Supercritical carbon dioxide cycle cold end pressure control system and method

Abstract

The application provides a supercritical carbon dioxide cycle cold end pressure control system and method, and the control system comprises a precooler, an inlet regulating valve, a low-pressure tank, a conveying pump, a high-pressure tank, an outlet regulating valve and a main compressor; the precooler has a first working medium side outlet and a second working medium side outlet; the first working medium side outlet of the precooler is connected with the inlet of the low-pressure tank through the inlet regulating valve, the outlet of the low-pressure tank is connected with the inlet of the conveying pump, the outlet of the conveying pump is connected with the inlet of the high-pressure tank, the outlet of the high-pressure tank is connected with the working medium side inlet of the precooler through the outlet regulating valve, and the second working medium side outlet of the precooler is connected with the inlet of the main compressor. One technical effect of the application is that the active control of the main compressor inlet pressure of the supercritical carbon dioxide is realized, the disturbance to the closed supercritical carbon dioxide cycle system is reduced to the maximum, and the peak shaving capacity of the supercritical carbon dioxide cycle generator set is improved.

Description

Technical Field

[0001] This invention belongs to the field of power cycle power generation technology, specifically relating to a supercritical carbon dioxide cycle cold end pressure control system and method. Background Technology

[0002] Against the backdrop of accelerating the construction of a new power system, coal-fired power units are transforming and upgrading towards basic support and system regulation power sources. With wide load ranges and rapid load changes becoming the new normal for coal-fired power units, the dramatic increase in energy consumption during load-changing operations has become a major pain point for the coal-fired power industry. Supercritical carbon dioxide cycle power generation technology, due to its high cycle thermal efficiency and flexible operation, has become an important development direction for low-carbon, flexible coal-fired power generation technology.

[0003] During the operation of a supercritical carbon dioxide cycle generator unit, when the compression process of carbon dioxide approaches the critical point, its density is close to that of a liquid and its viscosity is similar to that of a gas. This can significantly reduce the power consumption of compression and greatly improve the cycle thermal efficiency, thereby improving the power generation efficiency of coal-fired units and reducing carbon emissions from power plants.

[0004] However, ensuring that the compression process of supercritical carbon dioxide remains close to the critical point during large-scale peak-shaving operations has become a pressing technical problem that needs to be solved. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a new technical solution for a supercritical carbon dioxide cycle cold end pressure control system and method.

[0006] According to a first aspect of the present invention, a supercritical carbon dioxide cycle cold end pressure control system is provided, comprising a precooler, an inlet regulating valve, a low-pressure tank, a transfer pump, a high-pressure tank, an outlet regulating valve, and a main compressor;

[0007] The precooler has a first working fluid side outlet and a second working fluid side outlet; the first working fluid side outlet of the precooler is connected to the inlet of the low-pressure tank via the inlet regulating valve, the outlet of the low-pressure tank is connected to the inlet of the delivery pump, the outlet of the delivery pump is connected to the inlet of the high-pressure tank, the outlet of the high-pressure tank is connected to the working fluid side inlet of the precooler via the outlet regulating valve, and the second working fluid side outlet of the precooler is connected to the inlet of the main compressor.

[0008] Optionally, the supercritical carbon dioxide circulating cold end pressure control system further includes a circulating water tank, a circulating water pump, valves, and a cooling tower; the circulating water tank is located below the cooling tower.

[0009] The outlet of the circulating water tank is connected in sequence to the water-side inlet of the precooler via the circulating water pump and the valve. The water-side outlet of the precooler is connected to the inlet of the cooling tower, and the outlet of the cooling tower is connected to the inlet of the circulating water tank.

[0010] The circulating water passes through the precooler to regulate the temperature of the precooler, and the flow rate of the circulating water is adjusted by controlling the opening of the valve.

