Optimization Method for Organic Rankine Cycle System Based on Active Control of Pulsating Flow

Abstract

An optimization method for an organic Rankine cycle system based on active control of pulsating flow, which collects test data of the organic Rankine cycle system to be optimized for constructing a simulation model of the organic Rankine cycle system, screens pulsating waveforms suitable for the organic Rankine cycle system by conducting tests when the heat source state of the organic Rankine cycle system to be optimized is stable; calculates the performance of the screened pulsating waveforms under multi-heat source conditions by using the adjusted simulation model of the organic Rankine cycle system, and when the screened pulsating waveform is the optimal waveform, obtains the optimal pulsating flow parameters through adjusting the heat source conditions and using the particle swarm multi-objective optimization algorithm for iterative update, so as to establish a multi-objective optimization model dataset for cycle performance - economy. The present invention can not only give full play to the role of the working fluid circulation pump, but also design the main controller of the system by using the high-precision organic Rankine cycle system model in combination with the multi-objective optimization algorithm, further expand the advantages of pulsating flow, reduce the additional power consumption loss of the working fluid circulation pump, improve the economy of the system, and significantly improve the net output power of the organic Rankine cycle system.

Description

Technical Field

[0001] The present invention relates to a technology in the field of waste heat recovery, specifically to an optimization method of an organic Rankine cycle system based on active control of pulsating flow. Background Art

[0002] The existing methods for improving the efficiency of organic Rankine cycle systems include: changing the cycle structure (such as reheat cycle, heat recovery cycle and adding preheater, etc.), changing the system operating conditions (subcritical cycle, transcritical cycle, supercritical cycle), matching components and screening working fluids. Strengthening the performance of the heat exchanger in the organic Rankine cycle system is conducive to improving the efficiency of the organic Rankine cycle system. At present, passive enhanced heat transfer technology has been widely used in organic Rankine cycle systems. Active enhanced heat transfer technology requires the addition of additional working equipment. Whether the additional power consumption of the working equipment can be exchanged for sufficient improvement in heat exchange efficiency and ultimately achieve positive returns is the key to limiting the development of active enhanced heat transfer technology. So far, the application of active enhanced heat transfer technology is relatively small and its development is relatively lagging behind. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention proposes an optimization method for an organic Rankine cycle system based on active pulsating flow control, which can give full play to the role of the working fluid circulation pump. At the same time, a high-precision organic Rankine cycle system model is used in conjunction with a multi-objective optimization algorithm to design a system main controller, further expanding the advantages of the pulsating flow, reducing the additional power consumption of the working fluid circulation pump, improving the system economy, and significantly improving the net output power of the organic Rankine cycle system.

[0004] The present invention is achieved through the following technical solutions:

[0005] The present invention relates to an optimization method for an organic Rankine cycle system based on active pulsating flow control. Test data of an organic Rankine cycle system to be optimized is collected to construct a simulation model of the organic Rankine cycle system. A test is performed when the heat source state of the organic Rankine cycle system to be optimized is stable to screen a pulsating waveform suitable for the organic Rankine cycle system. The adjusted simulation model of the organic Rankine cycle system is used to calculate the performance of the screened pulsating waveform under a multi-heat source working condition. When the screened pulsating waveform is the optimal waveform, the heat source working condition is adjusted and a particle swarm multi-objective optimization algorithm is used to iteratively update the optimal pulsating flow parameters, which are used to establish a cycle performance-economy multi-objective optimization model data set.

[0006] The organic Rankine cycle system to be optimized includes a basic organic Rankine cycle and a regenerative cycle, a reheat cycle and a preheat cycle constructed on the basis of the basic organic Rankine cycle.

[0007] The described organic Rankine cycle system simulation model refers to: based on a finite element solver, simulating the working fluid circulation pump, evaporator, expander, and condenser. This simulation model includes: an input module, a heat recovery amount and cycle efficiency calculation module, and an output module. Among them: the data input module collects general data and physical field data; the heat recovery amount and cycle efficiency calculation module sets up the physical field, partial differential control equations, and high-precision empirical formulas and calls a numerical calculation solver to achieve accurate calculation; the output module outputs the model accuracy, the heat recovery amount of the organic Rankine cycle system, and the net cycle output power.

[0008] The described general data includes: the structure, material, and dimensions of each component.

