检索结果-南通市图书馆

Science china(Technological Sciences) 2010年第6期53卷 1666-1677页

作者： wei shuhuan,chen lingen & sun fengrui postgraduate school,naval university of engineering,wuhan 430033,china postgraduate school Naval University of Engineering

Using constructal entransy dissipation rate minimization method based on discrete variable cross-section conducting path,constructal optimizations of elemental area with variable cross-section conducting path are performed,and the results are compared with the optimization results of elemental area with the constant cross-section conducting *** comparison shows that the minimum mean temperature difference based on elemental area with variable cross-section conducting path increases and approaches a constant as the assembly's order increases,but the minimum mean temperature difference based on elemental area with constant cross-section conducting path decreases and approaches a constant as the assembly's order *** difference between them is caused by the different dimensionless mean temperature difference of the first order assembly.A universal constructal optimization method by self similar organization to improve heat transfer ability and its corresponding rule are *** the constructal optimization method by self similar organization based on entransy dissipation rate minimization objective,the mean temperature difference approaches a constant as the assembly's order increases.

关键词： constructal theory entransy entransy dissipation area-point conduction generalized thermodynamic optimization

“Volume-Point” heat conduction constructal optimization with entransy dissipation minimization objective based on rectangular element

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2008年第8期51卷 1283-1295页

作者： wei shuhuan, chen lingen & sun fengrui postgraduate school, naval university of engineering, wuhan 430033, china postgraduate school Naval University of Engineering

By taking equivalent thermal resistance, which reflects the average heat conduc- tion effect and is defined based on entransy dissipation, as optimization objective, the "volume to point" constructal problem of how to discharge the heat generated in a fixed volume to a heat sink on the border through relatively high conductive link is re-analyzed and re-optimized in this paper. The constructal shape of the control volume with the best average heat conduction effect is deduced. For the elemental area and the first order construct assembly, when the thermal current density in the high conductive link is linear with the length, the optimized shapes of assemble based on the minimization of entransy dissipation are the same as those based on minimization of maximum temperature difference, and the mean tem- perature difference is 2/3 of the maximum temperature difference. For the second and higher order construct assemblies, the thermal current densities in the high conductive link are not linear with the length, and the optimized shapes of assem- ble based on the minimization of entransy dissipation are different from those based on minimization of maximum temperature difference. For the same parame- ters, the constructs based on minimization of entransy dissipation and the con- structs based on minimization of maximum temperature difference are compared, and the results show that the constructs based on entransy dissipation can de- crease the mean temperature difference better than the constructs based on mini- mization of maximum temperature difference. But with the increase of the number of the order, the mean temperature difference does not always decrease, and there exist some fluctuations. Because the idea of entransy describes the heat transfer ability more suitably, all of the heat conduction constructal problems may be re-optimized based on it.

关键词： constructal theory entransy dissipation volume-point heat conduction generalized thermodynamic optimi- zation

Constructal optimization of a vertical insulating wall based on a complex objective combining heat flow and strength

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第8期53卷 2278-2290页

作者： XIE ZhiHui,chen lingen &sun fengrui postgraduate school,naval university of engineering,wuhan 430033,china postgraduate school Naval University of Engineering Wuhan China

For a vertical insulating wall,a product function of heat flow and strength with power weight is introduced as the complex optimization objective to compromise between insulating performance and mechanical *** the global constraints of fixed external dimensions and safety requirements,the constructal optimization of the wall is carried out by taking the complex function maximization as the *** is shown that the maximum of the complex-objective function and its corresponding optimal internal structure design under a certain environmental condition can be obtained by allowing the internal structure of the wall to vary(evolve)*** validity,effectivity and applicability of the complex function are proved by the results and the power weight parameter in the range from 0.4 to 4 can compromise between the requirements of insulating and strength simultaneously and *** constructal optimization with coequal attention to heat flow and strength and the corresponding results are discussed in *** optimal structure design and the corresponding performance analyses under various environmental conditions of application are *** the change of environment is greater and the total Rayleigh number is bigger,the insulating wall with large number of cavities should be *** the total Rayleigh number is small,the better performance can be obtained by reasonably employing the insulating wall with small number of *** complex function has better selfadaptability,and the results in the recent literature are special cases of this paper.

