Numerical Simulation of Heat Transfer Characteristics of Horizontal Ground Heat Exchanger in Frozen Soil Layer

At present ,during the design of ground source heatpump (GSHP) systems ,technical attention is always fo-cused on vertical borehole heat exchangers and surroundingsoil[1 ,2],butthe effects of their shallowhorizontal connect-ing pipes ,or horizontal ground…     

Modeling water and carbon fluxes above summer maize field in North China Plain with back-propagation neural networks

INTRODUCTION Dynamics of carbon and water vapor fluxesexchange between the atmosphere and the ecosystembiosphere, depend on complex and non-liner interplayamong physiological, ecological, biochemical andedaphic factors and meteorological conditions (Jarvis,1995; Leuning et al., 1995). There are many studiesquantifying the fluxes across different time and spacescales as well as assessing the environment con-straints on them by some kinds of biophysical orempirical models whose resul…     

大体积混凝土污水处理工程的施工技术

为防止大体积砼产生裂缝，采用HE微膨胀剂与LNF泵送剂行之有效。同时应进行温度应力与浇筑长度验算和精心施工。     

温度概念的热力学

热量是由温度来定义的,因而用热冷程度来定义温度就是不科学的.本文以热力学第一定律和第二定律为基础,用可逆热机的运转来建立温度概念.温度是体系的单一决定可逆热机效率的宏观可测性质.此一宏观可测性质的特征由可逆热机运转的三种情形可以明确地揭示出来.     

Measurement of conversion efficiency of soft X-ray from 0.35μm laser-irradiated aluminum planar targets

Conversion efficiency of soft X-ray from 0.35 μm pulse laser-irradiated aluminium planar target at laser intensities 10¹³–10¹⁵ W/cm² on the Xingguang-II facility (laser energy 5–90 J, focal spot ⊃ Ф 200 μm full width of half maximun (FWHM) 400–800 ps) was measured. A simple model was given to explain soft X-ray conversion efficiency. In this model, because of the heat conduction from the laser-heated spot, the conversion was very small at lower irradiance limit, while at higher limit it was bounded by the energy lost in blow off plasma. Consequently, at the laser intensity around 2×10¹⁴ W/cm², the X-ray conversion efficiency reaches a maximum. Project suppoted by Shanghai Leading Academic Discipline Foundation (Grant No. T0104), and Science Foundation of Shanghai Municipal Commission of Education (Grant No. 214680)     

用Mathematica计算机代数系统求解数理方程

用Mathematica4.0系统软件精确求解了具有定解条件的一维波动方程和一维热传导方程。     

弹性管束换热器传热与阻力特性的实验研究

对弹性管束水-水换热器的传热与阻力特性进行了研究。主要分析了换热器在不同工况下的传热系数的变化规律;研究了弹性管束在管外流体和管内流体的共同诱导作用下,管外和管内对流换热的情况;并对管程和壳程的流动阻力损失进行了实验测量,得出了管程和壳程的阻力损失变化的规律,以及换热器管程阻力损失的计算方法。     

EXPERIMENTAL STUDY ON SEMI-OPEN HEAT PIPES AND ITS APPLICATIONS

ＩＮＴＲＯＤＵＣＴＩＯＮＨｅａｔｐｉｐｅｓａｒｅｗｉｄｅｌｙｕｓｅｄｉｎｗａｓｔｅｈｅａｔｒｅ ｃｏｖｅｒｙｓｙｓｔｅｍｓ.Ｔｒａｄｉｔｉｏｎａｌｇｒａｖｉｔｙｈｅａｔｐｉｐｅ(ＣＨＰ)ｉｓｃｏｍｐｏｓｅｄｏｆｉｎｓｉｄｅｗｏｒｋｉｎｇｆｌｕｉｄａｎｄｏｕｔｓｉｄｅｃｌｏｓｅｄｓｈｅｌｌｗｉｔｈｈｉｇｈｖａｃｕｕｍｓｔａｔｅｉｎ ｓｉｄｅｉｔ.Ｓｏｍｅｐｒｏｂｌｅｍｓｗｅｒｅｆｏｕｎｄｄｕｒｉｎｇｔｈｅｉｎ ｄｕｓｔｒｉａｌａｐｐｌｉｃａｔｉｏｎｓｏｆｃｌｏｓｅｄｈｅａｔｐｉｐｅｓ (Ａｕｅｔａｌ.,2 0 0…     

微通道内单相水流动与换热的特性研究

微通道传热技术是近几年发展起来的一门新兴的传热技术,具有传热效率高、结构紧凑等优点,是当前流动与传热研究的重要课题。运用计算流体力学程序(CFX)对环形微通道内单相水的流动与换热进行数值模拟,可以形象地描述出管内的流场和温度场,从中分析各种因素对流动与换热所产生的影响。     

卫星热管传热测试台的制冷与真空系统的设计

介绍了能满足卫星环境要求的热管传热试验台的制冷与真空系统的设计方案，提出了一种采用液氮制冷和分子泵抽真空系统的方案。制冷系统能方便达到 60— -60℃的温度要求，并可以任意调节所需温度，且调温精度高、反映时间短。抽真空系统能满足0．1mPa的工作真空度和方便更换试样的要求，是一台简便、实用的卫星热管传热试验台。