High temperature dual track heat pump cycle achieving high performance over high temperature lift and high temperature range

Abstract

A dual track heat pump cycle includes a low temperature heat source; a two-stage high-temperature heat exchange process through which heat is exchanged with a thermal medium during operation; and a working fluid circuit. The working fluid circuit includes: an expansion process; a compression process; a regenerative process and a pair of parallel flow paths. The regenerative process is between the expansion process and the compression process and has a high pressure side defined by the compression process and a low pressure side defined by the expansion process. The pair of parallel flow paths is between a regenerative process and a high temperature heat exchange process on a high pressure side of the regenerative process.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to co-pending U.S. non-provisional patent application No. 17 / 974,913, filed in the name of Timothy Held on October 27, 2022. The entire contents of this application are incorporated herein by reference for all purposes, including priority, as if recited verbatim herein. Technical Field

[0002] The present disclosure relates to a heat pump cycle, and more particularly to a heat pump cycle for achieving high performance in a high temperature lift and high temperature range. Background Art

[0003] In some industrial processes, it is necessary to apply heat to one or more materials at relatively high temperatures. The most common method of generating this heat is by burning fossil fuels. However, as the world moves towards a carbon-free energy system, alternative technologies for providing industrial heat will be needed. Although direct electrical heating using devices such as resistance heaters, arc heaters, or electric induction heaters can reach the necessary temperatures, the coefficient of performance ("COP") of these processes will never be greater than 1. In this context, COP is defined as the amount of heat transferred to the process divided by the electrical power input.

[0004] These forms of direct electric heating discussed in the previous paragraph can also potentially be used to convert electrical energy into thermal energy, which can be stored for later use in so-called "electrical thermal energy storage" systems. In those cases, the round-trip efficiency of such a system is the mathematical product of the COP and the efficiency of the power generation cycle. Due to the characteristics of the heating system described above, the round-trip efficiency ("RTE") of the entire storage process will be lower than the efficiency of the power cycle used to convert thermal energy back into electricity, typically around 40% in the temperature range of 550°C to 600°C. Summary of the Invention

[0005] In a first aspect, a dual-track heat pump cycle includes: a low-temperature heat source; a two-stage high-temperature heat exchange process, through which heat is exchanged with a heat medium during operation; and a working fluid circuit. The working fluid circuit includes: an expansion process; a compression process; a regenerative process; and a pair of parallel flow paths. The regenerative process is located between the expansion process and the compression process, and has a high-pressure side defined by the compression process and a low-pressure side defined by the expansion process. The pair of parallel flow paths are located between the regenerative process and the high-temperature heat exchange process on the high-pressure side of the regenerative process.

[0006] In another aspect, a dual-rail heat pump cycle includes a low-temperature heat source and a working fluid circuit through which a working fluid circulates during operation. The working fluid circuit includes a regenerator, a compression device, an expansion device, a pair of high-temperature heat exchangers, and a pair of parallel flow paths. The expansion device is located downstream of the high-pressure side of the first regenerator and upstream of the low-temperature heat source, defining the low-pressure side of the regenerator. The pair of parallel flow paths extend between the regenerator and a high-temperature heat exchanger on the high-pressure side of the regenerator.

[0007] The above content presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the present invention. This summary is not an exhaustive overview of the present invention. It is not intended to identify key or important elements of the present disclosure, nor is it intended to outline the scope of the present invention. Its sole purpose is to present some concepts in a simplified form as a prelude to a more detailed description discussed later. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, in accordance with standard industry practice, the various features are not necessarily drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of discussion.

[0009] FIG. 1 depicts a prior art heat pump employing a conventional heat pump cycle, which may be referred to as a simple heat pump cycle.

[0010] FIG. 2 is a pressure-enthalpy (“PH”) diagram of a heat pump cycle of the heat pump in FIG. 1 .

[0011] FIG3 shows the maximum temperature (T h2 ) is a function of the coefficient of performance (“COP”) and the required compressor pressure ratio (“CPR”).

[0012] FIG4 depicts a prior art heat pump employing a simple recuperative heat pump cycle.

[0013] FIG5 plots the coefficient of performance and compressor pressure ratio as a function of the heat medium temperature for the simple regenerative cycle in FIG4 .

[0014] 6A and 6B are TQ graphs respectively plotting the relationship between the temperature of the simple regenerative cycle of the heat pump of FIG. 4 , the high-temperature heat exchanger, and the regenerator and the heat load.