关键词： constructal theory insulating wall multidiscipline generalized thermodynamic optimization

Optimal paths for a light-driven engine with a linear phenomenological heat transfer law

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2010年第4期53卷 917-926页

作者： MA Kang, chen lingen & sun fengrui postgraduate school, naval university of engineering, wuhan 430033, china postgraduate school Naval University of Engineering Wuhan China

An irreversible light-driven engine is described in this paper, in which the heat transfer between the working fluid and the environment obeys a linear phenomenological heat transfer law [ q ∝Δ(T -1)], with a working fluid composed of the bimolecular reacting system 2SO 3 F■S 2 O 6 F2. Piston trajectories maximizing work output and minimizing entropy generation are determined for such an engine with rate-dependent loss mechanisms of friction and heat leakage. The optimal control theory is applied to determine the optimal configurations of the piston motion trajectory and the fluid temperature. Numerical examples for the optimal configuration are provided, and the obtained results are compared with those derived with Newtonian heat transfer law [ q ∝Δ(T )].

关键词： linear phenomenological heat transfer law maximum work output minimum entropy generation irreversible lightdriven engine optimal control finite time thermodynamics

Constructal optimization of twice Y-shaped assemblies of fins by taking maximum thermal resistance minimization as objective

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第10期53卷 2756-2764页

作者： XIE ZhiHui, chen lingen & sun fengrui postgraduate school, naval university of engineering, wuhan 430033, china postgraduate school Naval University of Engineering

In this paper,constructal optimization of the twice Y-shaped assemblies of fins with six freedom degrees (characteristic parameters of geometry) is performed by employing finite element method and taking dimensionless maximum thermal resistance as a performance index,and the heat transfer performance of the twice Y-shaped assemblies of fins under various conditions with different freedom degrees are analyzed. The results show that the twice assemblies can improve the heat transfer performance of Y-shaped fin remarkably,and the minimum maximum thermal resistance of the twice Y-shaped assemblies of fins decreases by 36.37% compared with that of once Y-shaped assembly of fins. It is also proved again that the larger the number of freedom degrees for evolving is,the more perfect the system performance is. The effects of different characteristic parameters of geometry on the performance of the twice Y-shaped assemblies of fins are different,one should pay different attention to these parameters in practical engineering designs. The effects of two angles on the maximum thermal resistance are larger,but the optima of the two angles are robust. The effects of two height ratios on the maximum thermal resistance are more remarkable than those of two thickness ratios.

关键词： constructal theory fin multi-scale enhanced heat transfer generalized thermodynamic optimization

Entransy dissipation minimization for liquid-solid phase change processes

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第4期53卷 960-968页

作者： XIA ShaoJun,chen lingen & sun fengrui postgraduate school,naval university of engineering,wuhan 430033,china postgraduate school Naval University of Engineering

The liquid-solid phase change process of a simple one-dimensional slab is studied in this *** taking entransy dissipation minimization as optimization objective,the optimal external reservoir temperature profiles are derived by using optimal control theory under the condition of a fixed freezing or melting *** entransy dissipation corresponding to the optimal heat exchange strategies of minimum entransy dissipation is 8/9 of that corresponding to constant reservoir temperature operations,which is independent of all system *** obtained results for entransy dissipation minimization are also compared with those obtained for the optimal heat exchange strategies of minimum entropy generation and constant reservoir temperature operations by numerical *** obtained results can provide some theoretical guidelines for the choice of optimal cooling or heating strategy in practical liquid-solid phase change processes.

