With the entropy generation minimization （EGM） method, the thermodynamical performance optimization in a thermoelectric refrigeration system is studied. The optimization is affected by the irreversibility of heat tr...With the entropy generation minimization （EGM） method, the thermodynamical performance optimization in a thermoelectric refrigeration system is studied. The optimization is affected by the irreversibility of heat transfer caused by finite temperature differences, the heat leak between external heat reservoirs and the internal dissipation of working fluids. EGM is taken as an objective function for the optimization. The objective function and design parameters are obtained. Optimal performance curves are presented by thermal and electronic parameters. Effects of these parameters on general and optimal performances are investigated. Results are helpful in determining optimal design conditions in real thermoelectric refrigeration systems.展开更多
The growing demand for deployable phased-array antennas in space applications requires innovative solutions to optimize the folded configurations and reduce the computational complexity.Existing methods face limitatio...The growing demand for deployable phased-array antennas in space applications requires innovative solutions to optimize the folded configurations and reduce the computational complexity.Existing methods face limitations due to the low efficiency of traditional algorithms and the lack of effective constraint strategies,resulting in excessive solution spaces.This study proposes forward shannon entropy wave function collapse(FSE-WFC),a novel method for designing panel configurations of one-dimensional deployable phased-array antennas using the wave function collapse algorithm.This addresses two key challenges:the excessive number of panel layout options and high computational costs.First,it analyzes the relationship between the panel connection positions and the folded form to impose constraints on the panel combinations.It then calculates the information entropy of the potential configurations to identify low-entropy solutions,thereby narrowing the solution space.Finally,boundary constraints and interference check were applied to refine the results.This approach significantly reduced the calculation time while improving the folding state and envelope volume of the antenna.The results show that the FSE-WFC algorithm reduces the envelope area by 18.3%for a 350 mm high satellite and 9.0%for a 600 mm high satellite,while satisfying the connectivity constraints.As the first application of the wave-function collapse algorithm to antenna folding design,this study introduces an information entropy-based constraint generation method that provides an efficient solution for deployable antenna optimization.展开更多
Heat exchangers are widely used in industry, and analyses and optimizations of the performance of heat exchangers are important topics. In this paper, we define the concept of entropy resistance based on the entropy g...Heat exchangers are widely used in industry, and analyses and optimizations of the performance of heat exchangers are important topics. In this paper, we define the concept of entropy resistance based on the entropy generation analyses of a one-dimensional heat transfer process. With this concept, a two-stream parallel flow heat exchanger with viscous heating is analyzed and discussed. It is found that the minimization of entropy resistance always leads to the maximum heat transfer rate for the discussed two-stream parallel flow heat exchanger, while the minimizations of entropy generation rate, entropy generation numbers, and revised entropy generation number do not always.展开更多
The total entropy generation rate,internal exergy loss and exergy efficiency of the membrane reactor of methanol synthesis via carbon dioxide hydrogenation are compared,and the results show that the total entropy gene...The total entropy generation rate,internal exergy loss and exergy efficiency of the membrane reactor of methanol synthesis via carbon dioxide hydrogenation are compared,and the results show that the total entropy generation rate minimization is equivalent to the internal exergy loss minimization and the exergy efficiency maximization under the fixed inlet exergy.Therefore,this paper optimizes the membrane reactor with total entropy generation rate minimization as an optimization objective under a fixed methanol production rate.The optimal temperatures curves of exterior walls for three optimal membrane reactors with different boundary conditions are obtained by using optimal control theory and nonlinear programming.The influences of other geometric and operating parameters on optimization results of optimal membrane reactors are analyzed.The results indicate that when inlet temperatures of the reaction mixture and mixture in the permeable tube are unfixed,the optimizing curve of exterior wall temperature makes the total entropy generation rate of membrane reactor reduce by 12.39%compared with the total entropy generation rate of a reference membrane reactor with a linear exterior wall temperature.Decreasing the inlet molar flow rate of sweep gas and gas hourly space velocity and increasing inlet pressure of reaction mixture,the inlet pressure of mixture in the permeable tube and heat transfer coefficients are favorable for decreasing the total entropy generation rate in the membrane reactor.As the porosity of catalyst bed and reactor length increases,the minimum total entropy generation rate decreases first and then increases.From the perspective of engineering application,this paper establishes two membrane reactors(membrane reactor heated by three-stage furnaces of the same length and membrane reactor heated by threestage furnaces of different lengths),respectively.The minimum total entropy generation rates of the two reactors are reduced by11.67%and 11.79%compared with the total entropy generation rate in the reference membrane reactor,respectively.The obtained results are beneficial to the optimal design of energy-efficient membrane reactors.展开更多
