chapter-12 nulear heat energychapter-12 nuclear heat energychapter-12 nuclear heat energychapter-12 nuclear heat energy.pptVIP

Chapter 12 Nuclear Heat Energy （核热能） Most of the energy released in fission or fusion appears as kinetic energy of a few high-speed particles. As these pass through matter, they slow down by multiple collisions and impart (给予) thermal energy to the medium. It is the purpose of this chapter to discuss the means by which this energy is transferred (转移) to a cooling agent (介质) and transported (传送) to devices that convert mechanical energy into electrical energy. Methods for dealing with the large amounts of waste heat generated will be considered. 12.1 METHODS OF HEAT TRANSMISSION (热传递的方式) We learned in basic science that heat, as one form of energy, is transmitted by three methods: conduction (传导), convection (对流, 传递), and radiation (辐射, 发光). 接上页(P124第二段第二行) The physical processes for the methods are different: In conduction, molecular motion in a substance at a point where the temperature is high causes motion of adjacent (邻近的) molecules, and a flow of energy toward a region of low temperature takes place. The rate of flow is proportional to the slope (倾斜, 斜坡) of the temperature, i.e., the temperature gradient (温度梯度). 接上页(P124第二段第七行) In convection, molecules of a cooling agent such as air or water strike a heated surface, gain energy, and return to raise the temperature of the coolant. The rate of heat removal is proportional to the difference between the surface temperature and that of the surrounding medium, and also dependent on the amount of circulation of the coolant in the vicinity (附近) of the surface. 接上页 In radiation, molecules of a heated object emit and receive electromagnetic radiations, with a net transfer of energy that depends on the temperatures of the body and the adjacent (邻近的) regions, …. For reactors, this mode of heat transfer is generally of less importance than are the other two. 12.2 HEAT GENERATION AND REMOVAL (热能的产生和排除) The transfer of heat by conduction in a flat plate (insulated (绝缘的) on its edges) is reviewed. If the plate has a thi