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| 1 | Application of entransy dissipation extremum principle in radiative heat transfer optimization显示文摘The concepts of entransy flux and entransy dissipation in radiative heat transfer were introduced based on the analogy with heat conduction and heat convection processes. Entransy will be partially dissipated during the radiative heat transfer processes due to the irreversibility. The extremum principle of entransy dissipation was developed for optimizing radiative heat transfer processes. This principle states that for a fixed boundary temperature the radiative heat transfer is optimized when the entransy dissipation is maximized, while for a fixed boundary heat flux the radiative heat transfer process is optimized when the entransy dissipation is minimized. Finally, examples for the application of the entransy dissipation extre- mum principle are presented. | Jing Wu XinGang Liang | 2008 | Science China(Technological Sciences)2008，51，8： | 56 |
| 2 | Homogenization of temperature field and temperature gradient field显示文摘The homogenization of temperature field and temperature gradient field are very important for many devices, systems and equipments, such as satellites and electronic devices. This paper discusses the distribution optimization of the limited high conductivity material with the simulated annealing algorithm to homogenize the temperature field in a two-dimensional heat conduction problem. At the same time, the temperature gradient field is homogenized with the bionic optimization method. The results show that the two optimization targets are consistent to some extent, while the bionic optimization method could save much computing time. In addition, there are threshold values for the amount of high conductivity material and the ratio of the high conductivity to the low conductivity beyond which further increasing these values brings very little improvement on the homogenization of temperature field and temperature gradient field. | CHENG XueTao XU XiangHua LIANG XinGang | 2009 | Science China(Technological Sciences)2009，52，10： | 35 |
| 3 | Entransy decrease principle of heat transfer in an isolated system显示文摘The entropy increase principle for an isolated system and the criteria of thermal equilibrium for an isolated system and systems with prescribed temperature and volume can be derived on the basis of the concept of entropy and the first and second laws of thermodynamics. In this paper, the entransy decrease principle for an isolated system is introduced on the basis of the concept of entransy. It is found that the entransy of an isolated system always decreases during heat transfer. This principle can be taken as an expression of the second law of thermodynamics for heat transfer. The thermal equilibrium criteria for an isolated system and a closed system are also introduced. It is found that when an isolated system reaches thermal equilibrium, its entransy is a minimum value. This criterion is referred to as the minimum entransy principle. When a closed system reaches thermal equilibrium, its free entransy is also a minimum value. This criterion is referred to as the minimum free entransy principle. Therefore, like entropy, entransy can be considered an arrow of time in heat transfer and used to describe the thermal equilibrium state. | CHENG XueTao LIANG XinGang GUO ZengYuan | 2011 | Chinese Science Bulletin2011，56，9： | 29 |
| 4 | Radiative entransy flux in enclosures with non-isothermal or non-grey,opaque,diffuse surfaces and its application显示文摘The spectral radiative entransy flux and the total radiative entransy flux are defined for the steady radiative heat transfer processes in enclosures composed of non-isothermal or non-grey,opaque,diffuse surfaces.Based on the definitions,the radiative entransy flux balance equation and the radiative entransy dissipation functions are introduced under spectral and total wavelength condition.Furthermore,the minimum principle of radiative entransy loss,the extreme principle of radiative entransy dissipation and the minimum principle of radiative thermal resistance are developed.The minimum principle of radiative entransy loss shows that the potential and the net radiative heat flux distribution which meet the control equations and the boundary conditions would make the radiative entransy loss minimum if the net radiative heat flux or the potential distribution of the radiative heat transfer system is given.The extreme principle of radiative entransy dissipation indicates that the minimum radiative entransy dissipation leads to the minimum average potential difference for the prescribed total radiative heat exchange and the maximum radiative entransy dissipation leads to the maximum radiative heat exchange for the prescribed average potential difference.Moreover,the minimum principle of radiative thermal resistance tells us that the aforementioned extreme values of radiative entransy dissipation both correspond to the minimum value of radiative thermal resistance.Application examples are given for the extreme principle of spectral radiative entransy dissipation and the minimum principle of spectral radiative thermal resistance,and the principles are proved to be applicable. | CHENG XueTao XU XiangHua LIANG XinGang | 2011 | Science China(Technological Sciences)2011，54，9： | 20 |
