219 results about "Brayton cycle" patented technology

The invention discloses a control method and device for a supercritical carbon dioxide recompression cycle power generation system, and the method comprises the steps: predicting the load change of the supercritical carbon dioxide Brayton cycle power generation system according to the historical operation data and current operation state of the supercritical carbon dioxide Brayton cycle power generation system; predicting the surge risk of the compressor according to the load change of the supercritical carbon dioxide Brayton cycle power generation system; according to the load change of the supercritical carbon dioxide Brayton cycle power generation system, the split ratio is adjusted, so that the recompression Brayton cycle power generation system operates at the optimal efficiency; and the flow, pressure and temperature of a compressor working medium in the supercritical carbon dioxide Brayton cycle power generation system are adjusted according to the surge risk, so that the compressor works in a non-surge area. When the supercritical carbon dioxide Brayton cycle power generation system approaches the surge boundary, the system adjusts the opening degree of the bypass valve in advance for flow release, so that active closed-loop control of surge prediction-response-relief is achieved, a compressor is effectively prevented from entering an unstable area under sudden load change, start and stop or extreme disturbance, and the service life of the compressor is prolonged. And the safety stability and the operation continuity of the system are obviously improved.

The invention discloses an air Brayton cycle and water vapor Rankine cycle coupling system and a working method.The working medium of a Brayton cycle system is air, the Brayton cycle system is provided with a refrigeration end, a first power generation end and a plurality of first heat exchange parts, and the cycle working medium of a cycle energy storage system is a heat storage medium; the circulating energy storage system is provided with a plurality of second heat exchange parts and a plurality of third heat exchange parts, the second heat exchange parts and the first heat exchange parts conduct heat exchange in a first heat exchanger, a working medium of the Rankine cycle system is water vapor, and the Rankine cycle system is provided with a second power generation end and a plurality of fourth heat exchange parts. And the fourth heat exchange part and the third heat exchange part exchange heat in the second heat exchanger. According to the invention, refrigeration can be realized, and energy storage and power generation can be realized, so that electric energy can be utilized more reasonably, and the purpose of consumption reduction can be achieved; working media adopted by the Brayton cycle system and the Rankine cycle system are air and water respectively, and the two working media do not generate redundant carbon emission, so that the purpose of reducing carbon is achieved.

The invention discloses a coupled thermal power cycle system, which relates to the technical field of energy application, and effectively realizes coupling of an organic Rankine cycle module and a Brayton cycle module in fusion reactor heat source application by inputting an expanded first working medium and a deoxygenated second working medium into a heat exchanger module for heat exchange. On one hand, the temperature of the first working medium can be reduced through heat transfer to reduce the cooling cost of the first working medium, and on the other hand, heat in the Brayton cycle module can be utilized to reduce generation of waste heat. In addition, the organic Rankine cycle module has a reheating stage, and the energy conversion efficiency of the coupled thermal power cycle system can be effectively improved. In addition, the parameters of the coupled thermal power circulation system are set based on the enthalpy value, and the system heat efficiency can be further improved.

The invention discloses a decarburization coal power system coupled with a reversible Brayton cycle heat pump and a method thereof. The decarburization coal power system comprises a coal-fired power generation subsystem used for converting heat into electric energy, a decarburization subsystem used for treating carbon dioxide emission and a heat pump heat storage subsystem used for improving the energy utilization efficiency. Exhausted smoke of a boiler in the coal-fired power generation subsystem passes through a smoke steam cooler in the decarburization subsystem and then enters an absorption tower; the coal-fired power generation subsystem sends high-temperature steam generated by a boiler into the heat pump heat storage subsystem through a high-pressure cylinder and an intermediate-pressure cylinder, and the heat pump heat storage subsystem stores high-temperature molten salt after heat absorption into a high-temperature storage tank. The system has the beneficial effects that the heat pump heat storage subsystem is constructed through the reversible Brayton cycle, supercritical carbon dioxide is adopted as a cycle working medium, and a phase change material and molten salt are adopted as heat storage media, so that the energy storage density is improved, and the stability and high efficiency of the heat storage and release process are guaranteed; therefore, the system can better adapt to fluctuation of the power grid load, and quick response is realized.

