Ecosystem stays far from thermodynamic equilibrium. Through the interactions among biotic and abiotic components, and encompassing physical environments, ecosystem forms a dissipative struc- ture that allows it to dis...Ecosystem stays far from thermodynamic equilibrium. Through the interactions among biotic and abiotic components, and encompassing physical environments, ecosystem forms a dissipative struc- ture that allows it to dissipate energy continuously and thereby remains functional over time. Biotic regulation of energy and material fluxes in and out of the ecosystem allows it to maintain a homeostatic state which corresponds to a self-organized state emerged in a non-equilibrium thermodynamic system. While the associated self-organizational processes approach to homeostatic state, entropy (a measure of irre- versibility) degrades and dissipation of energy increases. We propose here that at a homeostatic state of ecosystem, biodiversity which includes both phenotypic and functional diversity, attains optimal values. As long as biodiversity remains within its optimal range, the corresponding homeostatic state is maintained. However, while embedded environmental conditions fluctuate along the gradient of accelerating changes, phenotypic diversity and functional diversity contribute inversely to the associated self-organizing proc- esses. Furthermore, an increase or decrease in biodiversity outside of its optimal range makes the eco- system vulnerable to transition into a different state.展开更多
A thermodynamic model has been built up for the interactions between molten Ti alloys and oxide molding materials in the way of decomposition and solution of molding materials, then the influences on the reaction free...A thermodynamic model has been built up for the interactions between molten Ti alloys and oxide molding materials in the way of decomposition and solution of molding materials, then the influences on the reaction free energy changes have been calculated and discussed.展开更多
The interactions of Ti - 6Al - 4V alloy with wide potential applications in aeronautics and aerospace indus-tries with the molding materials have been analyed and calculated by a thermodynamic method. The molding mate...The interactions of Ti - 6Al - 4V alloy with wide potential applications in aeronautics and aerospace indus-tries with the molding materials have been analyed and calculated by a thermodynamic method. The molding materials involved in the calculation are special refractory of carbide, nitride and haride, such as ZrB2, TiB2, SiN4, AlN,TiN, ZrN, BN, SiC, TiC, ZrC and CaC2. Based on the Miedema model on heat formation of binary alloys, the changes of Gibbs free energy of the interactions of molten Ti - 6Al - 4V alloy and the above molding materials have been analyzed and calculated hy calculating the activities and activity coefficients of alloying elements in the Ti melt.The results show that the changes of Cibbe free energy of the interactions of the molding materials are all negative. It means that such reactions are spontaneous. But the free energy increases slightly as the content of alloying element in the Ti melt increases, where the effect of Al element is more notable than that of V. Meanwhile, the chemical activity of Ti meli decreases as the alloying elements are added.展开更多
Non-equilibrium thermodynamics theory is used to analyze the transmembrane heat and moisture transfer process,which can be observed in a membrane-type total heat exchanger(THX).A theoretical model is developed to simu...Non-equilibrium thermodynamics theory is used to analyze the transmembrane heat and moisture transfer process,which can be observed in a membrane-type total heat exchanger(THX).A theoretical model is developed to simulate the coupled heat and mass transfer across a membrane,total coupling equations and the expressions for the four characteristic parameters including the heat transfer coefficient,molardriven heat transfer coefficient,thermal-driven mass transfer coefficient,and mass transfer coefficient are derived and provided,with the Onsager’s reciprocal relation being confirmed to verify the rationality of the model.Calculations are conducted to investigate the effects of the membrane property and air state on the coupling transport process.The results show that the four characteristic parameters directly affect the transmembrane heat and mass fluxes:the heat and mass transfer coefficients are both positive,meaning that the temperature difference has a positive contribution to the heat transfer and the humidity ratio difference has a positive contribution to the mass transfer.The molar-driven heat transfer and thermal-driven mass transfer coefficients are both negative,implying that the humidity ratio difference acts to reduce the heat transfer and the temperature difference works to diminish the mass transfer.The mass transfer affects the heat transfer by 1%–2%while the heat transfer influences the mass transfer by7%–14%.The entropy generation caused by the temperature difference-induced heat transfer is much larger than that by the humidity difference-induced mass transfer.展开更多