| 5 | Application of entransy to optimization design of parallel thermal network of thermal control system in spacecraft显示文摘For distribution optimization of the flow rate of cold fluid and heat transfer area in the parallel thermal network of the thermal control system in spacecraft,a physical and mathematical model is set up,analyzed and discussed with the entransy theory.It is found that the optimization objective of this problem and the optimization direction of the extremum entransy dissipation principle are consistent in theory.For a two-branch thermal network system,the distributions of the flow rate of the cold fluid and the heat transfer area are optimized by calculating the extremum entransy dissipation with the Newton method.The influential factors of the optimized distributions are also analyzed and discussed.The results show that the main influence factors are the heat transfer rate of the branches and the total heat transfer area.The total flow rate of the cold fluid has a threshold,beyond which further increasing its value brings very little influence on the optimization results.Moreover,the difference between the extremum entransy dissipation principle and the minimum entropy generation principle is also discussed when they are used to analyze the problem in this paper,and the extremum entransy dissipation principle is found to be more suitable.In addition,the Newton method is mathematically efficient to solve the problem,which could accomplish the optimized distribution in a very short time for a ten-branch thermal network system. | CHENG XueTao XU XiangHua LIANG XinGang | 2011 | Science China(Technological Sciences)2011，54，4： | 19 |
| 6 | Optimization of heat transfer and heat-work conversion based on generalized heat transfer law显示文摘Examples of heat transfer and heat-work conversion are optimized with entropy generation and entransy loss,respectively based on the generalized heat transfer law in this paper.The applicability of entropy generation and entransy loss evaluation in these optimization problems is analyzed and discussed.The results show that the entransy loss rate reduces to the entransy dissipation rate in heat transfer processes,and that the entransy loss evaluation is effective for heat transfer optimization.However,the maximum heat transfer rate does not correspond to the minimum entropy generation rate with prescribed heat transfer temperature difference,which indicates that the entropy generation minimization is not always appropriate to heat transfer optimization.For heat-work conversion processes,the maximum entransy loss rate and the minimum entropy generation rate both correspond to the maximum output power,and they are both appropriate to the optimization of the heat-work conversion processes discussed in this paper. | CHENG XueTao WANG WenHua LIANG XinGang | 2012 | Science China(Technological Sciences)2012，55，10： | 19 |
| 7 | Entransy analysis of open thermodynamic systems显示文摘The concept of entransy developed in recent years can describe the heat transport ability.This paper extends this concept to the open thermodynamic system and defines the concept of enthalpy entransy.The entransy balance equation of steady open thermodynamic systems,as well as the concept of entransy loss,is developed.The entransy balance equation is applied to analyzing and discussing the air standard cycle.It is found that the entransy loss rate can describe the change in net power output from the cycle but the entropy generation rate cannot when the heat absorbed by the working medium is from the combustion reaction of the gas fuel.When the working medium is heated by a high temperature stream,both the maximum entransy loss rate and the minimum entropy generation rate correspond to the maximum net power output from the cycle.Hence,the concept of entransy loss is an appropriate figure of merit that describes the cycle performance. | CHENG XueTao WANG WenHua LIANG XinGang | 2012 | Chinese Science Bulletin2012，57，22： | 16 |
| 8 | Work entransy and its applications显示文摘The entransy theory has been applied to the analyses of heat-work conversion systems. The physical meaning and the applications of work entransy are analyzed and discussed in this paper. Work entransy, which is clarified to be a process dependent quantity, is not the entransy of work, but the system entransy change accompanying work transfer. The relationship between the work entransy and the output work is set up. When the application preconditions are satisfied, larger work entransy leads to larger output work. Entransy loss, which was proposed and applied to heat work conversion processes with irreversible heat transfer, is the net entransy flow into the system and the summation of work entransy and entransy dissipation. The application preconditions of entransy loss are also discussed. | CHENG XueTao LIANG XinGang | 2015 | Science China(Technological Sciences)2015，58，12： | 14 |
