The classical Hertz–Knudsen–Schrage (HKS) relations for mass and heat transfer across liquid-vapor interfaces are valid for ideal gas vapors only. We propose a generalization of the HKS relations towards non-ideal vapors based on equilibrium and non-equilibrium property relations for a van-der-Waals-like gas obtained from the Enskog–Vlasov kinetic equation, and determine the corresponding dimensionless resistivities for mass and heat transfer across an interface. Considering constant evaporation and accommodation coefficients, it is found that all resistivities decay towards the critical point.
{"title":"Liquid-vapor interface resistivities for non-ideal gases","authors":"Henning Struchtrup","doi":"10.1515/jnet-2025-0104","DOIUrl":"https://doi.org/10.1515/jnet-2025-0104","url":null,"abstract":"The classical Hertz–Knudsen–Schrage (HKS) relations for mass and heat transfer across liquid-vapor interfaces are valid for ideal gas vapors only. We propose a generalization of the HKS relations towards non-ideal vapors based on equilibrium and non-equilibrium property relations for a van-der-Waals-like gas obtained from the Enskog–Vlasov kinetic equation, and determine the corresponding dimensionless resistivities for mass and heat transfer across an interface. Considering constant evaporation and accommodation coefficients, it is found that all resistivities decay towards the critical point.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"4 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146071514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on finite-time-thermodynamics and thermal-Brownian-engine cycle with external heat transfers, expressions for ecological function and efficient ecological function are derived firstly herein. Two temperatures for hot and cold viscous mediums are solved by combining heat flow balance equations, and ecological performances are analyzed. Next, with thermal-conductance-ratio, barrier-height and external-load as optimization variables, 15 combinations including power, efficiency, ecological-function and efficient-ecological-function as optimization objectives, single- and multi-objective optimizations are conducted utilizing non-dominated sorting genetic algorithm-II (NSGA-II), and Pareto frontiers for different combinations are obtained. Finally, the optimal schemes for different multi-objective optimizations are determined using three decision-making methods. Results indicate that this engine can operate under maximal ecological function or efficient ecological function objectives. Ecological-function, efficient-ecological-function and multi-objective optimizations can achieve trade-offs between power and efficiency, and multi-objective optimizations provide more suitable solutions. For four-objective optimization, optimal scheme with Shannon-Entropy method is closer to ideal solution, and barrier height and external load corresponding to Pareto frontier are distributed uniformly within their ranges, while thermal conductance ratio is concentrated around 0.5. Adjusting barrier height and external load is an effective way to achieve coordinated optimization of these four objectives.
基于有限时间热力学和考虑外换热的热-布朗-发动机循环，首先推导了生态函数和有效生态函数的表达式。结合热流平衡方程求解了热、冷两种粘性介质的温度，并对其生态性能进行了分析。其次，以热传导比、屏障高度和外部负荷为优化变量，以功率、效率、生态功能和效率-生态功能等15种组合为优化目标，利用非支配排序遗传算法- ii （NSGA-II）进行单目标和多目标优化，得到不同组合的Pareto边界。最后，采用三种决策方法确定了不同多目标优化的最优方案。结果表明，该发动机可在最大生态功能或有效生态功能目标下运行。生态-功能、效率-生态-功能和多目标优化可以实现功率与效率的权衡，多目标优化提供了更合适的解决方案。对于四目标优化，采用香农熵法的优化方案更接近理想解，障壁高度和帕累托边界对应的外负荷在其范围内分布均匀，热导比集中在0.5左右。调节屏障高度和外载荷是实现这四个目标协调优化的有效途径。
{"title":"Ecological performance analyses and multi-objective optimizations for thermal-Brownian-engine with external heat-transfer","authors":"Congzheng Qi, Lingen Chen, Huijun Feng, Yanlin Ge, Xubing Chen","doi":"10.1515/jnet-2025-0083","DOIUrl":"https://doi.org/10.1515/jnet-2025-0083","url":null,"abstract":"Based on finite-time-thermodynamics and thermal-Brownian-engine cycle with external heat transfers, expressions for ecological function and efficient ecological function are derived firstly herein. Two temperatures for hot and cold viscous mediums are solved by combining heat flow balance equations, and ecological performances are analyzed. Next, with thermal-conductance-ratio, barrier-height and external-load as optimization variables, 15 combinations including power, efficiency, ecological-function and efficient-ecological-function as optimization objectives, single- and multi-objective optimizations are conducted utilizing non-dominated sorting genetic algorithm-II (NSGA-II), and Pareto frontiers for different