[0015] Figure 7 is a process flow diagram of a first embodiment of a dual-rail heat pump cycle according to one or more embodiments of the subject matter claimed below.

[0016] Figure 8 yes Figure 7 The heat pump cycle in the dual-track heat pump cycle is in T h2 =565℃、T范围 = Pressure-enthalpy ("PH") diagram at 545°C.

[0017] Figures 9A to 9B yes Figure 7 TQ curves of the heat exchanger and regenerator in the dual-track heat pump cycle.

[0018] Figure 10 is a process flow diagram of a second embodiment of a dual-rail heat pump cycle according to one or more embodiments of the subject matter claimed below.

[0019] Figure 11 is a process flow diagram of a first embodiment of a dual-rail heat pump cycle according to one or more embodiments of the subject matter claimed below.

[0020] Figure 12 is a block diagram of a control system including a programmable controller, such as one that may be used to control fluid flow of a working fluid in some embodiments.

[0021] Figure 13 The dual-track and single-return heat pump cycles are taken as T 范围 function and in T h2 = The COP at 565°C was compared.

[0022] While the disclosed technology is susceptible to various modifications and alternative forms, the accompanying drawings illustrate specific embodiments described in detail herein by way of example. However, it should be understood that the description of specific embodiments herein is not intended to limit the claimed content to the particular forms disclosed, but rather, the invention is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims. DETAILED DESCRIPTION

[0023] Compared to direct electric heating, thermodynamic heat pump cycles can achieve COP values ​​far exceeding 1.0. However, cycle and working fluid limitations typically only allow heat pumps to reach moderate heating temperatures. FIG1 depicts a prior art heat pump 100 employing a conventional heat pump cycle. The heat pump 100 circulates a working fluid (not otherwise shown) through a working fluid circuit 105. The heat pump 100 employs a variety of well-known components to compress, expand, heat, cool, and other working fluids so that the working fluid is in various states defined by properties such as temperature and pressure. The state of the working fluid at various points in the working fluid circuit 105 will be indicated using conventions well known in the art, with numbers shown in circles.

[0024] In a conventional heat pump cycle 100, a compression device 110 (such as a compressor) is used to compress a working fluid from a first relatively low temperature, low pressure state 1 to one of a higher temperature and pressure state 2. The heat introduced into the working fluid by compression can then be transferred to a heat medium that receives and uses or stores the heat. In Figure 1, this transfer occurs in a heat exchanger ("HTX") 115. The heat medium starts with an initial temperature Th1 and can be referred to as a "cold" heating heat medium. The cold heating heat medium is heated to a higher temperature T h2 , at which point it can be called a "hot" heating medium.

[0025] During the process of heating the thermal medium, the working fluid is cooled to state 3. The fluid is then expanded to state 4 using expansion device 120. Expansion device 120 can be an expander, such as an adiabatic expansion valve, or a fluid expander that also extracts thermodynamic work from the fluid. The temperature and pressure of the working fluid in expansion device 120 are reduced to state 4. Low-temperature heat is then added to the working fluid from an external low-temperature source 125 to restore the working fluid to state 1. In many cases, the low-temperature heat source can be ambient heat from the environment in which the heat pump 100 is operating.

[0026] The thermodynamics of the heat pump cycle in Figure 1 can also be illustrated on the pressure-enthalpy diagram in Figure 2. For some applications, conventional heat pump cycles offer a good combination of performance and simplicity. For example, CO2 heat pumps are often used to heat water from ambient temperature to domestic hot water heating temperature.

[0027] The net specific work required to transfer heat can be expressed as the enthalpy increase during the compression process (state 1 to state 2) minus the enthalpy decrease during the expansion process (state 3 to state 4). The heat transferred to the heat medium is represented by the enthalpy change in the high-temperature heat exchanger 115 (state 2 to state 3). One performance parameter of the heat pump cycle previously introduced is the coefficient of performance ("COP"), which in this context is equal to the heat transferred divided by the net specific work. Consistent with the previous definition of COP, the COP can be expressed by the following expression:

[0028] In the above formula, Q h is the heat transferred, W net is the net specific work, and h1 to h4 are the specific enthalpies of the working fluid at states 1 to 4 in FIG. 1 , respectively.

