heat pump cycle 1002 of FIG. 10) may be incorporated into the first heat pump cycle 1002. In one embodiment of the first heat pump cycle 1002 with an SLHX, the SLHX receives a first working fluid 1018 from a heat exchanger 1022 in a first passage of the SLHX. In other words, the first working fluid 1018 exits the heat exchanger 1022 at a heat exchanger outlet 1030 and enters the SLHX at an SLHX inlet. A conduit connects the heat exchanger outlet 1030 to the SLHX inlet, thereby establishing fluid communication between the heat exchanger 1022 and the SLHX. Within the first passage of the SLHX, the first working fluid 1018 absorbs heat, thereby further heating (i.e., preheating) the first working fluid 1018 before exiting the SLHX at an SLHX outlet. The first working fluid 1018 then exits the SLHX at an SLHX outlet and enters the compressor 1038 at a compressor inlet 1040. A conduit connects the SLHX outlet to the compressor inlet 1040, thereby establishing fluid communication between the SLHX and the compressor 1038.

[0134] Continuing with the description of the first heat pump cycle 1002 as shown in Figure 10, the second compressor 1029 receives the first working fluid 1018 from the compressor 1038. In other words, the first working fluid 1018 exits the compressor 1038 at a compressor outlet 1042 and enters the second compressor 1029 at a second compressor inlet 1031. A conduit 1020 connects the compressor outlet 1042 to the second compressor inlet 1031, thereby establishing fluid communication between the compressor 1038 and the second compressor 1029.

[0135] In some cases, the first heat pump cycle 1002 may alternatively not include the second compressor 1029. That is, the first heat pump cycle 1002 may include only a single compressor 1038. In such cases, a heat exchanger 1044 receives the first working fluid 1018 from the compressor 1038. More specifically, the first working fluid 1018 exits the compressor 1038 at a compressor outlet 1042 and enters the heat exchanger 1044 at a heat exchanger inlet 1046. A conduit connects the compressor outlet 1042 to the heat exchanger inlet 1046, thereby establishing fluid communication between the compressor 1038 and the heat exchanger 1044.

[0136] Continuing with the first heat pump cycle 1002 as shown in FIG. 10, the first working fluid 1018 is compressed by the second compressor 1029 to a higher pressure, which increases the temperature before the first working fluid 1018 exits the second compressor 1029 at a second compressor outlet 1033. In one case, the second compressor 1029 is a high efficiency compressor. In one case, the second compressor 1029 may be a centrifugal compressor. In one case, the second compressor 1029 may be electrically powered. A motor 1027 may orbit a shaft that drives the second compressor 1029. In one case, the motor 1027 may be a high speed and / or high efficiency motor. In one case, the motor 1027 may be electrically powered. In one case, the motor 1027 may orbit a shaft that drives both the compressor 1038 and the second compressor 1029 (i.e., the compressors use the same shaft and motor). In another case, the motor 1027 orbits a shaft that drives the compressor 1038, and a second motor (i.e., a separate motor not shown in FIG. 10) orbits a separate shaft that drives the second compressor 1029 (i.e., the compressors use different motors and different shafts). Exemplary design specifications for the compressors are shown in FIG. 6.

[0137] A heat exchanger 1044 (i.e., an intermediate heat exchanger) thermally couples the first heat pump cycle 1002 and the second heat pump cycle 1004. In one case, the heat exchanger 1044 receives the first working fluid 1018 from the second compressor 1029. In other words, the first working fluid 1018 exits the second compressor 1029 at a second compressor outlet 1033 and enters the heat exchanger 1044 at a heat exchanger inlet 1046. A conduit 1020 connects the second compressor outlet 1033 to the heat exchanger inlet 1046, thereby establishing fluid communication between the second compressor 1029 and the heat exchanger 1044. In other cases, when the first heat pump cycle 1002 does not include the second compressor 1029, the heat exchanger 1044 receives the first working fluid 1018 from the compressor 1038, as described above.

[0138] In the heat exchanger 1044, the first working fluid 1018 gives up heat. This heat release may cause the first working fluid 1018 to condense before exiting the heat exchanger 1044 at a heat exchanger outlet 1048. In one case, the heat exchanger 1044 comprises a condenser of the first heat pump cycle 1002 and an evaporator of the second heat pump cycle 1004. Thus, in the heat exchanger 1044, the condenser of the first heat pump cycle 1002 gives up heat and the evaporator of the second heat pump cycle 1004 absorbs heat. In the heat exchanger 1044, the second working fluid 1050 circulating in a conduit 1052 in the second heat pump cycle 1004 absorbs heat. This heat absorption may vaporize the second working fluid 1050 such that it becomes low pressure steam as it exits the heat exchanger 1044. In one case, the heat exchanger 1044 may operate at an efficiency of greater than or equal to 90%.

[0139] Still referring to the first heat pump cycle 1002, an economizer 1035 (i.e., a heat exchanger) may be incorporated into the cycle 1002. When the first heat pump cycle 1002 includes the economizer 1035, the fluid stream of the first working fluid 1018 from the heat exchanger 1044 is split into a primary fluid stream and a secondary fluid stream. Within the economizer 1035, the primary fluid stream of the first working fluid 1018 gives up heat and the secondary fluid stream of the first working fluid 1018 absorbs heat.

[0140] In the primary fluid flow, the economizer 1035 receives the first working fluid 1018 from the heat exchanger 1044 in a first passage of the economizer 1035. In other words, the first working fluid 1018 exits the heat exchanger 1044 at a heat exchanger outlet 1048 and enters the economizer 1035 at an economizer inlet 1037. A conduit 1020 connects the heat exchanger outlet 1048 to the economizer inlet 1037, thereby establishing fluid communication between the heat exchanger 1044 and the economizer 1035. Within the first passage of the economizer 1035, the first working fluid 1018 releases heat, thereby cooling the first working fluid 1018 before exiting the economizer 1035 at an economizer outlet 1039.

[0141] In the secondary fluid flow, the expansion valve 1041 receives the first working fluid 1018 from the heat exchanger 1044. In other words, the first working fluid 1018 exits the heat exchanger 1044 at a heat exchanger outlet 1048 and enters the expansion valve 1041 at an expansion valve inlet 1043. A conduit 1020 connects the heat exchanger outlet 1048 to the expansion valve inlet 1043, thereby establishing fluid communication between the heat exchanger 1044 and the expansion valve 1041. Within the expansion valve 1041, the first working fluid 1018 is expanded to a lower pressure (i.e., the pressure is reduced), which reduces the temperature before the first working fluid 1018 exits the expansion valve 1041 at an expansion valve outlet 1045. In one case, the first working fluid 1018 may be partially vaporized, such that the first working fluid 1018 becomes a two-phase fluid within the expansion valve 1041 .

[0142] In the secondary fluid flow, the economizer 1035 receives the first working fluid 1018 from the expansion valve 1041 in a second passage of the economizer 1035. In other words, the first working fluid 1018 exits the expansion valve 1041 at the expansion valve outlet 1045 and enters the economizer 1035 at the economizer inlet 1047. A conduit 1020 connects the expansion valve outlet 1045 to the economizer inlet 1047, thereby establishing fluid communication between the expansion valve 1041 and the economizer 1035. Within the second passage of the economizer 1035, the first working fluid 1018 absorbs heat, thereby heating the first working fluid 1018 before exiting the economizer 1035 at the economizer outlet 1049. In one case where the first working fluid 1018 is a two-phase fluid, the heat absorption increases the water vapor quality of the two-phase fluid.

