1、1Chapter 1 Introduction to Thermal Science第一章 热科学基础Acoustic flow meter 声波流量计 Corrugated fin 波状散热片Adiabatic 绝热的 Cross product 矢量积Aerodynamics 空气动力学 Denominator 分母Affiliation 联系 Developed flow 充分发展流Airfoil 机翼，螺旋桨 Diffusion 扩散Alternative 替代燃料 Doppler effect 多普勒效应Anemometer 风速计 Double-pipe heat exchange
2、r 套管式换热器Angular speed 角速度 Dry saturated vapor 干饱和蒸汽Area density 表面密度 Electrode 电极Baffle 挡板 Electrolyte 电解，电解液Bifurcation 分形 Electrostatic 静电的Blackbody 黑体 Emissivity 发射率Blade 浆叶，叶片 Equilibrium 平衡Boiler 锅炉 Fluid mechanics 流体力学Boundary layer 边界层 Forced convection 强制对流Carnot Cycle 卡诺循环 Free convection 自
3、然对流Cartesian coordinates 笛卡尔坐标系 Friction loss 摩擦损失Celsius Degree 摄氏度 Glass ceramic 微晶玻璃，玻璃陶瓷Compact heat exchanger 紧凑式换热器 Heat engine 热机Composition 成分，合成物 Heat pump 热泵Compressed liquid 压缩液体 Hydrofoil 水翼Compressibility 可压缩性，压缩率 Hypersonic speed 高超音速Condensation 凝结 Infinitesimal 无穷小的Condenser 冷凝器 Infl
4、ating/deflating 充气/压缩Conduction 导热 Internal combustion engine 内燃机Control volume 控制体 Isentropic 等熵的Convection 对流 Isobaric 等压的Coriolis-accelaration flowmeter 科氏加速流量计Isolated system 孤立体系的2Isometric 等容的 Rough-wall tube 粗糙管Isothermal 等温的 Saturation 饱和Kinematic viscosity 运动黏度 Shear stress 剪切力、切应力Laminar 层
5、流 Shell-and-tube heat exchanger 管壳式换热器Manuscript 手稿，原稿 Specific volume 比容Moisture 湿度，水分 Steady 稳态的，定常的Molecule (化学)分子 Stifling engine 斯特林机Molten polymer 熔融聚合物 Strain rate 变形速度，应变率Muti-disciplinary 多学科的 Streamline 流线Newtonian Fluid 牛顿流体 Strut 支撑，支柱Nominal temperature gradient 法向温度梯度Subcooled liquid 过
6、冷液体Numerator （数学）分子 Superheated vapor 过热蒸汽Parallel flow 平行流动，并流 Surrounding 环境，外界Pathline 迹线 Thermal conductivity 热传导率Phase change 相变 Thermal efficiency 热效率Plane flow 平面流，二元流 Thermodynamics 热力学Plate and flame heat exchanger 板式换热器Torsional 扭力的，扭转的Polymer solution 胶浆 Trailing edge 机翼后缘、尾缘Proof 校样 Tran
7、smitter 传送装置、发送器Propeller 螺旋桨，推进器 Turbine meter 涡轮流量计Pump 泵 Turbulent 湍流的Qulity 干度 Ultrosonic 超声波的Qusi-equilibrium 准平衡、准静态 Uniform flow 均匀刘Radiation 辐射 Vacuum 真空Rankin Cycle 朗肯循环 View factor 角系数Regenerative heat exchanger 蓄热/再生式换热器Viscous 黏性的Reservoir 水库，蓄水池 Cortex shedding 漩涡脱落Reversible 可逆的 Water
8、faucet 水龙头，水嘴Rotameter 转子流量计 3Bi Biot number 比澳数 NPSH 汽蚀余量CFD 计算流体力学 NTU 传热单元数CHF 临界热流量 Nu 努谢尔特数COP 制冷系数 PE 势能Eu 欧拉数 Pr 普朗特数Fo 富立叶数 Ra 瑞利数Fr 弗劳德数 Re 雷诺数Gr 格拉晓夫数 Sc 施密特数KE 动能 St 斯坦顿数 ， 斯特劳哈数LMTD 对数平均温差 We 韦伯数1.1 Fundamental of Engineering Thermodynamics1.1 工程热力学基础Thermodynamics is a science in which
9、the storage, transformation and transfer of energy are studied. Energy is stored as internal energy (associated with temperature), kinetic energy (du to motion), potential energy (due to elevation) and chemical energy (due to chemical composition); it is transformed from one of these forms to anothe
10、r; and it is transferred across a boundary as either heat or work.热力学是一门研究能量储存、转换及传递的科学。能量以内能（与温度有关） 、动能（由物体运动引起） 、势能（由高度引起）和化学能（与化学组成相关）的形式储存。不同形式的能量可以相互转化，而且能量在边界上可以以热和功的形式进行传递。In thermodynamics, we will derive equations that relate the transformations and transfers of energy to properties such as