Taking the output power, thermal efficiency, and thermo-economic performance as the optimization objectives, we optimize the operation parameters of a thermodynamic system with combined endoreversible Carnot heat engi...Taking the output power, thermal efficiency, and thermo-economic performance as the optimization objectives, we optimize the operation parameters of a thermodynamic system with combined endoreversible Carnot heat engines in this paper. The applicabilities of the entropy generation minimization and entransy theory to the optimizations are discussed. For the discussed cases, only the entransy loss coefficient is always agreeable to the optimization of thermal efficiency. The applicabilities of the other discussed concepts to the optimizations are conditional. Different concepts and principles are needed for different optimization objectives, and the optimization principles have their application preconditions. When the preconditions are not satisfied, the principles may be not applicable.展开更多
Cold-end systems are heat sinks of thermal power cycles,which have an essential effect on the overall performance of thermal power plants.To enhance the efficiency of thermal power plants,multi-pressure condensers hav...Cold-end systems are heat sinks of thermal power cycles,which have an essential effect on the overall performance of thermal power plants.To enhance the efficiency of thermal power plants,multi-pressure condensers have been applied in some large-capacity thermal power plants.However,little attention has been paid to the optimization of the cold-end system with multi-pressure condensers which have multiple parameters to be identified.Therefore,the design optimization methods of coldend systems with single-and multi-pressure condensers are developed based on the entropy generation rate,and the genetic algorithm(GA)is used to optimize multiple parameters.Multiple parameters,including heat transfer area of multi-pressure condensers,steam distribution in condensers,and cooling water mass flow rate,are optimized while considering detailed entropy generation rate of the cold-end systems.The results show that the entropy generation rate of the multi-pressure cold-end system is less than that of the single-pressure cold-end system when the total condenser area is constant.Moreover,the economic performance can be improved with the adoption of the multi-pressure cold-end system.When compared with the single-pressure cold-end system,the excess revenues gained by using dual-and quadruplepressure cold-end systems are 575 and 580 k$/a,respectively.展开更多
An alternative option pricing method is proposed based on a random walk market model. The minimal entropy martingale measure which adopts no arbitrage opportunity in the market, is deduced for this market model and is...An alternative option pricing method is proposed based on a random walk market model. The minimal entropy martingale measure which adopts no arbitrage opportunity in the market, is deduced for this market model and is used as the pricing measure to evaluate European call options by a Monte Carlo simulation method. The proposed method is a purely data driven valuation method without any distributional assumption about the price process of underlying asset. The performance of the proposed method is compared with the canonical valuation method and the historical volatility-based Black-Scholes method in an artificial Black-Scholes world. The simulation results show that the proposed method has merits, and is valuable to financial engineering.展开更多
In this paper, the endoreversible Otto cycle is analyzed with the entropy generation minimization and the entransy theory. The output power and the heat-work conversion efficiency are taken as the optimization objecti...In this paper, the endoreversible Otto cycle is analyzed with the entropy generation minimization and the entransy theory. The output power and the heat-work conversion efficiency are taken as the optimization objectives, and the relationships of the output power, the heat-work conversion efficiency, the entropy generation rate, the entropy generation numbers, the entransy loss rate, the entransy loss coefficient, the entransy dissipation rate and the entransy variation rate associated with work are discussed. The applicability of the entropy generation minimization and the entransy theory to the analyses is also analyzed. It is found that smaller entropy generation rate does not always lead to larger output power, while smaller entropy generation numbers do not always lead to larger heat-work conversion efficiency, either. In our calculations, both larger entransy loss rate and larger entransy variation rate associated with work correspond to larger output power, while larger entransy loss coefficient results in larger heat-work conversion efficiency. It is also found that the concept of entransy dissipation is not always suitable for the analyses because it was developed for heat transfer.展开更多