[0009] The described physical field data includes: the thermophysical properties of the working fluid and the cold and heat source fluids, as well as the key parameters of system operation.

[0010] The described key parameters of system operation include: the power of the working fluid circulation pump The volume flow rate of the organic working fluid The mass flow rate of the heat source fluid The inlet temperature T of the heat source fluid at the evaporator eva,hin and the outlet temperature T of the heat source fluid at the evaporator eva,hout the inlet pressure p of the organic working fluid at the evaporator eva,in and the outlet pressure p of the organic working fluid at the evaporator eva,out the inlet temperature T of the organic working fluid at the evaporator eva,in and the outlet temperature T of the organic working fluid at the evaporator eva,out the inlet pressure p of the expander exp,in and the outlet pressure p of the expander exp,out the inlet temperature T of the expander exp,in and the output power of the expander The mass flow rate of the cold source fluid the inlet temperature T of the cold source fluid at the condenser con,cin and the outlet temperature T of the cold source fluid at the condenser con,cout the inlet pressure p of the organic working fluid at the condenser con,in and the outlet pressure p of the organic working fluid at the condenser con,in the inlet temperature T of the organic working fluid at the condenser con,in and the outlet temperature T of the organic working fluid at the condenser con,out .

[0011] Conducting tests when the heat source state is stable means: obtaining the heat entering the organic Rankine cycle system under pulsating flow conditions based on the readings of multiple high-precision thermometers and flow meters placed at the inlets and outlets of the working fluid and the heat fluid in the evaporator, and verifying in the constructed model under the same working conditions. When the model accuracy and accuracy do not meet the requirements, adjust the physical field settings of the heat recovery amount and cycle efficiency calculation module until the model accuracy and accuracy meet the requirements.

[0012] The described pulsating waveform refers to: the waveform generated by the periodic and regular variation of pressure and velocity of the organic working fluid over time under the action of the working fluid circulation pump; the instantaneous flow velocity of the organic working fluid in the system is always greater than 0, that is, the maximum oscillation speed amplitude of the pulsating flow is not greater than the flow velocity of the organic working fluid during stable flow; the pulsating flow frequency obtained by adjusting the working fluid circulation pump is not less than 1.

[0013] The described screening means: controlling the rotation speed motor of the working fluid circulation pump to operate according to the specified radio signal to achieve the pulsating flow of the working fluid, and analyzing the operating performance of the working fluid in the organic Rankine cycle system under the conditions of sinusoidal wave, sawtooth wave, triangular wave, square wave, pulse wave, and matrix wave pulsating flows during the test, and selecting the best pulsating flow waveform based on the net output power of the organic Rankine cycle system. The calculation formula for the net output power of the organic Rankine cycle system is as follows: Where: is the output power of the expander, is the power consumed by the working fluid circulation pump.

[0014] The described calculation of the performance of the pulsating waveform after screening under multi-heat source conditions means: based on the organic Rankine cycle system model, calculating the net output power of the organic Rankine cycle system with different pulsating flow operation parameters (maximum pulsating speed amplitude A and pulsating frequency ω) and using the best pulsating flow waveform under variable heat source conditions, obtaining the performance performance of different operating parameter pulsating flows under variable heat source conditions, and providing the optimization boundary of the pulsating flow operation parameters when designing the control system program.

[0015] In addition to the net output power of the organic Rankine cycle system, the performance of the described organic Rankine cycle system should also include relevant indicators characterizing the enhanced heat transfer effect in the evaporator, mainly including: the overall heat transfer coefficient of the evaporator and the flow pressure drop of the cold and hot fluids inside the evaporator.

[0016] The described iterative update means: taking the maximum cycle net output work, maximum heat recovery amount, and cycle economy of the organic Rankine cycle system as optimization objectives, using the particle swarm optimization algorithm to construct a multi-objective optimization model of cycle performance - economy, and obtaining the best pulsating flow parameters corresponding to each heat source condition.