| 9 | Discussion on the extensions of the entransy theory显示文摘In this paper,the preconditions forthe extensions of the entransy theory are summarized and discussed.As the physical meaning | CHENG XueTao ZHAO JianMing LIANG XinGang | 2017 | Science China(Technological Sciences)2017，60，3： | 13 |
| 10 | Theoretical analyses of the performance of a concentrating photovoltaic/thermal solar system with a mathematical and physical model, entropy generation minimization and entransy theory显示文摘In this paper, the performance of a concentrating photovoltaic/thermal solar system is numerically analyzed with a mathematical and physical model. The variations of the electrical efficiency and the thermal efficiency with the operation parameters are calculated. It is found that the electrical efficiency increases at first and then decreases with increasing concentration ratio of the sunlight, while the thermal efficiency acts in an opposite manner. When the velocity of the cooling water increases, the electrical efficiency increases. Considering the solar system, the surface of the sun, the atmosphere and the environment, we can get a coupled energy system, which is analyzed with the entropy generation minimization and the entransy theory. This is the first time that the entransy theory is used to analyze photovoltaic/thermal solar system. When the concentration ratio is fixed, it is found that both the minimum entropy generation rate and the maximum entransy loss rate lead to the maximum electrical output power,while both the minimum entropy generation numbers and the maximum entransy loss coefficient lead to the maximum electrical efficiency. When the concentrated sunlight is not fixed, it is shown that neither smaller entropy generation rate nor larger entransy loss rate corresponds to larger electrical output power. Smaller entropy generation numbers do not result in larger electrical efficiency, either. However, larger entransy loss coefficient still corresponds to larger electrical efficiency. | CHENG XueTao XU XiangHua LIANG XinGang | 2018 | Science China(Technological Sciences)2018，61，6： | 13 |
| 11 | Power output analyses and optimizations of the Stirling cycle显示文摘Based on the finite time thermodynamics theory,the entransy theory and the entropy theory,the Stirling cycles under different conditions are analyzed and optimized with the maximum output power as the target in this paper.The applicability of entransy loss(EL),entransy dissipation(ED),entropy generation(EG),entropy generation number(EGN) and modified entropy generation number(MEGN) to the system optimization is investigated.The results show that the maximum EL rate corresponds to the maximum power output of the cycle working under the infinite heat reservoirs whose temperatures are prescribed,while the minimum EG rate and the extremum ED rate do not.For the Stirling cycle working under the finite heat reservoirs provided by the hot and cold streams whose inlet temperatures and the heat capacity flow rates are prescribed,the maximum EL rate,the minimum EG rate,the minimum EGN and the minimum MEGN all correspond to the maximum power output,but the extremum ED rate does not.When the heat capacity flow rate of the hot stream increases,the power output,the EL rate,the EG rate and the ED rate increase monotonously,while the EGN and the MEGN decrease first and then increase.The EL has best consistency in the power output optimizations of the Stirling cycles discussed in this paper. | ZHOU Bing CHENG XueTao LIANG XinGang | 2013 | Science China(Technological Sciences)2013，56，1： | 12 |
| 12 | Entransy dissipation,entransy-dissipation-based thermal resistance and optimization of one-stream hybrid thermal network显示文摘The one-stream hybrid thermal network is analyzed and discussed based on the entransy theory,and the results are compared with those from the entropy generation optimization.The theoretical analysis indicates that the minimum heat-flow-weighted temperature of the thermal networks corresponds to the minimum entransy dissipation rate and the minimum thermal resistance.For a simple hybrid thermal network consisting of three thermal components,the expression of entransy dissipation is conducted,and the heat transfer area and the mass flow rate are calculated and optimized.The optimal results are obtained in order to minimize the entransy dissipation and the thermal resistance.The optimal results are calculated for various combinations,such as series connection,parallel connection and other hybrid connections.The numerical results are in accordance with the theoretical analysis.Both the theoretical analysis and the numerical results show that the minimum entransy dissipation and the minimum thermal resistance correspond to the minimum heat-flow-weighted temperature of the thermal networks while the minimum entropy generation does not. | WANG WenHua CHENG XueTao LIANG XinGang | 2013 | Science China(Technological Sciences)2013，56，2： | 11 |