[0011] Optionally, the supercritical carbon dioxide cycle cold end pressure control system also includes a low-temperature regenerator, a high-temperature regenerator, and a boiler;

[0012] The outlet of the main compressor is connected to the cold-side inlet of the low-temperature regenerator, the cold-side outlet of the low-temperature regenerator is connected to the cold-side inlet of the high-temperature regenerator, and the cold-side outlet of the high-temperature regenerator is connected to the inlet of the boiler.

[0013] Optionally, the supercritical carbon dioxide cycle cold end pressure control system also includes a high-pressure turbine;

[0014] The superheater outlet of the boiler is connected to the inlet of the high-pressure turbine, and the outlet of the high-pressure turbine is connected to the reheater inlet of the boiler.

[0015] Optionally, the supercritical carbon dioxide cycle cold end pressure control system also includes a low-pressure turbine;

[0016] The outlet of the boiler's reheater is connected to the inlet of the low-pressure turbine, the outlet of the low-pressure turbine is connected to the hot-side inlet of the high-temperature regenerator, and the hot-side outlet of the high-temperature regenerator is connected to the hot-side inlet of the low-temperature regenerator.

[0017] Optionally, the supercritical carbon dioxide cycle cold end pressure control system also includes a recompressor;

[0018] The hot-side outlet of the low-temperature regenerator is divided into two paths: one path connects to the working fluid side inlet of the precooler, and the other path connects to the inlet of the recompressor. The outlet of the recompressor is connected to the cold-side inlet of the high-temperature regenerator.

[0019] According to a second aspect of the present invention, a method for controlling the cold end pressure of a supercritical carbon dioxide cycle is provided, applied to the supercritical carbon dioxide cycle cold end pressure control system as described in the first aspect, comprising:

[0020] When the grid dispatch load increases, the supercritical carbon dioxide cycle generator increases the power generation, the speed of the main compressor increases, and the system circulation flow increases. If the inlet pressure of the main compressor is lower than the set value, the difference between the two is used to obtain the opening command of the outlet regulating valve through PID calculation, and then the outlet regulating valve is opened and adjusted to supplement the working medium from the high pressure tank to the working medium side inlet of the precooler in order to maintain the inlet pressure of the main compressor within the set range.

[0021] When the grid load decreases, the supercritical carbon dioxide cycle generator reduces its power generation, the main compressor speed decreases, and the system circulation flow decreases. If the inlet pressure of the main compressor is higher than the set value, the difference between the two is used to obtain the opening command of the inlet regulating valve through PID calculation, and then the opening of the inlet regulating valve is opened and adjusted, so that the working fluid is discharged from the first working fluid side outlet of the precooler to the low-pressure tank to maintain the inlet pressure of the main compressor within the set range.

[0022] Optionally, when the grid dispatch load increases and the inlet pressure of the main compressor is within the set range, if the working fluid side inlet temperature of the precooler fluctuates, it can be controlled by adjusting the circulating water flow rate.

[0023] Optionally, the set value of the inlet pressure of the main compressor is obtained by calculating the unit load command through a function, which is obtained by linear interpolation of the calculation results of the unit's thermal system under varying operating conditions.

[0024] Optionally, the difference between the inlet pressure of the main compressor and the set value needs to be passed through a dead zone limit before entering the PID controller for calculation, and the dead zone range is 0.1 MPa.

[0025] One technical advantage of this invention is that:

[0026] In this embodiment, the supercritical carbon dioxide cycle cold-end pressure control system and method employs a high-pressure tank to replenish the working fluid to the system, while a low-pressure tank receives the discharged working fluid. The working fluid in the low-pressure tank is transferred to the high-pressure tank via a transfer pump, thereby regulating the flow rate of the working fluid in the closed-loop supercritical carbon dioxide cycle and achieving active control of the inlet pressure of the supercritical carbon dioxide main compressor. Simultaneously, through the rational coupling of the dual-tank system (i.e., the high-pressure tank and the low-pressure tank) with the main compressor and precooler, disturbances to the closed-loop supercritical carbon dioxide cycle system are minimized, improving the peak-shaving capability of the supercritical carbon dioxide cycle generator set. Furthermore, the control system is simple and has low investment costs. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a supercritical carbon dioxide cycle cold end pressure control system according to an embodiment of the present invention;