[0017] The described multi-objective optimization model of cycle performance - economy refers to: taking the maximum cycle net output work η, the maximum heat recovery amount Q of the organic Rankine cycle system * and the cycle economy R as the objectives, and constructing a multi-objective optimization model by combining the finite element solver of the organic Rankine cycle system simulation model, the optimization boundary of the pulsating flow operation parameters, and the inherent constraints in the system. The objective function Where: OF is the objective function of the multi-objective optimization model; η is the maximum cycle net output work; Q *is the maximum heat recovery of the organic Rankine cycle system; R is the cycle economy; is the power of the working fluid circulation pump is the volume flow rate of the organic working fluid is the mass flow rate of the heat source fluid; T eva,hin is the inlet temperature of the heat source fluid evaporator; p eva,in is the inlet pressure of the organic working fluid evaporator; T eva,in is the inlet temperature of the organic working fluid evaporator; is the output power of the expander; is the mass flow rate of the cold source fluid; T con,cin is the inlet temperature of the cold source fluid condenser; p con,in is the inlet pressure of the organic working fluid condenser; A is the maximum pulsation velocity amplitude; ω is the pulsation frequency.

[0018] The best pulsating flow parameters obtained by iterative updating using the particle swarm multi-objective optimization algorithm refer to: generating initial particles based on the particle swarm multi-objective optimization algorithm, first calculating its own value once, and updating the movement globally based on this; the particles continuously track the individual extreme value and the social extreme value during the iteration to achieve optimization, traverse the heat source conditions, obtain the corresponding best pulsating flow parameters under each heat source condition, and calculate the heat recovery of the current organic Rankine cycle system, that is, the heat taken away by the working fluid in the evaporator and saved in the multi-objective optimization model data set.

[0019] The best pulsating flow parameters include the maximum pulsation velocity amplitude A i and the pulsation frequency ω i .

[0020] The updated movement includes: ① Updating its own speed:

[0021] v p+1 = ω p v p + c1r1(pbest p - x p ) + c2r2(gbest - x p ), where: v p+1 represents the speed of the next generation of particles; ω p is the inertia weight of the current particle swarm algorithm; v p is the current speed of the particle; c1 is the individual learning factor of the particle swarm algorithm; c2 is the social learning factor of the particle swarm algorithm; r1, r2 are random numbers in the [0-1] interval; pbest p is the historical best value of this particle; gbest is the best value of the overall cluster; ② Updating its own position: x p+1 = x p + v p+1 , where: x p+1 represents the position of the next generation of particles; xp The current position of the particle.

[0022] The present invention relates to an optimization system of an organic Rankine cycle system based on active pulsating flow control for realizing the above-mentioned method, comprising: a data acquisition unit, a data processing unit, a control unit and a feedback signal unit, wherein: the data acquisition unit collects data from a high-precision temperature sensor, a pressure sensor, a flow meter and a dynamometer and transmits the data to the data processing and control unit; the data processing unit retrieves the optimal output signal according to the data transmitted by the data acquisition unit and a data set of a multi-objective optimization model of cycle performance-economy; the control unit adjusts the operating state of a working fluid circulation pump according to the signal provided by the data processing unit to realize the pulsating flow of the working fluid in the organic Rankine cycle system; the feedback unit collects data from the high-precision temperature sensor and the flow rate sensor again and compares them with the data collected by the data acquisition unit last time; when the collected heat source fluid data changes, the latest data is provided to the data acquisition unit to realize the dynamic response of the pulsating flow of the working fluid in the organic Rankine cycle system under the condition of variable heat source working condition.

[0023] The high-precision temperature sensors are arranged at the inlet of the evaporator heat source fluid, the inlet of the evaporator organic working medium, the inlet of the condenser cold fluid and the inlet of the working medium circulation pump.

[0024] The pressure sensors are arranged at the inlet of the heat source fluid into the evaporator, the inlet of the organic working medium into the evaporator, the inlet of the cold fluid of the condenser and the inlet of the working medium circulation pump.

[0025] The flowmeter is arranged at the inlet of the heat source fluid into the evaporator, the inlet of the organic working fluid into the working fluid circulation pump and the inlet of the cold fluid of the condenser.

[0026] The dynamometer is arranged behind the expander and must be provided with a shock absorbing device and a separate reliable horizontal platform.

[0027] Preferably, the optimization system is arranged in a main control chip, and the main control chip is added to the organic Rankine cycle system to realize the dynamic response of the organic Rankine cycle system based on active control of pulsating flow to the transient working conditions of the heat source, ensuring that the circulation system always operates in the best state.