Nanofiltration of aqueous NaNO3 solution with a dynamically formed Zr(IV) hydrousoxide-PAA membrane is presented. The practical transpoft coefficients Lp, σ, ω were obtainedusing relationships of the non-equilibrium...Nanofiltration of aqueous NaNO3 solution with a dynamically formed Zr(IV) hydrousoxide-PAA membrane is presented. The practical transpoft coefficients Lp, σ, ω were obtainedusing relationships of the non-equilibrium thermodynamics and were used to calculate thefrictional coefficients of a friction model.展开更多
This contribution presents an outline of a new mathematical formulation for Classical Non-Equilibrium Thermodynamics (CNET) based on a contact structure in differential geometry. First a non-equilibrium state space is...This contribution presents an outline of a new mathematical formulation for Classical Non-Equilibrium Thermodynamics (CNET) based on a contact structure in differential geometry. First a non-equilibrium state space is introduced as the third key element besides the first and second law of thermodynamics. This state space provides the mathematical structure to generalize the Gibbs fundamental relation to non-equilibrium thermodynamics. A unique formulation for the second law of thermodynamics is postulated and it showed how the complying concept for non-equilibrium entropy is retrieved. The foundation of this formulation is a physical quantity, which is in non-equilibrium thermodynamics nowhere equal to zero. This is another perspective compared to the inequality, which is used in most other formulations in the literature. Based on this mathematical framework, it is proven that the thermodynamic potential is defined by the Gibbs free energy. The set of conjugated coordinates in the mathematical structure for the Gibbs fundamental relation will be identified for single component, closed systems. Only in the final section of this contribution will the equilibrium constraint be introduced and applied to obtain some familiar formulations for classical (equilibrium) thermodynamics.展开更多
The response of ecosystems to perturbations is considered from a thermodynamic perspective by acknowl-edging that, as for all macroscopic systems and processes, the dynamics and stability of ecosystems is sub-ject to ...The response of ecosystems to perturbations is considered from a thermodynamic perspective by acknowl-edging that, as for all macroscopic systems and processes, the dynamics and stability of ecosystems is sub-ject to definite thermodynamic law. For open ecosystems, exchanging energy, work, and mass with the en-vironment, the thermodynamic criteria come from non-equilibrium or irreversible thermodynamics. For ecosystems during periods in which the boundary conditions may be considered as being constant, it is shown that criteria from irreversible thermodynamic theory are sufficient to permit a quantitative prediction of ecosystem response to perturbation. This framework is shown to provide a new perspective on the popula-tion dynamics of real ecosystems.展开更多
Liquid vaporization under thermodynamic phase non-equilibrium condition at the gas-liquid interface is investigated over a wide range of fluid state typical of many liquid-fueled energy conversion systems. The validit...Liquid vaporization under thermodynamic phase non-equilibrium condition at the gas-liquid interface is investigated over a wide range of fluid state typical of many liquid-fueled energy conversion systems. The validity of the phase-equilibrium assumption commonly used in the existing study of liquid vaporization is examined using molecular dynamics theories. The interfacial mass flow rates on both sides of the liquid surface are compared to the net vaporization rate through an order-of-magnitude analysis.Results indicated that the phase-equilibrium assumption holds valid at relatively high pressures and low temperatures,and for droplets with relatively large initial diameters(for example,larger than 10 μm for vaporizing oxygen droplets in gaseous hydrogen in the pressure range from 10 atm to the oxygen critical state). Droplet vaporization under superheated conditions is also explored using classical binary homogeneous nucleation theory,in conjunction with a real-fluid equation of state. It is found that the bubble nucleation rate is very sensitive to changes in saturation ratio and pressure;it increases by several orders of magnitude when either the saturation ratio or the pressure is slightly increased. The kinetic limit of saturation ratio decreases with increasing pressure,leading to reduced difference between saturation and superheat conditions. As a result,the influence of nonequilibrium conditions on droplet vaporization is lower at a higher pressure.展开更多
The recent progress on thermodynamic properties of spectral radiant energy in the field of thermodynamics of radiation is reviewed. The effective temperature of photon Tλ representing the energy quality of photon is ...The recent progress on thermodynamic properties of spectral radiant energy in the field of thermodynamics of radiation is reviewed. The effective temperature of photon Tλ representing the energy quality of photon is introduced. The relation between Tλ and the wavelength λ is given as λTλ =c3=5.33016×10?3 m·K. The en- tropy constant of photon is given as sλ=3.72680×10?23 J/K. The exergy, entropy and enthalpy of the spectral blackbody radiation, the equilibrium cavity radiation, the radiation flux in open system are discussed by using Tλ and sλ, as well as the en- tropy change in the process of the state transformation of photon gas. By analyzing the exergy of spectral radiation, the exergy efficiency of spectral radiant energy available for photosynthesis is proved to be higher than that of light energy. The method for the irreversible loss of exergy calculation in radiant energy converters is also discussed.展开更多
