1UNIT 1Heat transfer is the area of engineering that deals with the mechanisms responsible for transferring energy from one place to another when a temperature difference exists.传热学是研究当温差存在时引起能量由一处传递到另一处的机理的工程学科。 The majority of time is spent studying equilibrium situations.大部分时间花在研究平衡态上。 in the case of climate control for a building,heat balances must be made that equate heat addition from light,electric motors,fossil-fuel fired engines,people and solar energy entering windows with heat losses through walls,cracks and doors.就建筑的气温控制来说，应当使来自灯光、电动机、烧矿物燃料的机械、人体以及由窗户进入的太阳能等的热量同通过墙壁、缝隙及门户所散失的热量相平衡。 for lunch she has corned beef hash cooked on her gas stove and watches her favorite soap opera on her television.她把咸牛肉丁烤菜放在煤气炉上煮以准备午餐，同时观看电视上她特别喜欢的连续剧。 the many problems related to generating the power necessary to put man in space and of shielding the space capsule upon reentry into the earths atmosphere made it necessary to embark upon a thorough study of the mechanisms of heat transfer.有关把人送入空间所必需产生的动力，以及重返地球穿过大气层时航天舱的隔热等许多问题，使得有必要对传热现象的机理作一番彻底的研究。UNITI 2the lattice vibration impede the motion of the free electrons,thus causing that component of the thermal To greater lattice vibrations.晶格振动会阻碍自由电子运动，因此导致导热系数减少的部分，超过晶格振动的加强而引起的导热系数增加的部分。UNIT 3 we should suspect that the heatt-ransfer rate might be different if we cooled the plate with water instead of air,but again,how much difference would there be?我们可能会猜想，如果用水而不用空气来冷却热板，热交换的快慢会有所不同，然而，差别又有多大呢？ if a heated plate were exposed to ambient room air without an external source of motion,a movement of the air would be experienced as a result of the density gradients near the plate.假如把一块加热的平板置露于室内空气之中，而没有外部动力源干扰，则空气的运动是由于平板附近空气的密度梯度而造成的。 the local flux and/or the total transfer rate are of paramount importance in any convection problem.在任何一个对流问题中，单位时间内所交换的总热量或局部的热流量，或这两者，都是很重要的。 this multiplicity of independent variables results from the fact that convection transfer is determined by the boundary layers that develop on the surface.之所以有那么多的独立变量，是因为对流换热是有换热表面上形成的热边界层所决定的这一事实。UNIT 4 If it is all specular,the angle made by the reflected beam with the normal to the surface will equal the angle made by the incident beam with the normal.如果是完全的镜面反射，则反射线与表面法线的夹角将等于射线与表面法线的夹角。2conductivity to decrease faster than the increased component of the thermal conductivity duea given temperature interval and working a conduction problem as though the material had a constant thermal conductivity.这种处理问题的方法就像在给定温度内选定平均的导热系数，然后把通过该物体的导热问题作为恒定的导热系数问题来处理一样。UNIT 5 Conversely,if the rubes are without fins,gas motion,and hence mixing in the transverse direction is possible.与此相反，如果管子上没有肋片，则在横向上气流的运动以及由此而引起的混合就可能产生。UNIT 6 Predictions of how much energy can be obtained from the working fluid and how well the extraction of energy from the working fluid can be accomplished are the province of an area of engineering called thermodynamics.要预测从工质中能够获得多少热量，要预知从工质中获得能量的过程能够完善到何种程度，这是称之为热力学这门工程学科研究的范围。 all the different types of energy must be accounted for and balanced out when a transformation occurs.出现能量转换时，必须计及各种不同形式的能量，并对它们进行平衡。 whereas the distribution of these various types of energy is clearly of importance to the engineer,who wants to obtain as much useful work as possible from a given quantity of fuel,the first law merely states that energy can be neither created nor destroyed,it does not provide information as to the ultimate distribution of the energy in its such an approach is similar to that of selecting an average thermal conductivity in 消灭，它并没有提供关于各种能量最终分配的资料。 an understanding of thermodynamics and the limitations it imposes on the conversion of energy from one form to another is very relevant to what is going on in the world today.懂得热力学及其对于从一种能量转换为另一种能量的限制，这同当前世界上发生的事情是密切相关的。 with limited supplies of conventional energy resources of oil and gas,and with increased demands for an improved standard of living and an accompanying increased demand for energy,it is important that we obtain the maximum utilization of our oil,gas,and coal reserves.由于对提高生活水平的要求日益增长，随之而来对能量的需求也越多，而石油和可燃气等常规能源的供应却受到限制，因此十分重要的是，我们应当最大限度地利用石油，可燃气和煤的储备。 why some things do not work the way that they were intended,and why other things just cannot possibly work.为什么有些东西不能按预期的那样起作用，为什么别的一些东西却根本不起作用。UNIT 7In its usual context the termsurroundings”is restricted to that specific localized region which interacts in some fashion with the system and hence has a detectable influence on the system.。一般说来， “外界”这一术语指的是某一特定的局部区域，它以某种方式同系统相互作用，从而对系统产生可以探测得出的影响。 the dashed line is a two-3various forms.尽管这些各种形式的能量的分配对工程技术人员显然是很重要的，因为他们想要从一定量的燃料获得尽量多的有效功；然而第一定律阐述的仅仅是：能量既不能创造，也不能的空间区域。 ,and it represents a real obstruction to the flow of matter.对于物质流动来说，管道内表面是真实的界面。 ,there is no real surface which delineates the position of the boundary at the open ends.在开口两端勾画出的边界位置并无真实的界面。 ,it is not necessary for any or all of the boundary to be physically distinguishable when making thermodynamic analyses.进行热力学分析时，边界