[0029] Other performance parameters include the temperature to which the heat medium is heated (T h2 ) and temperature “range”. The temperature range is the difference between the final temperature of the heat medium and its initial temperature (T 范围 =T h2 -Th1 ). Another parameter is “lift”, which can be expressed mathematically as Lift = T h2 -T 热源 , where T 热源 is the temperature of the heat source. Based on the basic principles of thermodynamics and heat transfer, in order to transfer heat to the heat medium, the working fluid temperature (T2) in state 2 must be greater than T h2 , and the working fluid temperature (T3) in state 3 must be greater than Th1.

[0030] To achieve this combination of performance parameters, the baseline heat pump cycle described above must use an extremely high compressor pressure ratio (“CPR”). This significantly increases the cost of the system, and above a certain pressure ratio (typically around 10:1), the solution becomes impractical. In the case shown in Figure 3, heat is extracted from a 15°C ambient and added to the T h1 =20℃ fluid. In fact, the maximum T that can be achieved by a simple heat pump cycle is h2 About 200℃.

[0031] The heat pump cycle shown in Figures 1 and 2 can be referred to as a "simple heat pump cycle." Figure 4 depicts a prior art heat pump 400 that utilizes a so-called recuperative simple heat pump cycle. Heat pump 400 includes a regenerator ("RCX") 405. Regenerator 405 transfers heat from a first portion of the working fluid circulating in the working fluid circuit to another portion of the working fluid.

[0032] For greater than approximately T h2 = T200°C to 250°C h2 The performance of the regenerative heat pump cycle is better than that of the simple heat pump cycle. For the simulations used to generate FIG5, the compressor pressure ratio was limited to no more than 10:1. FIG5 plots the coefficient of performance and compressor pressure ratio of the simple regenerative heat pump cycle 400 in FIG4 as a function of the heat medium temperature.

[0033] However, another factor in heat pump performance is high T 范围 With T h2 Here, a simple regenerative cycle is limited in its ability to provide this combination of properties. FIG6A is a TQ graph for heat exchanger 115, and FIG6B is a TQ graph for regenerator 405 of FIG4. The TQ graphs plot temperature versus heat load Q / Q tot .

[0034] As shown in Figures 6A and 6B, although a simple regenerative system can achieve a wide range, the limitations of the regenerative process itself result in a relatively high temperature of the working fluid leaving the heat exchanger 115, as shown in Figure 1. Therefore, the TQ curves have significantly different slopes, which represent the differences in the temperature of the regenerator and the heat exchanger 115. In addition, the large difference in specific heat capacity under different pressures in the system also leads to a large difference in the slope of the regenerator TQ curve in Figure 6B, further increasing the damage and reduced cycle performance.

[0035] Illustrative examples of the subject matter claimed below will now be disclosed. For the sake of clarity, this specification does not describe all features of an actual implementation. It should be understood that in the development of any such actual implementation, many implementation-specific decisions may be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from implementation to implementation. Furthermore, it should be understood that such development work, even if complex and time-consuming, will be a routine task for those of ordinary skill in the art having the benefit of this disclosure.

[0036] This disclosure describes a "dual-track" heat pump cycle that flexibly allows the flowing heat medium to be heated over a wide temperature range and achieves excellent heat pump performance values. The dual-track heat pump cycle increases the ability of the heat pump to increase T h2 , while also maintaining a large T 范围 , and still maintain a good COP. A second embodiment is then disclosed as a variation of the first embodiment. In the next more complex heat pump cycle, two internal heat exchangers (each referred to as a "regenerator") are used to transfer some of the waste heat to the downstream heat exchanger to preheat the working fluid before it enters the compression device.

[0037] Figure 7is a process flow diagram of a first embodiment of a dual-track heat pump cycle 700 in accordance with one or more embodiments of the subject matter claimed below. The dual-track heat pump cycle 700 derives its name from the parallel regenerator and HTX flow paths 705, 706. Note that the parallel flow paths or "rails" 705, 706 operate between the regeneration process 733 and the heat exchange process 720. More specifically, the first rail 705 includes: a flow path that diverges from point 755, where the working fluid is in states 3A and 4A; and a second high-temperature heat exchanger 711. The second rail 706 includes: a flow path that diverges from point 755, where the working fluid is in states 3B and 4B; and a second regenerator 716. Thus, "parallel paths" or "parallel rails" can be thought of as flow paths that originate at a point in the cycle where the working fluid flow diverges into multiple conduits that will recombine at another point in the cycle.