Numerous models have been proposed in the literature to include phase change into numerical simulations of two-phase flows.This review paper presents the modeling options that have been taken in order to obtain a mode...Numerous models have been proposed in the literature to include phase change into numerical simulations of two-phase flows.This review paper presents the modeling options that have been taken in order to obtain a model for violent separated flows with application to sloshing wave impacts.A relaxation model based on linear non-equilibrium thermodynamics has been chosen to compute the rate of phase change.The integration in the system of partial differential equations is done through a non-conservative advection term.For each of these modelling choices,some alternative models from the literature are presented and discussed.The theoretical framework for all phase change model(conservation equations and entropy growth)is also summarized.展开更多
This paper aims to find a more general analysis method for the refrigeration performance,and to design a high efficiency modular cooling structure of water-cooled plate.A new analysis method,namely current and refrige...This paper aims to find a more general analysis method for the refrigeration performance,and to design a high efficiency modular cooling structure of water-cooled plate.A new analysis method,namely current and refrigeration rate density analysis,is proposed.The general refrigeration performance calculation equations are obtained.A finite-time thermodynamic model of the thermoelectric device is established considering Thomson effect.The basic structure of water-cooled thermoelectric air-conditioner is designed and the specific calculation method is given.The influences of input current density,filling factor and heat transfer conditions on refrigeration performance of the thermoelectric air-conditioner are analyzed,which is compared with refrigeration performance of air-cooled thermoelectric air-conditioner.The results show that the maximum refrigeration rate density of the water-cooled thermoelectric air-conditioner is 8.65 k W/m^(2),and the maximum coefficient of performance(COP)is 2.27 in the case of the cooling temperature differenceΔT=5 K.Compared withΔT=5 K,the maximum refrigeration rate density and the maximum COP ofΔT=15 K decreases by 27.98%and 76.65%,respectively.At the filling factorθ=0.43,the refrigeration rate density and COP are 2.57 k W/m~2 and 1.24,respectively.The experimental device of thermoelectric air-conditioner is established to verify the model.The experimental results show that the maximum value of input current and COP is 4 A and 0.95 with the efficient water-cooling method,respectively.The experimental data coincides with the theoretical calculation,which shows the validity of the analysis method and cooling method.展开更多
基金supported by the U.S. National Science Foundation's Biocomplexity Program (DEB-0421530)Long-Term Ecological Research Program (Sevilleta LTER,DEB-0620482)
文摘Ecosystem stays far from thermodynamic equilibrium. Through the interactions among biotic and abiotic components, and encompassing physical environments, ecosystem forms a dissipative struc- ture that allows it to dissipate energy continuously and thereby remains functional over time. Biotic regulation of energy and material fluxes in and out of the ecosystem allows it to maintain a homeostatic state which corresponds to a self-organized state emerged in a non-equilibrium thermodynamic system. While the associated self-organizational processes approach to homeostatic state, entropy (a measure of irre- versibility) degrades and dissipation of energy increases. We propose here that at a homeostatic state of ecosystem, biodiversity which includes both phenotypic and functional diversity, attains optimal values. As long as biodiversity remains within its optimal range, the corresponding homeostatic state is maintained. However, while embedded environmental conditions fluctuate along the gradient of accelerating changes, phenotypic diversity and functional diversity contribute inversely to the associated self-organizing proc- esses. Furthermore, an increase or decrease in biodiversity outside of its optimal range makes the eco- system vulnerable to transition into a different state.
基金This work was supported by Postdoctoral Foundation of Northwestern Polytechnical University and Science Research FOundation o
文摘A thermodynamic model has been built up for the interactions between molten Ti alloys and oxide molding materials in the way of decomposition and solution of molding materials, then the influences on the reaction free energy changes have been calculated and discussed.