11、 temperature, pressure and density. Substances and their properties, thus, become very important in thermodynamics. Many of our equations will be based on experimental observations that have been organized into mathematical statements or laws, the first and second laws of thermodynamics are most wid
12、ely used.在热力学中，我们将推导有关能量转化和传递与物性参数，如温度、压强及密度等关系间的方程。因此，在热力学中，物质及其性质变得非常重要。许多热力学方程都是建立在实验观察的基础之上，而且这些实验观察的结果已被整理成数学表达式或定律的形式。其中，热力学第一定律和第二定律应用最为4广泛。1.1.1 Thermodynamic system and control volume1.1.1 热力系统和控制体A thermodynamic system is a fixed quantity of matter contained within some enclosure. The surf
13、ace is usually an obvious one (like that surrounding the gas in the cylinder). However, it may be an imagined boundary (like the deforming boundary of a certain amount of mass as it flows through a pump).热力系统是一包围在某一封闭边界内的具有固定质量的物质。系统边界通常是比较明显的（如气缸内气体的固定边界） 。然而，系统边界也可以是假想的（如一定质量的流体流经泵时不断变形的边界） 。All m
14、atter and space external to a system is collectively called its surroundings. Thermodynamics is concerned with the interaction of a system and its surroundings, or one system interacting with another. A system interacts with its surroundings by transferring energy across its boundary. No material cr
15、osses the boundary of a system. If the system does not exchange energy with the surroundings, it is an isolated system.系统之外的所有物质和空间统称外界或环境。热力学主要研究系统与外界或系统与系统之间的相互作用。系统通过在边界上进行能量传递，从而与外界进行相互作用，但在边界上没有质量交换。当系统与外界间没有能量交换时，这样的系统称为孤立系统。In many cases, an analysis is simplified if attention is focused on a
16、 particular volume in space into which, or from which, a substance flows. Such a volume is a control volume. A pump, a turbine, and an inflating or deflating balloon are examples of control volume. The surface that completely surrounds the control volume is called a control surface.在许多情况下，当我们只关心空间中有
17、物质流进或流出的某个特定体积时，分析可以得到简化。这样的特定体积称为控制体。例如泵、透平、充气或放气的气球都是控制体的例子。包含控制体的表面称为控制表面。Thus, we must choose, in a particular problem, whether a system is to be considered or whether a control volume is more useful. If there is mass flux across a boundary, then a control volume is required; otherwise, a system
18、 is identified.因此，对于具体的问题，我们必须确定是选取系统作为研究对象有利还是选取控制体5作为研究对象有利。如果边界上有质量交换，则选取控制体有利；反之，则应选取系统作为研究对象。1.1.2 Equilibrium, process and cycle平衡、过程和循环When the temperature of a system is referred to, it is assumed that all points of the system have the same, or essentially the same temperature. When the prop
19、erties are constant from point to point and when there is no tendency for change with time, a condition of thermodynamic equilibrium exists. If the temperature, say, is suddenly increased at some part of the system boundary, spontaneous redistribution is assumed to occur until all parts of the 教材 1
20、页system are at the same temperature.对于某一参考系统，假设系统内各点温度完全相同。当物质内部各点的特性参数均相同且不随时间变化时，则称系统处于热力学平衡状态。当系统边界某部分的温度突然上升时，则系统内的温度将自发地重新分布，直至处处相同。When a system changes from one equilibrium state to another, the path of successive sates through which the system passes is called process. If, in the passing one