The invention provides a volumetric supercritical carbon dioxide Brayton cycle variable load system, belongs to the technical field of supercritical carbon dioxide Brayton cycle power generation, and can at least partially solve the problems that an existing steam Rankine cycle unit does not utilize the supercritical carbon dioxide Brayton cycle to integrally operate on a supercritical point and has no project. The Brayton cycle system comprises a compressor, a main loop and an adjusting branch, the adjusting branch comprises a pressure adjusting assembly, the amount of circulating carbon dioxide working media in the system is adjusted, the inlet pressure of the compressor is adjusted, and the working point of the compressor is changed; the temperature and pressure of the carbon dioxide working medium at the turbine inlet are changed by adjusting the heat exchange amount of the heat source heat exchanger, and rapid load changing is achieved.

The invention provides a multifunctional comprehensive experimental platform and experimental method for a new working medium Brayton cycle system, and belongs to the technical field of thermal engineering experiments. The problem that an experimental device for researching unknown transient characteristics such as start / stop / power change of a new working medium Brayton cycle system, unknown transient safety characteristics under various typical accident conditions, a reliable start / stop / accident safety control strategy and composite control strategy thermal safety characteristics is lacked is solved. The device comprises a new working medium gas charging and discharging system, a Brayton cycle main loop system, a circulating cooling water system, a simulated crevasse system, a measuring instrument system and a power distribution cabinet, the simulation crevasse system comprises a first manual stop valve, a first crevasse test point, a movable crevasse eruption collecting device and the like which are located on a branch near an inlet of the temperature and pressure reducing device and connected in sequence. The device is mainly used for experimental research of the new working medium Brayton cycle system.

The invention discloses an energy comprehensive utilization system based on a fusion device and a control method thereof. The system comprises a divertor cooling circulation loop, a cladding tritium production loop, a first cooling loop, a second cooling loop, a Brayton circulation loop and a Rankine circulation loop. The first cooling loop and the second cooling loop are used for cooling and purifying the cladding, and when the thermal load of the fusion device is smaller than a preset threshold value, only the first cooling loop is operated; when the thermal load of the fusion device is larger than a preset threshold value, the first cooling loop and the second cooling loop operate in parallel. The second cooling loop is indirectly or directly connected with the Brayton cycle loop or the Rankine cycle loop through valve switching; the Brayton cycle loop and the Rankine cycle loop are power generation loops, and power generation modes comprise Rankine cycle power generation, Brayton cycle power generation and combined power generation of Rankine cycle and Brayton cycle. The energy comprehensive utilization of the fusion device can be realized, and meanwhile, the system flexibility is improved.

The present application relates to a flue gas low-heat recovery system based on reverse Brayton cycle heat pump energy storage and a control method thereof, and belongs to the technical field of heat pump energy storage peak shaving of heat engine units. The system comprises a boiler module, a high-heat cycle module and a low-heat cycle module, and realizes the hierarchical utilization of high-grade and low-grade flue gas low-heat through collaborative operation. The flue gas of the boiler module is coupled with the high-heat cycle module through a molten salt heat exchanger, and the low-heat cycle module utilizes the low-heat of the flue gas to generate power through an organic Rankine cycle. The high-heat cycle module stores electric energy and thermal energy during off-peak hours and releases energy during peak hours, thereby improving the peak shaving capacity of the system. The present application realizes the deep integration of efficient recovery of flue gas low-heat and energy storage technology, significantly improves the energy utilization efficiency, system flexibility and economy, and has environmental protection and sustainable development benefits.

The invention discloses a thermal power generating unit, supercritical carbon dioxide and compressed air combined cycle energy storage system and an operation method, and belongs to the technical field of peak and frequency regulation and waste heat utilization of energy systems. The system comprises a compressed air energy storage subsystem, a supercritical CO2 Brayton cycle subsystem, a thermal power collaborative heat exchange subsystem, a coupling heat exchange device and an intelligent control system. In the energy storage stage, efficient compression is achieved through multi-stage compression and intermediate cooling, and air and CO2 are stored separately; in the energy release stage, compressed air drives an air expansion machine to generate power after being subjected to steam extraction and flue gas preheating of the thermal power plant, and meanwhile supercritical CO2 circularly utilizes waste heat of boiler tail gas of the thermal power plant and system tail gas to be preheated and expanded to serve as a second heat source channel to improve the output power. The intelligent control system coordinates the operation conditions of all the subsystems, and flexible switching of the system under various load and heat source boundaries is achieved. The system has high energy efficiency, high response speed and high integration level, and the peak regulation capacity and the clean operation level of the thermal power generating unit are remarkably improved.