In plasma physics domain,the electron transport is described with the FokkerPlanck-Landau equation.The direct numerical solution of the kinetic equation is usually intractable due to the large number of independent va...In plasma physics domain,the electron transport is described with the FokkerPlanck-Landau equation.The direct numerical solution of the kinetic equation is usually intractable due to the large number of independent variables.That is why we propose in this paper a new model whose derivation is based on an angular closure in the phase space and retains only the energy of particles as kinetic dimension.To find a solution compatible with physics conditions,the closure of the moment system is obtained under a minimum entropy principle.This model is proved to satisfy the fundamental properties like a H theorem.Moreover an entropic discretization in the velocity variable is proposed on the semi-discrete model.Finally,we validate on numerical test cases the fundamental properties of the full discrete model.展开更多
This review paper summarizes constructal design progress performed by the authors for eight types of heat sinks with ten performance indexes being taken as the optimization objectives,respectively,by combining the met...This review paper summarizes constructal design progress performed by the authors for eight types of heat sinks with ten performance indexes being taken as the optimization objectives,respectively,by combining the methods of theoretical analysis and numerical calculation.The eight types of heat sinks are uniform height rectangular fin heat sink,non-uniform height rectangular fin heat sink,inline cylindrical pin-fin heat sink(ICPHS),plate single-row pin fin heat sink(PSRPHS),plate inline pin fin heat sink(PIPHS),plate staggered pin fin heat sink(PSPHS),single-layered microchannel heat sink(SLMCHS)with rectangular cross sections and double-layered microchannel heat sink(DLMCHS)with rectangular cross sections,respectively.And the ten performance indexes are heat transfer rate maximization,maximum thermal resistance minimization,minimization of equivalent thermal resistance which is defined based on the entransy dissipation rate(equivalent thermal resistance for short),field synergy number maximization,entropy generation rate minimization,operation cost minimization,thermo-economic function value minimization,pressure drop minimization,enhanced heat transfer factor maximization and efficiency evaluation criterion number maximization,respectively.The optimal constructs of the eight types of heat sinks with different constraints and based on the different optimization objectives are compared with each other.The results indicated that the optimal constructs mostly are different based on different optimization objectives under the same boundary condition.The optimization objective should be suitable chosen based on the focus when the constructal design for one heat sink is performed.The results obtained herein have some important theoretical significances and application values,and can provide scientific bases and theoretical guidelines for the thermal design of real heat sinks and their applications.展开更多
As an important process during the cement production,grate cooler plays significance roles on clinker cooling and waste heat recovery.In this paper,we measured experimentally the heat balance of the grate cooler,which...As an important process during the cement production,grate cooler plays significance roles on clinker cooling and waste heat recovery.In this paper,we measured experimentally the heat balance of the grate cooler,which provided initial operating parameters for optimization.Then,the grate cooler was simplified into a series-connected heat exchanger network by power flow method.Constructing the equivalent thermal resistance network provided the global constraints by Kirchhoff’s law.On this basis,with the objectives of the minimum entropy generation numbers caused by heat transfer and viscous dissipation,solving a multi-objective optimization model achieved the Pareto Front by genetic algorithm.Then selecting the scheme of the lowest fan power consumption obtained the optimal operating parameters of the grate cooler.The results showed that the total mass flow of the optimized scheme did not change significantly compared with the original scheme,but the fan power consumption was 25.44%lower,and the heat recovery efficiency was 88.43%,which was improved by 11.35%.Furthermore,the analysis showed that the optimal operating parameters were affected by the local heat load.After optimizing the diameter of clinker particles within the allowable industrial range,the clinker with particle diameter of 0.02 m had the optimal performance.展开更多
文摘With the entropy generation minimization （EGM） method, the thermodynamical performance optimization in a thermoelectric refrigeration system is studied. The optimization is affected by the irreversibility of heat transfer caused by finite temperature differences, the heat leak between external heat reservoirs and the internal dissipation of working fluids. EGM is taken as an objective function for the optimization. The objective function and design parameters are obtained. Optimal performance curves are presented by thermal and electronic parameters. Effects of these parameters on general and optimal performances are investigated. Results are helpful in determining optimal design conditions in real thermoelectric refrigeration systems.