[0028] Figure 2This is a schematic flowchart of a supercritical carbon dioxide cycle cold end pressure control method according to another embodiment of the present invention. Detailed Implementation

[0029] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0030] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0031] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0032] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] It should be noted that as coal-fired power units increasingly undertake peak shaving or peak power generation, these units often operate at low or variable loads. When the load increases or decreases, the working fluid parameters at various points in the system of a coal-fired power unit using supercritical carbon dioxide cycle will change significantly. The high efficiency of supercritical carbon dioxide cycle stems from the low power consumption of the main compressor 1 when operating near-critical conditions. Therefore, it is difficult to maintain a high efficiency level for supercritical carbon dioxide generator units operating at low or variable loads. To address this, this invention proposes a supercritical carbon dioxide cycle cold-end pressure control system and method. This system uses a high-pressure tank 6 to replenish the working fluid to the system, and a low-pressure tank 4 to receive the working fluid discharged from the system. It regulates the working fluid flow rate of the closed-loop supercritical carbon dioxide cycle, achieving active control of the inlet pressure of the supercritical carbon dioxide main compressor 1. Simultaneously, through the reasonable coupling of the dual-tank system (i.e., high-pressure tank 6 and low-pressure tank 4) with the main compressor 1 and precooler 2, the disturbance to the closed-loop supercritical carbon dioxide cycle system is minimized, improving the peak shaving capability of the supercritical carbon dioxide cycle generator unit. The structure and method of this invention are described in detail below.

[0035] According to a first aspect of the invention, see Figure 1 A supercritical carbon dioxide cycle cold end pressure control system is provided, including a precooler 2, an inlet regulating valve 3, a low-pressure tank 4, a transfer pump 5, a high-pressure tank 6, an outlet regulating valve 7, and a main compressor 1; wherein, the inlet regulating valve 3 is the inlet regulating valve of the low-pressure tank 4, and the outlet regulating valve 7 is the outlet regulating valve of the high-pressure tank 6.

[0036] The precooler 2 has a first working fluid side outlet and a second working fluid side outlet; the first working fluid side outlet of the precooler 2 is connected to the inlet of the low-pressure tank 4 through the inlet regulating valve 3, the outlet of the low-pressure tank 4 is connected to the inlet of the transfer pump 5, the outlet of the transfer pump 5 is connected to the inlet of the high-pressure tank 6, the outlet of the high-pressure tank 6 is connected to the working fluid side inlet of the precooler 2 through the outlet regulating valve 7, and the second working fluid side outlet of the precooler 2 is connected to the inlet of the main compressor 1.

[0037] In this embodiment, the supercritical carbon dioxide cycle cold-end pressure control system and method employs a high-pressure tank 6 to replenish the working fluid to the system, and a low-pressure tank 4 to receive the discharged working fluid. The working fluid in the low-pressure tank 4 is transferred to the high-pressure tank 6 via a transfer pump 5, thereby regulating the flow rate of the working fluid in the closed-loop supercritical carbon dioxide cycle and achieving active control of the inlet pressure of the supercritical carbon dioxide main compressor 1. Simultaneously, through the reasonable coupling of the dual-tank system (i.e., the high-pressure tank 6 and the low-pressure tank 4) with the main compressor 1 and the precooler 2, disturbances to the closed-loop supercritical carbon dioxide cycle system are minimized, improving the peak-shaving capacity of the supercritical carbon dioxide cycle generator set. Furthermore, the control system is simple and has low investment costs.