The application discloses a kind of energy comprehensive utilization system based on fusion device and its control method, the system includes: divertor cooling circulation loop, blanket tritium production loop, first cooling circuit, second cooling circuit, brayton cycle loop and rankine cycle loop;First cooling circuit and second cooling circuit are used for blanket cooling and purification, when the heat load of fusion device is less than preset threshold, only first cooling circuit is operated;When the heat load of fusion device is greater than preset threshold, first cooling circuit and the second cooling circuit are operated in parallel;Second cooling circuit is indirectly connected or directly connected with brayton cycle loop or rankine cycle loop by valve switching;Brayton cycle loop, rankine cycle loop is power generation circuit, and power generation mode includes rankine cycle power generation, brayton cycle power generation, combined power generation of rankine cycle and brayton cycle.The application can realize fusion device energy comprehensive utilization, and improve system flexibility simultaneously.

The application relates to the field of supercritical CO2 Brayton cycle, and provides a supercritical CO2 dry gas sealed closed heat management system based on a vortex tube, which comprises a vortex chamber connected with a compressor working medium outlet through a vortex tube gas inlet pipeline, hot gas flowing out of a hot end pipe at a higher temperature enters a compressor end sealing cavity through a vortex tube hot end gas outlet pipeline; the compressor end sealing cavity is connected with a compressor medium outlet through a compressor end sealing cavity gas outlet gap, so that working medium flowing in the compressor end sealing cavity flows back to the vortex tube gas inlet pipeline; a vortex tube cold end gas outlet pipeline is connected with a cooling cavity gas inlet hole, so that cold gas flowing out of the cold end pipe at a lower temperature enters the cooling cavity; and the cooling cavity gas outlet hole is connected with the compressor medium outlet, so that working medium flowing in the cooling cavity flows back to the vortex tube gas inlet pipeline. The application has important significance for efficient, low-leakage and stable operation of a supercritical CO2 Brayton cycle power generation turbine unit.

The application discloses a kind of based on Brayton cycle's combined heat and power system, it is related to flue gas waste heat technical field, wherein, based on Brayton cycle's combined heat and power system includes power generation cycle system, steam subsystem and flue gas subsystem;Power generation cycle system includes boiler and carbon dioxide shunt, the output end of carbon dioxide shunt is connected with first power generation pipeline and second power generation pipeline in parallel, first power generation pipeline and second power generation pipeline are connected boiler, wherein second power generation pipeline is provided with economizer;Steam subsystem includes steam generator;Flue gas subsystem includes flue gas pipeline, flue gas pipeline is connected with flue gas shunt after boiler, flue gas shunt is connected with first flue gas pipe and second flue gas pipe in parallel, first flue gas pipe is used for economizer heating, and second flue gas pipe is used for steam generator heating;The technical scheme provided in the application aims at increasing the functionality of system.

This invention discloses a high-pressure resistant hull cooler and cooling method for an underwater vehicle, comprising a cooling core and pressing plates at both ends thereof. The cooling core includes a plurality of sequentially sealed and stacked cooling plates. The cooling plates are hollow structures designed to be fitted onto a supercritical carbon dioxide Brayton cycle system. At least one side of each cooling plate has a cooling channel arranged circumferentially along the cooling plate, forming a circulation path with the heat source of the supercritical carbon dioxide Brayton cycle system.

The application discloses a waste heat recovery system based on supercritical carbon dioxide Brayton cycle, and relates to the field of waste heat recovery systems.The waste heat recovery system comprises a waste heat recovery unit, a reverse osmosis unit and a seawater preheating unit.The waste heat recovery unit is used for supercritical carbon dioxide Brayton cycle of high-temperature and high-pressure carbon dioxide, and the electric energy generated by the supercritical carbon dioxide Brayton cycle is used for reverse osmosis separation of seawater, and the low-temperature waste heat in the waste heat recovery unit is used for preheating of seawater.The reverse osmosis unit is used for reverse osmosis separation of seawater, so that the electric energy generated by the supercritical carbon dioxide cycle in the waste heat recovery unit is used for driving the reverse osmosis system, and the low-temperature waste heat is used for preheating of the inlet seawater of the reverse osmosis system, thereby realizing efficient utilization of waste heat and improving the efficiency of the waste heat recovery system.