combinations are obtained. Finally, the optimal schemes for different multi-objective optimizations are determined using three decision-making methods. Results indicate that this engine can operate under maximal ecological function or efficient ecological function objectives. Ecological-function, efficient-ecological-function and multi-objective optimizations can achieve trade-offs between power and efficiency, and multi-objective optimizations provide more suitable solutions. For four-objective optimization, optimal scheme with Shannon-Entropy method is closer to ideal solution, and barrier height and external load corresponding to Pareto frontier are distributed uniformly within their ranges, while thermal conductance ratio is concentrated around 0.5. Adjusting barrier height and external load is an effective way to achieve coordinated optimization of these four objectives.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"6 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work provides numerical solution for the dual-phase lag (DPL) theory, which accounts for non-equilibrium heating transfer in cylindrical living tissue during laser irradiation by finite element method. Given the complexity of the governing equation, the solution to such problems is pursued through the implementation of the finite element approach. The assessment of tissue thermal injuries includes determining the span of denatured proteins through the application of the Arrhenius formulation. The results of the finite element method are confirmed as valid by comparing its numerical solution with the data available from the existing experimental data. Furthermore, a comparison with validated experimental data confirms the efficacy of the mathematical model in assessing bioheat transfer in living tissues. The present findings highlight the importance of incorporating dual-phase lags in predictive thermal models to accurately capture the transient response of biological tissues under short-pulse laser exposure.
{"title":"Modeling and simulations of nonequilibrium bioheat transfer in biological tissue using FEM with experimental verifications","authors":"Areej Almuneef, Ibrahim Abbas","doi":"10.1515/jnet-2025-0152","DOIUrl":"https://doi.org/10.1515/jnet-2025-0152","url":null,"abstract":"This work provides numerical solution for the dual-phase lag (DPL) theory, which accounts for non-equilibrium heating transfer in cylindrical living tissue during laser irradiation by finite element method. Given the complexity of the governing equation, the solution to such problems is pursued through the implementation of the finite element approach. The assessment of tissue thermal injuries includes determining the span of denatured proteins through the application of the Arrhenius formulation. The results of the finite element method are confirmed as valid by comparing its numerical solution with the data available from the existing experimental data. Furthermore, a comparison with validated experimental data confirms the efficacy of the mathematical model in assessing bioheat transfer in living tissues. The present findings highlight the importance of incorporating dual-phase lags in predictive thermal models to accurately capture the transient response of biological tissues under short-pulse laser exposure.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"29 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145703975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In a rigid crystal, phonons are quasiparticles that carry heat, and they can be seen at various levels of description like phonon kinetic theory, phonon hydrodynamics, Guyer–Krumhansl equation, or Fourier heat conduction. In a previous paper, we extended the Guyer–Krumhansl equation by adding two internal state variables, a symmetric tensor and an antisymmetric tensor. These internal variables express the viscous and vortical motion of phonons. In the present paper, we analyze the model by means of asymptotic expansion, and we find a geometric analogue of the model. While the zeroth-order expansion reduces the model to the Guyer–Krumhansl equation, the first-order expansion gives a more complicated heat flux evolution equation, of which the stability conditions of equilibrium solutions are studied. The geometric formulation of the model gives the heat flux as a functional of the entropy flux, in contrast to the usual setting of Extended Irreversible Thermodynamics, and also the two fluxes cease to be proportional via the temperature (in contrast to the Clausius formula for entropy flux).
