一种富于启发性的热机实验演示与分析

利用试管、玻璃球、器、圆盘等易取材料研制了使玻璃球通过重力作用原理来转移工作物质的方法，并可用燃烧热、电阻热和光转化热作为高温热源的动力的热机实验演示，同时我们给出了相应的理论分析。     

探讨稳态法实验中的绝热问题

本文利用付立叶导热方程式 ,分析了导热系数测定仪在绝热问题上出现的漏洞与在制造上存在的缺陷 ,由此提出被测样品的侧面必须经过绝热处理 ,才能提高测量精确度的结论     

换热器表面结霜状态下翅片效率公式的理论分析及改进

１引言制冷设备中换热器是重要的部件，在进行换热器设计或对实际系统中换热性能进行计算时，采用的翅片效率的准确与否将会关系到整个系统的工作状况。对于换热器表面处于干或湿工况时，文献中的翅片效率公式形式较统一，但对结霜情况下的研究相对没有一致的结论［１］。Ｓａｎｄｅｒｓ［１］、Ｂａｒｒｏｗ［２］和Ｋｏｎｄｅｐｕｄｉ［３］都曾提及霜工况下换热器翅片效率公式，此外还有包含析湿系数的翅片效率形式。由于所采用的结霜翅片效率表达式不同，最终得到的翅片效率及翅片温度分布也难免存在差别。因而，从众多公式中选择相对准…     

Application of enthalpy method for moving boundary problem in laser surface melting

A numerical analysis was carried out to study the moving boundary problem in the physical process of pulsed Nd-YAG laser surface melting prior to vaporization. The enthalpy method was applied to solve this two-phase axisymmetrical melting problem. Computational results of temperature fields were obtained, which provide useful information to practical laser treatment processing. The validity of enthalpy method in solving such problems is pressented. Supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences     

Numerical solution of the heat equation with nonlinear boundary conditions in unbounded domains

The numerical solution of the heat equation in unbounded domains (for a 1D problem‐semi‐infinite line and for a 2D one semi‐infinite strip) is considered. The artificial boundaries are introduced and the exact artificial boundary conditions are derived. The original problems are transformed into problems on finite domains. The space semi‐discretization by finite element method and the full approximation by the implicit‐explicit Euler's method are presented. The solvability of the full discretization schemes is analyzed. Computational examples demonstrate the accuracy and the efficiency of the algorithms. Also, the behavior of blowing up solutions is examined numerically. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 23: 379–399, 2007     

Hybrid pseudospectral–finite difference method for solving a 3D heat conduction equation in a submicroscale thin film

This research aims to develop a time‐dependent pseudospectral‐finite difference scheme for solving a 3D dual‐phase‐lagging heat transport equation in a submicroscale thin film. The scheme uses periodic pseudospectral discretization in space and a fully second‐order finite difference discretization in time. The three consecutive time steps model is then solved explicitly, by using a preconditioned conjugate gradient method. The scheme is illustrated by an example which is used to investigate the heat transfer in a gold submicroscale thin film. Comparisons are made with available literature. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007     

Identification of temperature‐dependent thermophysical properties in a partial differential equation subject to extra final measurement data

We consider an inverse problem for estimating the two coefficient functions c and k in a parabolic type partial differential equation c(u)u_t = ?[k(u)u_x]/?x with the aid of the measurements of u at two different times. The first‐ and second‐order one‐step group preserving schemes are developed. Solving the resultant algebraic equations with a closed‐form, we can estimate the unknown temperature‐dependent thermal conductivity and heat capacity. The new methods possess threefold advantages: they do not require any a priori information on the functional forms of thermal conductivity and heat capacity; no initial guesses are required; and no iterations are required. Numerical examples are examined to show that the new approaches have high accuracy and efficiency, even there are rare measured data. When the measured temperatures are polluted by uniform or normal random noise, the estimated results are also good. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007     

机械加工多孔层在大气压和高于大气压时的沸腾换热

1引言在过去的二十年中，已研制出诸如HighFI。、Thermoexcel－E、Ge、－T、CIT等多种高性能强化沸腾换热结构［‘－’］，其中ThermoexcelE型结构是机械加工多孔层中有代表性的一种，并进行了较多研究＊‘］。但迄今为止，研究工作多限于一个大气压时的沸腾工况［‘，’］，而较少涉及非大气压时的情形。本文对一种ThermoexcelE型机械加工多孔层在大气压和高于大气压时的沸腾传热进行了实验，提出了简化物理模型，进行了流动与传热分析，综合实验数据，建立了相应的传热关联式。2实验研究实验装置参见文献＊。多孔层基体为厚壁紫铜管…     

Modulated‐temperature differential scanning calorimetry study of temperature‐induced mixing and demixing in poly(vinylmethylether)/water

The heat capacity or reversing heat flow signal from modulated‐temperature differential scanning calorimetry can be used to measure the onset of phase separation in a poly(vinylmethylether)/water mixture, clearly showing the special type III lower critical solution temperature demixing behavior. Characteristic of this demixing behavior is a three‐phase region, which is detected in the nonreversing heat flow signal. Stepwise quasi‐isothermal measurements through the phase transition show large excess contributions in the (apparent) heat capacity signal, caused by demixing/remixing heat effects on the timescale of the modulation (fast process). These excess contributions and their time‐dependent evolutions (slow process) are useful in understanding the kinetics of phase separation and the morphology (interphase) development. Care has to be taken, however, in interpreting the heat capacity signal derived from the amplitude of the modulated heat flow because nonlinear effects lead to the occurrence of higher harmonics. Therefore, the raw heat flow signal for quasi‐isothermal demixing and remixing measurements is also examined in the time domain. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1824–1836, 2003     

Temperature control of electrohydrodynamic micro heat pipes

Active thermal control was achieved by using an electrohydrodynamically (EHD) assisted micro heat pipe array. A simulation model of temperature control of EHD micro heat pipes was established in a Matlab Sinulink environment. An experimental model was designed and fabricated to verify the model and identify the factors most influential to the thermal control via EHD micro heat pipe array. Good correspondence between simulations and experiments was achieved. Electric field intensity, set-point temperature and the gap between the upper and lower set-point temperatures were shown to have a dramatic influence on the temperature control.