The invention discloses a supercritical CO2 centrifugal compressor and turbine performance test combined test bench system and method. The device is mainly composed of a compressor, a turbine, an electric heater, a cooler, a surge tank, a CO2 storage tank, valves and pipelines, a motor drives the compressor through a gearbox and is connected with a rotating shaft of the turbine through a clutch, and a main circulation loop is sequentially connected with the compressor, the turbine, the cooler, the surge tank and the electric heater in series. Through cooperation of bypass valve switching, clutch separation and reunion and a system control strategy, seamless switching of five test modes can be achieved without shutdown or pipeline disassembly and assembly, and the five test modes comprise a turbine connection and independent compressor performance test, a turbine performance test and a key component performance test. And a complete supercritical CO2 Brayton cycle system stable operation and control strategy verification test is carried out. The system has the characteristics of high efficiency and high test continuity, and provides a multifunctional and low-cost comprehensive test platform for research and development of a supercritical CO2 power device.

The invention provides a solar power supply device for oil field well site pressure driving equipment, which belongs to the technical field of power supply equipment and comprises a photovoltaic power generation system, a storage battery, a solar air Brayton cycle cogeneration system and a photothermal conversion system. Electric energy generated by the photovoltaic power generation system is supplied to the storage battery, the electric control center receives electric energy generated by the storage battery and the solar air Brayton cycle combined heat and power system, and the thermoelectric conversion system is connected with the solar air cycle combined heat and power system to achieve heat exchange and supply the exchanged heat to an oil well. Green energy and sustainable development can be provided, and green production and sustainable development are achieved; diversified supply and efficient utilization of energy are achieved, and the power supply reliability and economical efficiency of oil field fracturing equipment are improved.

The invention provides a performance test device for an air Brayton cycle power system. The performance test device comprises a test prototype (100), and the test prototype (100) comprises an air compressor (101) and a turbine (102); the high-altitude and high-cold simulation system comprises an air pressure simulation tank (201), a vacuum pump (202), an isolating valve (203), a refrigerating machine (204) and a cooler (205), the vacuum pump (202) and the isolating valve (203) are respectively connected to the air pressure simulation tank (201) and used for adjusting and maintaining the target pressure in the air pressure simulation tank (201), and an outlet of the air pressure simulation tank (201) is connected to an inlet of the air compressor (101) through the refrigerating machine (204) in sequence through a pipeline and used for providing a low-temperature and low-pressure working medium for the air compressor (101); an outlet of the turbine (102) is connected to an inlet of the air pressure simulation tank (201) through a pipeline via the cooler (205), and the turbine (102) is used for cooling the working medium after acting and enabling the working medium to flow back to the air pressure simulation tank (201). The device can test the performance of a test prototype in special environments such as high altitude and high cold.

The invention provides a coupling power generation process for directly synthesizing dimethyl ether through plasma co-gasification. According to the invention, the production process is simplified, the supercritical CO2 Brayton cycle is integrated, and efficient waste heat and power generation recovery is realized. In order to utilize carbon dioxide in waste gas, an alkaline electrolytic cell hydrogen production process and a carbon dioxide hydrogenation methanol process are systematically introduced. Model verification and sensitivity analysis confirm the reliability of the system and reveal the significant influence of key operation parameters on the system performance. The invention provides an innovative path for efficient utilization of biomass and clean production of methanol and dimethyl ether, and effectively balances resource utilization and environmental protection.

The invention discloses a Mars in-situ carbon dioxide cooling supply nuclear energy power generation system, belongs to the technical field of nuclear energy power generation systems, and particularly relates to an extraterrestrial celestial body in-situ resource utilization (ISRU) nuclear energy power generation technology. The problems that an existing Mars closed Brayton cycle nuclear power generation subsystem is difficult in heat dissipation and difficult in working medium supply are solved. The system comprises a carbon dioxide liquefaction subsystem and a closed Brayton cycle nuclear power generation subsystem. The Mars in-situ carbon dioxide cooling replenishment nuclear energy power generation system is suitable for deep space exploration and extraterrestrial energy utilization.

