热力学系统

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A thermodynamic system is a body of matter and/or radiation, confined in space by walls, with defined permeabilities, which separate it from its surroundings. The surroundings may include other thermodynamic systems, or physical systems that are not thermodynamic systems. A wall of a thermodynamic system may be purely notional, when it is described as being 'permeable' to all matter, all radiation, and all forces.

A thermodynamic system is a body of matter and/or radiation, confined in space by walls, with defined permeabilities, which separate it from its surroundings. The surroundings may include other thermodynamic systems, or physical systems that are not thermodynamic systems. A wall of a thermodynamic system may be purely notional, when it is described as being 'permeable' to all matter, all radiation, and all forces.

热力学系统thermodynamic system是一个由物质和/或辐射组成的物体,在空间中被壁限制,使其具有确定的渗透性,并将其与周围环境分隔开来。周围环境可能包括其他热力学系统,或不属于热力学系统的物理系统。一个热力学系统的墙可能是纯粹的概念,当它被描述为对所有物质、所有辐射和所有力都是 "可渗透的"时。

A widely used distinction is between isolated, closed, and open thermodynamic systems. An isolated thermodynamic system has walls that are non-conductive of heat and perfectly reflective of all radiation, that are rigid and immovable, and that are impermeable to all forms of matter and all forces. (Some writers use the word 'closed' when here the word 'isolated' is being used.)

A widely used distinction is between isolated, closed, and open thermodynamic systems. An isolated thermodynamic system has walls that are non-conductive of heat and perfectly reflective of all radiation, that are rigid and immovable, and that are impermeable to all forms of matter and all forces. (Some writers use the word 'closed' when here the word 'isolated' is being used.)

一个广泛使用的分类是孤立的,封闭的和开放的热力学系统。一个孤立的热力学系统的壁是不导热的,对所有辐射有完美的反射,是刚性的和不可移动的,对所有形式的物质和所有力是不可渗透的。(有些学者使用 "封闭 "一词,而这里使用的是 "孤立 "一词)

A closed thermodynamic system is confined by walls that are impermeable to matter, but, by thermodynamic operations, alternately can be made permeable (described as 'diathermal') or impermeable ('adiabatic') to heat, and that, for thermodynamic processes (initiated and terminated by thermodynamic operations), alternately can be allowed or not allowed to move, with system volume change or agitation with internal friction in system contents, as in Joule's original demonstration of the mechanical equivalent of heat, and alternately can be made rough or smooth, so as to allow or not allow heating of the system by friction on its surface.

A closed thermodynamic system is confined by walls that are impermeable to matter, but, by thermodynamic operations, alternately can be made permeable (described as 'diathermal') or impermeable ('adiabatic') to heat, and that, for thermodynamic processes (initiated and terminated by thermodynamic operations), alternately can be allowed or not allowed to move, with system volume change or agitation with internal friction in system contents, as in Joule's original demonstration of the mechanical equivalent of heat, and alternately can be made rough or smooth, so as to allow or not allow heating of the system by friction on its surface.

一个封闭的热力学系统被对物质不可渗透的壁所限制,但通过热力学操作,可以使其交替地对热量渗透(称为“透热”)或不透热(“绝热”) ;并且,对于热力学过程(由热力学操作启动和终止),可以交替地允许或不允许其运动,随着系统体积的变化或系统内部摩擦的搅拌,就像焦耳(Joule)最初展示的热的机械当量一样,并且可以交替地使其粗糙或光滑,以便允许或不允许通过其表面的摩擦对系统加热。

An open thermodynamic system has at least one wall that separates it from another thermodynamic system, which for this purpose is counted as part of the surroundings of the open system, the wall being permeable to at least one chemical substance, as well as to radiation; such a wall, when the open system is in thermodynamic equilibrium, does not sustain a temperature difference across itself.

