应用化学专业英语 教学课件 ppt 作者 黄忠 谢普会 付颖 主编lesson 22.ppt

Heat Transfer 一、教学内容：通过对本单元的学习，掌握热传递的相关基本词汇，了解热传递的几种类型和热传递的基本计算，并掌握热传递相关英语的翻译技巧。 二、本章节参考文献： From English for science and technology on chemistry and chemical engineering, by Liu yuhong, 2006 Introduction Introduction of heat transfer In the majority of chemical process heat is either given out or absorbed, and in a very wide range of chemical plant, fluids must often be either heated or cooled. in the majority of chemical process in a very wide range of chemical plant Thus in furnaces, evaporators, distillation units, driers, and reaction vessels，one of the major problems is that of transferring heat at the desired rate. 因此，在反应炉、蒸发器、蒸馏装置、干燥器和反应容器中，一个主要问题是以期望的速度传递热。 In a solid, the flow of heat by conduction is the result of the transfer of vibrational energy from one molecule to another, and in fluids it occurs in addition as a result of the transfer of kinetic energy. vibrational energy kinetic energy This process is particularly important with metals and accounts for their high thermal conductivities. 句中的their指 thermal conductivities In forced convection, it is due to eddy currents in a fluid in turbulent motion. forced convection eddy currents turbulent motion When this radiation falls on a second body it may be partially reflected, transmitted, or absorbed. It is only the fraction that is absorbed that appears as heat in the body. 当这种辐射碰到第二个物体它就可以发生部分的反射，传递或吸收。但只有被吸收的那部分表现为物体中的热。 Basic Considerations In the majority of heat exchanger units, the process is complicated in that the heat has to pass through a number of intervening layers before it reaches the material whose temperature is to be raised and the form of the equation may be complex. heat exchanger units in that intervening layers The heat from the flame is transferred by a combination of r