关键词： liquid-solid phase change process entransy dissipation minimization optimal control finite time thermodynamics generalized thermodynamic optimization

Thermodynamic characteristics of a Brownian heat pump in a spatially periodic temperature field

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 876-885页

作者： DING ZeMin,chen lingen & sun fengrui postgraduate school,naval university of engineering,wuhan 430033,china naval university of engineering Postgraduate School Wuhan China (GRID:grid.472481.c) (ISNI:***)

This paper has studied the thermodynamic performance of a thermal Brownian heat pump,which consists of Brownian particles moving at a periodic sawtooth potential with external forces and contacting with the alternating hot and cold reservoirs along the space *** heat flows driven by both potential and kinetic energies are taken into *** analytical expressions for the heating load,coefficient of performance(COP) and power input of the Brownian heat pump are derived and the performance characteristics are obtained by numerical *** is shown that due to the heat flow via the change of kinetic energy of the particles,the Brownian heat pump is always irreversible and the COP can never attain the Carnot *** study has also investigated the influences of the operating parameters,*** external force,barrier height of the potential,asymmetry of the sawtooth potential and temperature ratio of the heat reservoirs,on the performance of the Brownian heat *** effective regions of external force and barrier height of the potential in which the Brownian motor can operates as a heat pump are *** results show that the performance of the Brownian heat pump greatly depends on the parameters;if the parameters are properly chosen,the Brownian heat pump may be controlled to operate in the optimal regimes.

关键词： Brownian heat pump COP heating load heat flow performance characteristics finite time thermodynamics

Constructal multidisciplinary optimization of electromagnet based on entransy dissipation minimization

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2009年第10期52卷 2981-2989页

作者： wei shuhuan chen lingen sun fengrui postgraduate school Naval University of EngineeringWuhan 430033China

Based on entransy dissipation, the mean temperature difference of solenoid (electromagnet) with high thermal conductivity material inserted is deduced, which can be taken as the fundament for heat transfer optimization using the extremum principle of entransy dissipation. Then, the electromagnet working at steady state (constant magnetic field, constant heat generating rate per unit volume) is optimized for entransy dissipation minimization (i.e. mean temperature difference minimization) with and without volume constraint. Besides, the effect of high thermal conductivity material on the magnetic field is analyzed, and the minimum mean temperature versus volume and magnetic induction characteristic are also studied.

关键词： constructal theory entransy dissipation electromagnet multidisciplinary optimization

Improvement of tree-like network constructal method for heat conduction optimization

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2006年第3期49卷 332-341页

作者： WU Wenjun chen lingen sun fengrui postgraduate school Naval University of Engineering Wuhan 430033 China Postgraduate School Naval University of Engineering Wuhan 430033 China Postgraduate School Naval University of Engineering Wuhan 430033 China

The analysis of the “tree-like network” construct method has been repeated. The high effective conduction channel distribution has been optimized again, without the premise that the new order assembly construct must be assembled by the optimized last order construct. It is proved that the “tree-like network” construct method is faultiness. A more optimal construct is obtained,; when the thermal conductivity; the proportion of the two heat conduction materials are constant, the limit of the minimum heat resistance is derived. All these conclusions can be used to guide the engineering application.

关键词： constructal theory, 'tree-like network' construct method, high effective conduction channel distribution, generalized thermodynamic optimization.

Optimal performance of a generalized irreversible four-reservoir isothermal chemical potential transformer

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2008年第10期51卷 958-970页

作者： XIA Dan chen lingen sun fengrui postgraduate school Naval University of EngineeringWuhan 430033China

A new cyclic model of a four-reservoir isothermal chemical potential transformer with irreversible mass transfer, mass leakage and internal dissipation is put forward in this paper. The optimal relation be-tween the coefficient of performance (COP) and the rate of energy pumping of the generalized irre-versible four-reservoir isothermal chemical potential transformer has been derived by using finite-time thermodynamics or thermodynamic optimization. The maximum COP and the corresponding rate of energy pumping, as well as the maximum rate of energy pumping and the corresponding COP, have been obtained. Moreover, the influences of the irreversibility on the optimal performance of the iso-thermal chemical potential transformer have been revealed. It was found that the mass leakage affects the optimal performance both qualitatively and quantitatively, while the internal dissipation affects the optimal performance quantitatively. The results obtained herein can provide some new theoretical guidelines for the optimal design and development of a class of isothermal chemical potential trans-formers, such as mass exchangers, electrochemical, photochemical and solid state devices, fuel pumps, etc.

关键词： is othermal four-reservoir chemical potential transformer coefficient of performance rate of energy pumping finite time thermody-namics