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Optimization of heat transfer and heat-work conversion based on generalized heat transfer law

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Science China(Technological Sciences) 2012年第10期55卷 2847-2855页

作者： cheng xuetao WANG WenHua LIANG XinGang Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084China

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 *** applicability of entropy generation and entransy loss evaluation in these optimization problems is analyzed and *** 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 ***,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 *** 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.

关键词： entransy loss entropy generation generalized heat transfer law heat transfer optimization heat-work conversion optimization

Radiative entransy flux in enclosures with non-isothermal or non-grey,opaque,diffuse surfaces and its application

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Science China(Technological Sciences) 2011年第10期54卷 2446-2456页

作者： cheng xuetao XU XiangHua LIANG XinGang Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering Mechanics Tsinghua University Beijing 100084 China

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 prirlciple of radiative en- transy 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.

关键词： radiative entransy flux spectral radiative entransy flux non-grey surface radiative entransy principles, radiative heattransfer optimization

Application of entransy to optimization design of parallel thermal network of thermal control system in spacecraft

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Science China(Technological Sciences) 2011年第4期54卷 964-971页

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 *** is found that the optimization objective of this problem and the optimization direction of the extremum entransy dissipation principle are consistent in *** 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 *** influential factors of the optimized distributions are also analyzed and *** results show that the main influence factors are the heat transfer rate of the branches and the total heat transfer *** total flow rate of the cold fluid has a threshold,beyond which further increasing its value brings very little influence on the optimization ***,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 *** 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.

关键词： thermal control system parallel thermal network optimization design extremum entransy dissipation principle

Regulation of Toll-like receptor signaling in innate immunity

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Science China(Life Sciences) 2010年第1期53卷 34-43页

作者： AN HuaZhang,QIAN cheng & CAO xuetao National Key Laboratory of Medical Immunology & Institute of Immunology,Second Military Medical University,Shanghai 200433,China 1. National Key Laboratory of Medical Immunology & Institute of Immunology Second Military Medical University Shanghai 200433 China

Toll-like receptors sense invading pathogens by recognizing a wide variety of conserved pathogen-associated molecular patterns(PAMPs).The members of the TLR family selectively utilize adaptor proteins MyD88,TRIF,TIRAP and TRAM to activate overlapping but distinct signal transduction pathways which trigger production of different panels of mediators such as proinflammatory cytokines and type I *** mediators not only control innate immunity but also direct subsequently developed adaptive *** activation is strictly and finely regulated at multiple levels of the signal transduction pathways.

关键词： Toll-like receptors TLR signaling

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换热器优化中均分原则的适用性分析

中国科学：技术科学 2021年第10期51卷 1231-1244页

作者：程雪涛张龙飞梁新刚安徽省合肥市政务中心合肥230071 清华大学工程力学系热科学与动力工程教育部重点实验室北京100084

在许多物理过程的优化设计中,其优化结果反映为某些物理量或者函数的均匀分布,即相应的均分原则.针对两股流和三股流换热器的优化分析,讨论了热力学力场均匀性原则、ΔT/T场均匀性原则和温差场均匀性原则三项均分原则的适用性.研究表明... 详细信息

在许多物理过程的优化设计中,其优化结果反映为某些物理量或者函数的均匀分布,即相应的均分原则.针对两股流和三股流换热器的优化分析,讨论了热力学力场均匀性原则、ΔT/T场均匀性原则和温差场均匀性原则三项均分原则的适用性.研究表明,当换热量给定时,前两项原则既不能给出最小的换热器熵产率,又不能给出最高的换热器效能;而当换热器实现最佳传热性能时,前两项原则得不到满足.对于温差场均匀性原则,不论冷热流体间的传热系数是否为常数,均可基于理论对其进行数学证明.当冷热流体温差场完全均匀时,换热器的耗散热阻达到最小值.可见,温差场均匀性原则可以给出换热器的最佳传热性能.进一步,本文给出了简单的案例,直观地验证了上述结论.理论与案例分析的结果进一步表明,热力学力场均匀性原则和ΔT/T场均匀性原则都是基于熵产的概念得到的,而熵产从做功能力损失的角度衡量不可逆性,导致这两项原则与传热优化的目的不一致,而且其推导过程中所采用的传热定律也不符合实际的传热过程;而用于证明温差场均匀性原则的(火积)耗散则从传热能力损失的角度衡量传热过程的不可逆性,其优化目标与传热优化目标则是一致的.这就是前两项原则不适用于换热器优化分析而温差场均匀性原则适用的根本原因.