文摘The interactions of Ti - 6Al - 4V alloy with wide potential applications in aeronautics and aerospace indus-tries with the molding materials have been analyed and calculated by a thermodynamic method. The molding materials involved in the calculation are special refractory of carbide, nitride and haride, such as ZrB2, TiB2, SiN4, AlN,TiN, ZrN, BN, SiC, TiC, ZrC and CaC2. Based on the Miedema model on heat formation of binary alloys, the changes of Gibbs free energy of the interactions of molten Ti - 6Al - 4V alloy and the above molding materials have been analyzed and calculated hy calculating the activities and activity coefficients of alloying elements in the Ti melt.The results show that the changes of Cibbe free energy of the interactions of the molding materials are all negative. It means that such reactions are spontaneous. But the free energy increases slightly as the content of alloying element in the Ti melt increases, where the effect of Al element is more notable than that of V. Meanwhile, the chemical activity of Ti meli decreases as the alloying elements are added.
基金funded by Beijing Natural Science Foundation(3182015)。
文摘Non-equilibrium thermodynamics theory is used to analyze the transmembrane heat and moisture transfer process,which can be observed in a membrane-type total heat exchanger(THX).A theoretical model is developed to simulate the coupled heat and mass transfer across a membrane,total coupling equations and the expressions for the four characteristic parameters including the heat transfer coefficient,molardriven heat transfer coefficient,thermal-driven mass transfer coefficient,and mass transfer coefficient are derived and provided,with the Onsager’s reciprocal relation being confirmed to verify the rationality of the model.Calculations are conducted to investigate the effects of the membrane property and air state on the coupling transport process.The results show that the four characteristic parameters directly affect the transmembrane heat and mass fluxes:the heat and mass transfer coefficients are both positive,meaning that the temperature difference has a positive contribution to the heat transfer and the humidity ratio difference has a positive contribution to the mass transfer.The molar-driven heat transfer and thermal-driven mass transfer coefficients are both negative,implying that the humidity ratio difference acts to reduce the heat transfer and the temperature difference works to diminish the mass transfer.The mass transfer affects the heat transfer by 1%–2%while the heat transfer influences the mass transfer by7%–14%.The entropy generation caused by the temperature difference-induced heat transfer is much larger than that by the humidity difference-induced mass transfer.
文摘Nanofiltration of aqueous NaNO3 solution with a dynamically formed Zr(IV) hydrousoxide-PAA membrane is presented. The practical transpoft coefficients Lp, σ, ω were obtainedusing relationships of the non-equilibrium thermodynamics and were used to calculate thefrictional coefficients of a friction model.
文摘This contribution presents an outline of a new mathematical formulation for Classical Non-Equilibrium Thermodynamics (CNET) based on a contact structure in differential geometry. First a non-equilibrium state space is introduced as the third key element besides the first and second law of thermodynamics. This state space provides the mathematical structure to generalize the Gibbs fundamental relation to non-equilibrium thermodynamics. A unique formulation for the second law of thermodynamics is postulated and it showed how the complying concept for non-equilibrium entropy is retrieved. The foundation of this formulation is a physical quantity, which is in non-equilibrium thermodynamics nowhere equal to zero. This is another perspective compared to the inequality, which is used in most other formulations in the literature. Based on this mathematical framework, it is proven that the thermodynamic potential is defined by the Gibbs free energy. The set of conjugated coordinates in the mathematical structure for the Gibbs fundamental relation will be identified for single component, closed systems. Only in the final section of this contribution will the equilibrium constraint be introduced and applied to obtain some familiar formulations for classical (equilibrium) thermodynamics.
文摘The response of ecosystems to perturbations is considered from a thermodynamic perspective by acknowl-edging that, as for all macroscopic systems and processes, the dynamics and stability of ecosystems is sub-ject to definite thermodynamic law. For open ecosystems, exchanging energy, work, and mass with the en-vironment, the thermodynamic criteria come from non-equilibrium or irreversible thermodynamics. For ecosystems during periods in which the boundary conditions may be considered as being constant, it is shown that criteria from irreversible thermodynamic theory are sufficient to permit a quantitative prediction of ecosystem response to perturbation. This framework is shown to provide a new perspective on the popula-tion dynamics of real ecosystems.