基金Supported by National Natural Science Foundation of China(Grant Nos.52105035,62203094)Special Central Funds for Guiding Local Scientific and Technological Development(Grant No.236Z1801G)+2 种基金Higher Education Youth Top Talent Project of Hebei Province of China(Grant No.BJK2024042)Natural Science Foundation of Hebei Province of China(Grant Nos.E2021203109,F2023501021)Graduate Student Innovation Capability Training and Support Project of Hebei Province(Grant No.CXZZBS2024053).
文摘The growing demand for deployable phased-array antennas in space applications requires innovative solutions to optimize the folded configurations and reduce the computational complexity.Existing methods face limitations due to the low efficiency of traditional algorithms and the lack of effective constraint strategies,resulting in excessive solution spaces.This study proposes forward shannon entropy wave function collapse(FSE-WFC),a novel method for designing panel configurations of one-dimensional deployable phased-array antennas using the wave function collapse algorithm.This addresses two key challenges:the excessive number of panel layout options and high computational costs.First,it analyzes the relationship between the panel connection positions and the folded form to impose constraints on the panel combinations.It then calculates the information entropy of the potential configurations to identify low-entropy solutions,thereby narrowing the solution space.Finally,boundary constraints and interference check were applied to refine the results.This approach significantly reduced the calculation time while improving the folding state and envelope volume of the antenna.The results show that the FSE-WFC algorithm reduces the envelope area by 18.3%for a 350 mm high satellite and 9.0%for a 600 mm high satellite,while satisfying the connectivity constraints.As the first application of the wave-function collapse algorithm to antenna folding design,this study introduces an information entropy-based constraint generation method that provides an efficient solution for deployable antenna optimization.
基金supported by the National Natural Science Foundation of China(Grant No.51106082)the Tsinghua University Initiative Scientific Research Program
文摘Heat exchangers are widely used in industry, and analyses and optimizations of the performance of heat exchangers are important topics. In this paper, we define the concept of entropy resistance based on the entropy generation analyses of a one-dimensional heat transfer process. With this concept, a two-stream parallel flow heat exchanger with viscous heating is analyzed and discussed. It is found that the minimization of entropy resistance always leads to the maximum heat transfer rate for the discussed two-stream parallel flow heat exchanger, while the minimizations of entropy generation rate, entropy generation numbers, and revised entropy generation number do not always.
