检索结果-南通市图书馆

An exploration for the macroscopic physical meaning of entropy

science china(Technological sciences) 2010年第7期53卷 1809-1816页

作者： WU Jing1 & GUO ZengYuan2.1 College of Energy and power engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 2.0016,{2. 2.key laboratory for thermal science and power engineering of ministry of education, school of aerospace, tsinghua University, beijing 100084,{2. 1. College of Energy and power engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education School of Aerospace Tsinghua University Beijing 100084 China

The macroscopic physical meaning of entropy is analyzed based on the exergy (availability) of a combined system (a closed system and its environment), which is the maximum amount of useful work obtainable from the system and the environment as the system is brought into equilibrium with the environment. The process the system experiences can be divided in two sequent sub-processes, the process at constant volume, which represents the heat interaction of the system with the environment, and the adiabatic process, which represents the work interaction of the system with the environment. It is shown that the macroscopic physical meaning of entropy is a measure of the unavailable energy of a closed system for doing useful work through heat interaction. This statement is more precise than those reported in prior literature. The unavailability function of a closed system can be defined as T0S and p0V in volume constant process and adiabatic process, respectively. Their changes, that is, AiTgS) and A (p0V) represent the unusable parts of the internal energy of a closed system for doing useful work in corresponding processes. Finally, the relation between Clausius entropy and Boltzmann entropy is discussed based on the comparison of their expressions for absolute entropy.

关键词： entropy macroscopic physical meaning exergy heat interaction

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Molecular dynamics simulations of non-Fourier heat conduction

引用

Progress in Natural science:Materials International 2008年第8期18卷 999-1007页

作者： Qixin Liu, Peixue Jiang *, Heng Xiang key laboratory for {2. science and power engineering of ministry of education, Department of {2. engineering, tsinghua University, beijing 100084,{12. key laboratory for {2. science and power engineering of ministry of education Department of Thermal Engineering Tsinghua University Beijing 100084 China

Unsteady heat conduction is known to deviate significantly from Fourier’s law when the system time and length scales are within certain temporal and spatial windows of relaxation. Classical molecular dynamics simulations were used to investigate unsteady heat conduction in argon thin films with a sudden temperature increase or heat flux at one surface to study the non-Fourier heat conduction effects in argon thin films. The studies were conducted with both pure argon films and films with vacancy defects. The temperature profiles in the argon films showed the existence of mechanical waves when the thin film was suddenly heated and the wave nature of the heat propagation. The flux phase relaxation time, sq, and the temperature phase relaxation time, st, were calculated from the temporal variations of the energy flux and temperature distribution in the film. Comparisons of the MD temperature profiles with temperature profiles predicted by Fourier’s law show that Fourier’s law is not able to predict the temperature variations with time. Different film thicknesses were also studied to illustrate the variation of the time needed for the films to reach steady-state temperature profiles after a sudden temperature rise at one surface and to illustrate the finite speed of the energy waves.

关键词： Molecular dynamics simulation Non-Fourier heat conduction Argon thin film

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

CO_2.Mitigation in Coal Gasification Cogeneration Systems with Integration of the Shift Reaction, CO_2.Absorption and Methanol Production

引用

Journal of thermal science 2004年第3期13卷 193-198页

作者： Yuanyuan DUAN Jin ZHANG key laboratory of {2. science and power engineering, Department of {2. engineering, tsinghua University, beijing 100084, china key laboratory of {2. science and power engineering Department of Thermal Engineering Tsinghua University Beijing China

Cogeneration of electricity and liquid fuel can achieve higher efficiencies than electricity generation alone in Integrated Gasification Combined Cycle (IGCC), and cogeneration systems are also expected to mitigate CO2.emissions. A proposed methanol-electricity cogeneration system was analyzed in this paper using exergy method to evaluate the specified system. A simple cogeneration scheme and a complicated scheme including the shift reaction and CO2.removal were compared. The results show that the complicated scheme consumes more energy, but has a higher methanol synthesis ratio with partial capture of *** those methanol and electricity cogeneration systems, the CO2.mitigation is not merely an additional process that consumes energy and reduces the overall efficiency, but is integrated into the methanol production.