An open thermodynamic system has at least one wall that separates it from another thermodynamic system, which for this purpose is counted as part of the surroundings of the open system, the wall being permeable to at least one chemical substance, as well as to radiation; such a wall, when the open system is in thermodynamic equilibrium, does not sustain a temperature difference across itself.

一个开放的热力学系统至少有一堵壁将其与另一个开放的热力学系统隔开,为此,这个壁被算作开放系统周围环境的一部分,该壁对至少一种化学物质以及辐射是可渗透的;当开放系统处于热力学平衡状态时,这样的壁不会维持其本身的温度差异。

Furthermore, the state of a thermodynamic system is described by thermodynamic state variables, which may be intensive, such as temperature, or pressure, or extensive, such as entropy, or internal energy.

Furthermore, the state of a thermodynamic system is described by thermodynamic state variables, which may be intensive, such as temperature, or pressure, or extensive, such as entropy, or internal energy.

此外,热力学系统的状态是由热力学状态变量描述的,这些变量可能是强度量,如温度或压力,或广延量的,如熵或内能。

A thermodynamic system is subject to external interventions called thermodynamic operations; these alter the system's walls or its surroundings; as a result, the system undergoes transient thermodynamic processes according to the principles of thermodynamics. Such operations and processes effect changes in the thermodynamic state of the system.

A thermodynamic system is subject to external interventions called thermodynamic operations; these alter the system's walls or its surroundings; as a result, the system undergoes transient thermodynamic processes according to the principles of thermodynamics. Such operations and processes effect changes in the thermodynamic state of the system.

一个热力学系统会受到被称为热力学操作的外部干预;这些操作会改变系统的壁或其周围环境;因此,根据热力学原理,系统会经历短暂的热力学过程。这种操作和过程会影响系统的热力学状态的变化。

When the intensive state variables of its content vary in space, a thermodynamic system can be considered as many systems contiguous with each other, each being a different thermodynamical system.

When the intensive state variables of its content vary in space, a thermodynamic system can be considered as many systems contiguous with each other, each being a different thermodynamical system.

当其内部的强度量在空间中变化时,一个热力学系统可以被视为许多相邻的系统,每个系统都是一个不同的热力学系统。

A thermodynamic system may comprise several phases, such as ice, liquid water, and water vapour, in mutual thermodynamic equilibrium, mutually unseparated by any wall. Or it may be homogeneous. Such systems may be regarded as 'simple'.

A thermodynamic system may comprise several phases, such as ice, liquid water, and water vapour, in mutual thermodynamic equilibrium, mutually unseparated by any wall. Or it may be homogeneous. Such systems may be regarded as 'simple'.

一个热力学系统可能包括几个相,如冰、液态水和水蒸气,在相互的热力学平衡中,相互之间没有任何壁的分隔。或者它可能是同质的。这样的系统可以被视为 "简单"的。

A 'compound' thermodynamic system may comprise several simple thermodynamic sub-systems, mutually separated by one or several walls of definite respective permeabilities. It is often convenient to consider such a compound system initially isolated in a state of thermodynamic equilibrium, then affected by a thermodynamic operation of increase of some inter-sub-system wall permeability, to initiate a transient thermodynamic process, so as to generate a final new state of thermodynamic equilibrium. This idea was used, and perhaps introduced, by Carathéodory. In a compound system, initially isolated in a state of thermodynamic equilibrium, a reduction of a wall permeability does not effect a thermodynamic process, nor a change of thermodynamic state. This difference expresses the Second Law of thermodynamics. It illustrates that increase in entropy measures increase in dispersal of energy, due to increase of accessibility of microstates.[1]

A 'compound' thermodynamic system may comprise several simple thermodynamic sub-systems, mutually separated by one or several walls of definite respective permeabilities. It is often convenient to consider such a compound system initially isolated in a state of thermodynamic equilibrium, then affected by a thermodynamic operation of increase of some inter-sub-system wall permeability, to initiate a transient thermodynamic process, so as to generate a final new state of thermodynamic equilibrium. This idea was used, and perhaps introduced, by Carathéodory. In a compound system, initially isolated in a state of thermodynamic equilibrium, a reduction of a wall permeability does not effect a thermodynamic process, nor a change of thermodynamic state. This difference expresses the Second Law of thermodynamics. It illustrates that increase in entropy measures increase in dispersal of energy, due to increase of accessibility of microstates.

