Abstract For the given initial finite high-temperature heat reservoir temperature, continuous Hamilton–Jacobi–Bellman equations are established to obtain optimal finite high-temperature heat reservoir temperature for minimum power consumption of multistage Carnot heat pumping system with generalized convective heat transfer law [q ∝ (ΔT) m ]. Analytical expression of optimal heat reservoir temperature with Newtonian heat transfer law (m = 1) is obtained based on generalized optimization results for minimum power consumption. For other heat transfer laws (m ≠ 1), numerical solutions for minimum power consumption are provided. Optimization results for multistage Carnot heat pumps are compared with maximum power output solutions of multistage irreversible Carnot heat engines.
{"title":"Minimum power consumption of multistage irreversible Carnot heat pumps with heat transfer law of q ∝ (ΔT) m","authors":"Lingen Chen, Shaojun Xia","doi":"10.1515/jnet-2022-0068","DOIUrl":"https://doi.org/10.1515/jnet-2022-0068","url":null,"abstract":"Abstract For the given initial finite high-temperature heat reservoir temperature, continuous Hamilton–Jacobi–Bellman equations are established to obtain optimal finite high-temperature heat reservoir temperature for minimum power consumption of multistage Carnot heat pumping system with generalized convective heat transfer law [q ∝ (ΔT) m ]. Analytical expression of optimal heat reservoir temperature with Newtonian heat transfer law (m = 1) is obtained based on generalized optimization results for minimum power consumption. For other heat transfer laws (m ≠ 1), numerical solutions for minimum power consumption are provided. Optimization results for multistage Carnot heat pumps are compared with maximum power output solutions of multistage irreversible Carnot heat engines.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"48 1","pages":"107 - 118"},"PeriodicalIF":6.6,"publicationDate":"2022-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49375515","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}
A. Boudjemline, I. Ahmad, Sohail Rehman, Hashim, N. Khedher
Abstract We present a novel theoretical model to investigate the pressure-driven flow of a non-Newtonian Oldroyd-B nanofluid in an expanding channel. The momentum and temperature field equations are developed on the bases of momentum conservation law and Fourier’s principle of heat transfer in conjunction with Buongiorno’s model of nanofluids. Numerical investigations on a viscoelastic Oldroyd-B fluid flowing in horizontal, converging, and diverging channel have been carried out to collect point-by-point stress data i.e., the shear stresses and flow field). The constitutive model of a viscoelastic fluid adopting the Oldroyd-B model is considered to characterize the rheological behavior of the fluid. The flow equations are changed to a non-linear system and solved numerically using the Runge–Kutta Butcher method via MATLAB code. Numerous emerging flow parameters are probed for their effects on flow and heat transfer characteristics using extensive numerical computing. In converging flow, increasing the Reynolds number and channel angle leads to an increase in velocity distribution, indicating that backflow is eliminated. However, the velocity decreases as the retardation parameter increases significantly. Furthermore, the Oldroyd-B nano liquid literature is elevated by the Brownian motion and thermophoresis parameter, while for the concentration of the nanoparticles the behavior is contrary. The velocity field of an Oldroyd-B fluid is compared with the velocity fields for viscous fluids, which are then traced out as limiting instances. In comparison, the results for polymer solutions obtained in this analysis are compared with a Newtonian fluid.