[0038] Figure 8 yes Figure 7 The dual-track heat pump cycle in the 700 heat pump cycle is h2 =565℃、T 范围 = Pressure-enthalpy ("PH") diagram at 545°C. Figures 9A to 9B yes Figure 7 The TQ curve diagram of the high temperature heat exchangers 710, 711 and the regenerators 715, 716 of the dual-track heat pump cycle in FIG. Those skilled in the art who have benefited from this disclosure will note that in Figure 8 In the graph, states 7 and 8 occupy nearly the same point. That is, states 7 and 8 "overlap" each other. This fact means that the presence of regenerator 715 ("RCX1") provides a small performance advantage over regenerator 716 ("RCX2"), although the performance advantage provided by regenerator 715 is non-zero. Therefore, some embodiments may omit regenerator 716.

[0039] As used herein, the terms "low temperature" and "high temperature" in the context of heat exchange are defined relative to each other and relative to the temperature of the circulating working fluid. In the embodiments disclosed herein, "low temperature" may refer to temperatures in the range of -25°C to 50°C, while "high temperature" may refer to temperatures in the range of 80°C to 600°C. However, in other embodiments, these numbers may be different. For example, in some embodiments, the heat source may be the ambient environment. In other embodiments, the low temperature heat source may be a waste heat source rather than the ambient environment, in which case the low temperature and high temperature may be higher than in the embodiments disclosed herein. Nevertheless, the waste heat source may be at a temperature below the target heat sink temperature (T h2 ) in the sense that it will still be "cold". However, it will usually be warmer than its surroundings.

[0040] Thus, as used herein, a "low-temperature" heat exchanger (when in use) transfers heat from a heat source to a circulating working fluid. Thus, heat is transferred from a "higher" temperature heat source to a "lower" temperature working fluid. Conversely, a "high-temperature" heat exchanger transfers heat from a "higher" temperature circulating working fluid to a relatively "lower" temperature heat medium. The temperature at which heat exchange occurs in the "high-temperature" heat exchanger is higher than the temperature at which heat exchange occurs in the "low-temperature" heat exchanger.

[0041] The terms "high pressure" and "low pressure" are similarly defined relative to each other. For example, the regenerative process 733 can be considered to have a "high pressure side" and a "low pressure side" defined by the expansion process 725 and the compression process 730. The pressure of the working fluid in states 7 to 8 and 1 is lower than the pressure of the working fluid in states 3B, 4B, and 4 to 5. (This is due to the effects of the expansion process 725 and the compression process 730, respectively.) Therefore, the "side" of the regenerative process 733 where the working fluid is in states 7 to 8 and 1 can be referred to as the "low pressure side", while the "side" where the working fluid is in states 3B, 4B, and 4 to 5 can be referred to as the "high pressure side".

[0042] Therefore, in the context of heat exchange, the precise numerical quantification of the terms "high temperature," "low temperature," "high pressure," and "low pressure" will depend on the specific implementation details of any given embodiment. Although representative numerical quantifications may be provided herein for the illustrated embodiments, other embodiments not shown may employ other numerical quantifications. Those skilled in the art, having the benefit of this disclosure, will readily be able to determine the appropriate numerical quantification for a particular embodiment.

[0043] The dual-track heat pump cycle 700 includes a heat exchange process ("HTX") 720, an expansion process 725, a compression process 730, a regenerative process 733, and a low-temperature heat source 735. The working fluid circulates through the heat exchange process 720, the expansion process 725, the compression process 730, and the low-temperature heat source 735 via a working fluid loop 740. The working fluid in this particular embodiment is carbon dioxide (CO2). Alternative embodiments may employ other working fluids. The thermal medium heated by the heat exchange process 720 may be, for example, but not limited to, any flowing thermal medium, such as air, water, a heat transfer fluid, or a molten salt. In this particular embodiment, the working fluid loop 740 also includes a generator 745 driven by the expansion process 725 and a motor 750 driving the compression process 730.

[0044] The expansion process 725 and the compression process 730 respectively employ at least one expansion device 726 and at least one compression device 731. The compression device 731 may be a compressor, such as a fully enclosed reciprocating compressor, a scroll compressor, or a centrifugal compressor. The expansion device may be an expander, such as an adiabatic expansion valve or a fluid expander. The fluid expander may be, for example, a turbine, a reciprocating expander, or a scroll expander. Other implementations may be apparent to those skilled in the art having benefit of this disclosure.