[0143] In the secondary fluid flow, the second compressor 1029 may receive the first working fluid 1018 from the second passage of the economizer 1035. In other words, the first working fluid 1018 exits the economizer 1035 at an economizer outlet 1049 and enters the second compressor 1029 at a second compressor inlet 1031. A conduit 1020 connects the economizer outlet 1049 to the second compressor inlet 1031, thereby establishing fluid communication between the economizer 1035 and the second compressor 1029. In some cases, the conduit 1020 carrying the first working fluid 1018 from the economizer outlet 1049 (i.e., the conduit 1020 exiting the second passage of the economizer 1035) may merge with the conduit 1020 carrying the first working fluid 1018 from the compressor outlet 1042 (i.e., the conduit 1020 exiting the compressor 1038), thereby merging the two separate fluid streams (i.e., both fluids become the first working fluid 1018) before entering the second compressor 1029. In one case, the first working fluid 1018 in the conduit 1020 from the economizer outlet 1049 may be a two-phase fluid stream and the first working fluid 1018 in the conduit 1020 from the compressor outlet 1042 may be a medium pressure fluid. The two-phase fluid stream (i.e., the first working fluid 1018 exiting the economizer outlet 1049) may be at a lower temperature and approximately the same pressure as the intermediate pressure fluid (i.e., the first working fluid 1018 exiting the compressor outlet 1042). Thus, when the two fluid streams merge, thereby mixing the two fluids, the two-phase fluid stream may cool the intermediate pressure fluid stream, thereby reducing the specific work of the second compressor 1029 and improving the overall efficiency of the steam generation system 1000.

[0144] In instances such as when the first heat pump cycle 1002 does not include the second compressor 1029, the compressor 1038 may receive the first working fluid 1018 from the economizer 1035. In other words, the first working fluid 1018 exits the economizer 1035 at an economizer outlet 1049 and enters the compressor 1038 at a compressor inlet 1040. A conduit connects the economizer outlet 1049 to the compressor inlet 1040, thereby establishing fluid communication between the economizer 1035 and the compressor 1038.

[0145] In other cases, the first heat pump cycle 1002 does not include an economizer 1035. In such cases, the expansion valve 1024 receives the first working fluid 1018 from the heat exchanger 1044. In other words, the first working fluid 1018 exits the heat exchanger 1044 at a heat exchanger outlet 1048 and enters the expansion valve 1024 at an expansion valve inlet 1058. A conduit 1020 connects the heat exchanger outlet 1048 to the expansion valve inlet 1058, thereby establishing fluid communication between the heat exchanger 1044 and the expansion valve 1024.

[0146] In one case, the expansion valve 1024 receives the first working fluid 1018 from the economizer 1035. In other words, the first working fluid 1018 exits the economizer 1035 at an economizer outlet 1039 and enters the expansion valve 1024 at an expansion valve inlet 1058. A conduit 1020 connects the economizer outlet 1039 to the expansion valve inlet 1058, thereby establishing fluid communication between the economizer 1035 and the expansion valve 1024. In another case, when the first heat pump cycle 1002 does not include the economizer 1035, the expansion valve 1024 receives the first working fluid 1018 from the heat exchanger 1044, as described above. Within the expansion valve 1024 , the first working fluid 1018 is expanded to a lower pressure, which reduces the temperature before the first working fluid 1018 exits the expansion valve 31024 at the expansion valve outlet 1026 .

[0147] In one case, as shown in FIG. 10 , the first heat pump cycle 1002 does not include an SLHX. However, in other cases, the SLHX is incorporated into the first heat pump cycle 1002. In such cases, the SLHX receives the first working fluid 1018 from the economizer 1035 in a second passage of the SLHX. In other words, the first working fluid 1018 exits the economizer 1035 at an economizer outlet 1039 and enters the SLHX at an SLHX inlet. A conduit connects the economizer outlet 1039 to the SLHX inlet, thereby establishing fluid communication between the economizer 1035 and the SLHX. Within the second passage of the SLHX, the first working fluid 1018 dissipates heat, thereby cooling (i.e., pre-cooling) the first working fluid 1018 before it exits the SLHX at an SLHX outlet. This pre-cooling of the first working fluid 1018 may reduce the water vapor quality of the first working fluid 1018 before it enters the heat exchanger 1022 at a heat exchanger inlet 1028, and may increase the amount of latent heat transfer that may occur. The first working fluid 1018 then exits the SLHX at an SLHX outlet and enters the expansion valve 1024 at an expansion valve inlet 1058. A conduit 1020 connects the SLHX outlet to the expansion valve inlet 1058, thereby establishing fluid communication between the SLHX and the expansion valve 1024.

[0148] In one case, the first heat pump cycle 1002 includes an SLHX but does not include an economizer 1035. Thus, the fluid stream of the first working fluid 1018 is not split into a primary fluid stream and a secondary fluid stream. Thus, there is no expansion valve 1041 associated with the secondary fluid stream because there is no secondary fluid stream. In other words, the first working fluid 1018 exits the heat exchanger 1044 at a heat exchanger outlet 1048 and enters the SLHX at an SLHX inlet. A conduit 1020 connects the heat exchanger outlet 1048 to the SLHX inlet, thereby establishing fluid communication between the heat exchanger 1044 and the SLHX. The first working fluid 1018 then exits the SLHX at an SLHX outlet and enters the expansion valve 1024 at an expansion valve inlet 1058. A conduit 1020 connects the SLHX outlet to the expansion valve inlet 1058 , thereby establishing fluid communication between the SLHX and the expansion valve 1024 .

[0149] Turning to the second heat pump cycle 1004 of FIG. 10, the second heat pump cycle 1004 circulates a second working fluid 1050. In one case, the second working fluid 1050 may be a fluorocarbon. As a non-limiting example, the fluorocarbon may be R1234ze(z) or R1234ze(E). In one case, the second working fluid 1050 may be a hydrofluoroolefin. As a non-limiting example, the hydrofluoroolefin may be R514a. In one case, the second working fluid 1050 may be a hydrofluoroether. In one case, the second working fluid 1050 may be a hydrocarbon. In one case, the second working fluid 1050 may be carbon dioxide. In one case, the second working fluid 1050 may be ammonia. In one case, the second working fluid 1050 may be water. In one instance, the second working fluid 1050 may be an engineered fluid. As a non-limiting example, the engineered fluid may be Novec649.

[0150] In one case, the same fluid may be used for both the first working fluid 1018 and the second working fluid 1050. In other cases, different fluids may be used for the first working fluid 1018 and the second working fluid 1050.

[0151] In one case, the second heat pump cycle 1004 may contain the same components as the first heat pump cycle 1002. The components of the second heat pump cycle 1004 may be arranged in the same configuration as the components of the first heat pump cycle 1002. The components of the second heat pump cycle 1004 may be arranged in a different configuration than the components of the first heat pump cycle 1002. In other cases, the second heat pump cycle 1004 may contain different components than the first heat pump cycle 1002.