[0028] Technical Effects

[0029] Based on the operating characteristics of the working fluid circulation pump in the organic Rankine cycle, the present invention introduces the pulsating flow active heat transfer enhancement technology into the organic Rankine cycle system, and designs a pulsating flow active controller by constructing a multi-objective optimization model of cycle performance - economy, realizing the instantaneous response of the organic Rankine cycle system to the heat source condition. Compared with the general organic Rankine cycle system, the performance enhancement method of the organic Rankine cycle system based on pulsating flow active control proposed by the present invention introduces the pulsating flow of the active heat transfer enhancement technology, which can improve the heat recovery of the organic Rankine cycle system from another perspective. In addition, the organic Rankine cycle system can ensure that the whole system is always in the best state according to the instantaneous response to the heat source condition, which is beneficial to the efficient utilization of the heat of medium and low temperature heat sources. Brief Description of the Drawings

[0030] Figure 1 It is a flow chart of the present invention;

[0031] Figure 2 It is an example diagram of an internal combustion engine - organic Rankine cycle combined system based on pulsating flow active control in the embodiment;

[0032] In the figure: 1 is an internal combustion engine, 2 is a working fluid circulation pump, 3 is an evaporator, 4 is a gas - liquid separator, 5 is an expander, 6 is a dynamometer, 7 is a condenser, 8 is a liquid storage tank, 9 is a condensate tank, 10 is a main controller, 11 is a temperature sensor, 12 is a pressure sensor, 13 is a valve, 14 is a flow meter;

[0033] Figure 3 It is a flow chart of the particle swarm multi - objective optimization algorithm. Detailed Embodiment

[0034] As Figure 2 shown, in this embodiment, the exhaust waste heat of a certain type of internal combustion engine is used as the heat source to construct an organic Rankine cycle system based on pulsating flow active control. The organic Rankine cycle uses the exhaust of the internal combustion engine as the heat source, R245fa as the circulating working fluid, and water as the cooling medium. Among them: the organic Rankine cycle system and the cold - heat source circulation line include: the liquid organic working fluid absorbs the exhaust waste heat of the internal combustion engine 1 in the fin - tube evaporator 3 and gasifies, enters the expander 5 through the gas - liquid separator 4 to do work and is measured by the dynamometer 6, the exhausted gas after doing work enters the plate - type condenser 7 and is cooled to saturated liquid by the condensate (water) in the condensate tank 9 and then returns to the liquid storage tank 8, and the working fluid circulation pump 2 then pumps out the working fluid and sends it to the fin - tube evaporator 3, and the cycle repeats; the pulsating flow active control and feedback line include: the main controller 10 adjusts the operating state of the speed motor of the working fluid circulation pump 2 based on the multi - objective optimization model of cycle performance - economy, and receives the feedback from the temperature sensor 11, pressure sensor 12 and flow meter 14 of the exhaust waste heat of the internal combustion engine 1, the fin - tube evaporator 3, the plate - type condenser 7 and the dynamometer 6, and adjusts again according to the feedback signal.

[0035] Step 1) Establishment of the organic Rankine cycle system model: Construct a high-precision organic Rankine cycle system model, which includes: a working fluid circulation pump, a finned-tube evaporator, an expander, and a plate condenser model based on a finite element solver. The model is divided into three modules: an input module, a heat recovery amount and cycle efficiency calculation module, and an output module, where: the data input module is divided into general data and physical field data. The general data includes: the structure, material, and dimensions of the working fluid circulation pump, finned-tube evaporator, expander, and plate condenser; the physical field data includes: the thermophysical properties of the internal combustion engine exhaust gas, working fluid, and water, as well as the cycle parameters. The heat recovery amount and cycle efficiency calculation module includes: physical field settings, partial differential control equations, and high-precision empirical formulas, and can call a numerical calculation solver to achieve accurate calculation. The output module includes three items: model accuracy, heat recovery amount of the organic Rankine cycle system, and cycle net output power, to achieve the control of model accuracy.