[0038] Optionally, the supercritical carbon dioxide circulating cold end pressure control system further includes a circulating water tank 9, a circulating water pump 11, a valve 10, and a cooling tower 8; the circulating water tank 9 is located below the cooling tower 8;

[0039] The outlet of the circulating water tank 9 is connected to the water-side inlet of the precooler 2 via the circulating water pump 11 and the valve 10 in sequence. The water-side outlet of the precooler 2 is connected to the inlet of the cooling tower 8, and the outlet of the cooling tower 8 is connected to the inlet of the circulating water tank 9.

[0040] The circulating water passes through the precooler 2 to regulate the temperature of the precooler 2, and the flow rate of the circulating water is adjusted by controlling the opening of the valve 10.

[0041] In the above embodiment, the working fluid inlet temperature of the precooler 2 can be effectively adjusted by the cooperation of the circulating water tank 9, the circulating water pump 11, the valve 10 and the cooling tower 8, so as to ensure the stability of the working fluid inlet temperature of the precooler 2.

[0042] Optionally, the supercritical carbon dioxide cycle cold end pressure control system also includes a low-temperature regenerator 12, a high-temperature regenerator 13, and a boiler 14;

[0043] The outlet of the main compressor 1 is connected to the cold side inlet of the low-temperature regenerator 12, the cold side outlet of the low-temperature regenerator 12 is connected to the cold side inlet of the high-temperature regenerator 13, and the cold side outlet of the high-temperature regenerator 13 is connected to the inlet of the boiler 14.

[0044] In the above embodiments, it is helpful to realize that the working fluid passes through the low-temperature regenerator 12 and the high-temperature regenerator 13 in sequence before entering the boiler 14.

[0045] Optionally, the supercritical carbon dioxide cycle cold end pressure control system also includes a high-pressure turbine 15;

[0046] The superheater outlet of the boiler 14 is connected to the inlet of the high-pressure turbine 15, and the outlet of the high-pressure turbine 15 is connected to the reheater inlet of the boiler 14.

[0047] In the above embodiments, it is helpful to convert the energy contained in the working fluid (i.e., the fluid medium) into mechanical work through the high-pressure turbine 15.

[0048] Optionally, the supercritical carbon dioxide cycle cold end pressure control system also includes a low-pressure turbine 16;

[0049] The outlet of the reheater of the boiler 14 is connected to the inlet of the low-pressure turbine 16, the outlet of the low-pressure turbine 16 is connected to the hot-side inlet of the high-temperature regenerator 13, and the hot-side outlet of the high-temperature regenerator 13 is connected to the hot-side inlet of the low-temperature regenerator 12.

[0050] In the above embodiments, the energy of the fluid medium can be effectively utilized by the low-pressure turbine 16, thereby driving the turbine machinery to work.

[0051] Optionally, the supercritical carbon dioxide cycle cold end pressure control system also includes a recompressor 17;

[0052] The hot-side outlet of the low-temperature regenerator 12 is divided into two paths: one path is connected to the working fluid side inlet of the precooler 2, and the other path is connected to the inlet of the recompressor 17. The outlet of the recompressor 17 is connected to the cold-side inlet of the high-temperature regenerator 13.

[0053] In the above embodiments, the recompressor 17 can ensure the operational stability of the entire supercritical carbon dioxide cycle cold end pressure control system.

[0054] According to a second aspect of the invention, see Figure 2 A method for controlling the cold end pressure of a supercritical carbon dioxide cycle is provided, applied to the supercritical carbon dioxide cycle cold end pressure control system as described in the first aspect, comprising:

[0055] When the grid dispatch load increases, the supercritical carbon dioxide cycle generator increases the power generation, the speed of the main compressor 1 increases, and the system circulation flow increases. If the inlet pressure of the main compressor 1 is lower than the set value, the difference between the two is used to obtain the opening command of the outlet regulating valve 7 through PID calculation, and then the outlet regulating valve 7 is opened and adjusted. The working medium is supplemented from the high pressure tank 6 to the working medium side inlet of the precooler 2 to maintain the inlet pressure of the main compressor 1 within the set range.