关键词：均分原则换热器 (火积)耗散热阻温差场均匀性原则热力学力

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太阳能光伏发电供热系统的性能分析

太阳能学报 2009年第5期30卷 624-627页

作者：程雪涛徐向华梁新刚清华大学航天航空学院热能与动力工程教育部重点实验室北京100084

建立了一个二维模型以模拟系统工作性能,讨论了聚光比、冷却水流速度等参数对系统性能的影响。随聚光比增加,太阳电池温度近乎线性增加,而系统电效率先增加后减小,热效率则先减小后增加。冷却水流速度的增加能减小电池温度,增加系统电效... 详细信息

建立了一个二维模型以模拟系统工作性能,讨论了聚光比、冷却水流速度等参数对系统性能的影响。随聚光比增加,太阳电池温度近乎线性增加,而系统电效率先增加后减小,热效率则先减小后增加。冷却水流速度的增加能减小电池温度,增加系统电效率;增加水流速度对系统性能的影响大小与水流所处的流动状态(层流、过渡区、湍流)以及聚光比的大小有关。

关键词：太阳能光伏电池电热联供系统

用Lagrange乘子法优化并联液体冷却网络系统

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清华大学学报（自然科学版） 2008年第8期48卷 1359-1361,1367页

作者：程雪涛徐向华任建勋梁新刚清华大学航天航空学院传热与能源利用北京市重点实验室北京100084

对于并联网络液体冷却系统,现有的优化设计方法存在计算量大、不适应复杂系统的问题。为解决此问题,该文采用Lagrange乘子法求解各支路的最佳流量分配系数,在复杂系统中也能很快得到精确解。同时,该文还对系统的数学物理模型进行了讨论... 详细信息

对于并联网络液体冷却系统,现有的优化设计方法存在计算量大、不适应复杂系统的问题。为解决此问题,该文采用Lagrange乘子法求解各支路的最佳流量分配系数,在复杂系统中也能很快得到精确解。同时,该文还对系统的数学物理模型进行了讨论,研究结果表明,模型中换热系数关联式的指数对计算结果的影响小于4%,数学物理模型是可靠的。该文还给出了分配系数与支路权重因子之间的近似关联式,并对其进行了分析和讨论。

关键词：热网络优化并联传热

ANALYSIS OF A CONCENTRATING PHOTOVOLTAIC/THERMAL SOLAR SYSTEM

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ANALYSIS OF A CONCENTRATING PHOTOVOLTAIC/THERMAL SOLAR SYSTE...

2007世界太阳能大会：太阳能与人类居住

作者： cheng xuetao Xu Xianghua Liang Xingang Heat Transfer and Energy Conversion-The Key Laboratory of Beijing Municipality School of Aerospace Tsinghua University Beijing 100084 China

＜正＞Uses of solar energy both on heat energy and electricity at the same time by concentrating sunlight and tracking the maximum output power of solar cells is an efficient way, which will increase the utility of solar energy and reduce the cost.A reflective concentrator is adopted in the system to increase solar intensity on solar cells while they are cooled underneath by *** such a way,much less solar cell area is needed to produce the same amount of electricity and hence the cell cost is greatly *** hot water could be supplied at the same time.A mathematical model for a photovoltaic/thermal solar system is set *** performance of the system is *** influences are discussed,such as the concentration ratio,flow rate of the cooling water,thermal conductivity,thickness of solar cells,tracking of maximum output power of solar cells,*** the thermal efficiency, electrical efficiency and temperature of solar cells.A working cycle is designed and simulated.

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载人航天器热控系统并联回路的轻量化设计

载人航天 2010年第3期16卷 37-43页

作者：程雪涛徐向华梁新刚清华大学

为优化载人航天器热控系统的并联液体回路,减轻其质量,建立了并联回路传热和质量的数学物理模型;并以两支路系统为例,分析了其并联回路的轻量化设计问题,讨论了最优流量分配系数与流体流量、冷流体温度等参数之间的关系。研究发现,对并... 详细信息

为优化载人航天器热控系统的并联液体回路,减轻其质量,建立了并联回路传热和质量的数学物理模型;并以两支路系统为例,分析了其并联回路的轻量化设计问题,讨论了最优流量分配系数与流体流量、冷流体温度等参数之间的关系。研究发现,对并联回路而言,存在最佳管径与流量分配方案,使其质量最轻;随着流体总流量的增加,最优流量分配方案逐渐接近平均分配;给定流体总流量时,冷流体温度较低时最优的分配方式为平均分配,随着冷流体温度的提高,最优分配由支路散热任务、工作温度等因素决定。此外,还研究了支路管道长度和电源系统质量与泵功率之间的比例系数等因素对最优流量分配的影响。

关键词：载人航天器热控系统并联回路轻量化设计