关键词： cogeneration system methanol synthesis CO2 mitigation exergy analysis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Investigation of heavy metal partitioning influenced by flue gas moisture and chlorine content during waste incineration

引用

Journal of Environmental sciences 2010年第5期22卷 760-768页

作者： Qinghai Li,Aihong Meng,Jinyan Jia,Yanguo Zhang Department of thermal engineering,{2. laboratory for thermal science and power engineering of the ministry of education of china,tsinghua University,{12. 100084,china. [a] Department of thermal engineering Key Laboratory for Thermal Science power engineering of the {2. of education of china Tsinghua University Beijing 100084 China

The impact of moisture on the partitioning of the heavy metals including Pb,Zn,Cu and Cd in municipal solid waste （MSW） was studied in a laboratory tubular furnace.A thermodynamic investigation using CHEMKIN software was performed to compare the experimental *** waste,representative of typical MSW with and without chlorine compounds,was burned at the background temperature of 700 and 950°C,*** the absence of chlorine,the moisture content has no evident effect on the volatility of Pb,Zn and Cu at either 700 or 950°C,however,as flue gas moisture increasing the Cd distribution in the bottom ash increased at 700°C and reduced at 950°C,*** the presence of chlorine,the flue gas moisture reduced the volatility of Pb,Zn and Cu due to the transformation of the more volatile metal chlorides into less volatile metal oxides,and the reduction became significant as chlorine content *** Cd,the chlorine promotes its volatility through the formation of more volatile CdCl *** a result,the increased moisture content increases the Pb,Zn,Cu and Cd concentrations in the bottom ash,which limits the utilization of the bottom ash as a construction ***,in order to accumulate heavy metals into the fly ash,MSW should be dried before incineration.

关键词： heavy metals partitioning moisture chlorine municipal solid waste incineration

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Full-scale experimental research on fire fume refluence of sloped long and large curved tunnel

引用

science china(Technological sciences) 2011年第S1期54卷 89-94页

作者： ZHONG MaoHua 1,SHI CongLing 1,HE Li 1,SHI JieHong 1 & FU TaiRan 2.1 china Academy of Safety science and Technology,{2. 100012.china 2.key laboratory for thermal science and power engineering of ministry of education,Department of thermal engineering,tsinghua University,{2. 100084,china 1. china Academy of Safety science and Technology Beijing 100012 China 2. key laboratory for {2. science and power engineering of ministry of education Department of Thermal Engineering Tsinghua University Beijing 100084 China

A full-scale experimental research is conducted on the fire fume refluence of a sloped long and large curved tunnel in the underground plant of a hydraulic and hydropower engineering project under three different fire *** a result,the eddy effect and pattern of the fire fume flow in the tunnel in case of fire is discovered and the refluence of the fume layers in case of fire is *** analysis of the temperature measurement resulted in the course of the experiment,the main characteristics and performance of the fire fume refluence are discussed under the three different fire powers.

关键词： large and long tunnel fire fume refluence experiment

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Experimental study on drying of typical MSW under incinerator-like conditions

引用

science china(Technological sciences) 2007年第5期50卷 636-643页

作者： ZHANG YanGuo1, CHEN MeiQian2. MENG AiHong1, LI QingHai1 & CHEN YunXuan2.1 key laboratory for {2. science and power engineering of ministry of education, tsinghua University, beijing 100084, china 2.school of Mechanical, Electronical and Control engineering, beijing Jiaotong University, beijing 100044, china 1. key laboratory for {2. science and power engineering of ministry of education Tsinghua University Beijing 100084 China 2. school of Mechanical Electronical and Control Engineering Beijing Jiaotong University Beijing 100044 China

In this paper, a series of experiments were conducted to investigate the drying of typical municipal solid wastes (MSW) in a muffle incinerator. From the experimental drying characteristic curves, the effects of temperature on drying process were observed to be more obvious in the low temperature region than in the high tem- perature region in muffle incinerator. At a specified drying temperature, drying time was highly dependent upon the packed waste thickness, having an exponent rela- tion with the thickness. When the drying temperature increased or the thickness of potato bulks was diminished, the maximum drying rate reduced. Based on the first-order reaction, activation energy (Ea), and factor A of potato and cabbage were determined.

关键词： drying, MSW, potato blocks, cabbage stems, temperature, dying rate

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Analysis of residual stress distribution along interface asperity of thermal barrier coating system on macro curved surface

引用

Progress in Natural science:Materials International 2011年第3期21卷 262-267页

作者： Ming SONG,Yue MA,Sheng-kai GONG key laboratory of {2. Materials and Performance(ministry of education), school of Materials science and engineering,Beihang University,beijing 100191,china key laboratory of {2. Materials and Performance (ministry of education) School of Materials Science and Engineering Beihang University Beijing 100191 China