[0056] When the grid load decreases, the supercritical carbon dioxide cycle generator reduces its power generation, the speed of the main compressor 1 decreases, and the system circulation flow decreases. If the inlet pressure of the main compressor 1 is higher than the set value, the difference is used by PID calculation to obtain the opening command of the inlet regulating valve 3, which then opens and adjusts the opening of the inlet regulating valve 3, discharging the working fluid from the first working fluid side outlet of the precooler 2 to the low-pressure tank 4 to maintain the inlet pressure of the main compressor 1 within the set range. During this process, the low-pressure working fluid in the low-pressure tank 4 is sent to the high-pressure tank 6 via the transfer pump 5, and this process is not affected by changes in the unit load.

[0057] In the above embodiments, the supercritical carbon dioxide cycle cold end pressure control method realizes active control of the inlet pressure of the supercritical carbon dioxide main compressor 1, and can also minimize the disturbance to the closed supercritical carbon dioxide cycle system, thereby improving the peak shaving capacity of the supercritical carbon dioxide cycle generator set.

[0058] Optionally, when the grid dispatch load increases and the inlet pressure of the main compressor 1 is within the set range, if the working fluid side inlet temperature of the precooler 2 fluctuates, it can be controlled by adjusting the circulating water flow rate.

[0059] In the above embodiments, it helps to ensure the stability of the working fluid inlet temperature of the precooler 2.

[0060] Optionally, the set value of the inlet pressure of the main compressor 1 is obtained by calculating the unit load command through the function f1(x), and the function f1(x) is obtained by linear interpolation of the calculation results of the unit's thermal system under varying operating conditions.

[0061] In the above embodiments, the calculation method for the set value of the inlet pressure of the main compressor 1 is relatively simple and has high accuracy.

[0062] Optionally, the difference between the inlet pressure of the main compressor 1 and the set value needs to be limited by a dead zone before entering the PID controller for calculation, with the dead zone range set to 0.1 MPa. This helps to accurately obtain the opening command of the outlet regulating valve 7 or the opening command of the inlet regulating valve 3 based on the difference between the inlet pressure of the main compressor 1 and the set value.

[0063] In this embodiment, the present invention provides a supercritical carbon dioxide cycle cold end pressure control system and method. It can control the inlet pressure range of the main compressor 1 in real time by adjusting the flow rate of the circulating working fluid during the load increase and decrease phases of the supercritical carbon dioxide cycle generator set, thereby reducing the power consumption of the main compressor 1 and improving the cycle efficiency.

[0064] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for controlling the cold-end pressure of a supercritical carbon dioxide cycle, characterized in that, An application is made to a supercritical carbon dioxide cycle cold-end pressure control system, the supercritical carbon dioxide cycle cold-end pressure control system comprising a precooler, an inlet regulating valve, a low-pressure tank, a transfer pump, a high-pressure tank, an outlet regulating valve, and a main compressor; the precooler has a first working fluid side outlet and a second working fluid side outlet; the first working fluid side outlet of the precooler is connected to the inlet of the low-pressure tank via the inlet regulating valve, the outlet of the low-pressure tank is connected to the inlet of the transfer pump, the outlet of the transfer pump is connected to the inlet of the high-pressure tank, the outlet of the high-pressure tank is connected to the working fluid side inlet of the precooler via the outlet regulating valve, and the second working fluid side outlet of the precooler is connected to the inlet of the main compressor, the method comprising: When the grid dispatch load increases, the supercritical carbon dioxide cycle generator increases the power generation, the speed of the main compressor increases, and the system circulation flow increases. If the inlet pressure of the main compressor is lower than the set value, the difference between the two is used to obtain the opening command of the outlet regulating valve through PID calculation, and then the outlet regulating valve is opened and adjusted to supplement the working medium from the high pressure tank to the working medium side inlet of the precooler in order to maintain the inlet pressure of the main compressor within the set range. When the grid load decreases, the supercritical carbon dioxide cycle generator reduces its power generation, the main compressor speed decreases, and the system circulation flow decreases. If the inlet pressure of the main compressor is higher than the set value, the difference between the two is used to obtain the opening command of the inlet regulating valve through PID calculation, and then the opening of the inlet regulating valve is opened and adjusted, so that the working fluid is discharged from the first working fluid side outlet of the precooler to the low-pressure tank to maintain the inlet pressure of the main compressor within the set range.