{"title":"Jeffery-Hamel flow extension and thermal analysis of Oldroyd-B nanofluid in expanding channel","authors":"A. Boudjemline, I. Ahmad, Sohail Rehman, Hashim, N. Khedher","doi":"10.1515/jnet-2022-0052","DOIUrl":"https://doi.org/10.1515/jnet-2022-0052","url":null,"abstract":"Abstract We present a novel theoretical model to investigate the pressure-driven flow of a non-Newtonian Oldroyd-B nanofluid in an expanding channel. The momentum and temperature field equations are developed on the bases of momentum conservation law and Fourier’s principle of heat transfer in conjunction with Buongiorno’s model of nanofluids. Numerical investigations on a viscoelastic Oldroyd-B fluid flowing in horizontal, converging, and diverging channel have been carried out to collect point-by-point stress data i.e., the shear stresses and flow field). The constitutive model of a viscoelastic fluid adopting the Oldroyd-B model is considered to characterize the rheological behavior of the fluid. The flow equations are changed to a non-linear system and solved numerically using the Runge–Kutta Butcher method via MATLAB code. Numerous emerging flow parameters are probed for their effects on flow and heat transfer characteristics using extensive numerical computing. In converging flow, increasing the Reynolds number and channel angle leads to an increase in velocity distribution, indicating that backflow is eliminated. However, the velocity decreases as the retardation parameter increases significantly. Furthermore, the Oldroyd-B nano liquid literature is elevated by the Brownian motion and thermophoresis parameter, while for the concentration of the nanoparticles the behavior is contrary. The velocity field of an Oldroyd-B fluid is compared with the velocity fields for viscous fluids, which are then traced out as limiting instances. In comparison, the results for polymer solutions obtained in this analysis are compared with a Newtonian fluid.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"48 1","pages":"75 - 90"},"PeriodicalIF":6.6,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48192118","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}
M. Taghizadehfard, S. Hosseini, M. Pierantozzi, M. Alavianmehr
Abstract Densities and isothermal compressibilities of several nanofluids were modelled using a perturbed hard-chain equation of state (EoS) by an attractive term from Yukawa tail in 273–363 K range and pressure up to 45 MPa. The nanofluids of interest comprise TiO2-Anatase (-A), TiO2-Rutile (-R), SnO2, Co3O4, CuO, ZnO, and Al2O3 as nanoparticles dispersed in ethylene glycol, water, poly ethylene glycol, ethylene glycol + water, and poly ethylene glycol + water as base fluids. The EoS was capable of estimating 1397 density data of 9 nanofluids with the overall average absolute deviations (AAD) of 0.90%. The coefficients of isothermal compressibility of 6 selected nanofluids were also predicted using the EoS with the AAD of 5.74% for 1095 data points examined. The PHDC EoS was not capable of estimating the excess volumes of 3 selected EG-, PEG-, and water-based nanofluids accurately as the relative deviations from the literature data were greater than 34%, even though the trend of results against the nanoparticle concentration was in accord with the literature. To further investigate the density prediction, we have trained a neural network with a single hidden layer and 17 neurons which was able to predict the densities of nanofluids accurately.
{"title":"Densities and isothermal compressibilities from perturbed hard-dimer-chain equation of state: application to nanofluids","authors":"M. Taghizadehfard, S. Hosseini, M. Pierantozzi, M. Alavianmehr","doi":"10.1515/jnet-2022-0046","DOIUrl":"https://doi.org/10.1515/jnet-2022-0046","url":null,"abstract":"Abstract Densities and isothermal compressibilities of several nanofluids were modelled using a perturbed hard-chain equation of state (EoS) by an attractive term from Yukawa tail in 273–363 K range and pressure up to 45 MPa. The nanofluids of interest comprise TiO2-Anatase (-A), TiO2-Rutile (-R), SnO2, Co3O4, CuO, ZnO, and Al2O3 as nanoparticles dispersed in ethylene glycol, water, poly ethylene glycol, ethylene glycol + water, and poly ethylene glycol + water as base fluids. The EoS was capable of estimating 1397 density data of 9 nanofluids with the overall average absolute deviations (AAD) of 0.90%. The coefficients of isothermal compressibility of 6 selected nanofluids were also predicted using the EoS with the AAD of 5.74% for 1095 data points examined. The PHDC EoS was not capable of estimating the excess volumes of 3 selected EG-, PEG-, and water-based nanofluids accurately as the relative deviations from the literature data were greater than 34%, even though the trend of results against the nanoparticle concentration was in accord with the literature. To further investigate the density prediction, we have trained a neural network with a single hidden layer and 17 neurons which was able to predict the densities of nanofluids accurately.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"48 1","pages":"55 - 73"},"PeriodicalIF":6.6,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44211772","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}
D. Panda, M. Kumar, Suraj K. Behera, A. Satapathy, S. Sarangi
Abstract Continuous effort is made on Gifford-McMahon cryocoolers (GMC) to amplify its refrigeration power, so they can be used to cool the cryopumps, high Tc magnets and development of efficient small-scale hydrogen liquefiers, etc. The fluidic-driven GMC is considered to be more reliable and prominent candidate than the mechanically-driven GMC due to its structural simplicity and reliability. Nonetheless, cooling mechanism of the fluidic-driven GMC is complicated, as the displacer motion inside the displacer cylinder is simultaneously controlled by the pressure difference between drive chamber and compression/expansion chamber. Different paths of displacer can be traced inside the displacer cylinder for different drive-chamber discharging process, hence, pressure–volume power of compression and expansion chambers, and refrigeration power changes. A theoretical study is conducted in present paper to visualize the influence of drive-chamber discharging process on the thermodynamic characteristics of fluidic-driven GMC for the first time. Thermodynamic cycles are drawn at the expansion chamber of the fluidic-driven GMC for different values of drive-chamber discharging process for two types of valve timing arrangements. Energy and work loss behaviors in different components of the GMC are also analysed. Adequate experimental investigations have also been carried out on a fluidic-driven displacer type GMC to verify the simulation results.
