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Constructal optimization of cylindrical heat sources with forced convection based on entransy dissipation rate minimization

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Science China(Technological Sciences) 2016年第4期59卷 631-639页

作者： GONG ShuWen CHEN LinGen XIE ZhiHui feng huijun SUN fengRui Institute of Thermal Science and Power Engineering Naval University of Engineering Military Key Laboratory for Naval Ship Power Engineering Naval University of Engineering College of Power Engineering Naval University of Engineering

Based on constructal theory and entransy theory,the optimal designs of constant-and variable-cross-sectional cylindrical heat sources are carried out by taking dimensionless equivalent resistance minimization as optimization *** effects of the cylindrical height,the cylindrical shape and the ratio of thermal conductivity of the fin to that of the heat source are *** results show that when the volume of the heat source is fixed,there exists an optimal ratio of the center-to-centre distance of the fin and the heat source to the cylinder radius which leads to the minimum dimensionless equivalent thermal *** the increase in the height of the cylindrical heat source and the ratio of thermal conductivity,the minimum dimensionless equivalent thermal resistance decreases *** the heat source model with inverted variable-cross-sectional cylinder,there exist an optimal ratio of the center-to-centre distance of the fin and the heat source to the cylinder radius and an optimal radius ratio of the smaller and bigger circles of the cylindrical fin which lead to a double minimum dimensionless equivalent thermal ***,the heat transfer performance of the cylindrical heat source is improved by adopting the cylindrical model with *** optimal constructs of the cylindrical heat source based on the minimizations of dimensionless maximum thermal resistance and dimensionless equivalent thermal resistance are *** the thermal security is ensured,the optimal construct of the cylindrical heat source based on minimum equivalent thermal resistance can provide a new alternative scheme for the practical design of heat *** results obtained herein enrich the work of constructal theory and entransy theory in the optimal design field of the heat sources,and they can provide some guidelines for the designs of practical heat source systems.

关键词： constructal theory entransy theory entransy dissipation rate minimization three-dimensional cylindrical heat source generalized thermodynamic optimization

Generalized constructal optimization for the secondary cooling process of slab continuous casting based on entransy theory

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Science China(Technological Sciences) 2014年第4期57卷 784-795页

作者： feng huijun CHEN LinGen XIE ZhiHui DING ZeMin SUN fengRui Institute of Thermal Science and Power Engineering Naval University of Engineering Military Key Laboratory for Naval Ship Power Engineering Naval University of Engineering College of Power Engineering Naval University of Engineering

Based on constructal theory and entransy theory,a generalized constructal optimization of a solidification heat transfer process of slab continuous casting for a specified total water flow rate in the secondary cooling zone was carried out.A complex function was taken as the optimization objective to perform the *** complex function was composed of the functions of the entransy dissipation and surface temperature gradient of the *** optimal water distribution at the sections of the secondary cooling zone were *** effects of the total water flow rate in the secondary cooling zone,casting speed,superheat and water distribution on the generalized constructal optimizations of the secondary cooling process were *** results show that on comparing the optimization results obtained based on the optimal water distributions of the 8 sections in the secondary cooling zone with those based on the initial ones,the complex function and the functions of the entransy dissipation and surface temperature gradient after optimization decreased by 43.25%,5.90%and 80.60%,*** quality and energy storage of the slab had obviously improved in this *** complex function,composed of the functions of the entransy dissipation and surface temperature gradient of the slab,was a compromise between the internal and surface temperature gradients of the ***,it is also the compromise between energy storage and quality of the ***"generalized constructal optimization"based on the minimum complex function can provide an optimal alternative scheme from the point of view of improving energy storage and quality for the parameter design and dynamic operation of the solidification heat transfer process of slab continuous casting.