[0152] In the second heat pump cycle 1004, the heat exchanger 1044 receives a second working fluid 1050 from an expansion valve 1060. In other words, the second working fluid 1050 exits the expansion valve 1060 at an expansion valve outlet 1062 and enters the heat exchanger 1044 at a heat exchanger inlet 1064. A conduit 1052 connects the expansion valve outlet 1062 to the heat exchanger inlet 1064, thereby establishing fluid communication between the expansion valve 1060 and the heat exchanger 1044. Within the heat exchanger 1044, the second working fluid 1050 absorbs heat from the first working fluid 1018 of the first heat pump cycle 1002. This heat absorption may vaporize the second working fluid 1050, such that the second working fluid 1050 becomes low pressure steam when it exits the heat exchanger 1044 at the heat exchanger outlet 1066. In one case, the heat exchanger 1044 includes a condenser of the first heat pump cycle 1002 and an evaporator of the second heat pump cycle 1004. Thus, within the heat exchanger 1044, the condenser of the first heat pump cycle 1002 releases heat and the evaporator of the second heat pump cycle 1004 absorbs heat. In one case, the heat exchanger 1044 may operate at an efficiency greater than or equal to 90%.

[0153] In one case, a suction line heat exchanger ("SLHX") 1068 may be incorporated into the second heat pump cycle 1004, as can be seen in FIG. 10. The SLHX 1068 receives a second working fluid 1050 from the heat exchanger 1044 in a first passage of the SLHX 1068. In other words, the second working fluid 1050 exits the heat exchanger 1044 at a heat exchanger outlet 1066 and enters the SLHX 1068 at a SLHX inlet 1070. A conduit 1052 connects the heat exchanger outlet 1066 to the SLHX inlet 1070, thereby establishing fluid communication between the heat exchanger 1044 and the SLHX 1068. Within the first passage of the SLHX 1068, the second working fluid 1050 absorbs heat, thereby further heating (i.e., preheating) the second working fluid 1050 before exiting the SLHX 1068 at a SLHX outlet 1072. The second working fluid 1050 then exits the SLHX 1068 at a SLHX outlet 1072 and enters the compressor 1074 at a compressor inlet 1076. A conduit connects the SLHX outlet 1072 to the compressor inlet 1076, thereby establishing fluid communication between the SLHX 1068 and the compressor 1074.

[0154] In other cases, the second heat pump cycle 1004 does not include a SLHX 1068. In other words, the second working fluid 1050 exits the heat exchanger 1044 at a heat exchanger outlet 1066 and enters the compressor 1074 at a compressor inlet 1076. A conduit 1052 connects the heat exchanger outlet 1066 to the compressor inlet 1076, thereby establishing fluid communication between the heat exchanger 1044 and the compressor 1074.

[0155] Continuing with the second heat pump cycle 1004 shown in FIG. 10, the compressor 1074 receives the second working fluid 1050 from the SLHX 1068. In other words, the second working fluid 1050 exits the SLHX 1068 at the SLHX outlet 1072 and enters the compressor 1074 at the compressor inlet 1076. A conduit 1052 connects the SLHX outlet 1072 to the compressor inlet 1076, thereby establishing fluid communication between the SLHX 1068 and the compressor 1074. Within the compressor 1074, the second working fluid 1050 is compressed to a higher pressure, which increases the temperature before the second working fluid 1050 exits the compressor 1074 at the compressor outlet 1078. Thus, the low pressure water vapor is compressed to a higher pressure. In one case, the second working fluid 1050 is a medium pressure fluid as it exits the compressor 1074 at a compressor outlet 1078. In one case, the compressor 1074 is a high efficiency compressor. In one case, the compressor 1074 may be a centrifugal compressor. In one case, the compressor 1074 may be a two-stage centrifugal compressor. In one case, the compressor 1074 may be electrically powered. A motor 1061 may orbit a shaft that drives the compressor 1074. In one case, the motor 1061 may be a high speed and / or high efficiency motor. In one case, the motor 1061 may be electrically powered.

[0156] In one case, a second compressor 1063 may be incorporated into the second heat pump cycle 1004 as shown in FIG. 10. The second compressor 1063 receives the second working fluid 1050 from the compressor 1074. In other words, the second working fluid 1050 exits the compressor 1074 at a compressor outlet 1078 and enters the second compressor 1063 at a second compressor inlet 1065. A conduit 1052 connects the compressor outlet 1078 to the second compressor inlet 1065, thereby establishing fluid communication between the compressor 1074 and the second compressor 1063. In other cases, the second heat pump cycle 1004 does not include the second compressor 1063. Thus, the heat exchanger 1080 receives the second working fluid 1050 from the compressor 1074. In other words, the second working fluid 1050 exits the compressor 1074 at a compressor outlet 1078 and enters the heat exchanger 1080 at a heat exchanger inlet 1082. A conduit connects the compressor outlet 1078 to the heat exchanger inlet 1082, thereby establishing fluid communication between the compressor 1074 and the heat exchanger 1080.

[0157] Within the second compressor 1063, the second working fluid 1050 is compressed to a higher pressure, which increases the temperature before the second working fluid 1050 exits the second compressor 1063 at a second compressor outlet 1067. In one case, the second compressor 1063 is a high efficiency compressor. In one case, the second compressor 1063 may be a centrifugal compressor. In one case, the second compressor 1063 may be electrically powered. A motor 1069 may orbit a shaft that drives the second compressor 1063. In one case, the motor 1069 may be a high speed and / or high efficiency motor. In one case, the motor 1069 may be electrically powered. In one case, motor 1061 may turn a shaft that drives compressor 1074, and motor 1069 may turn a separate shaft that drives second compressor 1063 (i.e., the compressors use different motors and shafts). In another case, one motor (either motor 1061 or motor 1069) may turn a shaft that drives both compressor 1074 and second compressor 1063 (i.e., the compressors use the same motor and shaft). Example design specifications for the compressors can be seen in FIG. 8.

[0158] A heat exchanger 1080 thermally couples the second heat pump cycle 1004 and the third working fluid 1008. In one case, the heat exchanger 1080 receives the second working fluid 1050 from the second compressor 1063. In other words, the second working fluid 1050 exits the second compressor 1063 at a second compressor outlet 1067 and enters the heat exchanger 1080 at a heat exchanger inlet 1082. A conduit 1052 connects the second compressor outlet 1067 to the heat exchanger inlet 1082, thereby establishing fluid communication between the second compressor 1063 and the heat exchanger 1080. In other cases, when the second heat pump cycle 1004 does not include a second compressor 1063, the heat exchanger 1080 receives the second working fluid 1050 from the compressor 1074, as described above.