{"title":"Influence of drive chamber discharging process on non-linear displacer dynamics and thermodynamic processes of a fluidic-driven Gifford-McMahon cryocooler","authors":"D. Panda, M. Kumar, Suraj K. Behera, A. Satapathy, S. Sarangi","doi":"10.1515/jnet-2022-0073","DOIUrl":"https://doi.org/10.1515/jnet-2022-0073","url":null,"abstract":"Abstract Continuous effort is made on Gifford-McMahon cryocoolers (GMC) to amplify its refrigeration power, so they can be used to cool the cryopumps, high Tc magnets and development of efficient small-scale hydrogen liquefiers, etc. The fluidic-driven GMC is considered to be more reliable and prominent candidate than the mechanically-driven GMC due to its structural simplicity and reliability. Nonetheless, cooling mechanism of the fluidic-driven GMC is complicated, as the displacer motion inside the displacer cylinder is simultaneously controlled by the pressure difference between drive chamber and compression/expansion chamber. Different paths of displacer can be traced inside the displacer cylinder for different drive-chamber discharging process, hence, pressure–volume power of compression and expansion chambers, and refrigeration power changes. A theoretical study is conducted in present paper to visualize the influence of drive-chamber discharging process on the thermodynamic characteristics of fluidic-driven GMC for the first time. Thermodynamic cycles are drawn at the expansion chamber of the fluidic-driven GMC for different values of drive-chamber discharging process for two types of valve timing arrangements. Energy and work loss behaviors in different components of the GMC are also analysed. Adequate experimental investigations have also been carried out on a fluidic-driven displacer type GMC to verify the simulation results.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"48 1","pages":"1 - 23"},"PeriodicalIF":6.6,"publicationDate":"2022-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47751819","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}
Abstract Chemical engine is an abstract model of some devices, such as solid state, photochemical, and electrochemical devices, photovoltaic cell, and mass exchangers. Finite chemical-potential source is one of its features. Finite time thermodynamics provides effective theoretical tool for determining performance limits for given thermal systems, and determining optimal process paths of thermal systems for given performance objectives. Endoreversible model is its basic model. A model of endoreversible non-isothermal chemical engines operating between a finite chemical-potential source and an infinite chemical-potential sink with mass resistance and heat resistance is established. Mass transfer processes between chemical potential reservoir and working fluid of the model are assumed to obey Onsager equations in linear irreversible thermodynamics. With a fixed cycle period, optimal cycle configuration for the maximum work output of the model is derived by applying optimal control theory. The results obtained include optimal performance and optimal path results in many previous literatures, and can provide some theoretical guidelines for optimal designs of practical chemical plants.