基金supported by the National Natural Science Foundation of China(Grant Nos.51976235 and 51606218)the Hubei Province Natural Science Foundation of China(Grant No.2018CFB708)。
文摘The total entropy generation rate,internal exergy loss and exergy efficiency of the membrane reactor of methanol synthesis via carbon dioxide hydrogenation are compared,and the results show that the total entropy generation rate minimization is equivalent to the internal exergy loss minimization and the exergy efficiency maximization under the fixed inlet exergy.Therefore,this paper optimizes the membrane reactor with total entropy generation rate minimization as an optimization objective under a fixed methanol production rate.The optimal temperatures curves of exterior walls for three optimal membrane reactors with different boundary conditions are obtained by using optimal control theory and nonlinear programming.The influences of other geometric and operating parameters on optimization results of optimal membrane reactors are analyzed.The results indicate that when inlet temperatures of the reaction mixture and mixture in the permeable tube are unfixed,the optimizing curve of exterior wall temperature makes the total entropy generation rate of membrane reactor reduce by 12.39%compared with the total entropy generation rate of a reference membrane reactor with a linear exterior wall temperature.Decreasing the inlet molar flow rate of sweep gas and gas hourly space velocity and increasing inlet pressure of reaction mixture,the inlet pressure of mixture in the permeable tube and heat transfer coefficients are favorable for decreasing the total entropy generation rate in the membrane reactor.As the porosity of catalyst bed and reactor length increases,the minimum total entropy generation rate decreases first and then increases.From the perspective of engineering application,this paper establishes two membrane reactors(membrane reactor heated by three-stage furnaces of the same length and membrane reactor heated by threestage furnaces of different lengths),respectively.The minimum total entropy generation rates of the two reactors are reduced by11.67%and 11.79%compared with the total entropy generation rate in the reference membrane reactor,respectively.The obtained results are beneficial to the optimal design of energy-efficient membrane reactors.
基金Project supported by the National Natural Science Foundation of China(Grant No.51376101)the Science Fund for Creative Research Groups,China(Grant No.51321002)
文摘Taking the output power, thermal efficiency, and thermo-economic performance as the optimization objectives, we optimize the operation parameters of a thermodynamic system with combined endoreversible Carnot heat engines in this paper. The applicabilities of the entropy generation minimization and entransy theory to the optimizations are discussed. For the discussed cases, only the entransy loss coefficient is always agreeable to the optimization of thermal efficiency. The applicabilities of the other discussed concepts to the optimizations are conditional. Different concepts and principles are needed for different optimization objectives, and the optimization principles have their application preconditions. When the preconditions are not satisfied, the principles may be not applicable.
基金supported the National Key R&D Program of China(No.2018YFB0604405).
文摘Cold-end systems are heat sinks of thermal power cycles,which have an essential effect on the overall performance of thermal power plants.To enhance the efficiency of thermal power plants,multi-pressure condensers have been applied in some large-capacity thermal power plants.However,little attention has been paid to the optimization of the cold-end system with multi-pressure condensers which have multiple parameters to be identified.Therefore,the design optimization methods of coldend systems with single-and multi-pressure condensers are developed based on the entropy generation rate,and the genetic algorithm(GA)is used to optimize multiple parameters.Multiple parameters,including heat transfer area of multi-pressure condensers,steam distribution in condensers,and cooling water mass flow rate,are optimized while considering detailed entropy generation rate of the cold-end systems.The results show that the entropy generation rate of the multi-pressure cold-end system is less than that of the single-pressure cold-end system when the total condenser area is constant.Moreover,the economic performance can be improved with the adoption of the multi-pressure cold-end system.When compared with the single-pressure cold-end system,the excess revenues gained by using dual-and quadruplepressure cold-end systems are 575 and 580 k$/a,respectively.
基金Funded by the Natural Science Foundation of China under Grant No.10571065.
文摘An alternative option pricing method is proposed based on a random walk market model. The minimal entropy martingale measure which adopts no arbitrage opportunity in the market, is deduced for this market model and is used as the pricing measure to evaluate European call options by a Monte Carlo simulation method. The proposed method is a purely data driven valuation method without any distributional assumption about the price process of underlying asset. The performance of the proposed method is compared with the canonical valuation method and the historical volatility-based Black-Scholes method in an artificial Black-Scholes world. The simulation results show that the proposed method has merits, and is valuable to financial engineering.
基金supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant No.KJ1710251)
文摘In this paper, the endoreversible Otto cycle is analyzed with the entropy generation minimization and the entransy theory. The output power and the heat-work conversion efficiency are taken as the optimization objectives, and the relationships of the output power, the heat-work conversion efficiency, the entropy generation rate, the entropy generation numbers, the entransy loss rate, the entransy loss coefficient, the entransy dissipation rate and the entransy variation rate associated with work are discussed. The applicability of the entropy generation minimization and the entransy theory to the analyses is also analyzed. It is found that smaller entropy generation rate does not always lead to larger output power, while smaller entropy generation numbers do not always lead to larger heat-work conversion efficiency, either. In our calculations, both larger entransy loss rate and larger entransy variation rate associated with work correspond to larger output power, while larger entransy loss coefficient results in larger heat-work conversion efficiency. It is also found that the concept of entransy dissipation is not always suitable for the analyses because it was developed for heat transfer.