一个 "复合 "的热力学系统可能包括几个简单的热力学子系统,相互之间由一个或几个具有明确各自渗透性的壁隔开。考虑这样一个复合系统,最初在热力学平衡状态下被孤立,然后受到一些子系统间壁的渗透性增加的热力学操作的影响,启动一个瞬时的热力学过程,从而比较方便地产生一个最终的新的热力学平衡状态。这个想法被卡拉西奥多里(Carathéodory)采用,也许就是由他引入的。在一个最初被孤立在热力学平衡状态下的复合系统中,壁的渗透性的减少并不影响热力学过程,也不影响热力学状态的改变。这种差异反映了热力学第二定律。它说明,由于微观状态的可及性增加,熵的增加衡量的是能量分散的增加。[1]

In equilibrium thermodynamics, the state of a thermodynamic system is a state of thermodynamic equilibrium, as opposed to a non-equilibrium state.

In equilibrium thermodynamics, the state of a thermodynamic system is a state of thermodynamic equilibrium, as opposed to a non-equilibrium state.

平衡热力学equilibrium thermodynamics中,热力学系统的状态是一种热力学平衡状态,与非平衡状态相对应。

According to the permeabilities of the walls of a system, transfers of energy and matter occur between it and its surroundings, which are assumed to be unchanging over time, until a state of thermodynamic equilibrium is attained. The only states considered in equilibrium thermodynamics are equilibrium states. Classical thermodynamics includes (a) equilibrium thermodynamics; (b) systems considered in terms of cyclic sequences of processes rather than of states of the system; such were historically important in the conceptual development of the subject. Systems considered in terms of continuously persisting processes described by steady flows are important in engineering.

According to the permeabilities of the walls of a system, transfers of energy and matter occur between it and its surroundings, which are assumed to be unchanging over time, until a state of thermodynamic equilibrium is attained. The only states considered in equilibrium thermodynamics are equilibrium states. Classical thermodynamics includes (a) equilibrium thermodynamics; (b) systems considered in terms of cyclic sequences of processes rather than of states of the system; such were historically important in the conceptual development of the subject. Systems considered in terms of continuously persisting processes described by steady flows are important in engineering.

根据一个系统壁的渗透性,能量和物质的转移在它和它的周围环境之间发生,这被认为是随时间变化的,直到达到一个热力学平衡状态。平衡热力学中考虑的唯一状态是平衡状态。经典热力学包括(a)平衡热力学;(b)从过程的循环序列而不是系统的状态方面考虑的系统;这类系统在该学科的概念发展中具有历史重要性。以稳定流动所描述的持续存在的过程来考虑的系统,在工程中很重要。


The very existence of thermodynamic equilibrium, defining states of thermodynamic systems, is the essential, characteristic, and most fundamental postulate of thermodynamics, though it is only rarely cited as a numbered law.[2][3][4] According to Bailyn, the commonly rehearsed statement of the zeroth law of thermodynamics is a consequence of this fundamental postulate.[5] In reality, practically nothing in nature is in strict thermodynamic equilibrium, but the postulate of thermodynamic equilibrium often provides very useful idealizations or approximations, both theoretically and experimentally; experiments can provide scenarios of practical thermodynamic equilibrium.