{"title":"On the identification of two internal tensorial variables and a heat transport equation with inertial, thermal viscosity and vorticity terms","authors":"Liliana Restuccia, David Jou, Michal Pavelka","doi":"10.1515/jnet-2024-0100","DOIUrl":"https://doi.org/10.1515/jnet-2024-0100","url":null,"abstract":"In a rigid crystal, phonons are quasiparticles that carry heat, and they can be seen at various levels of description like phonon kinetic theory, phonon hydrodynamics, Guyer–Krumhansl equation, or Fourier heat conduction. In a previous paper, we extended the Guyer–Krumhansl equation by adding two internal state variables, a symmetric tensor and an antisymmetric tensor. These internal variables express the viscous and vortical motion of phonons. In the present paper, we analyze the model by means of asymptotic expansion, and we find a geometric analogue of the model. While the zeroth-order expansion reduces the model to the Guyer–Krumhansl equation, the first-order expansion gives a more complicated heat flux evolution equation, of which the stability conditions of equilibrium solutions are studied. The geometric formulation of the model gives the heat flux as a functional of the entropy flux, in contrast to the usual setting of Extended Irreversible Thermodynamics, and also the two fluxes cease to be proportional via the temperature (in contrast to the Clausius formula for entropy flux).","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"35 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145680052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eduardo González-Mora, Ram Poudel, María Dolores Durán-García
Sustainable cooling is critical for climate change mitigation and energy resilience, potentially reducing global greenhouse gas emissions while addressing rising demand for cooling. Solar refrigeration technologies offer alternatives to electricity-intensive refrigeration systems but remain underutilised in industrial applications where thermal energy is required for many manufacturing processes. Specifically, Vuilleumier refrigerators – heat-driven devices with mechanical simplicity – show unexplored potential when powered by concentrated solar energy, as no existing models integrate a solar concentrator with the refrigeration cycle irreversibilities. Here, we develop an endoreversible thermodynamic model of a solar-driven Vuilleumier refrigerator, coupling optical concentration, absorber design, and regeneration effect. Numerical analysis reveals that the coefficient of performance ( β ) exhibits concentration-dependent thresholds ( ξ > 0.18 at 273 K; ξ > 0.11 at 253 K), with asymptotic plateaus at β ≈ 9 and β ≈ 4 respectively. Normalised sensitivity analysis identifies regenerator effectiveness ( ɛ ) as the dominant parameter (12–16 times more influential), compared with the solar-specific parameters. These results resolve a critical gap in solar-thermal refrigeration by demonstrating that regenerator design – not concentrator scaling – limits maximum coefficient of performance. This work provides a thermodynamic blueprint delineating the fundamental performance boundaries of solar-Vuilleumier technology, governed by irreversibility constraints and asymptotic efficiency limits.
{"title":"Endoreversible description of photothermal Vuilleumier refrigeration machines","authors":"Eduardo González-Mora, Ram Poudel, María Dolores Durán-García","doi":"10.1515/jnet-2025-0094","DOIUrl":"https://doi.org/10.1515/jnet-2025-0094","url":null,"abstract":"Sustainable cooling is critical for climate change mitigation and energy resilience, potentially reducing global greenhouse gas emissions while addressing rising demand for cooling. Solar refrigeration technologies offer alternatives to electricity-intensive refrigeration systems but remain underutilised in industrial applications where thermal energy is required for many manufacturing processes. Specifically, Vuilleumier refrigerators – heat-driven devices with mechanical simplicity – show unexplored potential when powered by concentrated solar energy, as no existing models integrate a solar concentrator with the refrigeration cycle irreversibilities. Here, we develop an endoreversible thermodynamic model of a solar-driven Vuilleumier refrigerator, coupling optical concentration, absorber design, and regeneration effect. Numerical analysis reveals that the coefficient of performance ( <jats:italic>β</jats:italic> ) exhibits concentration-dependent thresholds ( <jats:italic>ξ</jats:italic> > 0.18 at 273 K; <jats:italic>ξ</jats:italic> > 0.11 at 253 K), with asymptotic plateaus at <jats:italic>β</jats:italic> ≈ 9 and <jats:italic>β</jats:italic> ≈ 4 respectively. Normalised sensitivity analysis identifies regenerator effectiveness ( <jats:italic>ɛ</jats:italic> ) as the dominant parameter (12–16 times more influential), compared with the solar-specific parameters. These results resolve a critical gap in solar-thermal refrigeration by demonstrating that regenerator design – not concentrator scaling – limits maximum coefficient of performance. This work provides a thermodynamic blueprint delineating the fundamental performance boundaries of solar-Vuilleumier technology, governed by irreversibility constraints and asymptotic efficiency limits.