基金supported by EURATOM within the"Keep-in-Touch"activities and was granted access to the HPC resources of CINES under the allocation 2011-056129 made by GENCI(Grand Equipement National de Calcul Intensif).
文摘In plasma physics domain,the electron transport is described with the FokkerPlanck-Landau equation.The direct numerical solution of the kinetic equation is usually intractable due to the large number of independent variables.That is why we propose in this paper a new model whose derivation is based on an angular closure in the phase space and retains only the energy of particles as kinetic dimension.To find a solution compatible with physics conditions,the closure of the moment system is obtained under a minimum entropy principle.This model is proved to satisfy the fundamental properties like a H theorem.Moreover an entropic discretization in the velocity variable is proposed on the semi-discrete model.Finally,we validate on numerical test cases the fundamental properties of the full discrete model.
基金supported by the National Natural Science Foundation of China(Grant Nos.51779262,51506220 and 51579244)。
文摘This review paper summarizes constructal design progress performed by the authors for eight types of heat sinks with ten performance indexes being taken as the optimization objectives,respectively,by combining the methods of theoretical analysis and numerical calculation.The eight types of heat sinks are uniform height rectangular fin heat sink,non-uniform height rectangular fin heat sink,inline cylindrical pin-fin heat sink(ICPHS),plate single-row pin fin heat sink(PSRPHS),plate inline pin fin heat sink(PIPHS),plate staggered pin fin heat sink(PSPHS),single-layered microchannel heat sink(SLMCHS)with rectangular cross sections and double-layered microchannel heat sink(DLMCHS)with rectangular cross sections,respectively.And the ten performance indexes are heat transfer rate maximization,maximum thermal resistance minimization,minimization of equivalent thermal resistance which is defined based on the entransy dissipation rate(equivalent thermal resistance for short),field synergy number maximization,entropy generation rate minimization,operation cost minimization,thermo-economic function value minimization,pressure drop minimization,enhanced heat transfer factor maximization and efficiency evaluation criterion number maximization,respectively.The optimal constructs of the eight types of heat sinks with different constraints and based on the different optimization objectives are compared with each other.The results indicated that the optimal constructs mostly are different based on different optimization objectives under the same boundary condition.The optimization objective should be suitable chosen based on the focus when the constructal design for one heat sink is performed.The results obtained herein have some important theoretical significances and application values,and can provide scientific bases and theoretical guidelines for the thermal design of real heat sinks and their applications.
基金supported by the Shandong Provincial Natural Science Foundation(Grant No.ZR2019QEE016)。
文摘As an important process during the cement production,grate cooler plays significance roles on clinker cooling and waste heat recovery.In this paper,we measured experimentally the heat balance of the grate cooler,which provided initial operating parameters for optimization.Then,the grate cooler was simplified into a series-connected heat exchanger network by power flow method.Constructing the equivalent thermal resistance network provided the global constraints by Kirchhoff’s law.On this basis,with the objectives of the minimum entropy generation numbers caused by heat transfer and viscous dissipation,solving a multi-objective optimization model achieved the Pareto Front by genetic algorithm.Then selecting the scheme of the lowest fan power consumption obtained the optimal operating parameters of the grate cooler.The results showed that the total mass flow of the optimized scheme did not change significantly compared with the original scheme,but the fan power consumption was 25.44%lower,and the heat recovery efficiency was 88.43%,which was improved by 11.35%.Furthermore,the analysis showed that the optimal operating parameters were affected by the local heat load.After optimizing the diameter of clinker particles within the allowable industrial range,the clinker with particle diameter of 0.02 m had the optimal performance.