[0036] Step 2) Use sensors to collect the key operating parameters of the organic Rankine cycle system: Under the stable operating conditions of the internal combustion engine, the power of the working fluid circulation pump Volume flow rate of R245fa Mass flow rate of the internal combustion engine exhaust gas Exhaust gas temperature of the internal combustion engine at the evaporator inlet (T eva,hin ), exhaust gas temperature of the internal combustion engine at the evaporator outlet (T eva,hout ), pressure of R245fa at the evaporator inlet (p eva,in ), pressure of R245fa at the evaporator outlet (p eva,out ), temperature of R245fa at the evaporator inlet (T eva,in ), temperature of R245fa at the evaporator outlet (T eva,out ), pressure of R245fa at the expander inlet (p exp,in ), pressure of R245fa at the expander outlet (p exp,out ), temperature at the expander inlet (T exp,in ), output power of the expander Mass flow rate of water Temperature of water at the condenser inlet (T con,cin ), temperature of water at the condenser outlet (T con,cout ), pressure of R245fa at the condenser inlet (p con,in ), pressure of R245fa at the condenser outlet (p con,in ), temperature of R245fa at the condenser inlet (T con,in ), temperature of R245fa at the condenser outlet (T con,out ).

[0037] Step 3) Screening and performance testing of the optimal pulsating flow waveform: Select the operating conditions of the internal combustion engine under stable operation for experiments and calculations to screen out the optimal pulsating flow waveform suitable for the current system. Obtain the heat entering the organic Rankine cycle system under pulsating flow conditions based on the readings of multiple high-precision thermometers and flow meters placed at the inlet and outlet of the working fluid and the hot fluid of the evaporator, and verify in the model constructed in (2) under the same operating conditions. If the accuracy and accuracy of the model do not meet the requirements, adjust the settings of the heat recovery amount and cycle efficiency calculation module until the accuracy and accuracy of the model reach the requirements. Based on the organic Rankine cycle system model, calculate the net output power of the pulsating flow with different operating parameters (maximum pulsating speed amplitude A and pulsating frequency ω) of the organic Rankine cycle system under different internal combustion engine operating conditions, obtain the performance of the pulsating flow with different operating parameters under multiple internal combustion engine operating conditions, and provide the optimization boundary of the pulsating flow operating parameters when designing the control system program.

[0038] Step 4) Design of the pulsating flow active control program: Taking the maximum cycle net output work η, the maximum heat recovery amount Q of the organic Rankine cycle system * and the cycle economy R as the objectives, combine the finite element solver, the pulsating flow operating parameter optimization boundary and the inherent constraint conditions in the system to construct a multi-objective optimization model of cycle performance-economy where: OF is the objective function of the multi-objective optimization model; η is the maximum cycle net output work; Q * is the maximum heat recovery amount of the organic Rankine cycle system; R is the cycle economy; is the power of the working fluid circulation pump is the volume flow rate of the organic working fluid is the exhaust mass flow rate of the internal combustion engine; T eva,hin is the temperature when the exhaust of the internal combustion engine enters the evaporator; p eva,in is the pressure of R245fa at the inlet of the evaporator; T eva,in is the temperature of R245fa at the inlet of the evaporator; is the output power of the expander; is the mass flow rate of water; T con,cin is the temperature when water enters the condenser; p con,in is the inlet pressure of the organic working fluid condenser; A is the maximum pulsating speed amplitude; ω is the pulsating frequency.

[0039] Based on the particle swarm multi-objective optimization algorithm and generate initial particles. The initial particles first perform a calculation on their own values and move globally based on this. The particles continuously track the individual extreme value and the social extreme value during the iteration process to achieve optimization. The way for the particles to update their own speed and position is: v p+1 = ω p v p + c1r1(pbest p - x p) + c2r2(gbest - x p ), where: v p+1 represents the velocity of the next generation of particles; ω p is the inertia weight of the current particle swarm algorithm; v p is the current velocity of the particle; c1 is the individual learning factor of the particle swarm algorithm; c2 is the social learning factor of the particle swarm algorithm; r1, r2 are random numbers within the range of [0 - 1]; pbest p is the historical best value of the particle; gbest is the best value of the entire cluster. x p+1 = x p + v p+1 , where: x p+1 represents the position of the next generation of particles; x p is the position where the current particle is located.

[0040] Traverse each working condition of the internal combustion engine based on the cyclic performance - economy multi - objective optimization model, obtain the optimal pulsating flow parameters (maximum pulsating velocity amplitude A i and pulsating frequency ω i ) corresponding to different exhaust parameters of the internal combustion engine, and summarize them into the multi - objective optimization model data set to establish a pulsating flow active control program.