The very existence of thermodynamic equilibrium, defining states of thermodynamic systems, is the essential, characteristic, and most fundamental postulate of thermodynamics, though it is only rarely cited as a numbered law. According to Bailyn, the commonly rehearsed statement of the zeroth law of thermodynamics is a consequence of this fundamental postulate. In reality, practically nothing in nature is in strict thermodynamic equilibrium, but the postulate of thermodynamic equilibrium often provides very useful idealizations or approximations, both theoretically and experimentally; experiments can provide scenarios of practical thermodynamic equilibrium.

热力学平衡thermodynamic equilibrium的存在,定义了热力学系统的状态,是热力学的基本、特征和最基本的假设,尽管它只是很少被作为一个编号的定律来引用。[2][3][4] 根据拜伦(Bailyn)的说法,通常认为的热力学第三定律是这个基本假设的结果。[5] 在现实中,自然界几乎没有任何东西处于严格的热力学平衡状态,但热力学平衡的假设往往能理论上和实验上进行非常有用的理想化或近似;实验可以提供实际热力学平衡的场景。

In equilibrium thermodynamics the state variables do not include fluxes because in a state of thermodynamic equilibrium all fluxes have zero values by definition. Equilibrium thermodynamic processes may involve fluxes but these must have ceased by the time a thermodynamic process or operation is complete bringing a system to its eventual thermodynamic state. Non-equilibrium thermodynamics allows its state variables to include non-zero fluxes, that describe transfers of mass or energy or entropy between a system and its surroundings.[6]

In equilibrium thermodynamics the state variables do not include fluxes because in a state of thermodynamic equilibrium all fluxes have zero values by definition. Equilibrium thermodynamic processes may involve fluxes but these must have ceased by the time a thermodynamic process or operation is complete bringing a system to its eventual thermodynamic state. Non-equilibrium thermodynamics allows its state variables to include non-zero fluxes, that describe transfers of mass or energy or entropy between a system and its surroundings.

平衡热力学中,状态变量不包括通量,因为在热力学平衡状态下,所有通量的定义是零值。平衡热力学过程可能涉及通量,但在热力学过程或操作完成时,这些通量必须停止,使系统达到最终的热力学状态。非平衡热力学允许其状态变量包括非零通量,这些通量描述了系统与其周围环境之间的质量或能量或熵的转移。[6]

In 1824 Sadi Carnot described a thermodynamic system as the working substance (such as the volume of steam) of any heat engine under study.

In 1824 Sadi Carnot described a thermodynamic system as the working substance (such as the volume of steam) of any heat engine under study.

1824年,萨迪·卡诺(Sadi Carnot)将热力学系统描述为所研究的任何热机的工作物质(如蒸汽的体积)。



Overview 概述

模板:Thermodynamics

Thermodynamic equilibrium is characterized by absence of flow of mass or energy. Equilibrium thermodynamics, as a subject in physics, considers macroscopic bodies of matter and energy in states of internal thermodynamic equilibrium. It uses the concept of thermodynamic processes, by which bodies pass from one equilibrium state to another by transfer of matter and energy between them. The term 'thermodynamic system' is used to refer to bodies of matter and energy in the special context of thermodynamics. The possible equilibria between bodies are determined by the physical properties of the walls that separate the bodies. Equilibrium thermodynamics in general does not measure time. Equilibrium thermodynamics is a relatively simple and well settled subject. One reason for this is the existence of a well defined physical quantity called 'the entropy of a body'.

Thermodynamic equilibrium is characterized by absence of flow of mass or energy. Equilibrium thermodynamics, as a subject in physics, considers macroscopic bodies of matter and energy in states of internal thermodynamic equilibrium. It uses the concept of thermodynamic processes, by which bodies pass from one equilibrium state to another by transfer of matter and energy between them. The term 'thermodynamic system' is used to refer to bodies of matter and energy in the special context of thermodynamics. The possible equilibria between bodies are determined by the physical properties of the walls that separate the bodies. Equilibrium thermodynamics in general does not measure time. Equilibrium thermodynamics is a relatively simple and well settled subject. One reason for this is the existence of a well defined physical quantity called 'the entropy of a body'.