[0045] Now refer to Figure 7 and Figure 8 In both cases, the dual-rail heat pump cycle 700 exchanges heat between a heat medium and a working fluid in a heat exchange process 720. In this first embodiment of the dual-rail heat pump cycle, the heat exchange process 720 is divided into two stages. Each of the two stages is represented by a respective heat exchanger in high-temperature heat exchangers 710 ("HTX1") and 711 ("HTX2").

[0046] In the first stage, the working fluid transfers heat to the thermal medium in heat exchanger 710, thereby heating the thermal medium and cooling the working fluid. The working fluid enters heat exchanger 710 in state 2, where it then exchanges heat with the thermal medium. This heat exchange heats the thermal medium and cools the working fluid.

[0047] Upon exiting the first stage of the heat exchange process 720 in State 3, the working fluid is split into two parts at point 755. The first part in State 3A enters the second stage 720 of the heat exchange process. In the second stage, represented by heat exchanger 711, the working fluid is further cooled, thereby preheating the heat medium. Note that the terms "first" and "second" with respect to the heat exchange process 720 are from the perspective of the working fluid circulation. The heat medium flows in a direction opposite to that of the working fluid. Therefore, from the perspective of the heat medium, the heat medium is preheated in the second heat exchanger 711 and then heated a second time in the first heat exchanger 710, with the working fluid being cooled in both exchanges. The second part of the working fluid in State 3B enters the second regenerator 716 ("RCX2"), where it is cooled and preheats the working fluid on the low pressure side of the system (State 8 to State 1).

[0048] As the first portion exits the second stage 720 of the heat exchange process (represented by heat exchanger 711 in state 4A and second regenerator 716 in state 4B), the flow recombines the first and second portions at point 760. The recombined working fluid in state 4 then enters an additional first regenerator ("RCX1") 715 to further cool the high pressure working fluid (state 4 to state 5) and preheat the low pressure working fluid (state 7 to state 8). The high pressure working fluid then enters the expansion device 726 in state 5 where work can be extracted and the working fluid pressure and temperature are reduced to state 6. As the working fluid enters state 7 from state 6, heat is then added from the ambient or similar source (i.e., low temperature heat source 735).

[0049] Splitting the working fluid into two parts allows for better matching of the heat capacity of both sides of the second regenerator (716), i.e., the high pressure side (state 3B to state 4B) and the low pressure side (state 8 to state 1), which is defined as the mathematical product of mass flow rate and specific heat capacity. Additionally, the working fluid can then be cooled to a lower temperature than it would in a single regenerator cycle, which also allows its TQ slope to better match the thermal slope of the heat medium, as shown in FIG. Figure 9A and Figure 9B Both of these effects will reduce the circulation loss (exergy destruction) and improve its performance.

[0050] Figure 10 A second embodiment of a dual rail heat pump cycle is shown, which may be referred to as an "extended" dual rail heat pump cycle. Figure 10 Dual-track heat pump cycle and Figure 7 The dual-track heat pump cycles share some common components. These common parts have the same number and will not be discussed here. This discussion will focus on Figure 7 and Figure 10 The difference between the dual-track heat pump cycle.

[0051] In the extended dual-rail heat pump cycle 1000, the working fluid can be additionally split at State 4, where the first portion (State 4C) enters an additional low-temperature stage of the heat exchange process 1005 ("HTX") represented by the high-temperature heat exchanger 1010 ("HTX3"). The working fluid is then further cooled while further preheating the heat medium in the third high-temperature heat exchanger. The second portion of the working fluid (State 4D) enters the first regenerator 1015 ("RCX1"), where it is cooled while simultaneously heating the low-pressure working fluid (State 7 to State 8).

[0052] Note the presence of third parallel flow path 1020 and fourth parallel flow path 1021. Third parallel flow path 1020, more specifically third track 1020, includes a flow path that diverges starting at point 1030, where the working fluid is at states 4C and 4D, and a third high-temperature heat exchanger 1010. Fourth track 1021 includes a flow path that diverges starting at point 1030, where the working fluid is at states 4D and 5D, and a second regenerator 1015. Those skilled in the art, with the benefit of this disclosure, will appreciate that additional configurations are contemplated that repeat the diverging and parallel HTX and RCX flow paths any number of times to further match the thermal capacities of the fluids on either side of the heat exchanger.