[0041] To obtain the heat recovery amount of the current organic Rankine cycle system, that is, the heat taken away by the working fluid in the evaporator, calculate the overall heat transfer coefficient of the evaporator and the flow pressure drop of the internal fluid. In the fin - tube evaporator, the Nusselt number of convective heat transfer of the internal combustion engine exhaust: where: s1 and s2 are the transverse pitch and longitudinal pitch of the tube bundle respectively; Re is the Reynolds number of the internal combustion engine exhaust; Pr represents the Prandtl number, and the subscripts f and w represent the Prandtl number of the internal combustion engine exhaust and the Prandtl number at the wall respectively; ε is the correction coefficient, with a value of 0.923; ρ is the density of the internal combustion engine exhaust; u is the velocity of the internal combustion engine exhaust; μ is the viscosity coefficient; c p is the specific heat capacity at constant pressure; D e is the equivalent diameter; A is the flow cross - sectional area; D is the wetted perimeter.

[0042] The Nusselt number of convective heat transfer of R245fa in the evaporator described above: where: f represents the friction factor; in different regions of the R245fa flow, the value of α is different, and the relevant calculation formulas are described as follows: The phase change process and flow heat transfer process of R245fa in the evaporator where: the correction factor for film boiling the correction factor for nucleate boiling H f0 and H nbare the film boiling convective heat transfer coefficient and the nucleate boiling convective heat transfer coefficient, respectively, which are calculated by the pipeline forced convection heat transfer correlation and boiling heat transfer empirical formula: Where: f represents the thermal conductivity of R245fa; d is the pipe diameter; p is the pressure; M is the molecular weight; q w is the wall heat flux. Finally, the total heat transfer coefficient of the finned tube evaporator is obtained

[0043] In the fin-tube evaporator, the flow pressure drop of the internal combustion engine exhaust gas and the flow pressure drop of R245fa are evaluated by the Euler number Eu and the pressure drop Δp, respectively, where N represents the number of rows of finned tube evaporator tubes, ρ is the density of the exhaust gas of the internal combustion engine, and u is the maximum velocity of the exhaust gas of the internal combustion engine flowing in the evaporator.

[0044] Step 5) Establish an organic Rankine cycle system based on active control of pulsating flow: compile and burn the optimal waveform of the pulsating flow of the organic working fluid obtained in step 3) and step 4) together with the multi-objective optimization model data set and the pulsating flow active control program into the main controller chip. The main controller can control the operating state of the speed motor of the working fluid circulation pump to achieve regular pulsating flow of the working fluid in the organic Rankine cycle system. When the heat source fluid enters the evaporator of the organic Rankine cycle system, the high-precision temperature sensor and the flow rate sensor continuously feed back the current data to the main controller. The main controller retrieves the optimal pulsating flow parameters of the pulsating flow in the multi-objective optimization model data set according to the feedback data, and adjusts the operating state of the working fluid circulation pump through the pulsating flow active control program to achieve the dynamic response of the organic Rankine cycle system based on active control of pulsating flow to the instantaneous working condition of the heat source, and ensure that the circulation system always operates in the best state.

[0045] When the internal combustion engine is running under CADC road conditions, it is calculated that the heat recovery capacity of the internal combustion engine-organic Rankine cycle combined system can be increased by an average of 58.1% by using this method.

[0046] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the present invention. The protection scope of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. Each implementation scheme within its scope shall be subject to the constraints of the present invention.

