Based on the second law or the rmodynamics,the authors proposed the unit entropy generation analysis method for evaluation and analysis of the comprehensive thermal characteristics of different enhanced heat transfer ...Based on the second law or the rmodynamics,the authors proposed the unit entropy generation analysis method for evaluation and analysis of the comprehensive thermal characteristics of different enhanced heat transfer methods.The optimum operation condition of the enhanced heat transfer methods,such as fin type and swirl flow,is obtained through thermal characteristic analysis.This work provides a theoretical basis for engineering design.展开更多
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
In order to evaluate the safety production situation of the coal mine effectively,selected the indicators about mine production safety, applied entropy method to determinethe objective weight of each index, calculated...In order to evaluate the safety production situation of the coal mine effectively,selected the indicators about mine production safety, applied entropy method to determinethe objective weight of each index, calculated the distance and close degree between themines and the ideal point and negative ideal point, and then evaluated the safety productionsituation of the mines according to the close degree.The results show that the methodprovides a reasonable, concise and more objective idea to evaluate the safety productionsituation of the mines.展开更多
Thermal transport in porous media has stimulated substantial interest in engineering sciences due to increasing applications in filtration systems,porous bearings,porous layer insulation,biomechanics,geomechanics etc....Thermal transport in porous media has stimulated substantial interest in engineering sciences due to increasing applications in filtration systems,porous bearings,porous layer insulation,biomechanics,geomechanics etc.Motivated by such applications,in this article,a numerical study of entropy generation impacts on the heat and momentum transfer in time-dependent laminar incompressible boundary layer flow of a Casson viscoplastic fluid over a uniformly heated vertical cylinder embedded in a porous medium is presented.Darcy’s law is used to simulate bulk drag effects at low Reynolds number for an isotropic,homogenous porous medium.Heat line visualization is also included.The mathematical model is derived and normalized using appropriate transformation variables.The resulting non-linear time-dependent coupled governing equations with associated boundary conditions are solved via an implicit finite difference method which is efficient and unconditionally stable.The outcomes show that entropy generation and Bejan number are both elevated with increasing values of Darcy number,Casson fluid parameter,group parameter and Grashof number.To analyze the heat transfer process in a two-dimensional domain,plotting heat lines provides an excellent approach in addition to streamlines and isotherms.It is remarked that as the Darcy number increases,the deviations of heat lines from the hot wall are reduced.展开更多
文摘Based on the second law or the rmodynamics,the authors proposed the unit entropy generation analysis method for evaluation and analysis of the comprehensive thermal characteristics of different enhanced heat transfer methods.The optimum operation condition of the enhanced heat transfer methods,such as fin type and swirl flow,is obtained through thermal characteristic analysis.This work provides a theoretical basis for engineering design.
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.
文摘In order to evaluate the safety production situation of the coal mine effectively,selected the indicators about mine production safety, applied entropy method to determinethe objective weight of each index, calculated the distance and close degree between themines and the ideal point and negative ideal point, and then evaluated the safety productionsituation of the mines according to the close degree.The results show that the methodprovides a reasonable, concise and more objective idea to evaluate the safety productionsituation of the mines.
基金DST-INSPIRE (Code No. IF160028) for the grant of research fellowship
文摘Thermal transport in porous media has stimulated substantial interest in engineering sciences due to increasing applications in filtration systems,porous bearings,porous layer insulation,biomechanics,geomechanics etc.Motivated by such applications,in this article,a numerical study of entropy generation impacts on the heat and momentum transfer in time-dependent laminar incompressible boundary layer flow of a Casson viscoplastic fluid over a uniformly heated vertical cylinder embedded in a porous medium is presented.Darcy’s law is used to simulate bulk drag effects at low Reynolds number for an isotropic,homogenous porous medium.Heat line visualization is also included.The mathematical model is derived and normalized using appropriate transformation variables.The resulting non-linear time-dependent coupled governing equations with associated boundary conditions are solved via an implicit finite difference method which is efficient and unconditionally stable.The outcomes show that entropy generation and Bejan number are both elevated with increasing values of Darcy number,Casson fluid parameter,group parameter and Grashof number.To analyze the heat transfer process in a two-dimensional domain,plotting heat lines provides an excellent approach in addition to streamlines and isotherms.It is remarked that as the Darcy number increases,the deviations of heat lines from the hot wall are reduced.