This invention belongs to the field of supercritical carbon dioxide property monitoring and discloses a method and system for predicting the thermal properties of CO2 in an SCO2 Brayton cycle system. The method includes: acquiring index data of the CO2 working fluid as it flows through a preset property measurement module; calculating the static pressure data within the Coriolis density meter based on the readings of a Coriolis density meter, a temperature sensor, and a pressure sensor; determining the phase state of the CO2 working fluid based on the static pressure data and the temperature sensor reading; and obtaining the predicted results of preset thermal property indicators of the CO2 working fluid based on the phase state of the CO2 working fluid and in conjunction with the static pressure data and the Coriolis density meter reading or the temperature sensor reading. This invention can accurately predict the thermal property parameters of the CO2 working fluid, providing reliable data support for the precise control of the precooler, thereby ensuring the safe and stable operation of the entire SCO2 Brayton cycle system.

This application proposes a dual-cycle solar thermal power generation system and method for compressed CO₂ energy storage. This application includes a CO₂ dual-cycle power generation system, a compressed CO₂ energy storage system, and a concentrating solar heat collection system. The CO₂ dual-cycle power generation system includes a supercritical CO₂ Brayton cycle system and a transcritical CO₂ Brayton cycle system in which the CO₂ working fluid circulates, and the two are heat-exchanged and connected; the compressed CO₂ energy storage system is connected to the supercritical CO₂ Brayton cycle system and is used to input the CO₂ working fluid to the supercritical CO₂ Brayton cycle system or receive the CO₂ working fluid output by the supercritical CO₂ Brayton cycle system under different working conditions; the concentrating solar heat collection system uses solar energy to heat the CO₂ working fluid entering the supercritical CO₂ Brayton cycle system and the compressed CO₂ energy storage system. This application constitutes a dual cycle and an energy storage system with pure CO₂ as the working fluid, maximizing the energy utilization rate.

This invention discloses a thermodynamic optimization method for a lead-bismuth stack coupled supercritical carbon dioxide Brayton cycle system. The method includes seven steps: 1. Initialization of the Brayton cycle system's thermodynamic parameters; 2. Dividing the Brayton cycle system into different modules; 3. Calculating the supercritical carbon dioxide thermodynamic parameters of the hot-end module; 4. Calculating the supercritical carbon dioxide thermodynamic parameters of the cold-end module; 5. Calculating the supercritical carbon dioxide thermodynamic parameters of the regenerator module; 6. Optimizing the Brayton cycle system configuration; 7. Calculating the optimal configuration thermodynamic parameters of the Brayton cycle system. This invention enables the coordinated calculation and optimization of the configuration, parameters, and stress of a lead-bismuth stack coupled supercritical carbon dioxide Brayton cycle system, significantly shortening the design cycle and improving the thermal efficiency and operational reliability of the system.

The invention discloses a device and a method for detecting heat-carrying capacity of a residual heat removal system of a miniature gas-cooled reactor. Comprising a Brayton cycle system used for simulating the normal operation condition of the miniature gas cooled reactor, a data acquisition and control system connected with the Brayton cycle system, and a residual heat removal system used for simulating the operation state of an active and passive residual heat removal system under the shutdown or accident condition of the miniature gas cooled reactor, according to the invention, different gas working media, different reactor core simulation sections and heat exchangers can be flexibly adjusted to simulate active and passive residual heat removal characteristics under different gas working media and different reactor core and heat exchanger configurations, and a Brayton cycle state, an active residual heat removal state and a passive residual heat removal state of a miniature gas cooled reactor; and switching of different operation states can be realized.

The invention relates to a thermal and electric conversion system of a thermal power battery based on a closed Brayton cycle. The invention relates to the field of thermal power systems, and aims to overcome the defects of low energy density, large volume, large weight and the like of an existing battery system and overlarge mass-volume ratio of a power system. The device comprises an energy-work conversion unit, a heat source, power generation equipment, a partition plate, an outer package, a pre-cooling pipeline and the like. The energy-work conversion unit is indirectly connected with a heat source through a heat exchange pipeline, heat generated by the heat source transmits a working medium to do work, the energy-work conversion unit is connected with power generation equipment through a power shaft and converts mechanical energy into electric energy, and the power generation equipment is connected with an external connection point through a wire pipeline to achieve external output of the electric energy. The outer packaging structure further communicates with a pre-cooling pipeline, and the energy-work conversion unit is connected with the pre-cooling pipeline and used for cooling the working medium. And the energy-work conversion unit, the heat source, the power generation equipment, the partition plate and the pre-cooling pipeline are respectively mounted in the outer package to form an integral system. The invention is applied to the field of thermal and electric conversion of thermal power batteries.