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"17 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145491817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An endoreversible-model of air-standard modified Atkinson-cycle via isothermal-heat-addition is built in this study, power ( P ), efficiency ( η ), power-density ( Pd ), ecological-function ( E ), and efficient-power ( Ep ) performances of modified Atkinson-cycle are analyzed and compared firstly. Taking P̄$bar{P}$ , η , Pd , E and Ēp${bar{E}}_{p}$ as objective-functions (OFs), and compression-ratio ( γ ) as optimization variable, the one five-objective optimization, five quadru-objective optimizations, ten tri-objective optimizations, ten bi-objective optimizations and five single-objective optimizations are completed by using NSGA-II furtherly. To find optimal solution, deviation indices ( Ds ) of three decision-making-methods (DMMs) which include Shannon Entropy, LINMAP and TOPSIS are utilized to compare optimization results. Results show that curves P versus η and Pd versus η are loop-shaped ones, and curves P versus γ and Pd versus γ are parabolic-like ones. With the increases of pre-expansion-ratio ( ρ ) and the maximum-temperature-ratio ( τ ), Pd is improved. Modified Atkinson-cycle designed with Pd as the OF has smaller size and higher η . Compared with traditio
本文建立了空气标准改进阿特金森循环的等温加热不可逆模型，首先对改进阿特金森循环的功率(P)、效率（η）、功率密度（P d）、生态功能(E)和效率功率（E P）性能进行了分析比较。以P $bar{P}$, η, P d， E和E $ P ${bar{E}}_{P}$为目标函数（OFs），以压缩比（γ）为优化变量，利用NSGA-II进一步完成了1个五目标优化、5个四目标优化、10个三目标优化、10个双目标优化和5个单目标优化。为了寻找最优解，利用Shannon熵、LINMAP和TOPSIS三种决策方法的偏差指数（Ds）对优化结果进行比较。结果表明，P - η曲线和P - d - η曲线为环状曲线，P - γ曲线和P - d - γ曲线为抛物线型曲线。随着预膨胀比（ρ）和最高温度比（τ）的增大，P d增大。以P d为OF设计的改进阿特金森循环具有更小的尺寸和更高的η值。与传统的阿特金森循环相比，等温加热改善了阿特金森循环的性能，P′$bar{P}$、η、E′$bar{E}$、P′d ${bar{P}}_{d}$、E′P ${bar{E}}_{P}$分别提高了30.18%、7.31%、39.57%、32.27%、47.60%。当以5个、4个、3个或2个目标进行优化时，目标数越多，改进的阿特金森循环的设计方案越合理，权衡设计性能越好。本文的主要贡献是建立了改进的阿特金森循环，并实现了5个OFs的moo。
{"title":"An air-standard isothermal-heating modified Atkinson-cycle and its performance optimizations with five objectives and NSGA-II","authors":"Haosheng Feng, Yanlin Ge, Lingen Chen, Huijun Feng","doi":"10.1515/jnet-2025-0039","DOIUrl":"https://doi.org/10.1515/jnet-2025-0039","url":null,"abstract":"An endoreversible-model of air-standard modified Atkinson-cycle via isothermal-heat-addition is built in this study, power ( <jats:italic>P</jats:italic> ), efficiency ( <jats:italic>η</jats:italic> ), power-density ( <jats:italic>P</jats:italic> <jats:sub> <jats:italic>d</jats:italic> </jats:sub> ), ecological-function ( <jats:italic>E</jats:italic> ), and efficient-power ( <jats:italic>E</jats:italic> <jats:sub> <jats:italic>p</jats:italic> </jats:sub> ) performances of modified Atkinson-cycle are analyzed and compared firstly. Taking <jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:mrow> <m:mover accent=\"true\"> <m:mi>P</m:mi> <m:mo>̄</m:mo> </m:mover> </m:mrow> </m:math> <jats:tex-math>$bar{P}$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_jnetdy-2025-0039_ineq_001.png\"/> </jats:alternatives> </jats:inline-formula> , <jats:italic>η</jats:italic> , <jats:italic>P</jats:italic> <jats:sub> <jats:italic>d</jats:italic> </jats:sub> , <jats:italic>E</jats:italic> and <jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:mrow> <m:msub> <m:mover accent=\"true\"> <m:mi>E</m:mi> <m:mo>̄</m:mo> </m:mover> <m:mi>p</m:mi> </m:msub> </m:mrow> </m:math> <jats:tex-math>${bar{E}}_{p}$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_jnetdy-2025-0039_ineq_002.png\"/> </jats:alternatives> </jats:inline-formula> as objective-functions (OFs), and compression-ratio ( <jats:italic>γ</jats:italic> ) as optimization variable, the one five-objective optimization, five quadru-objective optimizations, ten tri-objective optimizations, ten bi-objective optimizations and five single-objective optimizations are completed by using NSGA-II furtherly. To find optimal solution, deviation indices ( <jats:italic>Ds</jats:italic> ) of three decision-making-methods (DMMs) which include Shannon Entropy, LINMAP and TOPSIS are utilized to compare optimization results. Results show that curves <jats:italic>P</jats:italic> versus <jats:italic>η</jats:italic> and <jats:italic>P</jats:italic> <jats:sub> <jats:italic>d</jats:italic> </jats:sub> versus <jats:italic>η</jats:italic> are loop-shaped ones, and curves <jats:italic>P</jats:italic> versus <jats:italic>γ</jats:italic> and <jats:italic>P</jats:italic> <jats:sub> <jats:italic>d</jats:italic> </jats:sub> versus <jats:italic>γ</jats:italic> are