检索结果-南通市图书馆

Asymptotic solution of thermocapillary convection in two immiscible liquid layers in a shallow annular cavity

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第6期53卷 1655-1665页

作者： li yourong,WANG ShuangCheng,wu ShuangYing & SHI WanYuan college of power engineering,chongqing university,chongqing 400044,china 1. college of power engineering Chongqing University Chongqing 400044 China

The steady laminar two-dimensional thermocapillary convection of two superposed horizontal liquid layers in a shallow annular cavity was investigated using asymptotical *** liquids were supposed to be immiscible with a nondeformable *** cavity was heated from the outer cylindrical wall and cooled at the inner *** and top surfaces were rigid and *** solutions were obtained in the core region in the limit as the aspect ratio,which was defined as the ratio of the lower layer thickness to the gap width,and trended to *** numerical experiments were also carried out to compare with the asymptotic solution of the steady two-dimensional thermocapillary *** is found that the expressions of velocity and temperature fields in the core region are valid in the limit of the small aspect ratio.

关键词： asymptotic solution thermocapillary flow two-layer system shallow annular cavity

在线全文

学校读者我要写书评

暂无评论

纳米孔内的吸附过程及其动力学特性研究

工程热物理学报 2024年第1期45卷 157-162页

作者：何转桃吴春梅李友荣重庆大学低品位能源利用技术及系统教育部重点实验室能源与动力工程学院重庆400044

为了阐明气体在纳米多孔结构内的吸附及动力学过程,采用分子动力学方法建立了纳米多孔材料的吸附与解吸模型,探究了氩气在多孔结构表面的吸附特性,并对其吸附与解吸的动力学特性进行了分析。结果表明:纳米孔内的吸附机制有两种:一是吸... 详细信息

为了阐明气体在纳米多孔结构内的吸附及动力学过程,采用分子动力学方法建立了纳米多孔材料的吸附与解吸模型,探究了氩气在多孔结构表面的吸附特性,并对其吸附与解吸的动力学特性进行了分析。结果表明:纳米孔内的吸附机制有两种:一是吸附层生长过程中,相对壁面的吸附层不断靠近后孔内发生的液体桥接。二是孔隙内发生毛细管凝结后引起的弯月面推进。低压比时,吸附层持续增长,压比增加时孔隙内观察到液体桥接效应,由于液膜表面不稳定出现液桥的生长与收缩断裂;高压比时,纳米孔入口附近形成稳定的液桥,孔隙内出现空腔,空腔内的快速吸附可导致液体的二次桥接,这种现象不断重复直至空腔被填满。另外,解吸过程是在弯月面后退和空化作用下进行的。

关键词：纳米孔吸附解吸动力学液桥

在线全文

学校读者我要写书评

暂无评论

太阳能集热器的能质分析

太阳能学报 2003年第2期24卷 202-205页

作者：吴双应曾丹苓李友荣重庆大学动力工程学院重庆400044

依据热力学第一、二定律 ,对平板型太阳能集热器的传热和流动过程进行了能质综合分析 ,提出了一项评价太阳能集热器热力学性能的指标———单位有用收益的损 ,讨论了雷诺数。

关键词：太阳能集热器传热流动能质分析

Steady thermal-solutal capillary convection in a shallow annular pool with the radial temperature and concentration gradients

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2012年第8期55卷 2176-2183页

作者： li yourong GONG ZhenXing wu chunmei wu ShuangYing Key Laboratory of Low-grade Energy Utilization Technologies and Systems of Ministry of Education College of Power EngineeringChongqing UniversityChongqing 400044China

Using asymptotical analysis,we investigate the characteristics of the coupled thermal and solutal capillary convection with the radial temperature and solute concentration gradients in a shallow annular pool with the free *** pool is heated from the outer cylinder with high solutal concentration and cooled at the inner cylinder with low solutal *** asymptotic solution is obtained in the core region in the limit as the aspect ratio,which is defined as the ratio of the depth to the width of the pool,goes to *** comparison with the previous work certifies that the asymptotic solution is right and *** influences of the solutal capillary force,the buoyant force,the Soret effect and the geometric parameters on the fluid flow are analyzed.