{"title":"Maximum work configuration of finite potential source endoreversible non-isothermal chemical engines","authors":"Lingen Chen, Shaojun Xia","doi":"10.1515/jnet-2022-0045","DOIUrl":"https://doi.org/10.1515/jnet-2022-0045","url":null,"abstract":"Abstract Chemical engine is an abstract model of some devices, such as solid state, photochemical, and electrochemical devices, photovoltaic cell, and mass exchangers. Finite chemical-potential source is one of its features. Finite time thermodynamics provides effective theoretical tool for determining performance limits for given thermal systems, and determining optimal process paths of thermal systems for given performance objectives. Endoreversible model is its basic model. A model of endoreversible non-isothermal chemical engines operating between a finite chemical-potential source and an infinite chemical-potential sink with mass resistance and heat resistance is established. Mass transfer processes between chemical potential reservoir and working fluid of the model are assumed to obey Onsager equations in linear irreversible thermodynamics. With a fixed cycle period, optimal cycle configuration for the maximum work output of the model is derived by applying optimal control theory. The results obtained include optimal performance and optimal path results in many previous literatures, and can provide some theoretical guidelines for optimal designs of practical chemical plants.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"48 1","pages":"41 - 53"},"PeriodicalIF":6.6,"publicationDate":"2022-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49584299","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}
Abstract The internal heat source and reaction effects on the onset of thermosolutal convection in a local thermal non-equilibrium porous medium are examined, where the temperature of the fluid and the solid skeleton may differ. The linear instability and nonlinear stability theories of Darcy–Brinkman type with fixed boundary condition are carried out where the layer is heated and salted from below. The D 2 {D^{2}} Chebyshev tau technique is used to calculate the associated system of equations subject to the boundary conditions for both theories. Three different types of internal heat source function are considered, the first type increases across the layer, while the second decreases, and the third type heats and cools in a nonuniform way. The effect of different parameters on the Rayleigh number is depicted graphically. Moreover, the results detect that utilizing the internal heat source, reaction, and non-equilibrium have pronounced effects in determining the convection stability and instability thresholds.
{"title":"Stability Analysis of Double Diffusive Convection in Local Thermal Non-equilibrium Porous Medium with Internal Heat Source and Reaction Effects","authors":"N. Noon, S. Haddad","doi":"10.1515/jnet-2022-0047","DOIUrl":"https://doi.org/10.1515/jnet-2022-0047","url":null,"abstract":"Abstract The internal heat source and reaction effects on the onset of thermosolutal convection in a local thermal non-equilibrium porous medium are examined, where the temperature of the fluid and the solid skeleton may differ. The linear instability and nonlinear stability theories of Darcy–Brinkman type with fixed boundary condition are carried out where the layer is heated and salted from below. The D 2 {D^{2}} Chebyshev tau technique is used to calculate the associated system of equations subject to the boundary conditions for both theories. Three different types of internal heat source function are considered, the first type increases across the layer, while the second decreases, and the third type heats and cools in a nonuniform way. The effect of different parameters on the Rayleigh number is depicted graphically. Moreover, the results detect that utilizing the internal heat source, reaction, and non-equilibrium have pronounced effects in determining the convection stability and instability thresholds.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"48 1","pages":"25 - 39"},"PeriodicalIF":6.6,"publicationDate":"2022-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45973065","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}
Zhanxuan Wang, Xiulian Cheng, K. Guo, Enling Tang, Lei Li, Hui Peng, Yafei Han, Chuang Chen, Mengzhou Chang, Liping He
Abstract In actual operation, the operating environment temperature of thermoelectric devices are constantly changing and rarely remain stable, and the electrical output characteristics of thermoelectric devices are largely determined by thermoelectric materials. In response to this question, the thermoelectric properties of thermoelectric materials (p and n type Bi 2 Te 3 {mathrm{Bi}_{2}}{mathrm{Te}_{3}}) are measured under different temperature difference environments. The Seebeck coefficient, resistivity, and thermal conductivity of the specimens at T = 300 – 600 KT=300text{--}600hspace{0.1667em}text{K} were measured by CTA-4 and CLA1000 (laser flash method), respectively; the thermal and electrical output responses of the thermoelectric materials under different temperature difference conditions were collected in real time by using a self-built thermoelectric performance test platform, thermal/electrical test system with infrared thermal imager, and voltage acquisition system, respectively. The experimental results show that when the temperature difference between the two ends of the specimen increases uniformly, the electrical output signal amplitude also increases uniformly; when the temperature difference is stable, the two ends of the specimen also produce a stable electrical output signal. After stabilization, the electrical output signal amplitude also decreases uniformly when the temperature decreases at a uniform rate. In the temperature range of 298 ∼ 573 K298sim 573hspace{0.1667em}text{K}, the larger the temperature difference between the two ends of the specimen was, the larger the amplitude of the electrical output signal was after stabilization; and vice versa. The greater the loading rate of the thermal load was, the greater the rate of increase of the electrical output signal amplitude at both ends of the specimen was, and the steady-state equilibrium time required was less.
