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1、A thermodynamic system is a region in space or a quantity of matter bounded by a closed surface。 The surroundings include everything external to the system， and the system is separated from the surroundings by the system boundaries。 These boundaries can be movable or fixed, real or imaginary. 一个热力学系
2、统是一个在空间或有事项的数量由一个封闭的表面范围内的区域。周围环境包括一切外部系统，系统是从周围环境隔开的系统边界.这些边界可以是动产或固定的，真实的或想象.The concepts that operate in any thermodynamic system are entropy and energy. Entropy measures the molecular disorder of a system。 The more mixed a system, the greater its entropy; conversely, an orderly or unmixed config
3、uration is one of low entropy. Energy has the capacity for producing an effect and can be categorized into either stored or transient forms as described in the following sections。 熵和能量的概念,在任何热力学系统操作。熵措施分子系统紊乱。更为复杂的系统，其熵值越大,反之，有序或纯配置是低熵之一。能源已经产生效果的能力,并在下面的章节中所述，可以存储或短暂形式分类。Heat Q is the mechanism tha
4、t transfers energy across the boundaries of systems with differing temperatures， always toward the lower temperature. Heat is positive when energy is added to the system. Work is the mechanism that transfers energy across the boundaries of systems with differing pressures （or force of any kind), alw
5、ays toward the lower pressure。 If the total effect produced in the system can be reduced to the raising of a weight， then nothing but work has crossed the boundary。 Work is positive when energy is removed from the system。 热量Q与不同的温度,跨系统的边界传输能量总是向温度较低的机制。热是积极的，当能量被添加到系统中。 功是指通过存在压差(任一种力）的系统边界传递能量的作用过程
6、，总是指向低压,如果系统中产生的总效果能被简化为一个重物的提升，那么只有功通过了边界,当能量从系统中一出时，功是正的.A property of a system is any observable characteristic of the system. The state of a system is defined by listing its properties。 The most common thermodynamic properties are temperature T， pressure p， and specific volume v or density . Add
7、itional thermodynamic properties include entropy， stored forms of energy， and enthalpy. Frequently， thermodynamic properties combine to form other properties。 Enthalpy h, a result of combining properties， is defined as:h=u+pv where u is the internal energy per unit mass系统属性是系统的任何观察到的特征。系统状态的定义是通过列出其
8、属性.最常见的热力学性质的温度T，压力P，和特定的体积V或密度。其他热力学性质包括熵，能量储存形式,和焓.通常情况下,热力学性质相结合，形成其他属性。焓H，一个属性相结合的结果，被定义为：H = U + PV其中u是每单位质量的内部能量Each property in a given state has only one definite value， and any property always has the same value for a given state， regardless of how the substance arrived at that state. A pro
9、cess is a change in state that can be defined as any change in the properties of a system. A process is described by specifying the initial and final equilibrium states, the path (if identifiable）, and the interactions that take place across system boundaries during the process. 中的每一个给定的状态的属性只有一个定值，
10、和任何财产总是有相同的值给定的状态，不管如何抵达该国的物质。一个进程是一个状态的改变，在系统属性的任何改变，可作为定义。一个过程是指定的初始和最终的平衡状态，路径(如果识别）,并采取跨系统的边界，在这个过程中发生的相互作用。A cycle is a process or a series of processes wherein the initial and final states of the system are identical。 Therefore, at the conclusion of a cycle， all the properties have the same va
11、lue they had at the beginning。 A pure substance has a homogeneous and invariable chemical composition。 It can exist in more than one phase, but the chemical composition is the same in all phases一个周期进程的一个过程或一个系列，其中系统的初始和最终状态是相同的的。因此，在一个周期结束时，所有属性具有相同的价值，他们开始.纯物质均匀的和不变的化学成分.它可以存在于超过一个阶段，但在各个阶段的化学成分是一样
12、的If a substance is liquid at the saturation temperature and pressure， it is called a 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 （the temperature is lower than the saturation temperature
13、 for the given pressure） or a compressed liquid (the pressure is greater than the saturation pressure for the given temperature）. 如果一种物质在饱和温度和压力的液体，它被称为饱和液体.如果液体的温度低于现有的压力的饱和温度,它被称为是过冷液体（温度低于给定压力的饱和温度）或压缩液体（压力大于饱和为给定的温度压力)。If a substance exists as a vapor at saturation temperature and pressure, it i
14、s called a saturated vapor. When the vapor is at a temperature greater than the saturation temperature, it is a superheated vapor. Pressure and temperature of a superheated vapor are independent properties, because the temperature can increase while pressure remains constant. Gases such as air at ro
15、om temperature and pressure are highly superheated vapors.如果一种物质在饱和温度和压力的蒸气存在，它被称为饱和蒸气。当蒸汽温度大于饱和温度,它是一个热蒸气。过热蒸汽压力和温度是独立的属性,因为温度增加，而压力保持不变。如在常温常压下空气的气体是高度过热蒸汽。The second law of thermodynamics differentiates and quantifies processes that only proceed in a certain direction (irreversible） from those th
16、at are reversible. The second law may be described in several ways。 One method uses the concept of entropy flow in an open system and the irreversibility associated with the process. The concept of irreversibility provides added insight into the operation of cycles. 热力学第二定律的区别和量化，只有在某一个方向，是可逆的(不可逆）进行的过程.第二定律可能在几个方面.一种方法是使用在一个开放的系统，并与进程关联的不可逆性的熵流的概念.不可逆转的概念到周期的运作提供额外的洞