2. The method for controlling the cold end pressure of a supercritical carbon dioxide cycle according to claim 1, characterized in that, When the grid load increases and the inlet pressure of the main compressor is within the set range, the working fluid inlet temperature of the precooler can be controlled by adjusting the circulating water flow rate if fluctuations occur.

3. The method for controlling the cold end pressure of a supercritical carbon dioxide cycle according to claim 2, characterized in that, The set value of the inlet pressure of the main compressor is obtained by the unit load command through function calculation, and the function is obtained by linear interpolation of the calculation results of the unit's thermal system under varying operating conditions.

4. The method for controlling the cold end pressure of a supercritical carbon dioxide cycle according to claim 3, characterized in that, The difference between the inlet pressure of the main compressor and the set value needs to be passed through the dead zone limit before entering the PID controller for calculation. The dead zone range is 0.1 MPa.

5. The method for controlling the cold end pressure of a supercritical carbon dioxide cycle according to claim 1, characterized in that, The supercritical carbon dioxide circulating cold end pressure control system also includes a circulating water tank, a circulating water pump, valves, and a cooling tower; the circulating water tank is located below the cooling tower; The outlet of the circulating water tank is connected in sequence to the water-side inlet of the precooler via the circulating water pump and the valve. The water-side outlet of the precooler is connected to the inlet of the cooling tower, and the outlet of the cooling tower is connected to the inlet of the circulating water tank. The circulating water passes through the precooler to regulate the temperature of the precooler, and the flow rate of the circulating water is adjusted by controlling the opening of the valve.

6. The method for controlling the cold end pressure of a supercritical carbon dioxide cycle according to claim 5, characterized in that, The supercritical carbon dioxide cycle cold end pressure control system also includes a low-temperature regenerator, a high-temperature regenerator, and a boiler; The outlet of the main compressor is connected to the cold-side inlet of the low-temperature regenerator, the cold-side outlet of the low-temperature regenerator is connected to the cold-side inlet of the high-temperature regenerator, and the cold-side outlet of the high-temperature regenerator is connected to the inlet of the boiler.

7. The method for controlling the cold end pressure of a supercritical carbon dioxide cycle according to claim 6, characterized in that, The supercritical carbon dioxide cycle cold end pressure control system also includes a high-pressure turbine; The superheater outlet of the boiler is connected to the inlet of the high-pressure turbine, and the outlet of the high-pressure turbine is connected to the reheater inlet of the boiler.

8. The method for controlling the cold end pressure of a supercritical carbon dioxide cycle according to claim 7, characterized in that, The supercritical carbon dioxide cycle cold end pressure control system also includes a low-pressure turbine; The outlet of the boiler's reheater is connected to the inlet of the low-pressure turbine, the outlet of the low-pressure turbine is connected to the hot-side inlet of the high-temperature regenerator, and the hot-side outlet of the high-temperature regenerator is connected to the hot-side inlet of the low-temperature regenerator.

9. The method for controlling the cold end pressure of a supercritical carbon dioxide cycle according to claim 8, characterized in that, The supercritical carbon dioxide cycle cold end pressure control system also includes a recompressor; The hot-side outlet of the low-temperature regenerator is divided into two paths: one path connects to the working fluid side inlet of the precooler, and the other path connects to the inlet of the recompressor. The outlet of the recompressor is connected to the cold-side inlet of the high-temperature regenerator.

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