{"title":"Thermoelectric Response Characteristics of Bi2Te3 Based Semiconductor Materials","authors":"Zhanxuan Wang, Xiulian Cheng, K. Guo, Enling Tang, Lei Li, Hui Peng, Yafei Han, Chuang Chen, Mengzhou Chang, Liping He","doi":"10.1515/jnet-2022-0049","DOIUrl":"https://doi.org/10.1515/jnet-2022-0049","url":null,"abstract":"Abstract In actual operation, the operating environment temperature of thermoelectric devices are constantly changing and rarely remain stable, and the electrical output characteristics of thermoelectric devices are largely determined by thermoelectric materials. In response to this question, the thermoelectric properties of thermoelectric materials (p and n type Bi 2 Te 3 {mathrm{Bi}_{2}}{mathrm{Te}_{3}}) are measured under different temperature difference environments. The Seebeck coefficient, resistivity, and thermal conductivity of the specimens at T = 300 – 600 KT=300text{--}600hspace{0.1667em}text{K} were measured by CTA-4 and CLA1000 (laser flash method), respectively; the thermal and electrical output responses of the thermoelectric materials under different temperature difference conditions were collected in real time by using a self-built thermoelectric performance test platform, thermal/electrical test system with infrared thermal imager, and voltage acquisition system, respectively. The experimental results show that when the temperature difference between the two ends of the specimen increases uniformly, the electrical output signal amplitude also increases uniformly; when the temperature difference is stable, the two ends of the specimen also produce a stable electrical output signal. After stabilization, the electrical output signal amplitude also decreases uniformly when the temperature decreases at a uniform rate. In the temperature range of 298 ∼ 573 K298sim 573hspace{0.1667em}text{K}, the larger the temperature difference between the two ends of the specimen was, the larger the amplitude of the electrical output signal was after stabilization; and vice versa. The greater the loading rate of the thermal load was, the greater the rate of increase of the electrical output signal amplitude at both ends of the specimen was, and the steady-state equilibrium time required was less.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"47 1","pages":"355 - 373"},"PeriodicalIF":6.6,"publicationDate":"2022-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49267425","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}
Abstract A class of two finite-heat-reservoir endoreversible heat engine with the generalized models of both the reservoir thermal capacities and heat resistances is investigated. The optimality condition for cycle maximum work output is derived by applying optimal control theory, and impacts of both thermal capacity characteristics of heat reservoirs and heat transfer laws on the optimal configurations are discussed. The results obtained in some previous researches are special cases of those obtained herein, which can provide some guidelines for optimal design of actual heat engines.
{"title":"Heat Engine Cycle Configurations for Maximum Work Output with Generalized Models of Reservoir Thermal Capacity and Heat Resistance","authors":"Lingen Chen, Shaojun Xia","doi":"10.1515/jnet-2022-0029","DOIUrl":"https://doi.org/10.1515/jnet-2022-0029","url":null,"abstract":"Abstract A class of two finite-heat-reservoir endoreversible heat engine with the generalized models of both the reservoir thermal capacities and heat resistances is investigated. The optimality condition for cycle maximum work output is derived by applying optimal control theory, and impacts of both thermal capacity characteristics of heat reservoirs and heat transfer laws on the optimal configurations are discussed. The results obtained in some previous researches are special cases of those obtained herein, which can provide some guidelines for optimal design of actual heat engines.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"47 1","pages":"329 - 338"},"PeriodicalIF":6.6,"publicationDate":"2022-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49104753","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}
L.G. Lafaurie-Ponce, F. Chejne, Luis M. Ramirez-Aristeguieta, Carlos Gomez
Abstract This work describes the nonlinear Thomson effect produced by a transient current source powering a thermoelectric cooler. The electric effect of the capacitive impedance in the semiconductors was considered in the equations as a novelty term that naturally appears by solving the Boltzmann equation to find the mathematical form of the current density. Thus, considering the new term and heath energy balances, a one-dimensional mathematical model for a thermoelectric cooler (TEC) powered by a time-dependent current was developed, finding a new nonlinear Thomson effect in the heath transfer equations. To evaluate the impact of the nonlinear effect on the thermodynamic behavior of the thermoelectric cooler, a continuous, sinusoidal and square-pulse current conditions were simulated. The temperature profile, temporal evolution, and the effective coefficient of performance (COP) were calculated. The results revealed a new thermoelectric heat transfer in addition to the Thomson flow created by virtual junctions throughout the semiconductors caused by the instantaneous change of current. This fact was evidenced by three results: the shifting of the temperature mean value due to the peak current change 0.45 A is 1.68 K1.68hspace{0.1667em}mathrm{K} and 2.56 K2.56hspace{0.1667em}mathrm{K} to sinusoidal and square current supplies, respectively; it was determined that a TEC powered by a square-pulse current signal had greater effective efficacy, having more pronounced cold side supercooling temperature peaks compared to those powered by a constant sinusoidal current signal.