关键词： coupled thermal and solutal capillary convection asymptotic solution buoyancy Soret effect

Bifurcation of thermocapillary convection in a shallow annular pool of silicon melt

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2007年第1期23卷 43-48页

作者： yourong li Lan Peng Shuangying wu Nobuyuki Imaishi college of power engineering Chongqing University Chongqing 400044 China Institute for Materials Chemistry and engineering Kyushu University Fukuoka 816-8580 Japan

In order to understand the nature of surface patterns on silicon melts in industrial Czochralski furnaces, we conducted a series of unsteady threedimensional numerical simulations of thermocapillary convections in thin silicon melt pools in an annular container. The pool is heated from the outer cylindrical wall and cooled at the inner wall. Bottom and top surfaces are adiabatic. The results show that the flow is steady and axisymmetric at small temperature difference in the radial direction. When the temperature difference exceeds a certain threshold value, hydrothermal waves appear and bifurcation occurs. In this case, the flow is unsteady and there are two possible groups of hydrothermal waves with different number of waves, which are characterized by spoke patterns traveling in the clockwise and counter-clockwise directions. Details of the flow and temperature disturbances are discussed and number of waves and traveling velocity of the hydro- thermal wave are determined.

关键词： Computer simulation Thermocapillary convection Semiconducting silicon Bifurcation

在线全文

学校读者我要写书评

暂无评论

热能储存过程的热经济学性能评价

太阳能学报 2001年第3期22卷 338-341页

作者：吴双应李友荣曾丹苓重庆大学动力工程学院重庆400044

从以热力学第二定律为基础的热经济学角度出发 ,对一个显热热能储存过程进行了热经济学分析 ,并提出了一个评价热能储存过程热经济学性能的指标———储存单位热能的净收益 ,讨论了传热单元数、无因次充热时间以及加热气流和被加热液体... 详细信息

从以热力学第二定律为基础的热经济学角度出发 ,对一个显热热能储存过程进行了热经济学分析 ,并提出了一个评价热能储存过程热经济学性能的指标———储存单位热能的净收益 ,讨论了传热单元数、无因次充热时间以及加热气流和被加热液体的热容量之比等参数对其性能的影响。结果表明 ,对热能储存过程存在一最佳的传热单元数和无因次充热时间 ,在传热单元数较大时。

关键词：热能储存热经济学性能评价

A comparative study on thermo-economic performance between subcritical and transcritical Organic Rankine Cycles under different heat source temperatures

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2014年第28期59卷 4379-4387页

作者： Shuangying wu Chun li Lan Xiao Chao liu yourong li Key Laboratory of Low-grade Energy Utilization Technologies and Systems Ministry of Education Chongqing University college of power engineering Chongqing University

In this paper, the net power output, exergy efficiency and levelized energy cost of system were selected as performance indicators for assessing Organic Rankine Cycle(ORC). Firstly, the turbine inlet temperature and pressure meeting the requirement of pinch point temperature difference of evaporator in transcritical ORC(trans-ORC) were determined based on performance optimization. Subsequently, the thermo-economic performance of a subcritical ORC(sub-ORC) using R601 as working fluid and a trans-ORC using R134 a as working fluid were compared under different heat source temperatures and a fixed outlet temperature of flue gas. Results show that for trans-ORC, when the pinch point temperature difference of evaporator lies between the inlet and outlet of evaporator, a lower inlet pressure of turbine is favorable; when the pinch point temperature difference of evaporator is located at the outlet of evaporator, there exists an optimal inlet pressure of turbine. Either for sub-ORC or trans-ORC, the net power output increases and levelized energy cost decreases with the increase in heat source temperature. For sub-ORC,exergy efficiency of system increases monotonously with heat source temperature, while for trans-ORC, exergy efficiency of system grows up firstly and then reduces(or keeps constant) with the increasing of heat source temperature. Moreover, for net power output and exergy efficiency of system, there exist a range of heat source temperatures making trans-ORC better than sub-ORC, and the heat source temperature region extends with the increase in pinch point temperature difference of evaporator. For levelized energy cost of system, the sub-ORC is always superior to trans-ORC.