21、 state to the next, the deviation from equilibrium is infinitesimal, a quasi-equilibrium process occurs, and each state in the process may be idealized as an equilibrium state. Quasi-equilibrium processes can approximate many processes, such as the compression and expansion of gases in an internal c
22、ombustion engine, with no significant loss of accuracy. If the system goes from one equilibrium state to another through a series of non-equilibrium states (as in combustion), a non-equilibrium process occurs.当系统从一个平衡状态转变为另一个平衡状态时，系统所经历的一系列由中间状态组成的变化历程称为过程。若从一个状态到达另一个状态的过程中，始终无限小地偏离平衡态，则称该过程为准静态过程，可
23、以把其中任一个中间状态看作为平衡状态。准静态过程可近似视为许多过程的叠加结果，而不会显著减小其精确性，例如气体在内燃机内的压缩和膨胀过程。如果系统经历一系列不平衡状态（如燃烧） ，从一个平衡状态转变为另一个平衡状态，则其过程为非平衡过程。When a system in a given initial state experiences a series of process and returns 6to the initial state, the system goes a cycle. At the end of the cycle, the properties of the sys
24、tem have the same values they had at the beginning.当系统从一个给定的初始状态出发，经历一系列中间过程又回到其初始状态，则称系统经历了一个循环。循环结束时，系统中的各参数又与初始参数相同。The prefix iso- is attached to the names of any property that remain unchanged in a process. An isothermal process is one in which the temperature is held constant; in an iso-baric
25、process, the pressure remains constant; an isometric process is a constant-volume process.在任一特性参数名称前加上前缀 iso-，表示该参数在整个过程保持不变。等温（isothermal）过程中温度保持不变；等压（isobaric）过程中压强恒定；等容（isometric）过程中体积保持不变。1.1.3 Vapor-liquid phase equilibrium in pure substance纯物质的气-液相平衡Consider as a system 1 kg of water contained
26、 in the piston or cylinder arrangement shown in Fig.1-1(a). Suppose the piston and weight maintain a pressure of 0.1MPa in the cylinder and that the initial temperature is 20. As heat is transferred to the water, the temperature increase appreciably, the specific volume increase slightly, and the pr
27、essure remains constant. When the temperature reaches 99.6, additional heat transfer results in a change of phase, as indicated in Fig.1-1 (b). That is, some of the liquid becomes vapor, and during this process both the temperature and pressure remain constant, but the specific volume increases cons
28、iderably. When the last drop of liquid has vaporized, further transfer of heat results in an increase in both temperature and specific volume of the vapor, as shown in Fig.1-1(c).如图 1-1(a)所示，由活塞和气缸组成的装置中装有 1kg 水。假定活塞和其上的重物使气缸内压强维持在 0.1Mpa，初始温度 20。当有热量开始传递给水时，缸内水温迅速上升，而比容略有增加，气缸内压强保持恒定不变。当水温达到 99.6时，
29、如若再增加传热量，水将发生相变，如图 1-1(b)所示。也就是说，一部分水开始气化变为蒸汽，在此相变过程中，温度和压强始终保持不变，但比容却有大幅度的增加。当最后一滴液体被气化时，进一步的加热将使蒸汽温度和比容均有所增加，如同 1-1(c)所示。图 1-1 液体在常压下的蒸发过程7The term saturation temperature designates the temperature at which vaporization takes place at a given pressure. This pressure is called the saturation pressu
30、re for the given temperature. Thus, for water at 99.6, the saturation pressure is 0.1MPa, and for water at 0.1MPa the saturation temperature is 99.6.在给定压强下发生气化的温度称为饱和温度，压强称为给定温度下的饱和压强。因此，99.6水的饱和压强是 0.1MPa，0.1MPa 水的饱和温度为 99.6。If a substance exists as liquid at the saturation temperature, it is calle