{"title":"A Study of the Nonlinear Thomson Effect Produced by Changing the Current in a Thermoelectric Cooler","authors":"L.G. Lafaurie-Ponce, F. Chejne, Luis M. Ramirez-Aristeguieta, Carlos Gomez","doi":"10.1515/jnet-2022-0037","DOIUrl":"https://doi.org/10.1515/jnet-2022-0037","url":null,"abstract":"Abstract This work describes the nonlinear Thomson effect produced by a transient current source powering a thermoelectric cooler. The electric effect of the capacitive impedance in the semiconductors was considered in the equations as a novelty term that naturally appears by solving the Boltzmann equation to find the mathematical form of the current density. Thus, considering the new term and heath energy balances, a one-dimensional mathematical model for a thermoelectric cooler (TEC) powered by a time-dependent current was developed, finding a new nonlinear Thomson effect in the heath transfer equations. To evaluate the impact of the nonlinear effect on the thermodynamic behavior of the thermoelectric cooler, a continuous, sinusoidal and square-pulse current conditions were simulated. The temperature profile, temporal evolution, and the effective coefficient of performance (COP) were calculated. The results revealed a new thermoelectric heat transfer in addition to the Thomson flow created by virtual junctions throughout the semiconductors caused by the instantaneous change of current. This fact was evidenced by three results: the shifting of the temperature mean value due to the peak current change 0.45 A is 1.68 K1.68hspace{0.1667em}mathrm{K} and 2.56 K2.56hspace{0.1667em}mathrm{K} to sinusoidal and square current supplies, respectively; it was determined that a TEC powered by a square-pulse current signal had greater effective efficacy, having more pronounced cold side supercooling temperature peaks compared to those powered by a constant sinusoidal current signal.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":"47 1","pages":"339 - 354"},"PeriodicalIF":6.6,"publicationDate":"2022-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48843893","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}
E. Ragupathi, D. Prakash, M. Muthtamilselvan, Q. Al‐Mdallal
Abstract The current study is made to analyze the impact of local thermal nonequilibrium (LTNE) on the steady, incompressible, and viscous Ostwald-de-Waele nano-liquid over a rotating disk in a porous medium with the various power law index, due to many remarkable applications, such as aeronautical systems, rotating machineries, air cleaning machineries, electrical power-generating systems, heat exchangers, gas turbines, centrifugal pumps. To describe the modeling of the nano-liquid, Brownian movement and thermophoresis are employed with the passive control boundaries. Three temperature model is adopted to distinguish the temperature among the fluid, particle, and solid. The governing transport equations have been converted to a system of nonlinear coupled ordinary differential equations by employing von Karman transformation. Numerical results of the flow and heat and transfer characteristics of the fluid, particle, and solid are obtained by applying Runge–Kutta–Fehlberg method (RKF) together with the shooting technique. The numerical results in the present work are compared with the published results for the case of thermal equilibrium and found that they are in good agreement. It is observed that the temperature profile significantly varies with the fluid-particle, fluid-solid interphase heat transfer coefficients and the modified thermal capacity ratios.
摘要本研究分析了局部热非平衡（LTNE）对具有不同幂律指数的多孔介质中旋转圆盘上稳定、不可压缩和粘性的Ostwald de Waele纳米液体的影响，这些液体具有许多显著的应用，如航空系统、旋转机械、空气净化机械、发电系统，热交换器、燃气轮机、离心泵。为了描述纳米液体的建模，采用了布朗运动和热泳法以及被动控制边界。采用三温度模型来区分流体、颗粒和固体的温度。利用von Karman变换将控制输运方程转化为非线性耦合常微分方程组。采用Runge–Kutta–Fehlberg方法（RKF）和射击技术，获得了流体、颗粒和固体的流动和传热特性的数值结果。将本工作中的数值结果与已发表的热平衡情况下的结果进行了比较，发现它们非常一致。观察到，温度分布随流体颗粒、流固相间传热系数和修正的热容量比而显著变化。
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