[0053] As above Figure 7 As mentioned in the discussion of , some embodiments may omit one of the regenerators 715 , 716 in the regeneration process 733 . Figure 11 The heat pump cycle 1100 is shown, wherein the regeneration process 1133 uses only a single regenerator 716. The design of the heat pump cycle 1100 is Figure 7 700 , and like parts have like reference numerals. Note that the number of working fluid states is reduced from eight to six, and the rails 705 , 706 remain unchanged.

[0054] Those skilled in the art who have the benefit of this disclosure will understand that Figure 7 、 Figure 10 and Figure 11 The heat pump cycle and other embodiments may also include heat reservoirs, other heat exchangers, piping, pumps, valves, and other controls not shown separately. For example, the flow of the working fluid through the working fluid circuit is typically a function of programmable control of the fluid flow valve. For clarity, Figure 7 、 Figure 10 and Figure 11 These other components are not shown in the figures so as not to obscure the content protected below in this discussion.

[0055] Although such control systems are readily understood by those skilled in the art, for the sake of completeness, they are described in detail below. Figure 12 One such control system 1200 is shown in . The control system 1200 may include a plurality of fluid flow valves 1205 and a controller 1210 that sends control signals via electrical wires 1215. A controller, such as controller 1210, may send control signals to the fluid flow valves 1205 to control the flow of the working fluid as described above.

[0056] The controller 1210 includes a processor-based resource 1220, which may be, for example, but not limited to, a microcontroller, a microprocessor, an application-specific integrated circuit ("ASIC"), an electrically erasable programmable read-only memory ("EEPROM"), or the like. Depending on the implementation of the processor-based resource, the controller 1210 may also include a memory 1225 encoded with instructions (not shown) executable by the processor-based resource 1220 to implement the functionality of the controller 1210. Similarly, depending on the implementation of the processor-based resource 1220, the memory 1225 may be part of the processor-based resource 1220 or a separate device. For example, the instructions may be firmware stored in a memory portion of the microprocessor, or they may be routines stored in a separate read-only or random access memory chip. Similarly, in some implementations of the processor-based resource 1220 (e.g., an ASIC), the memory 1235 may be omitted entirely.

[0057] More specifically, a flow control system can be used to control the flow of a working fluid between two parallel paths or rails. For example, referring to Figure 7 , the flow control system can control the flow of the working fluid between the first guide rail 705 and the second guide rail 706. A programmable fluid control system (such as Figure 12 The fluid control system 1200 in FIG. 1 may be particularly useful for achieving variable distribution between parallel flow paths to accommodate changes in operating conditions or design parameters. However, in some embodiments, a programmable flow control system may be used to achieve a fixed distribution of working fluid between parallel flow paths. Still other embodiments may utilize a non-programmable flow control system. For example, valves may be manually set or controlled.

[0058] Figure 13 This demonstrates the effectiveness of the currently disclosed technology. Figure 11 Targeting T h2 =565℃、T 范围 = 265°C to 545°C shows a single regenerative cycle heat pump and Figure 7 The relative performance of the dual-track heat pump in the relatively small T 范围 Under the condition of T<350℃, the dual-track heat pump cycle has no obvious advantage over the single regenerative cycle. 范围 When the value is high, the dual-track cycle has a clear performance advantage evaluated by COP.

[0059] As used herein, the qualifiers "a" and "an" are intended to have their ordinary meaning in the patent art, i.e., "one or more". In this document, unless expressly provided otherwise, the term "about" when applied to a numerical value generally means within the tolerance range of the device used to generate the value, or in some examples means plus or minus 10%, or plus or minus 5%, or plus or minus 1%. In addition, the term "substantially" as used herein means, for example, most, or nearly all, or all, or an amount within a range of, for example, about 51% to about 100%. In addition, the examples herein are intended to be illustrative only and are presented for discussion purposes only and not for limitation.

[0060] For the purpose of explanation, the foregoing description uses specific terms to provide a thorough understanding of the present disclosure. However, it will be understood by those skilled in the art that the systems and methods described herein can be practiced without the specific details. The foregoing descriptions of specific examples are presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the present disclosure to the precise form described. Obviously, many modifications and variations are possible in light of the above teachings. The examples are selected and described in order to best explain the principles and practical applications of the present disclosure, thereby enabling others skilled in the art to best utilize the present disclosure and various examples with various modifications suitable for the specific purposes contemplated. The scope of the present disclosure is intended to be defined by the claims and their equivalents.