[0159] In the heat exchanger 1080, the second working fluid 1050 gives up heat. This heat release may cause the second working fluid 1050 to condense before exiting the heat exchanger 1080 at a heat exchanger outlet 1084. In one case, the heat exchanger 1080 may be a condenser of the second heat pump cycle 1004, whereby the condenser gives up heat and the second working fluid 1050 condenses in the condenser. In the heat exchanger 1080, the third working fluid 1008, which may flow in a conduit, absorbs heat. This heat absorption may cause the third working fluid 1008 to vaporize, whereby the third working fluid 1008 becomes a vapor when it exits the heat exchanger 1080. In one case, the heat exchanger 1080 may operate at an efficiency greater than or equal to 90%. A third working fluid 1008 may flow through a system that further includes a pump and a compressor, as illustrated in FIG.

[0160] 10, an economizer 1071 (i.e., a heat exchanger) may be incorporated into the second heat pump cycle 1004. When the second heat pump cycle 1004 includes the economizer 1071, the fluid stream of the second working fluid 1050 is split into a primary fluid stream and a secondary fluid stream. Within the economizer 1071, the primary fluid stream of the second working fluid 1050 dissipates heat and the secondary fluid stream of the second working fluid 1050 absorbs heat.

[0161] In the primary fluid flow, the economizer 1071 receives the second working fluid 1050 from the heat exchanger 1080 in a first passage of the economizer 1071. In other words, the second working fluid 1050 exits the heat exchanger 1080 at a heat exchanger outlet 1084 and enters the economizer 1071 at an economizer inlet 1073. A conduit 1052 connects the heat exchanger outlet 1084 to the economizer inlet 1073, thereby establishing fluid communication between the heat exchanger 1080 and the economizer 1071. Within the first passage of the economizer 1071, the second working fluid 1050 releases heat, thereby cooling the second working fluid 1050 before exiting the economizer 1071 at an economizer outlet 1075.

[0162] In the secondary fluid flow, the expansion valve 1077 receives the second working fluid 1050 from the heat exchanger 1080. In other words, the second working fluid 1050 exits the heat exchanger 1080 at a heat exchanger outlet 1084 and enters the expansion valve 1077 at an expansion valve inlet 1079. A conduit 1052 connects the heat exchanger outlet 1084 to the expansion valve inlet 1079, thereby establishing fluid communication between the heat exchanger 1080 and the expansion valve 1077. Within the expansion valve 1077, the second working fluid 1050 is expanded to a lower pressure (i.e., the pressure is reduced), which reduces the temperature before the second working fluid 1050 exits the expansion valve 1077 at an expansion valve outlet 1081. In one case, the second working fluid 1050 may be partially vaporized, such that the second working fluid 1050 becomes a two-phase fluid within the expansion valve 1077 .

[0163] In the secondary fluid flow, the economizer 1071 receives the second working fluid 1050 from the expansion valve 1077 in a second passage of the economizer 1071. In other words, the second working fluid 1050 exits the expansion valve 1077 at the expansion valve outlet 1081 and enters the economizer 1071 at the economizer inlet 1083. A conduit 1052 connects the expansion valve outlet 1081 to the economizer inlet 1083, thereby establishing fluid communication between the expansion valve 1077 and the economizer 1071. Within the second passage of the economizer 1071, the second working fluid 1050 absorbs heat, thereby heating the second working fluid 1050 before exiting the economizer 1071 at the economizer outlet 1085. In one case where the second working fluid 1050 is a two-phase fluid, the heat absorption increases the water vapor quality of the two-phase fluid.

[0164] In the secondary fluid flow, the second compressor 1063 may receive the second working fluid 1050 from the second passage of the economizer 1071. In other words, the second working fluid 1050 exits the economizer 1071 at an economizer outlet 1085 and enters the second compressor 1063 at a second compressor inlet 1065. A conduit 1052 connects the economizer outlet 1085 to the second compressor inlet 1065, thereby establishing fluid communication between the economizer 1071 and the second compressor 1063. In some cases, the conduit 1052 carrying the second working fluid 1050 from the economizer outlet 1085 (i.e., the conduit 1052 exiting the second passage of the economizer 1071) may merge with the conduit 1052 carrying the second working fluid 1050 from the compressor outlet 1078 (i.e., the conduit 1052 exiting the compressor 1074), thereby merging the two separate fluid streams (i.e., both fluids become the second working fluid 1050) before entering the second compressor 1063. In one case, the second working fluid 1050 in the conduit 1052 from the economizer outlet 1085 may be a two-phase fluid stream and the second working fluid 1050 in the conduit 1052 from the compressor outlet 1078 may be a medium pressure fluid. The two-phase fluid stream (i.e., the second working fluid 1050 exiting the economizer outlet 1085) may be at a lower temperature and approximately the same pressure as the intermediate pressure fluid (i.e., the second working fluid 1050 exiting the compressor outlet 1078). Thus, when the two fluid streams merge, thereby mixing the two fluids, the two-phase fluid stream may cool the intermediate pressure fluid stream, thereby reducing the specific work of the second compressor 1063 and improving the overall efficiency of the steam generation system 1000.

[0165] In those instances where the second heat pump cycle 1004 does not include a second compressor 1063, the compressor 1074 may receive the second working fluid 1050 from the economizer 1071. In other words, the second working fluid 1050 exits the economizer 1071 at an economizer outlet 1085 and enters the compressor 1074 at a compressor inlet 1076. A conduit connects the economizer outlet 1085 to the compressor inlet 1076, thereby establishing fluid communication between the economizer 1071 and the compressor 1074.

[0166] In cases such as when the SLHX 1068 is incorporated into the second heat pump cycle 1004 (as can be seen in FIG. 10 ), the SLHX 1068 receives the second working fluid 1050 from the heat exchanger 1080 in a second passage of the SLHX 1068. In other words, the second working fluid 1050 exits the heat exchanger 1080 at a heat exchanger outlet 1084 and enters the SLHX 1068 at a SLHX inlet 1088. A conduit 1052 connects the heat exchanger outlet 1084 to the SLHX inlet 1088, thereby establishing fluid communication between the heat exchanger 1080 and the SLHX 1068. Within the second passage of the SLHX 1068, the second working fluid 1050 dissipates heat, thereby cooling (i.e., pre-cooling) the second working fluid 1050 before it exits the SLHX 1068 at SLHX outlet 1090. This pre-cooling of the second working fluid 1050 may reduce the water vapor quality of the second working fluid 1050 before it enters the heat exchanger 1022 at heat exchanger inlet 1028, and may increase the amount of latent heat transfer that may occur. The second working fluid 1050 then exits the SLHX 1068 at SLHX outlet 1090 and enters the expansion valve 1060 at expansion valve inlet 1092. A conduit 1052 connects the SLHX outlet 1090 to the expansion valve inlet 1092 , thereby establishing fluid communication between the SLHX 1068 and the expansion valve 1060 .

[0167] In cases such as when the second heat pump cycle 1004 does not include the SLHX 1068, the second working fluid 1050 exits the economizer 1071 at an economizer outlet 1075 and enters the expansion valve 1060 at an expansion valve inlet 1092. A conduit 1052 connects the economizer outlet 1075 to the expansion valve inlet 1092, thereby establishing fluid communication between the economizer 1071 and the expansion valve 1060.