关键词： slab continuous casting solidification heat transfer entransy dissipation complex function generalized constructal op- timization generalized thermodynamic optimization

Power and efficiency optimizations for an open cycle two-shaft gas turbine power plant

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Propulsion and Power Research 2023年第4期12卷 457-466页

作者： Lingen Chen huijun feng Yanlin Ge Shuangshuang Shi Institute of Thermal Science and Power Engineering Wuhan Institute of TechnologyWuhan 430205China Hubei Provincial Engineering Technology Research Center of Green Chemical Equipment Wuhan 430205China School of Mechanical&Electrical Engineering Wuhan Institute of TechnologyWuhan 430205China

In finite-time thermodynamic analyses for various gas turbine cycles,there are two common models:one is closed-cycle model with thermal conductance optimization of heat exchangers,and another is open-cycle model with optimization of pressure drop(PD)*** of optimization also with searching optimal compressor pressure ratio(PR).This paper focuses on an open-cycle model.A two-shaft open-cycle gas turbine power plant(OCGTPP)is modeled in this *** of power output(PP)and thermal conversion efficiency(TCE)are deduced,and these performances are optimized by varying the relative PD and compressor *** results show that there exist the optimal values(0.32 and 14.0)of PD and PR which lead to double maximum dimensionless PP(1.75).There also exists an optimal value(0.38)of area allocation ratio which leads to maximum TCE(0.37).Moreover,the performances of three types of gas turbine cycles,such as one-shaft and two-shaft ones,are *** the relative pressure drop at the compressor inlet is small,the TCE of third cycle is the biggest one;when this pressure drop is large,the PP of second cycle is the biggest *** results herein can be applied to guide the preliminary designs of OCGTPPs.

关键词： Two-shaft gas turbine power plant Efficiency Power Area distribution Pressure drop Finite-time thermodynamics

变温热源内可逆Braysson循环性能分析与优化

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热力透平 2024年第1期53卷 26-31,57页

作者：刘旭戈延林陈林根冯辉君武汉工程大学热科学与动力工程研究所武汉430205 武汉工程大学机电工程学院武汉430205 湖北省绿色化工装备工程技术研究中心武汉430205

用有限时间热力学理论建立了变温热源内可逆Braysson循环模型,导出了功率和效率的数学表达式,分析了循环参数对二者的影响,并通过优化热导率分配和热容率匹配来进一步优化循环功率和效率。结果表明:优化高、低温侧换热器热导率分配过程... 详细信息

用有限时间热力学理论建立了变温热源内可逆Braysson循环模型,导出了功率和效率的数学表达式,分析了循环参数对二者的影响,并通过优化热导率分配和热容率匹配来进一步优化循环功率和效率。结果表明:优化高、低温侧换热器热导率分配过程中,存在一个最佳工质对数温比,使得效率达到最大值;存在一组最佳热导率分配和最佳工质对数温比,使得功率和效率达到双重最大值;优化工质与热源间热容率匹配过程中,存在一组最佳热容率匹配、最佳工质对数温比和最佳热导率分配,使得功率达到三重最大值。因此通过同时优化热导率分配和热容率匹配得到的循环性能更接近实际情况,且此时循环功率存在三重最大值。研究成果可为Braysson循环的相关研究提供一定的参考。

关键词：有限时间热力学内可逆Braysson循环工质对数温比热导率分配热容率匹配性能优化

T1期乳腺癌超声特征与ER、PR、HER-2、Ki-67表达的相关性分析

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大理大学学报 2024年第2期9卷 55-62页

作者：魏伟徐静雅冯慧俊张霞武静张伟江峰皖南医学院弋矶山医院超声医学科安徽芜湖241000 皖南医学院弋矶山医院影像中心安徽芜湖241000 皖南医学院弋矶山医院病理科安徽芜湖241000

目的:探讨T1期乳腺癌超声声像图特征与雌激素受体(ER)、孕激素受体(PR)、人类表皮生长因子受体2(HER-2)、细胞增殖相关抗原Ki-67表达的相关性。方法:回顾性收集2012年1月至2021年6月经病理证实为单发乳腺恶性肿瘤患者493例的病历资料,... 详细信息

