Heat Exchangers, LMTD Method Where we’ ve been. So far have focused on detailed heat transfer analysis of specific conditions, such as external heat transfer coefficient Where were going: Investigate methods for larger system level analysis that combine all these modes of heat transfer in heat exchangers

Natural Convection Where we’ ve been. Up to now, have considered forced convection that is an external driving force causes the flow. Where we’ re going: Consider the case where fluid movement is by buoyancy effects caused by temperature differential Heat Transfer Su Yongkang

Heat Exchangers. NTU-8 Method Where we’ ve been∴ Analysis of heat exchangers using log mean temperature difference (LMTD)

Natural Convection Where we’ ve been Up to now, have considered basic concepts of natural convection, the governing equations and laminar free convection on vertical surface Where were going Consider empirical correlations for natural convection Heat Transfer

激光又名莱塞(Laser) 全名是“辐射的受激发射光放大 (Light amplification by stimulated emission of radiation 世界上第一台激光器诞生于1960年 1954年制成了受激发射的微波放大器 梅塞( Maser) 它们的基本原理都是基于1916年爱因斯坦 提出的受激辐射理论

一、德布罗意波 历史 德布罗意假设:不仅光具有波粒二象性,一切实物粒子如电 子、原子、分子都具有波粒二象性。 他提出:一个质量为m,速度为v的粒子具有波动性,只有 一个波长为λ,频率为v的波与之相对应,各量的关系为:

光电效应: 光照射某些金属时能从表面释放出电子的效应 产生的电子称为光电子 光电效应是赫兹在1887年发现的.1896年汤姆逊发现了电 子之后,勒纳德证明了光电效应中发出的是电子

1.全息照相的原理(Principle of holography) 普通摄影(照相,电影,电视)只记录光 的强度,即景象反射的与振幅平方成正比的光 强。所以只记录物体光波的强度(振幅)信息。 全息照相:既记录光波振幅信息,又记 录光波相位信息

一、实验规律 散射线中有两种波长λ、λ,△=-λ0随散射角θ的增大而增大

经典物理(18-19世纪) 牛顿力学热力学经典统计力学经典电磁理论 19世纪末趋于完善 电磁理论解释了波动光学 开尔文:大厦基本建成…两朵乌云