[0168] In other cases, the second heat pump cycle 1004 includes the SLHX 1068 but does not include the economizer 1071. Thus, the fluid stream of the second working fluid 1050 is not split into a primary fluid stream and a secondary fluid stream. Thus, there is no expansion valve 1077 associated with the secondary fluid stream because there is no secondary fluid stream. In other words, the second working fluid 1050 exits the heat exchanger 1080 at a heat exchanger outlet 1084 and enters the SLHX 1068 at a SLHX inlet 1088. A conduit 1052 connects the heat exchanger outlet 1084 to the SLHX inlet 1088, thereby establishing fluid communication between the heat exchanger 1080 and the SLHX 1068. The second working fluid 1050 then exits the SLHX 1068 at a SLHX outlet 1090 and enters the expansion valve 1060 at an expansion valve inlet 1092. A conduit 1052 connects the SLHX outlet 1090 to the expansion valve inlet 1092, thereby establishing fluid communication between the SLHX 1068 and the expansion valve 1060.

[0169] In other cases, the second heat pump cycle 1004 does not include an economizer 1071 and does not include an SLHX 1068. Thus, the expansion valve 1060 receives the second working fluid 1050 from the heat exchanger 1080. In other words, the second working fluid 1050 exits the heat exchanger 1080 at a heat exchanger outlet 1084 and enters the expansion valve 1060 at an expansion valve inlet 1092. A conduit 1052 connects the heat exchanger outlet 1084 to the expansion valve inlet 1092, thereby establishing fluid communication between the heat exchanger 1080 and the expansion valve 1060.

[0170] In one case, the expansion valve 1060 receives the second working fluid 1050 from the SLHX 1068. In other words, the second working fluid 1050 exits the SLHX 1068 at an SLHX outlet 1090 and enters the expansion valve 1060 at an expansion valve inlet 1092. A conduit 1052 connects the SLHX outlet 1090 to the expansion valve inlet 1092, thereby establishing fluid communication between the SLHX 1068 and the expansion valve 1060. In another case, when the second heat pump cycle 1004 does not include the SLHX 1068, the expansion valve 1060 receives the second working fluid from the economizer 1071, as described above. In another case, when the second heat pump cycle 1004 does not include an economizer 1071 and does not include an SLHX 1068, the expansion valve 1060 receives the second working fluid 1050 from the heat exchanger 1080, as described above. Within the expansion valve 1060, the second working fluid 1050 is expanded to a lower pressure, which reduces the temperature before the second working fluid 1050 exits the expansion valve 1060 at an expansion valve outlet 1062.

[0171] The third working fluid 1008 may absorb heat from the heat exchanger 1080 as illustrated in FIG. 10. In other words, the heat exchanger 1080 may receive the third working fluid 1008. In the heat exchanger 1080, the second working fluid 1050 releases heat and the third working fluid 1008 absorbs heat. In one case, the heat exchanger 1080 may include a condenser of the second heat pump cycle 1004, whereby the condenser releases heat and the third working fluid 1008 absorbs heat. The second working fluid 1050 condenses as it releases heat in the condenser. In one case, the heat exchanger 1080 may be a steam generator. In the steam generator, the third working fluid 1008 may absorb enough heat to become water vapor.

[0172] In one case, the third working fluid 1008 may be provided to the heat exchanger 1080 via a conduit (not shown in FIG. 10 ). In other words, the conduit for the third working fluid 1008 is coupled to the second heat pump cycle 1004 by the heat exchanger 1080.

[0173] In one case, a mechanical pump (not shown in FIG. 10) may increase the pressure of the third working fluid 1008. A similar embodiment of pump 301 is shown in FIG. 3. The mechanical pump may be upstream of the heat exchanger 1080, whereby the heat exchanger 1080 receives the third working fluid 1008 from the mechanical pump. In other words, the third working fluid 1008 exits the mechanical pump at a mechanical pump outlet and enters the heat exchanger 1080 at a heat exchanger inlet. A conduit connects the mechanical pump outlet to the heat exchanger inlet, thereby establishing fluid communication between the mechanical pump and the heat exchanger 1080. The third working fluid 1008 may exit the heat exchanger 1080 at the heat exchanger outlet and enter the conduit.

[0174] In one case, a steam compressor (not shown in FIG. 10) may increase the pressure and temperature of the third working fluid 1008. A similar embodiment of the steam compressor 306 may be seen in FIG. 3. The steam compressor may be downstream of the heat exchanger 1080, whereby the steam compressor receives the third working fluid 1008 from the heat exchanger 1080. In other words, the third working fluid 1008 exits the heat exchanger 1080 at a heat exchanger outlet and enters the steam compressor at a steam compressor inlet. A conduit connects the heat exchanger outlet to the steam compressor inlet, thereby establishing fluid communication between the heat exchanger 1080 and the steam compressor.

[0175] In the steam compressor, the third working fluid 1008 is compressed to a higher pressure and temperature. In one case, the steam compressor increases the pressure and temperature of the third working fluid 1008, turning the third working fluid 1008 into steam before it exits the steam compressor at a steam compressor outlet. The steam may enter a conduit that is connected to the steam compressor outlet. In one case, the steam compressor delivers steam at a temperature equal to or greater than 120 degrees Celsius. In one case, the steam compressor is a high efficiency compressor. In one case, the steam compressor may be a centrifugal compressor. In one case, the steam compressor may be electrically powered.

[0176] In one case, the third working fluid 1008 is water. In the heat exchanger 1080, the water absorbs heat from the second working fluid 1050 of the second heat pump cycle 1004. In one embodiment, the pressure of the water may be above or equal to the target vapor saturation temperature when the water exits the heat exchanger 1080 at the heat exchanger outlet. In other words, the water may absorb enough heat from the second heat pump cycle 1004 to evaporate into vapor. After the heat exchanger 1080, a steam compressor may be used to directly increase the pressure and temperature of the vapor. In one embodiment, the pressure of the water may be below the target vapor saturation temperature when the water exits the heat exchanger 1080 at the heat exchanger outlet. Thus, the steam compressor may be used to increase the pressure of the water to the required saturation temperature.

[0177] Referring back to the first heat pump cycle 1002 of FIG. 10, the transfer fluid 1013 may dissipate heat to the heat exchanger 1022. In other words, the heat exchanger 1022 receives the transfer fluid 1013. In the heat exchanger 1022, the transfer fluid 1013 dissipates heat and the first working fluid 1018 absorbs heat. In one case, the heat exchanger 1022 may include an evaporator of the first heat pump cycle 1002, whereby the transfer fluid 1013 dissipates heat and the evaporator absorbs heat. The first working fluid 1018 is evaporated as it absorbs heat in the evaporator. In one case, the heat exchanger 1022 may be a low-temperature evaporator.

[0178] In one case, the transfer fluid 1013 may be provided to the heat exchanger 1022 via a conduit (not shown in FIG. 10 ). In other words, a conduit for the transfer fluid 1013 is coupled to the first heat pump cycle 1002 by the heat exchanger 1022.

[0179] In one case, a mechanical pump (not shown in FIG. 10) may increase the pressure of the transfer fluid 1013. The mechanical pump may be upstream of the heat exchanger 1022, such that the heat exchanger 1022 receives the transfer fluid 1013 from the mechanical pump. In other words, the transfer fluid 1013 exits the mechanical pump at a mechanical pump outlet and enters the heat exchanger 1022 at a heat exchanger inlet. A conduit connects the mechanical pump outlet to the heat exchanger inlet, thereby establishing fluid communication between the mechanical pump and the heat exchanger 1022. The transfer fluid 1013 may exit the heat exchanger 1022 at the heat exchanger outlet and enter the conduit.