Claims

1. A dual-track heat pump cycle, comprising: Low temperature heat source; a two-stage high-temperature heat exchange process, wherein heat is exchanged with a heat medium during operation through the two-stage high-temperature heat exchange process; as well as A working fluid circuit, the working fluid circuit comprising: expansion process; Compression process; a regenerative process between the expansion process and the compression process, the regenerative process having a high-pressure side defined by the compression process and a low-pressure side defined by the expansion process; and A pair of parallel flow paths is located between the regenerative process and the high temperature heat exchange process on the high pressure side of the regenerative process.

2. The dual-rail heat pump cycle according to claim 1, wherein the dual-rail heat pump cycle is an extended dual-rail heat pump cycle, and wherein: The two-stage high-temperature heat exchange process includes an expansion stage, and in operation, heat is exchanged with the heat medium through the expansion stage; and The working fluid circuit includes a third parallel flow path between the expansion stage and the regenerator.

3. The dual-rail heat pump cycle according to claim 1, wherein the heat medium flows through the heat exchange process.

4. The dual-rail heat pump cycle according to claim 1, wherein the dual-rail heat pump cycle is an extended dual-rail heat pump cycle, and the extended dual-rail heat pump cycle further comprises: The third stage of the high-temperature heat exchange process; as well as A second pair of parallel flow paths is located between the regenerative process and the high temperature heat exchange process. The dual-track heat pump cycle according to claim 1 , wherein the regenerative process comprises a pair of regenerators.

6. The dual-track heat pump cycle according to claim 1, further comprising: a generator driven by said expansion process; as well as A motor drives the compression process.

7. The dual-rail heat pump cycle according to claim 1, wherein the compression process comprises at least one compression device. The dual-rail heat pump cycle according to claim 7 , wherein the compression device comprises a compressor. 9 . The dual-rail heat pump cycle according to claim 8 , wherein the compressor is a fully enclosed reciprocating compressor, a scroll compressor, or a centrifugal compressor.

10. The dual-rail heat pump cycle of claim 1, wherein the expansion process comprises at least one expansion device. The dual-rail heat pump cycle according to claim 10 , wherein the expansion device comprises an expander. 12 . The dual-rail heat pump cycle according to claim 11 , wherein the expander is an adiabatic expansion valve or a fluid expander. 13 . The dual-rail heat pump cycle according to claim 12 , wherein the fluid expander is a turbine, a reciprocating expander, or a scroll expander.

14. A dual-track heat pump cycle comprising: Low temperature heat source; as well as a working fluid circuit through which, in operation, a working fluid circulates, the working fluid circuit comprising: Regenerator; a compression device defining a high pressure side of the regenerator; an expansion device located downstream of the high-pressure side of the regenerator and upstream of the low-temperature heat source, defining a low-pressure side of the regenerator; a pair of high-temperature heat exchangers for the heat medium to flow through; and A pair of parallel flow paths are located between the regenerator and the high temperature heat exchanger on the high pressure side of the regenerator.

15. The dual-rail heat pump cycle according to claim 14, wherein the dual-rail heat pump cycle is an extended dual-rail heat pump cycle, and the extended dual-rail heat pump cycle further comprises: a third high-temperature heat exchanger for the heat medium to flow through; as well as A second pair of parallel flow paths is located between the third high temperature heat exchanger and the regenerator.

16. The dual-track heat pump cycle according to claim 14, further comprising: a generator driven by the expansion device; as well as A motor drives the compression device.

17. The dual-rail heat pump cycle according to claim 14, wherein the compression device comprises a compressor.

18. The dual-rail heat pump cycle according to claim 17, wherein the compressor is a fully enclosed reciprocating compressor, a scroll compressor, or a centrifugal compressor.

19. The dual-rail heat pump cycle of claim 14, wherein the expansion device comprises an expander. 20 . The dual-rail heat pump cycle according to claim 19 , wherein the expander is an adiabatic expansion valve or a fluid expander.

21. The dual-rail heat pump cycle according to claim 20, wherein the fluid expander is a turbine, a reciprocating expander, or a scroll expander.

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