文摘Liquid vaporization under thermodynamic phase non-equilibrium condition at the gas-liquid interface is investigated over a wide range of fluid state typical of many liquid-fueled energy conversion systems. The validity of the phase-equilibrium assumption commonly used in the existing study of liquid vaporization is examined using molecular dynamics theories. The interfacial mass flow rates on both sides of the liquid surface are compared to the net vaporization rate through an order-of-magnitude analysis.Results indicated that the phase-equilibrium assumption holds valid at relatively high pressures and low temperatures,and for droplets with relatively large initial diameters(for example,larger than 10 μm for vaporizing oxygen droplets in gaseous hydrogen in the pressure range from 10 atm to the oxygen critical state). Droplet vaporization under superheated conditions is also explored using classical binary homogeneous nucleation theory,in conjunction with a real-fluid equation of state. It is found that the bubble nucleation rate is very sensitive to changes in saturation ratio and pressure;it increases by several orders of magnitude when either the saturation ratio or the pressure is slightly increased. The kinetic limit of saturation ratio decreases with increasing pressure,leading to reduced difference between saturation and superheat conditions. As a result,the influence of nonequilibrium conditions on droplet vaporization is lower at a higher pressure.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 50576092 and 50736005)
文摘The recent progress on thermodynamic properties of spectral radiant energy in the field of thermodynamics of radiation is reviewed. The effective temperature of photon Tλ representing the energy quality of photon is introduced. The relation between Tλ and the wavelength λ is given as λTλ =c3=5.33016×10?3 m·K. The en- tropy constant of photon is given as sλ=3.72680×10?23 J/K. The exergy, entropy and enthalpy of the spectral blackbody radiation, the equilibrium cavity radiation, the radiation flux in open system are discussed by using Tλ and sλ, as well as the en- tropy change in the process of the state transformation of photon gas. By analyzing the exergy of spectral radiation, the exergy efficiency of spectral radiant energy available for photosynthesis is proved to be higher than that of light energy. The method for the irreversible loss of exergy calculation in radiant energy converters is also discussed.
文摘Numerous models have been proposed in the literature to include phase change into numerical simulations of two-phase flows.This review paper presents the modeling options that have been taken in order to obtain a model for violent separated flows with application to sloshing wave impacts.A relaxation model based on linear non-equilibrium thermodynamics has been chosen to compute the rate of phase change.The integration in the system of partial differential equations is done through a non-conservative advection term.For each of these modelling choices,some alternative models from the literature are presented and discussed.The theoretical framework for all phase change model(conservation equations and entropy growth)is also summarized.
基金supported by The National Natural Science Foundation of P.R.China(Project No.11974429 and Project No.51576207)the Natural Science Foundation of Naval University of Engineering(20161505)。
文摘This paper aims to find a more general analysis method for the refrigeration performance,and to design a high efficiency modular cooling structure of water-cooled plate.A new analysis method,namely current and refrigeration rate density analysis,is proposed.The general refrigeration performance calculation equations are obtained.A finite-time thermodynamic model of the thermoelectric device is established considering Thomson effect.The basic structure of water-cooled thermoelectric air-conditioner is designed and the specific calculation method is given.The influences of input current density,filling factor and heat transfer conditions on refrigeration performance of the thermoelectric air-conditioner are analyzed,which is compared with refrigeration performance of air-cooled thermoelectric air-conditioner.The results show that the maximum refrigeration rate density of the water-cooled thermoelectric air-conditioner is 8.65 k W/m^(2),and the maximum coefficient of performance(COP)is 2.27 in the case of the cooling temperature differenceΔT=5 K.Compared withΔT=5 K,the maximum refrigeration rate density and the maximum COP ofΔT=15 K decreases by 27.98%and 76.65%,respectively.At the filling factorθ=0.43,the refrigeration rate density and COP are 2.57 k W/m~2 and 1.24,respectively.The experimental device of thermoelectric air-conditioner is established to verify the model.The experimental results show that the maximum value of input current and COP is 4 A and 0.95 with the efficient water-cooling method,respectively.The experimental data coincides with the theoretical calculation,which shows the validity of the analysis method and cooling method.