热力学平衡thermodynamic equilibrium的特点是没有质量或能量的流动。平衡热力学作为物理学的一门学科,认为宏观的物质和能量体处于内部热力学平衡状态。它使用热力学过程的概念,通过它们之间的物质和能量的转移,身体从一个平衡状态转移到另一个平衡状态。术语 "热力学系统 "在热力学的特殊背景下被用来指代物质和能量。物体之间可能的平衡状态是由分隔物体的壁的物理特性决定的。一般来说,平衡热力学不测量时间。平衡热力学是一个相对简单和解决良好的主题。其原因之一是存在一个定义明确的物理量,称为 "熵"。

Non-equilibrium thermodynamics, as a subject in physics, considers bodies of matter and energy that are not in states of internal thermodynamic equilibrium, but are usually participating in processes of transfer that are slow enough to allow description in terms of quantities that are closely related to thermodynamic state variables. It is characterized by presence of flows of matter and energy. For this topic, very often the bodies considered have smooth spatial inhomogeneities, so that spatial gradients, for example a temperature gradient, are well enough defined. Thus the description of non-equilibrium thermodynamic systems is a field theory, more complicated than the theory of equilibrium thermodynamics. Non-equilibrium thermodynamics is a growing subject, not an established edifice. In general, it is not possible to find an exactly defined entropy for non-equilibrium problems. For many non-equilibrium thermodynamical problems, an approximately defined quantity called 'time rate of entropy production' is very useful. Non-equilibrium thermodynamics is mostly beyond the scope of the present article.

Non-equilibrium thermodynamics, as a subject in physics, considers bodies of matter and energy that are not in states of internal thermodynamic equilibrium, but are usually participating in processes of transfer that are slow enough to allow description in terms of quantities that are closely related to thermodynamic state variables. It is characterized by presence of flows of matter and energy. For this topic, very often the bodies considered have smooth spatial inhomogeneities, so that spatial gradients, for example a temperature gradient, are well enough defined. Thus the description of non-equilibrium thermodynamic systems is a field theory, more complicated than the theory of equilibrium thermodynamics. Non-equilibrium thermodynamics is a growing subject, not an established edifice. In general, it is not possible to find an exactly defined entropy for non-equilibrium problems. For many non-equilibrium thermodynamical problems, an approximately defined quantity called 'time rate of entropy production' is very useful. Non-equilibrium thermodynamics is mostly beyond the scope of the present article.

非平衡热力学Non-equilibrium thermodynamics,作为物理学中的一门学科,考虑的是不处于内部热力学平衡状态的物质和能量,但通常参与足够缓慢的转移过程,以允许用与热力学状态变量密切相关的量来描述。它的特点是存在着物质和能量的流动。对于这个主题,所考虑的物体往往具有平滑的空间不均匀性,因此空间梯度,例如温度梯度,是足够明确的。因此,对非平衡热力学系统的描述是一种场理论,比平衡热力学理论更复杂。非平衡热力学是一个不断发展的学科,不是一个已经建筑完成的大厦。一般来说,不可能为非平衡问题找到一个精确定义的熵。对于许多非平衡热力学问题,一个被称为 "熵产生的时间率 "的近似定义的量是非常有用的。非平衡热力学大多超出了本文的范围。

Another kind of thermodynamic system is considered in engineering. It takes part in a flow process. The account is in terms that approximate, well enough in practice in many cases, equilibrium thermodynamical concepts. This is mostly beyond the scope of the present article, and is set out in other articles, for example the article Flow process.

Another kind of thermodynamic system is considered in engineering. It takes part in a flow process. The account is in terms that approximate, well enough in practice in many cases, equilibrium thermodynamical concepts. This is mostly beyond the scope of the present article, and is set out in other articles, for example the article Flow process.