[0180] In one case, the transfer fluid 1013 is ambient air, whereby the heat exchanger 1022 of the first heat pump cycle 1002 utilizes the ambient air as a heat source (i.e., air-fed). The heat exchanger 1022 of the first heat pump cycle 1002 may capture heat from the ambient air. The heat is absorbed by the heat exchanger 1022 of the first heat pump cycle 1002, thereby evaporating the first working fluid 1018 in the first heat pump cycle 1002.

[0181] In other cases, the transfer fluid 1013 may be a liquid that is connected to a low temperature heat source. In one case, the low temperature heat source may be ambient air. In other cases, the first heat pump cycle 1002 may be coupled to another low temperature heat source. For example, the low temperature heat source may be a liquid loop that dissipates heat to the air, ground, or another co-located cooling load. In one example, the liquid loop may contain water.

[0182] The heat generation system of FIG. 10 may additionally include a control system in electrical communication with the first heat pump cycle 1002 and the second heat pump cycle 1004. The control system may control the delivery of heat from the first heat source and / or the second heat source to the third working fluid 1008. The first heat source may include the first heat pump cycle 1002 and the second heat pump cycle 1004. The second heat source may include an alternative heat source, such as a thermal storage unit, heated via a renewable energy source (e.g., a solar thermal array). Additionally or alternatively, the control system may control a source of electrical power supplied to the first and second heat pump cycles 1002, 1004. The electrical power may be selectively supplied by the electrical grid or a renewable energy source.

[0183] To this end, reference is made to FIG. 11, which is a schematic diagram of an energy arbitrage system 1100 incorporating a hierarchical heat pump system 1102 (such as the first and second heat pump cycles 1002 and 1004 from FIG. 10 or the first and second heat pump cycles 302 and 304 of FIG. 3) for steam production. The energy arbitrage system 1100 includes multiple thermal energy sources for supplying heat to generate steam for industrial applications, among other uses. Additionally or alternatively, one or more of the thermal energy sources may supply steam as opposed to supplying heat for a central steam production system.

[0184] In one example, the energy arbitrage system 1100 includes a renewable energy source 1104, which may be a solar array or grid in electrical communication with an electrical grid 1106. The electrical grid 1106 is in electrical communication with and capable of powering the hierarchical heat pump system 1102. The hierarchical heat pump system 1102 is also in electrical communication with and capable of powering the renewable energy source 1104. The renewable energy source 1104 is coupled to an energy storage system 1108, such as a thermal energy storage system, capable of storing energy in the form of heat. The thermal storage system 1108 may include one or more storage vessels capable of storing a heated fluid (e.g., steam). The energy storage system 1108 may be an electrical storage unit, such as one or more batteries, which may provide electricity to the hierarchical heat pump system 1102.

[0185] The energy arbitrage system 1100 may also include a boiler 1110, such as a natural gas boiler. However, the boiler 1110 may be a different type of boiler, such as one burning coal, biomass, waste, or another suitable fuel. The boiler 1110, the hierarchical heat pump system 1102, the renewable energy source 1104, and the energy storage system 1108 may each be electronically controlled by a control system 1112. The control system 1112 may control the delivery of either steam and / or heat to an industrial application. In one instance, the boiler 1110, the hierarchical heat pump system 1102, and the energy storage system 1108 each (when configured as a thermal energy storage unit) delivers steam 1114 for use in an industrial application or for another use. In such a case, the boiler 1110 is capable of delivering steam 1114 when operated by the control system 1112, the hierarchical heat pump system 1102 (including steam generating components such as pump 301, heat exchanger 380, and steam compressor 306) is capable of delivering steam 1114 when operated by the control system 1112, and the energy storage system 1108 is capable of delivering steam 1114 when operated by the control system 1112. The energy arbitrage system 1110 functions without the control system 1112 and thus may be manually controlled.

[0186] The control system 1112 may utilize the following example parameters in the arbitrage system 1000 to determine which system to operate at a given time. The parameters include, but are not limited to, renewable power generation (kW and kWh), thermal storage capacity or amount of stored energy (kW and kWh), amount of steam output per device (e.g., heat pump, boiler, thermal storage), facility steam demand (steam mass or volumetric flow rate and steam pressure), and operating costs (e.g., PPA rates, grid electricity rate structure, and fuel prices), among other factors. The control system 1112 can measure steam mass, volumetric flow rate, and steam pressure resulting from various sources. The control system 1112 can also selectively turn on and off various energy sources of the arbitrage system 1100 based on, among other factors, the parameters listed above.

[0187] The control system 1112 may calculate system performance using the following metrics: steam output divided by electricity input = heat pump efficiency; steam output divided by natural gas input = boiler efficiency. These metrics may be used to determine if it is more economical to operate a heat pump, boiler, or other system. Operating costs, including PPA rates, grid electricity rate structures, and fuel prices, may be used as factors when considering which system to utilize to provide steam. The energy arbitrage system 1110 can be used to efficiently and cost-effectively deliver steam by selectively delivering it from one or more of the energy input sources. The energy arbitrage system 1110 can maximize decarbonization in the steam production process.

[0188] The following includes a list of example embodiments of an energy arbitrage system 1110. Traditionally, industrial steam 1114 is generated from a boiler (e.g., a natural gas boiler) 1110. In this configuration, there is no arbitrage because the steam is provided by only one source and there is no ability to modify the energy source input.

[0189] The first arbitrage configuration using the energy arbitrage system 1100 is to provide steam 1114 solely via renewable energy sources 1104 utilizing the thermal storage system 1108. That is, in this configuration, there is no boiler. Energy is provided by renewable sources, but this is an expensive decarbonization option.

[0190] A second arbitrage configuration using the energy arbitrage system 1100 is to selectively provide steam 1114 from one or both of a boiler 1110 and a hierarchical heat pump system 1102 supplied with electricity from a renewable energy source 1104.

[0191] The control system communicates with the renewable energy source 1104 (how much kWh is being generated). In this case, all electricity generated is sent to the heat pump 1102. The control system 1112 can monitor the steam output (e.g., flow rate and pressure) of the heat pump 1102 and the steam demand (e.g., flow rate and pressure) from the facility. The control system 1102 can communicate with the boiler 1110 and generate the remainder of the steam required by the facility. The steam output (e.g., flow rate and pressure) of the boiler 1110 can also be measured by the control system 1112.

[0192] A third arbitrage configuration using the energy arbitrage system 1100 is to provide steam 1114 from one or both of the boiler 1110 and the hierarchical heat pump system 1102, which is supplied with electricity from a renewable energy source 1104. In this configuration, the renewable energy source 1104 also provides electricity to the electrical grid 1106 when the supply of electricity exceeds the demand of the hierarchical heat pump system 1102.