31、d saturated liquid. If the temperature of the liquid is lower than the saturation temperature for the existing pressure, it is called either a subcooled liquid (implying that the temperature is lower 教材 2 页than the saturation temperature for the given pressure) or a compressed liquid (implying that
32、the pressure is greater than the saturation pressure for the given temperature).如果某一工质为液态并处于其饱和温度和饱和压强下，则称该液体为饱和液体。如果液体温度低于当前压强下的饱和温度，则称该液体为过冷液体（表明液体的当前温度低于给定压强下的饱和温度）或压缩液体（表明液体的当前压强大于给定温度下的饱和压强） 。When a substance exists as part liquid and part vapor at the saturation temperature, its quality is def
33、ined as the ratio of the mass of vapor to the total mass. Thus, in Fig.1-1(b), if the mass of vapor is 0.2 kg and the mass of liquid is 0.8 kg, the quality is 0.2 or 20%. Quality has meaning only when the substance is in a saturated state.若某一工质在饱和温度下以液、气共存的形式存在，则称蒸汽质量与总质量之比为干度。因此，如图 1-1(b)所示，若蒸汽质量为
34、0.2kg，液体质量为 0.8kg，则其干度为 0.2 或20%。干度只有在饱和状态下才有意义。If a substance exists as vapor at the saturation temperature, it is called saturation vapor (Some times the term dry saturation vapor is used to emphasize that the quality is 100%). When the vapor is at a temperature greater than the saturation tempera
35、ture, it is said to exist as superheated vapor. The pressure and temperature of superheated vapor are independent properties, since the temperature may increase while the pressure remains constant. 8若某一工质处于饱和温度下并以蒸汽形态存在，则称该蒸汽为饱和蒸汽（有时称为干饱和蒸汽，意在强调其干度为 100%） 。当蒸汽温度高于其饱和温度时，则称之为过热蒸汽。过热蒸汽的压强和温度是彼此独立的，因为温
36、度上升时，压强可能保持不变。Let us plot on the temperature-value diagram of Fig.1-2 the constant-pressure line that represents the states through which the water passes as it is heated from the initial state of 0.1 MPa and 20. Let state A represent the initial state, B the saturated-liquid state(99.6), and line A
37、B the process in which the liquid is heated from the initial temperature to the saturation temperature. Point C is the saturated-vapor state, and line BC is the constant-temperature process in which the change of phase from liquid to vapor occurs. Line CD represents the process in which the steam is
38、 superheated at constant pressure. Temperature and volume both increase during this process.在图 1-2 所示的温度-比容图上作等压线，表示水由初压 0.1MPa、初温 20被加热的过程。点 A 代表初始状态，点 B 为饱和液态（99.6） ，线 AB 表示液体由初始温度被加热至饱和温度所经历的过程。点 C 表示饱和蒸汽状态，线 BC 表示等温过程，即液体气化转变为蒸汽的过程。线 CD 表示在等压条件下蒸汽被加热至过热的过程，在此过程中，温度和比容均增大。图 1-2 温度-比容曲线表 1-1 一些物质的
39、临界参数In a similar name, a constant pressure of 10 MPa is represented by line IJKL, for which the saturation temperature is 311.1. At a pressure of 22.09MPa, represented by line MNO, we find, however, that there is no constant-temperature vaporization process. Instead, point N is a point of inflection
40、 with a zero slope. This point is called the critical point. At the critical point the saturated-liquid and saturated-vapor states are identical. The temperature, pressure and specific volume at critical point are called the critical temperature, critical pressure and critical volume. The critical-p