另一种热力学系统在工程学中被考虑。它参与了一个流动过程。在许多情况下,这种说法与实践中的平衡热力学概念相近,而且足够好。这主要超出了本文的范围,并在其他文章中阐述,例如《流动过程》(Flow process)一文。

History 历史

The first to create the concept of a thermodynamic system was the French physicist Sadi Carnot whose 1824 Reflections on the Motive Power of Fire studied what he called the working substance, e.g., typically a body of water vapor, in steam engines, in regards to the system's ability to do work when heat is applied to it. The working substance could be put in contact with either a heat reservoir (a boiler), a cold reservoir (a stream of cold water), or a piston (to which the working body could do work by pushing on it). In 1850, the German physicist Rudolf Clausius generalized this picture to include the concept of the surroundings, and began referring to the system as a "working body". In his 1850 manuscript On the Motive Power of Fire, Clausius wrote:

The first to create the concept of a thermodynamic system was the French physicist Sadi Carnot whose 1824 Reflections on the Motive Power of Fire studied what he called the working substance, e.g., typically a body of water vapor, in steam engines, in regards to the system's ability to do work when heat is applied to it. The working substance could be put in contact with either a heat reservoir (a boiler), a cold reservoir (a stream of cold water), or a piston (to which the working body could do work by pushing on it). In 1850, the German physicist Rudolf Clausius generalized this picture to include the concept of the surroundings, and began referring to the system as a "working body". In his 1850 manuscript On the Motive Power of Fire, Clausius wrote:

第一个提出热力学系统概念的是法国物理学家萨迪·卡诺(Sadi Cannot),他1824年的《对火的动力的思考》(Reflections on the Motive Power of Fire)中研究了他称之为工作物质的东西,例如,在蒸汽机中典型的水蒸气,当热量被施加到它时做功的能力。工作物质可以与蓄热体(锅炉)、蓄冷体(冷水流)或活塞(工作体可以通过推动它来做功)接触。1850年,德国物理学家鲁道夫·克劳修斯(Rudolf Clausius)将这一图景概括为包括周围环境的概念,并开始将该系统称为 "工作体"。在他1850年的手稿《论火的动力》(On the Motive Power of Fire)中,克劳修斯写道:

"With every change of volume (to the working body) a certain amount work must be done by the gas or upon it, since by its expansion it overcomes an external pressure, and since its compression can be brought about only by an exertion of external pressure. To this excess of work done by the gas or upon it there must correspond, by our principle, a proportional excess of heat consumed or produced, and the gas cannot give up to the "surrounding medium" the same amount of heat as it receives." “随着(工作体)体积的每一次变化,气体必须做一定量的功,因为它的膨胀克服了外部压力,而它的压缩只有通过施加外部压力才能实现。根据我们的原则,气体所做的或在它身上所做的过量的功,必须与所消耗或产生的热的比例过量相对应,而且气体向 "周围介质 "放弃的热量不能与它所接受的热量相同。”


The article Carnot heat engine shows the original piston-and-cylinder diagram used by Carnot in discussing his ideal engine; below, we see the Carnot engine as is typically modeled in current use:

The article Carnot heat engine shows the original piston-and-cylinder diagram used by Carnot in discussing his ideal engine; below, we see the Carnot engine as is typically modeled in current use:

卡诺热机》(Carnot heat engine)一文显示了卡诺在讨论他的理想发动机时使用的原始活塞和气缸图;下面,展示了卡诺发动机的典型模型:

文件:Carnot heat engine 2.svg
Carnot engine diagram (modern) – where heat flows from a high temperature TH furnace through the fluid of the "working body" (working substance) and into the cold sink TC, thus forcing the working substance to do mechanical work W on the surroundings, via cycles of contractions and expansions. 卡诺发动机图(现代)——热量从高温的T_H炉流过 "工作体"(工作物质)的液体,进入冷的水槽T_C,从而迫使工作物质通过收缩和膨胀的循环对周围环境做机械功W。