| 13 | Entransy and entropy analyses of heat pump systems显示文摘In this paper,heat pump systems are analyzed with entransy increase and entropy generation.The extremum entransy increase principle is developed.When the equivalent temperatures of the high and low temperature heat sources are fixed,the theoretical analyses and numerical results both show that the maximum COP leads to the maximum entransy increase rate for fixed input power,while it leads to the minimum entransy increase rate for fixed heat flow absorbed from the low temperature heat source.The minimum entropy generation principle shows that the minimum entropy generation rate always leads to the maximum COP for fixed input power or fixed heat flow absorbed from the low temperature heat source when the equivalent thermodynamic forces of the high and low temperature heat sources are given.Further discussions show that only the entransy increase rate always increases with increasing heat flow rate into the high temperature heat source for the discussed cases. | CHENG XueTao LIANG XinGang | 2013 | Chinese Science Bulletin2013，58，36： | 10 |
| 14 | Entransy analyses of the thermodynamic cycle in a turbojet engine显示文摘The analysis and the design of turbojet engines are of great importance to the improvement of the system performance.Many researchers focus on these topics,and many important and interesting results have been obtained.In this paper,the thermodynamic cycle in a turbojet engine is analyzed with the entransy theory and the T-Q diagram.The ideal thermodynamic cycle in which there is no inner irreversibility is analyzed,as well as the influences from some inner irreversible factors,such as the heat transfer process,the change of the component of the working fluid and the viscosity of the working fluid.For the discussed cases,it is shown that larger entransy loss rate always results in larger output power,while smaller entropy generation rate does not always.The corresponding T-Q diagrams are also presented,with which the change tendencies of the entransy loss rate and the output power can be shown very intuitively.It is shown that the entransy theory is applicable for analyzing the inner irreversible thermodynamic cycles discussed in this paper.Compared with the concept of entropy generation,the concept of entransy loss and the corresponding T-Q diagram are more suitable for describing the change of the output power of the analyzed turbojet engine no matter if the inner irreversible factors are considered. | CHENG XueTao LIANG XinGang | 2017 | Science China(Technological Sciences)2017，60，8： | 7 |
| 15 | Molecular dynamics study on thermal conductivity of nano-scale thin films显示文摘A simple and effective model of heat conduction across thin films is set up and molecular dynamics simulations are implemented to explore the thermal conductivity of nanoscale thin dielectric films in the direction perpendicular to the film plane. Solid argon is selected as the model system due to its reliable experimental data and potential function. Size effects of the thermal conductivity across thin films are found by computer simulations: in a film thickness range of 2-10 nm, the conductivity values are remarkably lower than the corresponding bulk experimental data and increase as the thickness increases. The consistency between the approximate solution of the phonon Boltzmann transport equation and the simulation results ascribes the thermal conductivity size effect to the phonon scattering at film boundaries. | Xiaoli Feng Zhixin Li Xingang Liang Zengyuan Guo | 2001 | Chinese Science Bulletin2001，46，7： | 7 |
| 16 | Entransy dissipation and irreversibility of some thermodynamic processes显示文摘The relationship between entransy dissipation and the irreversibility of some thermodynamic processes, such as heat transfer, work-heat conversion, free expansion, isothermal diffusion etc., are analyzed in this paper. The results show that there is entropy generation but no entransy dissipation in irreversible work-heat conversion, free expansion and isothermal diffusion. Therefore, entransy dissipation cannot be used to describe the irreversibility of these processes. Both entropy generation and entransy dissipation exist in heat transfer process, which indicates that the entransy dissipation can be used to describe the irreversibility of heat transfer processes. Furthermore, the irreversibility of endoreversible cycles is analyzed. As all the irreversibility in endoreversible cycles is attributed to heat transfer between the heat sources and the working medium, entransy dissipation can be used to describe the irreversibility of this kind of cycles. To verify this conclusion, numerical examples of the endoreversible Carnot cycle are discussed. | WANG WenHua CHENG XueTao LIANG XinGang | 2012 | Chinese Science Bulletin2012，57，31： | 6 |