41、oint data for some substances are given in Table 1-1.类似地，线 IJKL 表示压强为 10MPa 下的等压线，相应的饱和温度为 311.1。但是，在压强为 22.09MPa 条件下（线 MNO） ，不存在等温蒸发过程。相反，点 N 是个转折点，在该点上，切线斜率为零，通常把 N 点称为临界点。在临界点处，饱和液体和饱和气体的状态都是相同的。临界点下的温度、压强和比容分别称为临界温度、临界压强和临界比容。一些工质的临界点数据如表 1-1 所示。91.1.4 The first law of thermodynamicsThe first la
42、w of the thermodynamics is commonly called the law of conservation of energy. 教材 3 页In elementary physics courses, the study of conservation of energy emphasizes changes in kinetic and potential energy and their relationship to work. A more general form of conservation of energy includes the effects
43、 of heat transfer and internal energy changes. Other forms of energy could also be included, such as electrostatic, magnetic, strain and surface energy.1.1.4 热力学第一定律通常把热力学第一定律称为能量守恒定律。在基础物理课程中，能量守恒定律侧重动能、势能的变化以及和功之间的相互关系。更为常见的能量守恒形式还包括传热效应和内能的变化。当然，也包括其它形式的能，如静电能、磁场能、应变能和表面能。Historically, the first
44、law of thermodynamics was stated for a cycle: the net heat transfer is equal to the net work done for a system undergoing a cycle.历史上，用热力学第一定律来描述循环过程：净传热量等于循环过程中对系统所做的净功。1.1.5 The second law of thermodynamicsThe second law of thermodynamics can be stated in a variety of ways. Here we present two: th
45、e Clausius statement and the Kelvin-Planck statement.1.1.5 热力学第二定律热力学第二定律有多种表述形式。在此列举两种：克劳修斯表述和凯尔文-普朗克表述。Clausius statementIt is impossible to construct a device that operates in a cycle and whose sole effect is transfer of heat from a cooler body to a hotter body.克劳修斯表述：制造一台唯一功能是把热量从低温物体传给高温物体的循环设备
46、是不可能的。图 1-3 第二定律的违背10This statement relates to a refrigerator (or a heat pump). It states that it is impossible to construct a refrigerator that transfers energy from a cooler body to a hotter body without the input of work; this violation is shown in Fig.1-3(a).以冰箱（或热泵）为例，不可能制造一台不用输入功就能把热量从低温物体传给高温
47、物体的冰箱，如图 1-3(a)所示。It is impossible to construct a device that operates in a cycle and produces no other effect than the production of work and the transfer of heat from a single body.凯尔文-普朗克表述：制造一台从单一热源吸热和做功的循环设备是不可能的。In other words, it is impossible to construct a heat engine that extracts energy f
48、rom reservoir, does work, and does not transfer heat to a low-temperature reservoir. This rules out any heat engine that is 100 percent efficient, like the one shown in Fig.1-3(b).换句话说，制造这样一台从某一热源吸热并对外做功，而没有与低温热源进行换热的热机是不可能的。因此，该表述说明了不存在工作效率为 100%的热机，如图 1-3(b)所示。1.1.6 The Carnot CycleThe heat engine
49、 that operates most efficiently between a high-temperature reservoir and a low-temperature reservoir is the Carnot engine. This is an ideal engine that uses reversible process to form its cycle of operation; such a cycle is Carnot cycle. The Carnot engine is very useful, since its efficiency establishes the maximum possible efficiency of any real engine. If the efficiency of a real is significantly lower than the efficiency of Carnot engine between the same temperature limits, then additional improvements may be possible.1.1.6 卡诺循环卡诺机是低温热源和高温热源间运行效率最高的热机。卡诺机是一个理想热机，利用