parabolic-like ones. With the increases of pre-expansion-ratio ( <jats:italic>ρ</jats:italic> ) and the maximum-temperature-ratio ( <jats:italic>τ</jats:italic> ), <jats:italic>P</jats:italic> <jats:sub> <jats:italic>d</jats:italic> </jats:sub> is improved. Modified Atkinson-cycle designed with <jats:italic>P</jats:italic> <jats:sub> <jats:italic>d</jats:italic> </jats:sub> as the OF has smaller size and higher <jats:italic>η</jats:italic> . Compared with traditio","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"80 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145397929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study develops a novel thermoelectric generator system to utilize vehicle exhaust gas waste heat and convert it into electrical energy. A three-dimensional thermoelectric generator system with innovative heat sinks on both the hot and cold sides is designed to boost the thermoelectric generator’s output power and conversion efficiency. Three novel heat sink models for both sides of the thermoelectric generator are generated according to the square-pin fin size and the gaps between the fins to investigate the effects of the exhaust gas temperature and its flow rate. According to the findings, the highest temperature difference between both sides of the thermoelectric generator and the highest hot side heat transfer rate are obtained as 185.56 K and 113.69 W for Model C, and the maximum output power reached up to 4.44 W with a conversion efficiency of 3.90 % for the same model. As a result, the net output power is maximized with Model C at 4.07 W concerning the pressure drop and the pumping power. Considering waste heat recovery systems, Model C yields an increase in thermoelectric power generation by 23.3 % from 3.6 W to 4.44 W compared to the systems in the literature.
{"title":"Heat sink fin optimization on thermoelectric generator surfaces to improve thermoelectric power generation","authors":"Yasir Shakir Abdulsattar, Enes Kilinc (Kılınç)","doi":"10.1515/jnet-2025-0029","DOIUrl":"https://doi.org/10.1515/jnet-2025-0029","url":null,"abstract":"This study develops a novel thermoelectric generator system to utilize vehicle exhaust gas waste heat and convert it into electrical energy. A three-dimensional thermoelectric generator system with innovative heat sinks on both the hot and cold sides is designed to boost the thermoelectric generator’s output power and conversion efficiency. Three novel heat sink models for both sides of the thermoelectric generator are generated according to the square-pin fin size and the gaps between the fins to investigate the effects of the exhaust gas temperature and its flow rate. According to the findings, the highest temperature difference between both sides of the thermoelectric generator and the highest hot side heat transfer rate are obtained as 185.56 K and 113.69 W for Model C, and the maximum output power reached up to 4.44 W with a conversion efficiency of 3.90 % for the same model. As a result, the net output power is maximized with Model C at 4.07 W concerning the pressure drop and the pumping power. Considering waste heat recovery systems, Model C yields an increase in thermoelectric power generation by 23.3 % from 3.6 W to 4.44 W compared to the systems in the literature.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"151 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145397931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Travis Leadbetter, Prashant K. Purohit, Celia Reina
Given a particle system obeying overdamped Langevin dynamics, we demonstrate that it is always possible to construct a thermodynamically consistent macroscopic model which obeys a gradient flow with respect to its non-equilibrium free energy. To do so, we significantly extend the recent Stochastic Thermodynamics with Internal Variables (STIV) framework, a method for producing macroscopic thermodynamic models far-from-equilibrium from the underlying mesoscopic dynamics and an approximate probability density of states parameterized with so-called internal variables. Though originally explored for Gaussian probability distributions, we here allow for an arbitrary choice of the approximate probability density while retaining a gradient flow dynamics. This greatly extends its range of applicability and automatically ensures consistency with the second law of thermodynamics, without the need for secondary verification. We demonstrate numerical convergence, in the limit of increasing internal variables, to the true probability density of states for both a multi-modal relaxation problem, a protein diffusing on a strand of DNA, and for an externally driven particle in a periodic landscape. Finally, we provide a reformulation of STIV with the quasi-equilibrium approximations in terms of the averages of observables of the mesostate, and show that these, too, obey a gradient flow.