[0193] In this configuration, there may be excess electricity from the renewable energy source 1104. This excess electricity can be provided to the grid 1106, which in turn can provide a credit for demand on the electrical grid 1106 (e.g., to provide electricity to the heat pump system 1102). In this configuration, the control system 1112 may monitor the facility steam demand and the steam output of the heat pump 1102. When the steam output of the heat pump 1102 delivers the entire facility demand, the control system 1102 communicates with the renewable energy source 1104 and the excess electricity is diverted to the grid 1106 (net metering). When the renewable energy source 1104 does not produce enough electricity for the heat pump 1102, the control system 1112 communicates with the boiler 1110 and will provide the remaining steam required for the facility. The control system 1112 may determine the most economically efficient fuel source (electricity from the grid vs. fuel for the boiler) given the current energy costs of electricity and fuel, respectively.

[0194] A fourth arbitrage configuration using the energy arbitrage system 1100 is to provide steam 1114 only from the hierarchical heat pump system 1102, which is supplied with electricity from the renewable energy source 1104. In this configuration, the renewable energy source 1104 also provides electricity to the electrical grid 1106 when the supply of electricity exceeds the demand of the hierarchical heat pump system 1102. The boiler is not used in this configuration. Similar to the third arbitrage configuration, in the fourth arbitrage configuration, excess electricity produced from the renewable energy source can be diverted to the grid 1106. In this case, the control system 1112 receives the steam demand from the facility as an input. All steam would be provided by the hierarchical heat pump system 1102 in this arbitrage configuration, and the control system 1112 would selectively determine the source of electrical power to the heat pump system 1102. If the renewable energy sources 1104 are able to provide all of the electrical needs of the heat pump system 1102, the heat pump system 1102 will not draw any electricity from the grid 1106. If there is excess electricity produced from the renewable energy sources 1104, the excess will be sent to the grid 1106 (net metering). If the electrical needs of the heat pump system 1102 exceed the amount that can be produced by the renewable energy sources 1104, the control system 1112 will utilize as much of the renewable energy 1104 as possible, and the remainder of the electricity will be taken from the grid 1106.

[0195] In this embodiment, the system 1100 may include a boiler 1110. If the renewable energy source 1104 does not provide excess electricity, the control system 1112 signals the boiler 1110 to communicate with the grid 1106 and take grid electricity to power the heat pump 1102 instead of delivering steam 1114. This may occur if the control system 1112 determines that the heat pump 1102 running on a portion of the electricity from the grid 1106 is more economical than operating the gas boiler 1110.

[0196] A fifth arbitrage configuration using the energy arbitrage system 1100 is to provide steam 1114 from one or both of a hierarchical heat pump system 1102 supplied with electricity from a renewable energy source 1104 and an energy storage system 1108 connected to the renewable energy source 1104. This configuration avoids grid demand charges and results in complete decarbonization. The grid and gas boiler are not utilized in this configuration. The control system 1112 may monitor the amount of steam output from the heat pump system 1102, the steam demand of the facility, and the amount of renewable power generation in the renewable energy source 1104.

[0197] If the heat pump system 1102 provides the full steam demand for the facility and there is excess electricity from the renewable energy source, the electricity may be diverted to the energy storage device 1108 to charge the device (e.g., energy storage unit, heat storage unit) (measure the charge / capacity of the device). If there is no excess electricity from the renewable energy source 1104, the control system 1112 may communicate with the energy storage device 1108 to release heat / steam 1114 and in combination with the heat pump 1102 to meet the facility steam demand.

[0198] If the energy storage device is fully charged and there is still excess electricity, the electricity will be diverted to the grid 1106.

[0199] Having an energy arbitrage system 1110, including renewable energy sources 1104, connected to an electric grid 1106 allows the system to use net metering, an electric grid billing mechanism in which users are charged for the difference between the cost of energy taken from the grid (consumption) and the cost of energy sent to the grid (generation).

[0200] The following is a description of an exemplary computer 1200 that is part of or can be used in conjunction with the energy arbitrage system 1110 described herein. Figure 12 illustrates an example of a suitable computing and networking environment 1200 that may be used to implement various aspects of the disclosure described herein, such as the control system 1112 of Figure 11. As illustrated in Figure 12, the computing and networking environment 1200 includes a general purpose computing device 1200, however, it is contemplated that the networking environment 1200 may include other computing systems, such as smartphones, server computers, handheld or laptop devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronic devices, network PCs, minicomputers, mainframe computers, digital signal processors, state machines, logic circuits, distributed computing environments including any of the above computing systems or devices, and the like.

[0201] The components of the computer 1200 may include various hardware components, such as a processing unit 1202, data storage 1204 (e.g., system memory), and a system bus 1206 that couples various system components of the computer 1200 to the processing unit 1202. The system bus 1206 may be any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. For example, such architectures may include an Industry Standard Architecture (ISA) bus, a MicroChannel Architecture (MCA) bus, an Enhanced ISA (EISA) bus, a Video Electronics Standards Association (VESA) local bus, and a Peripheral Component Interconnect (PCI) bus, also known as a Mezzanine bus.

[0202] The computer 1200 may further include various computer readable media 1208, including removable / non-removable media and volatile / non-volatile media, but excluding transitory propagating signals. The computer readable media 1208 may also include computer storage media and communication media. Computer storage media includes removable / non-removable media and volatile / non-volatile media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data, such as RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired information / data and that can be accessed by the computer 1200. Communication media includes computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave or other transport mechanism, and includes any information delivery media. The term "modulated data signal" means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. For example, communication media may include wired media, such as a wired network or direct-wired connection, and wireless media, such as acoustic, RF, infrared, and / or other wireless media, or some combination thereof. Computer-readable media may be embodied as a computer program product, such as software stored on a computer storage medium.

[0203] The data storage or system memory 1204 includes computer storage media in the form of volatile and nonvolatile memory such as read only memory (ROM) and random access memory (RAM). A basic input / output system (BIOS), containing the basic routines that help to transfer information between elements within the computer 1200 (e.g., during start-up), is typically stored in ROM. RAM typically contains data and / or program modules that are immediately accessible to and / or presently being operated on by the processing unit 1202. For example, in one embodiment, the data storage 1204 holds the operating system, application programs, and other program modules and program data.

[0204] Data storage 1204 may also include other removable / non-removable volatile / non-volatile computer storage media. For example, data storage 1204 may be a hard disk drive that reads from or is written to a non-removable non-volatile magnetic medium, a magnetic disk drive that reads from or is written to a removable non-volatile magnetic disk, and / or an optical disk drive that reads from or is written to a removable non-volatile optical disk, such as a CD-ROM or other optical media. Other removable / non-removable volatile / non-volatile computer storage media may include magnetic tape cassettes, flash memory cards, digital versatile disks, digital video tape, solid state RAM, solid state ROM, and the like. The drives and their associated computer storage media, described above and illustrated in FIG. 12, provide storage of computer-readable instructions, data structures, program modules, and other data for computer 1200.

