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1、实用标准 文档 Chapter 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
2、exchanger 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 con
3、vection 自然对流 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 Conden
4、ser 冷凝器Inflating/deflating 充气/ 压缩 Conduction 导热Internal combustion engine 内燃机 Control volume 控制体Isentropic 等熵的 实用标准 文档 Convection 对流Isobaric 等压的 Coriolis-accelaration flowmeter 科 氏加速流量计 Isolated system 孤立体系的 Isometric 等容的Rough-wall tube 粗糙管 Isothermal 等温的Saturation 饱和 Kinematic viscosity 运动黏度Shear s
5、tress 剪切力、切应力 Laminar 层流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
6、法向 温度梯度 Subcooled liquid过冷液体 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
7、 edge 机翼后缘、尾缘 Proof 校样Transmitter 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 实用标准 文档 Reservoir 水库，蓄水池Cort
8、ex shedding 漩涡脱落 Reversible 可逆的Water faucet 水龙头，水嘴 Rotameter 转子流量计 Bi 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 Thermodynamics 1.1工程热力学基础
9、Thermodynamics is a science in which 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 transfor
10、med from one of these forms to another; 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 an
11、d transfers of energy to properties such as 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
12、 second laws of 实用标准 文档 thermodynamics are most widely 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广泛。 1.1.1Thermodynamic system and control volume 1.1.1热力系统和控制体 A thermodynamic system is a fixed quan
13、tity of matter contained within some enclosure. The surface 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
14、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 matter 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
15、by transferring energy across its boundary. No material crosses 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
16、 cases, an analysis is simplified if attention is focused on a 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 th
17、e control volume is called a control surface. 在许多情况下，当我们只关心空间中有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 实用标准 文档 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 f
18、lux across a boundary, then a control volume is required; otherwise, a system 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 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。 1.1.2Equilibrium, process and cycle 平衡、过程和循环 When the temperature of a system is referred to, it is assumed that all point
19、s of the system have the same, or essentially the same temperature. When the properties 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 boun
20、dary, spontaneous redistribution is assumed to occur until all parts of the 教材 1 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 suc
21、cessive sates through which the system passes is called process. If, in the passing one 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 appr
22、oximate many processes, such as the compression and expansion of gases in an internal combustion engine, with no significant loss of accuracy. If the system goes from one equilibrium state to another 实用标准 文档 through a series of non-equilibrium states (as in combustion), a non-equilibrium process occ
23、urs. 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 retur
24、ns to the initial state, the system goes a cycle. At the end of the cycle, the properties of the system 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
25、 in a process. An isothermal process is one in which the temperature is held constant; in an iso-baric 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。
26、1.1.3Vapor-liquid phase equilibrium in pure substance 纯物质的气 -液相平衡 Consider as a system 1 kg of water contained 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 tra
27、nsferred to the water, the temperature increase appreciably, the specific volume increase slightly, and the pressure 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, an
28、d during this 实用标准 文档 process both the temperature and pressure remain constant, but the specific volume increases considerably. 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
29、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，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 The term saturation temperature des
30、ignates the temperature at which vaporization takes place at a given pressure. This pressure is called the saturation pressure 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
31、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 called 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 tha
32、t the temperature is lower 教材 2 页 than the saturation temperature for the given pressure) or a compressed liquid (implying that 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
33、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 defined as the ratio of the mass of vapor to 实用标准 文档 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.
34、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 t
35、erm dry saturation vapor is used to emphasize that the quality is 100%). When the vapor is at a temperature greater than the saturation temperature, it is said to exist as superheated vapor. The pressure and temperature of superheated vapor are independent properties, since the temperature may incre
36、ase while the pressure remains constant. 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
37、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 AB 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 i
38、s 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 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
39、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。 实用标准 文档 图 1-2 温度- 比容曲线 表 1-1 一些物质的临界参数 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 o
40、f 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 with a zero slope. This point is called the critical point. At the critical point the saturated-liquid and saturated-vapor states are identical
41、. The temperature, pressure and specific volume at critical point are called the critical temperature, critical pressure and critical volume. The critical-point 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，
42、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。 1.1.4 The first law of thermodynamics The first law 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 e
43、nergy emphasizes changes in kinetic and potential energy and their relationship to work. A more general form of conservation of energy includes the effects of heat transfer and internal energy changes. Other forms of energy could also be included, such as electrostatic, magnetic, strain and surface
44、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。 实用标准 文档 Historically, the first 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
45、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 thermodynamics The second law of thermodynamics can be stated in a variety of ways. Here we present two: the 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 statement
46、 It 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是不可 能的。 图 1-3 第二定律的违背 This statement relates to a refrigerator (or a heat pump). It states that it is impossible to cons
47、truct 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 th
48、an 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 from reservoir, does work, and does not transfer heat to 实用标准 文档 a low-temperature reservoir. This rules out
49、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 Cycle The heat engine 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 eff