{"title":"From Langevin dynamics to macroscopic thermodynamic models: a general framework valid far from equilibrium","authors":"Travis Leadbetter, Prashant K. Purohit, Celia Reina","doi":"10.1515/jnet-2025-0071","DOIUrl":"https://doi.org/10.1515/jnet-2025-0071","url":null,"abstract":"Given a particle system obeying overdamped Langevin dynamics, we demonstrate that it is always possible to construct a thermodynamically consistent macroscopic model which obeys a gradient flow with respect to its non-equilibrium free energy. To do so, we significantly extend the recent Stochastic Thermodynamics with Internal Variables (STIV) framework, a method for producing macroscopic thermodynamic models far-from-equilibrium from the underlying mesoscopic dynamics and an approximate probability density of states parameterized with so-called internal variables. Though originally explored for Gaussian probability distributions, we here allow for an arbitrary choice of the approximate probability density while retaining a gradient flow dynamics. This greatly extends its range of applicability and automatically ensures consistency with the second law of thermodynamics, without the need for secondary verification. We demonstrate numerical convergence, in the limit of increasing internal variables, to the true probability density of states for both a multi-modal relaxation problem, a protein diffusing on a strand of DNA, and for an externally driven particle in a periodic landscape. Finally, we provide a reformulation of STIV with the quasi-equilibrium approximations in terms of the averages of observables of the mesostate, and show that these, too, obey a gradient flow.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"95 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, a theoretical study is carried out on the effects of the thickness of a semiconductor thin film on the transport of heat and particles under the action of an external temperature difference. The dependence of the Seebeck effect on the thickness is considered. The thickness film is introduced through the transport coefficients of the material, namely, the thermal and electrical conductivities and the intrinsic Seebeck coefficient, by resorting to known results of irreversible thermodynamics. Graphs of the generated electric potential difference by an external temperature difference versus film thickness are obtained in the range 0.1 µm–1 µm. We compare the results of two slightly doped materials, namely, silicon and bismuth telluride of the n- and p- types. The n-type silicon shows an optimal thickness where the generated electric potential difference is maximum, while the electric potential difference in the n-type bismuth telluride decreases with decreasing thickness. The electric response of p-type silicon and p-type bismuth telluride also worsens as the thickness decreases. The results presented may be useful in the design of thermoelectric devices on the sub-micrometer length scale.
{"title":"Size scaling effects on heat and particle transport in semiconductor thin films: a near-equilibrium thermodynamic approach","authors":"Ruth Estephania Gonzalez-Narvaez, Iván Rivera, Víctor Hernández, Aldo Figueroa, Federico Vázquez","doi":"10.1515/jnet-2025-0056","DOIUrl":"https://doi.org/10.1515/jnet-2025-0056","url":null,"abstract":"In this work, a theoretical study is carried out on the effects of the thickness of a semiconductor thin film on the transport of heat and particles under the action of an external temperature difference. The dependence of the Seebeck effect on the thickness is considered. The thickness film is introduced through the transport coefficients of the material, namely, the thermal and electrical conductivities and the intrinsic Seebeck coefficient, by resorting to known results of irreversible thermodynamics. Graphs of the generated electric potential difference by an external temperature difference versus film thickness are obtained in the range 0.1 µm–1 µm. We compare the results of two slightly doped materials, namely, silicon and bismuth telluride of the <jats:italic>n</jats:italic>- and <jats:italic>p</jats:italic>- types. The <jats:italic>n</jats:italic>-type silicon shows an optimal thickness where the generated electric potential difference is maximum, while the electric potential difference in the <jats:italic>n</jats:italic>-type bismuth telluride decreases with decreasing thickness. The electric response of <jats:italic>p</jats:italic>-type silicon and <jats:italic>p</jats:italic>-type bismuth telluride also worsens as the thickness decreases. The results presented may be useful in the design of thermoelectric devices on the sub-micrometer length scale.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"117 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：