关键词：热源温度经济性能朗肯循环跨临界亚临界功率输出能源成本出口温度

同方期刊数据库

在线全文

学校读者我要写书评

暂无评论

界面吸附团簇演化与润湿机理研究

工程热物理学报 2022年第7期43卷 1751-1760页

作者：魏翔吴春梅李友荣低品位能源利用技术及系统教育部重点实验室重庆大学能源与动力工程学院重庆400044

为了阐明界面吸附团簇的形成及其演化机理,采用理论分析和分子动力学模拟相结合的方法研究了氩在金表面的吸附特性,分析了吸附团簇演化过程与界面润湿机制。结果表明:吸附质以团簇形式吸附在固体表面吸附单元上,随着吸附的进行,表面零... 详细信息

为了阐明界面吸附团簇的形成及其演化机理,采用理论分析和分子动力学模拟相结合的方法研究了氩在金表面的吸附特性,分析了吸附团簇演化过程与界面润湿机制。结果表明:吸附质以团簇形式吸附在固体表面吸附单元上,随着吸附的进行,表面零吸附单元减小并逐渐趋于零,单分子团簇不断生成;随着压比的增大,单分子团簇增长速率不断下降,当单分子团簇占比达到极大值之后,小分子团簇逐渐合并为大分子团簇。模拟得到的吸附单元数及团簇演化规律均与理论预测结果吻合很好。大压比下,团簇所含分子数增加,吸附层内原子平均能量降低,结构更稳定。探讨了吸附熵及界面张力的演化规律,当吸附熵达到极值时,发生吸附相变,并进一步确定了界面润湿条件。

关键词：团簇演化润湿界面张力吸附熵

乙醇蒸汽氛围中水滴蒸发热动力学特性实验研究

在线全文

学校读者我要写书评

暂无评论

工程热物理学报 2023年第6期44卷 1653-1658页

作者：林园青吴春梅李友荣低品位能源利用技术及系统教育部重点实验室重庆大学能源与动力工程学院重庆400044

为了探究异质蒸气氛围对附壁液滴蒸发过程的影响,采用实验观测的方式分析了低压乙醇蒸气氛围中水滴蒸发热动力学特性。实验结果表明,液滴蒸发冷却效应诱导产生气液界面处的切向温度梯度及液滴内部的法向温度梯度。液滴蒸发初期,切向温... 详细信息

为了探究异质蒸气氛围对附壁液滴蒸发过程的影响,采用实验观测的方式分析了低压乙醇蒸气氛围中水滴蒸发热动力学特性。实验结果表明,液滴蒸发冷却效应诱导产生气液界面处的切向温度梯度及液滴内部的法向温度梯度。液滴蒸发初期,切向温度梯度诱导产生的Marangoni流动占据主导地位,自由界面近三相线处温度分布呈齿轮状。随着蒸发的进行,齿轮状热流型逐渐演变为多流胞状结构,并逐渐脱离三相线朝自由界面中心处移动。随着液滴高度的降低,法向温度梯度逐渐占据主导地位,浮力效应诱导产生Bérnard-Marangoni流胞。在低压乙醇蒸气氛围中,乙醇在液滴界面生成溶解热,使得界面热质传递过程更为复杂,观察到多类不稳定流型演化过程。随着初始时刻乙醇蒸气压力的降低,液滴蒸发速率增加,流动不稳定性增强。

关键词：附壁水滴蒸发乙醇氛围热流型蒸发速率