The invention relates to a carbon dioxide combined cooling and power supply system, which realizes liquid carbon dioxide energy storage and combined cooling and power supply through the technologies of liquid carbon dioxide energy storage, Brayton cycle power generation, carbon dioxide variable-capacitance voltage-stabilizing storage and gas transmission, and provides a new method for safe and long-period operation and large-scale or small-scale application of an energy storage device, and'valley shifting and peak filling 'of photovoltaic power, wind power and a power grid. And an efficient and feasible technical path is provided.

The present application belongs to the technical field of aviation turbine engine, and discloses an intercooling regenerative water enhanced turbofan engine, which comprises a Brayton cycle and a supercritical water vapor Rankine cycle in a main flow path, the two cycles are closely related, and are coupled by increasing a steam turbine, a steam generator and a condenser. The steam turbine does work to supply a high-pressure compressor, and liquid water appears at the steam turbine outlet, the liquid water is injected into the high-low pressure compressor for intercooling, the intermediate temperature of the compressor is reduced, the power consumption of the compressor is reduced, the unit working medium thrust is improved, the intercooler is saved, and the application is facilitated, the low-temperature steam at the steam turbine outlet can be injected into the low-pressure turbine inlet for cooling, and the cold air amount can be effectively reduced and the unit working medium thrust can be improved. The present application effectively overcomes the high temperature difference and large loss of the steam generator, compared with the conventional aviation engine, the total efficiency of the engine can be greatly improved, the fuel consumption rate and the pollutant emission are reduced.

The disclosure provides a hybrid energy storage system, wherein the Brayton cycle unit comprises a first compressor, a first air-salt heat exchanger and an air-air heat exchanger forming a circulation loop, the cold side of the first air-salt heat exchanger is provided with a first inlet and a first outlet, the cold side of the air-air heat exchanger is provided with a second inlet and a second outlet, and the second inlet is used for air entering; the energy storage unit comprises a molten salt heat storage unit, the molten salt heat storage unit is connected with the first inlet and the first outlet to form a circulation loop; a Rankine cycle unit is connected with the molten salt heat storage unit to generate power by obtaining heat; and the processing unit comprises a first unit, the first unit comprises a compression section and an expansion section connected with the compression section, the compression section is connected with the second outlet, has a gas compression function, and is connected with the molten salt heat storage unit to deliver first temperature heat to the molten salt heat storage unit and second temperature compressed air smaller than the first temperature to the expansion section, and the expansion section has a gas expansion function to generate power.

A system and method for preparing and supplying a densified liquid oxidant to a spacecraft launch facility is provided. Liquid oxygen streams obtained from co-located air separation devices for liquid preparation are densified in an integrated densification system of two refrigeration stages. The first refrigeration stage is a nitrogen-based inverse Brayton cycle refrigeration cycle that provides refrigeration to the second refrigeration stage. The second refrigeration stage is a refrigerant circuit comprising helium and / or neon that densifies the liquid oxygen to a temperature between about 70 Kelvin and 57 Kelvin. The integrated densification system may also be configured to densify liquid methane or other propellants used in a spacecraft.

The invention belongs to the technical field of nuclear energy power generation, and discloses an advanced high-temperature reactor coupled Brayton cycle power generation system which comprises an advanced high-temperature reactor subsystem and a Brayton cycle subsystem, the advanced high-temperature reactor subsystem comprises an advanced high-temperature reactor, the outlet temperature of helium is 750-1000 DEG C, and the outlet temperature of nitrogen is 750-1000 DEG C; the Brayton cycle subsystem comprises a compression device, a heat regeneration device, a turbine device and a cooling device, the temperature of carbon dioxide fluid at an inlet of the turbine device is 500-700 DEG C, the optimal operation state of the Brayton cycle subsystem can be achieved, the heat-work conversion efficiency is improved, and even if carbon dioxide enters a reactor core of an advanced high-temperature reactor due to leakage of a heat exchanger, the carbon dioxide can be recycled. And moreover, the supercritical fluid does not generate phase change in the heat exchanger, so that the operation safety is improved.