| 17 | Vertical distribution of aerosol optical properties based on aircraft measurements over the Loess Plateau in China显示文摘Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients(σsc), absorption coefficients(σab),Angstr?m exponent(α), single scattering albedo(ω), backscattering ratio(βsc), aerosol mass scattering proficiency(Q sc) and aerosol surface scattering proficiency(Q sc′) were obtained. The mean statistical values of σsc were 77.45 Mm-1(at 450 nm), 50.72 Mm-1(at 550 nm), and32.02 Mm-1(at 700 nm). The mean value of σab was 7.62 Mm-1(at 550 nm). The mean values ofα, βsc and ω were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. Most effective diameters(ED) of aerosols were less than 0.8 μm. The vertical profiles of σsc,, α, βsc, Q sc and Q sc′ showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both α and βsc had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of σsc, α, βsc, Q sc, Q sc′, σab and ω at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions. | Junxia Li Xingang Liu Liang Yuan Yan Yin Zhanqing Li Peiren Li Gang Ren Lijun Jin Runjun Li Zipeng Dong Yiyu Li Junmei Yang | 2015 | Journal of Environmental Sciences2015，27，8： | 6 |
| 18 | Entransy functions for steady heat transfer显示文摘In this paper, the entransy functions for steady heat transfer are summarized and discussed based on the variational theory and the entransy theory. The entransy functions for steady convective heat transfer are derived for the first time. In steady heat transfer processes, it is shown that the steady distributions of heat flux and temperature(radiative thermal potential) should make the corresponding entransy functions reach their minimum values when the temperature(radiative thermal potential) or the heat flux of the boundary is given. The extremum entransy dissipation principles and the minimum entransy-dissipation-based thermal resistance principles are compared with the entransy functions. It is shown that the entransy functions can describe a steady state,but cannot directly give a way to optimize heat transfer processes, while the extremum entransy dissipation principles and the minimum entransy-dissipation-based thermal resistance principles act in an opposite way. | CHENG XueTao LIANG XinGang | 2019 | Science China(Technological Sciences)2019，62，10： | 5 |
| 19 | Some effects of interface on fluid flow and heat transfer on micro-and nanoscale显示文摘The interfacial effects on flow and heat transfer on micro/nano scale are discussed in this paper. Dif- ferent from bulk cases where interfaces can be simply treated as a boundary, the interfacial effects are not limited to the interface on a microscale but could extend into a significant, even the whole domain of the flow and heat transfer field when the characteristic size of the domain is close to the mean free path (MFP) of the carriers inside an object. Most of microscale thermal phenomena result from interfa- cial interactions. Any changes in the interactions between the object and boundary particles, such as the force between fluid and solid wall particles, microstructure of interfaces, could affect thermal properties, flow and heat transfer characteristics and hence change thermal conductivity, velocity and temperature profiles, friction coefficient and thermal radiative properties, etc. The properties of nano- structure or flow and heat transfer features of fluid in micro/nanostructures not only depend on them- selves, but also on the interaction with the interface because the interface impact can go deep inside the flow. The same fluid, same channel geometry but different wall materials could have different flow and heat transport characteristics on microscale. | LIANG XinGang | 2007 | Chinese Science Bulletin2007，52，18： | 4 |
| 20 | Relationship between microstate number and available entransy显示文摘Based on the relationship between entransy and microstate number, we discuss the variations of the available transport entransy, the unavailable transport entransy, the available conversion entransy and the unavailable conversion entransy with the microstate number. We focus on physical processes in which heat is used for heating/cooling or doing work. When heat is transported for heating or cooling, the available transport entransy increases if the increase in microstate number is due to the increase in internal energy of the system, and decreases if the increase in microstate number is due to spontaneous heat transfer. When heat is used to do work, both the available conversion entransy and the unavailable conversion entransy increase if the increase in microstate number relates to the growth in internal energy of the system. The available conversion entransy decreases and the unavailable conversion entransy increases if the increase in microstate number results from spontaneous heat transfer. | CHENG XueTao LIANG XinGang | 2012 | Chinese Science Bulletin2012，57，24： | 3 |
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