目的:探讨T1期乳腺癌超声声像图特征与雌激素受体(ER)、孕激素受体(PR)、人类表皮生长因子受体2(HER-2)、细胞增殖相关抗原Ki-67表达的相关性。方法:回顾性收集2012年1月至2021年6月经病理证实为单发乳腺恶性肿瘤患者493例的病历资料,记录超声特征及免疫组化结果,并对二者进行相关性分析。结果:ER、PR、HER-2、Ki-67阳性率分别为78.09%、67.34%、21.10%、71.60%;ER与PR表达呈正相关,HER-2与ER、PR表达呈负相关;Ki-67与HER-2表达呈正相关,与ER、PR表达呈负相关。ER阳性表达与形态不规则、边缘不规整、间质脂肪侵犯、有高回声晕等超声特征有关,PR阳性表达与病灶内部成分、腋窝淋巴结转移等超声特征有关,Ki-67阳性表达与边界不清晰、间质脂肪侵犯、有高回声晕等超声特征有关,差异均有统计学意义(P<0.05)。结论:T1期乳腺癌的超声征象与ER、PR、Ki-67表达存在一定的相关性,超声声像图的变化可以提示肿瘤生物学行为,为医生临床决策提供参考。

关键词： T1期乳腺癌超声特征雌激素受体孕激素受体人类表皮生长因子

空气标准等温加热修正Brayton循环:(2)多目标优化

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热力透平 2024年第1期53卷 6-10,25页

作者：危思戈延林陈林根冯辉君武汉工程大学热科学与动力工程研究所武汉430205 湖北省绿色化工装备工程技术研究中心武汉430205 武汉工程大学机电工程学院武汉430205

基于第1部分对循环功率和效率特性的研究,进一步以效率、生态学函数、功率和功率密度为优化目标,以压缩比为优化变量,利用NSGA-Ⅱ算法对内可逆空气标准等温加热修正Brayton循环进行不同目标组合的单、双、三和四目标优化,并利用偏差指数... 详细信息

基于第1部分对循环功率和效率特性的研究,进一步以效率、生态学函数、功率和功率密度为优化目标,以压缩比为优化变量,利用NSGA-Ⅱ算法对内可逆空气标准等温加热修正Brayton循环进行不同目标组合的单、双、三和四目标优化,并利用偏差指数对3种决策方式的优化结果进行分析对比,从而寻找最优解集。结果表明三目标优化中偏差指数最小,为0.129 2。故多目标优化能更有效地找到最优解集。研究成果可为Brayton热机循环的优化设计提供一定参考。

关键词：内可逆循环空气标准等温加热修正Brayton循环多目标优化 NSGA-Ⅱ算法决策方法

Constructal optimization for H-shaped multi-scale heat exchanger based on entransy theory

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Science China(Technological Sciences) 2013年第2期56卷 299-307页

作者： feng huijun CHEN LinGen XIE ZhiHui SUN fengRui College of Power Engineering Naval University of Engineering

Analogizing with the definition of thermal efficiency of a heat exchanger,the entransy dissipation efficiency of a heat exchanger is defined as the ratio of dimensionless entransy dissipation rate to dimensionless pumping power of the heat *** the constraints of the total tube volume and total tube surface area of the heat exchanger,the constructal optimization of an H-shaped multi-scale heat exchanger is carried out by taking entransy dissipation efficiency maximization as optimization objective,and the optimal construct of the H-shaped multi-scale heat exchanger with maximum entransy dissipation efficiency is *** results show that for the specified total tube volume of the heat exchanger,the optimal constructs of the first order T-shaped heat exchanger based on the maximizations of the thermal efficiency and entransy dissipation efficiency are obviously different with the lower mass flow rates of the cold and hot *** the H-shaped multi-scale heat exchanger,the entransy dissipation efficiency decreases with the increase in mass flow rate when the heat exchanger order is fixed;for the specified dimensionless mass flow rate M(M<32.9),the entransy dissipation efficiency decreases with the increase in the heat exchanger *** performance of the multi-scale heat exchanger is obviously improved compared with that of the single-scale heat ***,the heat exchanger subjected to the total tube surface area constraint is also discussed in the *** optimization results obtained in this paper can provide a great compromise between the heat transfer and flow performances of the heat exchanger,provide some guidelines for the optimal designs of heat exchangers,and also enrich the connotation of entransy theory.