Claims

1. An optimization method for an organic Rankine cycle system based on active control of pulsating flow, characterized in that Collect the test data of the organic Rankine cycle system to be optimized for constructing the simulation model of the organic Rankine cycle system. Conduct tests when the heat source state of the organic Rankine cycle system to be optimized is stable to screen the pulsating waveforms applicable to the organic Rankine cycle system. Use the adjusted simulation model of the organic Rankine cycle system to calculate the performance of the screened pulsating waveforms under multi-heat source conditions. When the screened pulsating waveform is the optimal waveform, adjust the heat source conditions and use the particle swarm multi-objective optimization algorithm to iteratively update to obtain the optimal pulsating flow parameters, which are used to establish the multi-objective optimization model dataset of cycle performance - economy. The simulation model of the organic Rankine cycle system mentioned above refers to: based on a finite element solver, simulating the working fluid circulation pump, evaporator, expander, and condenser. This simulation model includes: an input module, a heat recovery amount and cycle efficiency calculation module, and an output module. Among them: the data input module collects general data and physical field data; the heat recovery amount and cycle efficiency calculation module sets the physical field, partial differential control equations, and high-precision empirical formulas and calls the numerical calculation solver to achieve accurate calculation; the output module outputs the model accuracy, the heat recovery amount of the organic Rankine cycle system, and the net output power of the cycle. The pulsating waveform mentioned above refers to: the waveform generated by the periodic and regular change of pressure and velocity over time when the organic working fluid is under the action of the working fluid circulation pump. The organic Rankine cycle system to be optimized mentioned above includes the basic organic Rankine cycle and the regenerative cycle, reheat cycle, and preheat cycle constructed based on it. The described multi-objective optimization model for cycle performance and economy means: with the maximum cycle net output work η, the maximum heat recovery Q of the organic Rankine cycle system * and the cycle economy R as the objectives, a multi-objective optimization model is constructed by combining the finite element solver of the organic Rankine cycle system simulation model, the optimized boundary of the pulsating flow operating parameters and the inherent constraint conditions in the system. The objective function , where: OF is the objective function of the multi-objective optimization model; η is the maximum cycle net output work; Q * is the maximum heat recovery of the organic Rankine cycle system; R is the cycle economy; is the power of the working fluid circulation pump ; is the volume flow rate of the organic working fluid ; is the mass flow rate of the heat source fluid; is the inlet temperature of the heat source fluid at the evaporator; is the inlet pressure of the organic working fluid at the evaporator; is the inlet temperature of the organic working fluid at the evaporator; is the output power of the expander; is the mass flow rate of the cold source fluid; is the inlet temperature of the cold source fluid at the condenser; is the inlet pressure of the organic working fluid at the condenser; A is the maximum pulsation speed amplitude; is the pulsation frequency.

2. The optimization method of the organic Rankine cycle system based on pulsating flow active control according to claim 1, characterized in that The general data mentioned above includes: the structure, material, and size of each component; the physical field data includes: the thermophysical properties of the working fluid and the cold and heat source fluids, and the key parameters of the system operation. The key parameters for the operation of the described system include: the power of the working fluid circulation pump , the volume flow rate of the organic working fluid , the mass flow rate of the heat source fluid , the inlet temperature of the heat source fluid at the evaporator , the outlet temperature of the heat source fluid at the evaporator , the inlet pressure of the organic working fluid at the evaporator , the outlet pressure of the organic working fluid at the evaporator , the inlet temperature of the organic working fluid at the evaporator , the outlet temperature of the organic working fluid at the evaporator , the inlet pressure of the expander , the outlet pressure of the expander , the inlet temperature of the expander , the output power of the expander , the mass flow rate of the cold source fluid , the inlet temperature of the cold source fluid at the condenser , the outlet temperature of the cold source fluid at the condenser , the inlet pressure of the organic working fluid at the condenser , the outlet pressure of the organic working fluid at the condenser , the inlet temperature of the organic working fluid at the condenser , the outlet temperature of the organic working fluid at the condenser .

3. The optimization method of the organic Rankine cycle system based on pulsating flow active control according to claim 1, characterized in that Conducting tests when the heat source state is stable means: obtaining the heat entering the organic Rankine cycle system under pulsating flow conditions according to the readings of multiple high-precision thermometers and flow meters placed at the inlet and outlet of the working fluid and the hot fluid in the evaporator, and verifying in the constructed model under the same working conditions. When the model accuracy and accuracy do not meet the requirements, adjust the physical field setting of the heat recovery amount and cycle efficiency calculation module until the model accuracy and accuracy reach the requirements.

4. The optimization method of the organic Rankine cycle system based on active control of pulsating flow according to claim 1, characterized in that The screening mentioned above means: controlling the speed of the working fluid circulation pump motor to operate according to the specified radio wave signal to achieve the pulsating flow of the working fluid. During the test, analyze the operating performance of the working fluid in the organic Rankine cycle system under the conditions of pulsating flow of sine wave, sawtooth wave, triangular wave, square wave, pulse wave, and matrix wave, and select the best pulsating flow waveform based on the net output power of the organic Rankine cycle system. The calculation formula for the net output power of the organic Rankine cycle system is as follows: , where: is the output power of the expander, is the power consumed by the working fluid circulation pump.