Based on the study of the radial residual stress distribution on the macro curved interfaces of thermal barrier coating system(TBCs) for the hollow curved substrate structures,the hollow four-concentric-circle model was *** the concentric-circle model with a fine scaled sinusoidal interface was proposed to describe the stresses distribution on the rough interface of TBCs with macro curved *** influences of the geometric and thermophysical parameters were discussed by the developed *** results showed that the radial stress on the rough interface can be separated into two sections:the overall level stress from macro surface curvature and the local stress from local asperity of the *** overall level stress was determined by the thicknesses and the thermophysical parameters of each *** has been found that the ratio of local stress and overall level stress was influenced by the interface asperity,the ratio of elastic modulus and the ratio of thermal expansion coefficients of the layers beside the rough ***,the convex macro curvature of the substrate can induce tensile stress onto the *** at the sharp corners of the substrate,the small curvature radius can cause high stress which should be taken more care about the occurrence of spalling cracking at interface

关键词： barrier coating system(TBC) residual stress interface asperity thermal grown oxide(TGO) concentric-circle model

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Deterioration Mechanisms of Sulfate Attack on Concrete under Alternate Action

引用

Journal of Wuhan University of Technology(Materials science) 2010年第2期25卷 355-359页

作者：高润东 State key laboratory of Hydro{2. and engineering Tsinghua University

By micro- and macro-observations, the deterioration mechanisms of concrete under alternate action between repeated sub-high temperature/cooling by water and sodium sulfate solution attack （TW-SA） were studied; meanwhile, the single sodium sulfate solution attack （SA） was also done as comparison. Micro-observations included the analysis of attack products by thermal analysis method and the determination of sulfate-ion content from surface to interior by chemical titrating method （modified barium sulfate gravimetric method）. Macro-observations mainly included the mechanical behaviors such as compressive strength, splitting strength. The experimental results indicate, in both cases, the main attack product is ettringite, only in the first layer of case SA some gypsum is checked; in case SA, the sulfate ions mainly concentrate in the surface layer, so the attack is relatively mild; but in case TW-SA, the repeated sub-high temperature/cooling by water promotes the sulfate ions diffusing inwards, which leads to obvious strength degradation.

关键词： concrete sulfate repeated sub-high temperature/cooling by water attack product sulfate-ion content strength

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effects of surface modification on isothermal oxidation behavior of HVOF-sprayed NiCrA1Y coatings

引用

Progress in Natural science:Materials International 2011年第2期21卷 173-179页

作者： Li-yong NI,Zi-long WU,Chun-gen ZHOU key laboratory of {2. Materials and Performance(ministry of education), Department of Materials science and engineering,Beihang University,beijing 100191,china key laboratory of {2. Materials and Performance (ministry of education) Department of Materials Science and Engineering Beihang University Beijing 100191 China

NiCrAlY coatings were deposited on Ni-based superalloy by high-velocity oxygen-fuel spraying(HVOF).Surface modification by means of grit-blasted,shot-peened and ground methods was used in order to study the effect of surface conditions on the isothermal oxidation behavior of HVOF-sprayed NiCrAlY coatings at 1 050℃.The results showed that surface modification had an obvious effect on the isothermal oxidation behavior of the *** was a large decrease in growth rate compared with the as-sprayed *** scale formed on the grit-blasted and shot-peened coatings was a mixture of Al2.3and NiCr2.4,while the oxide formed on the ground coating was composed mainly of *** surface modification,the content of NiCr2.4spinels decreased compared with the as-sprayed coating.

关键词： NiCrAlY HVOF isothermal oxidation thermal barrier coating

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

水电站振源识别及其对厂房结构的影响研究

引用

水力发电学报 2008年第4期27卷 135-140页

作者：秦亮王正伟中交天津航道局有限公司天津300042 清华大学热科学与动力工程教育部重点实验室清华大学水沙科学与水利水电工程国家重点实验室北京100084

本文首先利用CFD技术对某大型电站水轮机组进行不稳定流动计算,重点分析了水轮机流道内的压力脉动频率特征,进而对真机试验所测得的机组水压脉动及厂房结构振动频率进行识别,确定各种频率振动的动荷载来源。在此基础上,结合对原型观测... 详细信息

本文首先利用CFD技术对某大型电站水轮机组进行不稳定流动计算,重点分析了水轮机流道内的压力脉动频率特征,进而对真机试验所测得的机组水压脉动及厂房结构振动频率进行识别,确定各种频率振动的动荷载来源。在此基础上,结合对原型观测信号的数据分析分别统计出厂房结构主要部位振动达到峰值时的各种频率动荷载所占比重、全体所实测负荷工况下的各种频带能量对总振动响应的贡献、各种分频振动随负荷的变化等规律,证明涡带是影响厂房结构振动的最为主要振源。该结果有助于从量级上评估水电站厂房振动问题中的各种动荷载的作用效果。

关键词：水工结构振动响应振源分析水电站动荷载

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：