关键词： constructal theory thermal efficiency entransy dissipation efficiency H-shaped multi-scale heat exchanger generalizedthermodynamic optimization

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闭式简单燃气轮机循环生态学有效功率特性

热力透平 2024年第3期53卷 153-160页

作者：李婉峰陈林根戈延林冯辉君齐丛正武汉工程大学热科学与动力工程研究所武汉430205 湖北省绿色化工装备工程技术研究中心武汉430205 武汉工程大学机电工程学院武汉430205

内可逆闭式简单燃气轮机循环(Brayton循环)模型是基于有限时间热力学理论和已有文献建立的热力学循环模型。以生态学有效功率为优化目标,研究了该循环的性能特性,导出了生态学有效功率的表达式,分析了不同热源温比下该循环的无因次生态... 详细信息

内可逆闭式简单燃气轮机循环(Brayton循环)模型是基于有限时间热力学理论和已有文献建立的热力学循环模型。以生态学有效功率为优化目标,研究了该循环的性能特性,导出了生态学有效功率的表达式,分析了不同热源温比下该循环的无因次生态学有效功率与压比、效率和无因次功率的关系,比较了该循环的生态学有效功率与其他多个目标函数的性能差异。结果表明:无因次生态学有效功率与压比和效率的关系呈类抛物线型,存在最优压比使无因次生态学有效功率最大;无因次生态学有效功率与无因次功率的关系呈扭叶型,任一给定的无因次生态学有效功率值都对应2个无因次功率值,实际设计时,热机应选择功率较大的工况点;如果将热源温比提高,则无因次生态学有效功率及其目标下的无因次功率、效率和最佳压比均提高;追求生态学有效功率以牺牲热机的部分功率来提升循环的热效率,可大幅度降低熵产率。研究成果可以为Brayton循环热机的设计和优化提供参考。

关键词：简单燃气轮机循环内可逆闭式循环生态学有效功率最优性能性能比较有限时间热力学

Pre-reduction of WO_(3)-Co_(3)O_(4)by H_(2)-C_(2)H_4 in a fluidized bed

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Chinese Journal of Chemical Engineering 2024年第2期66卷 273-284页

作者： huijun Shang Hengli Li Weijun Li feng Pan Zhan Du State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences(CAS)Beijing 100190China College of Chemical Engineering Nanjing Technology UniversityNanjing 211816China School of Chemistry and Chemical Engineering Shihezi UniversityShihezi 832003China College of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China Chinalco Environmental Protection and Energy Conservation Group Co. Ltd.Xiong’an 071700China

In order to avoid the formation ofηphase(W_(6)Co_(6)C or W_(3)Co_(3)C)that adversely affects the sintering process and its products in the preparation process of ultra-fine WC-Co powder,a technical route of prereduction of WO_(3)-Co_(3)O_(4)to WO_(2)-Co and then deep reduction carbonization to WC-Co powder has been *** study mainly investigates the influence of gas partial pressure on the pre-reduction process of WO_(3)-Co_(3)O_(4)under a mixed atmosphere of H_(2)-C_(2)H_(4)-Ar at 600℃and establishes the kinetic equations of pre-reduction and carbon *** results indicate that increasing the partial pressure of hydrogen is conducive to the rapid and complete conversion of WO_(3) to WO_(2).High carbon content can be generated by the deposition of C_(2)H_(4),and it hinders the diffusion of the reducing gas;WO_(3)still cannot be completely reduced to WO_(2)as the partial pressure of C_(2)H_(4) increases to 60%.For the carbon evolution of C_(2)H_(4),the carbon amount is positively related to the H_(2)partial pressure,but it shows the highest amount and evolution rate when the ethylene partial pressure is 20%.Based on the reduction rate curves of WO_(3) and carbon evolution rate curves of C_(2)H_(4),the rate equations of pre-reduction and carbon evolution of WO_(3)-Co_(3)O_(4)system at 600℃are *** pre-reduction reaction belongs to the first-order reaction,and its equation is expressed as follows:r=-(dw_(WO_(3)))/dt=(9±0.15)×10^(-2)×P_(H_(2))^(0.44)P_(C_(2)H_(4))&(0.57)The carbon deposition rate equation of C_(2)H_(4) can be expressed as follows:r=-(dc_C)/dt=r_f-r_b≌7.35×10^(-2)×P_(C_(2)H_(4))^(0.31)

关键词： Fluidization WO_(3)-Co_(3)O_(4) Reduction Carbon deposition Rate equation