5. The optimization method of the organic Rankine cycle system based on pulsating flow active control according to claim 1, characterized in that, Calculating the performance of the screened pulsating waveforms under multi-heat source conditions means: based on the organic Rankine cycle system model, calculating the net output power of different organic Rankine cycle systems under variable heat source conditions with the optimal pulsating flow waveform and pulsating flow operation parameters, obtaining the performance performance of pulsating flows with different operation parameters under variable heat source conditions, and providing the optimization boundary of pulsating flow operation parameters when designing the control system program.

6. The optimization method of the organic Rankine cycle system based on pulsating flow active control according to claim 1, characterized in that, The iterative update mentioned above means: taking the maximum cycle net output work, maximum heat recovery amount, and cycle economy of the organic Rankine cycle system as optimization objectives, using the particle swarm optimization algorithm to construct a multi-objective optimization model of cycle performance - economy, and obtaining the optimal pulsating flow parameters of the pulsating flow corresponding to each heat source condition.

7. The optimization method of the organic Rankine cycle system based on pulsating flow active control according to claim 1, characterized in that, The best pulsating flow parameters obtained by iterative update using the particle swarm multi-objective optimization algorithm refer to: generating initial particles based on the particle swarm multi-objective optimization algorithm, first calculating its own value once, and updating the movement globally based on this; the particles continuously track the individual extreme value and the social extreme value during the iteration process to achieve optimization, traverse the heat source conditions, obtain the corresponding best pulsating flow parameters under each heat source condition, and calculate the heat recovery amount of the current organic Rankine cycle system, that is, the heat taken away by the working fluid in the evaporator and save it in the multi-objective optimization model data set; The described update movement includes: ① Updating its own speed: , where: v p+1 represents the speed of the next-generation particles; ω p is the inertia weight of the current particle swarm algorithm; v p is the current speed of the particle; c1 is the individual learning factor of the particle swarm algorithm; c2 is the social learning factor of the particle swarm algorithm; r1, r2 are random numbers in the interval [0 - 1]; pbest p is the historical best value of this particle; gbest is the best value of the overall cluster; ② Updating its own position: , where: x p+1 represents the position of the next-generation particles; x p is the position where the current particle is located.

8. An optimization system of an organic Rankine cycle system based on pulsating flow active control for implementing the method according to any one of claims 1-7, characterized in that, Including: A data acquisition unit, a data processing unit, a control unit, and a feedback signal unit. Among them: the data acquisition unit collects the data of high-precision temperature sensors, pressure sensors, flow meters, and dynamometers and transmits them to the data processing and control unit. The data processing unit retrieves the best output signal according to the data transmitted by the data acquisition unit and the cycle performance - economy multi-objective optimization model data set. The control unit adjusts the operating state of the working fluid circulation pump according to the signal provided by the data processing unit to achieve the pulsating flow of the working fluid in the organic Rankine cycle system. The feedback unit collects the data of the high-precision temperature sensor and the flow velocity sensor again and compares it with the data collected by the data acquisition unit last time. When the heat source fluid data collected changes, it provides the latest data to the data acquisition unit to achieve the dynamic response of the pulsating flow of the working fluid in the organic Rankine cycle system under variable heat source conditions; The high-precision temperature sensors are arranged at the inlet of the heat source fluid of the evaporator, the inlet of the organic working fluid of the evaporator, the inlet of the cold fluid of the condenser, and the inlet of the working fluid circulation pump; The pressure sensors are arranged at the inlet of the heat source fluid entering the evaporator, the inlet of the organic working fluid entering the evaporator, the inlet of the cold fluid of the condenser, and the inlet of the working fluid circulation pump; The flow meters are arranged at the inlet of the heat source fluid entering the evaporator, the inlet of the organic working fluid entering the working fluid circulation pump, and the inlet of the cold fluid of the condenser; The dynamometer is arranged behind the expander and must be provided with a shock absorption device and a separate and reliable horizontal platform.

9. The optimization system according to claim 8, characterized in that, The optimization system is arranged in the main control chip, and the main control chip is added to the organic Rankine cycle system to achieve the dynamic response of the organic Rankine cycle system based on pulsating flow active control to the instantaneous conditions of the heat source, and ensure that the cycle system always operates in the best state.

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