[0205] A user may type in commands and information through a user interface 1210 or other input devices such as a tablet, electronic digitizer, microphone, keyboard, and / or pointing device, commonly referred to as a mouse, trackball, or touchpad. The commands and information may be for setting lighting and / or watering schedules, including their respective specific parameters. Other input devices may include a joystick, gamepad, satellite dish, scanner, or the like. In addition, voice input, gesture input (e.g., via hands or fingers), or other natural user interfaces may also be used in conjunction with appropriate input devices such as microphones, cameras, tablets, touchpads, gloves, or other sensors. These and other input devices are connected to the processing unit 1202 through a user interface 1210, which is often coupled to the system bus 1206, but may also be connected by other interface and bus structures, such as a parallel port, game port, or universal serial bus (USB). A monitor 1212 or other type of display device is also connected to the system bus 1206 via an interface, such as a video interface. The monitor 1212 may also be integrated with a touch screen panel or equivalent.

[0206] When the computer 1200 operates as the control system 1112, there may be various inputs and outputs associated with the energy arbitrage system 1100 of FIG. 11. For example, the computer 1200 may include various inputs associated with facility steam requirements, steam output from the boiler 1110, steam output from the heat pump cycle 1102, and steam output from the thermal storage unit 1108. Additional inputs may include electricity production from the renewable energy source 1104, and outflows from the renewable energy source, including to the grid 1106, to the heat pump 1102, and to the thermal storage unit 1108. Additional inputs may also include electrical requirements of the heat pump system 1102 and the amount of electricity being provided from the grid 1106. The computer 1200 may be in electrical communication with each of the heat pump system 1102, the renewable energy source 1104, and the thermal storage unit 1108, such that the computer 1200 can actuate the components of the system 1100 to operate based on various inputs received. In this manner, communications with the various systems can also be output, such that the computer 1200 can control their operation.

[0207] The computer 1200 may operate in a networked or cloud-computing environment using a network interface or adapter 1214 and logical connections to one or more remote devices, such as a remote computer. The remote computer may be a personal computer, a server, a router, a network PC, a peer device, or other common network node, and typically includes many or all of the elements described above with respect to the computer 1200. The logical connections depicted in FIG. 12 include one or more local area networks (LANs) and one or more wide area networks (WANs), but may also include other networks. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets, and the Internet.

[0208] When used in a networked or cloud-computing environment, the computer 1200 may be connected to public and / or private networks through a network interface or adapter 1214. In such an embodiment, a modem or other means for establishing communications over a network is connected to the system bus 1206 via the network interface or adapter 1214 or other appropriate mechanism. Wireless networking components, including interfaces and antennas, may be coupled to the network through suitable devices such as an access point or peer computer. In a networked environment, the program modules depicted relative to the computer 1200, or portions thereof, may be stored in a remote memory storage device.

[0209] The foregoing merely illustrates the principles of the invention. Various modifications and alterations to the described embodiments will become apparent to those skilled in the art in light of the teachings herein. It should thus be understood that those skilled in the art can devise numerous systems, arrangements, and methods which, although not explicitly shown or described herein, embody the principles of the invention and are therefore within the spirit and scope of the invention. From the above description and drawings, it will be understood by those skilled in the art that the specific embodiments shown and described are for illustrative purposes only and are not intended to limit the scope of the invention. Reference to details of specific embodiments is not intended to limit the scope of the invention.

Claims

**Claim 1**: A system for generating steam, the system comprising: Two or more heat pump cycles configured to transfer heat from an ambient air source via one or more working fluids, the two or more heat pump cycles adding energy to a feed stream containing water to generate an output stream containing the steam at a saturation temperature of at least 120 degrees Celsius, the two or more heat pump cycles comprising a bottom heat pump cycle and a top heat pump cycle coupled via at least a first heat exchanger, the bottom heat pump cycle being configured to condense the first working fluid by circulating the first working fluid through the first heat exchanger; Two or more heat pump cycles; A second heat exchanger configured to evaporate the first working fluid by transferring heat from the ambient air source to the bottom heat pump cycle, the top heat pump cycle being configured to evaporate the second working fluid by circulating the second working fluid through the first heat exchanger; A second heat exchanger; A first compressor of the bottom heat pump cycle and a second compressor of the top heat pump cycle; A third heat exchanger configured to condense the second working fluid, transfer heat to the feed stream, and evaporate the water in the feed stream into steam A system comprising. **Claim 2**: The system according to claim 1, further comprising an additional heat exchanger located within a heat pump cycle of the two or more heat pump cycles, the additional heat exchanger being configured to preheat the working fluid prior to compressing the working fluid of the one or more working fluids. **Claim 3**: The system according to claim 2, wherein the additional heat exchanger is a suction line heat exchanger in fluid communication between at least two sections of the heat pump cycle, the at least two sections being at different temperatures. **Claim 4**: The system according to claim 1, wherein the one or more working fluids comprise at least one of a fluorocarbon, a hydrofluoroolefin, a hydrofluoroether, a hydrocarbon, carbon dioxide, ammonia, or water.

5. The system according to claim 1, wherein one or both of the first compressor and the second compressor is a centrifugal compressor.

6. The system according to claim 1, wherein at least one of the first compressor or the second compressor is electrically powered.

7. The system according to claim 1, wherein at least one of the two or more heat pump cycles comprises an economizer.

8. The system according to claim 1, wherein the temperature of the steam is at least 150 degrees Celsius.

9. The system according to claim 1, wherein the temperature of the steam is between 120 degrees Celsius and 150 degrees Celsius.

10. The system according to claim 1, wherein the heat pump cycle among the two or more heat pump cycles comprises at least two compressors in series.

11. The system according to claim 1, wherein the heat pump cycle among the two or more heat pump cycles comprises at least two compressors rotatably coupled together on a shaft.

12. The system according to claim 1, wherein the temperature of the ambient air source is 20 degrees Celsius or less.

13. The system according to claim 1, further comprising a steam compressor for compressing the stream containing water downstream of the two or more heat pump cycles, the steam compressor outputting superheated or saturated steam.

14. The system according to claim 13, wherein the steam exiting the two or more heat pump cycles has a saturation temperature of less than 120 degrees Celsius, and the steam compressor increases the saturation temperature of the steam to at least 120 degrees Celsius.

15. The system according to claim 13, wherein the steam compressor is electrically powered.

16. The system according to claim 13, wherein the third heat exchanger is directly coupled to the steam compressor.

17. The system according to claim 13, further comprising a conduit directly coupling the third heat exchanger to the steam compressor, the conduit configured to transfer a fluid stream containing the steam from the third heat exchanger to the steam compressor.

18. The system according to claim 1, wherein the third heat exchanger comprises an outlet configured to direct the water, and at least a portion of the water is evaporated.

19. The system according to claim 1, wherein the second heat exchanger is configured to transfer heat from the ambient air source, and the ambient air source has a temperature of -6.5 degrees Celsius or less.

20. The system according to claim 1, further comprising a control system configured to control the heat transfer from one or more heat sources to the second working fluid.

21. The system according to claim 1, further comprising one or more expansion valves located within the heat pump cycle of the two or more heat pump cycles.

22. The system according to claim 1, wherein the first compressor is configured to receive the first working fluid from the second heat exchanger.

23. The system according to claim 1, wherein the first heat exchanger is configured to receive the first working fluid from the first compressor.

24. The system according to claim 1, wherein the second compressor is configured to receive the second working fluid from the first heat exchanger.

25. The system according to claim 1, wherein the third heat exchanger is configured to receive the second working fluid from the second compressor.

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