In the diagram shown, the "working body" (system), a term introduced by Clausius in 1850, can be any fluid or vapor body through which heat Q can be introduced or transmitted through to produce work. In 1824, Sadi Carnot, in his famous paper Reflections on the Motive Power of Fire, had postulated that the fluid body could be any substance capable of expansion, such as vapor of water, vapor of alcohol, vapor of mercury, a permanent gas, or air, etc. Though, in these early years, engines came in a number of configurations, typically QH was supplied by a boiler, wherein water boiled over a furnace; QC was typically a stream of cold flowing water in the form of a condenser located on a separate part of the engine. The output work W was the movement of the piston as it turned a crank-arm, which typically turned a pulley to lift water out of flooded salt mines. Carnot defined work as "weight lifted through a height".

In the diagram shown, the "working body" (system), a term introduced by Clausius in 1850, can be any fluid or vapor body through which heat Q can be introduced or transmitted through to produce work. In 1824, Sadi Carnot, in his famous paper Reflections on the Motive Power of Fire, had postulated that the fluid body could be any substance capable of expansion, such as vapor of water, vapor of alcohol, vapor of mercury, a permanent gas, or air, etc. Though, in these early years, engines came in a number of configurations, typically QH was supplied by a boiler, wherein water boiled over a furnace; QC was typically a stream of cold flowing water in the form of a condenser located on a separate part of the engine. The output work W was the movement of the piston as it turned a crank-arm, which typically turned a pulley to lift water out of flooded salt mines. Carnot defined work as "weight lifted through a height".

在图中,"工作体"(系统)是克劳修斯在1850年提出的一个术语,可以是任何流体或蒸汽体,通过它可以引入或传递热量Q以产生功。1824年,萨迪·卡诺(Sadi Carnot,)在他著名的论文《关于火的动力的思考》(Reflections on the Motive Power of Fire)中提出,流体可以是任何能够膨胀的物质,如水蒸气、酒精蒸气、汞蒸气、永久气体或空气等。尽管在早期,发动机有许多配置,但典型的QH是由锅炉提供的,水在炉子上沸腾;QC是典型的冷水流,以冷凝器的形式位于发动机的一个独立部分上。输出的功W是活塞转动曲柄臂时的运动,曲柄臂通常转动滑轮,将水从被淹没的盐矿中提升出来。卡诺将功定义为 "通过一个高度提升的重量"。

Systems in equilibrium 处于平衡状态的系统

At thermodynamic equilibrium, a system's properties are, by definition, unchanging in time. Systems in equilibrium are much simpler and easier to understand than systems not in equilibrium. In some cases, when analyzing a thermodynamic process, one can assume that each intermediate state in the process is at equilibrium. This considerably simplifies the analysis.

在热力学平衡状态下,根据定义,一个系统的属性在时间上是不变的。处于平衡状态的系统比不处于平衡状态的系统要简单和容易理解。在某些情况下,当分析一个热力学过程时,我们可以假设该过程中的每个中间状态都处于平衡状态。这大大简化了分析。

In isolated systems it is consistently observed that as time goes on internal rearrangements diminish and stable conditions are approached. Pressures and temperatures tend to equalize, and matter arranges itself into one or a few relatively homogeneous phases. A system in which all processes of change have gone practically to completion is considered in a state of thermodynamic equilibrium. The thermodynamic properties of a system in equilibrium are unchanging in time. Equilibrium system states are much easier to describe in a deterministic manner than non-equilibrium states.

In isolated systems it is consistently observed that as time goes on internal rearrangements diminish and stable conditions are approached. Pressures and temperatures tend to equalize, and matter arranges itself into one or a few relatively homogeneous phases. A system in which all processes of change have gone practically to completion is considered in a state of thermodynamic equilibrium. The thermodynamic properties of a system in equilibrium are unchanging in time. Equilibrium system states are much easier to describe in a deterministic manner than non-equilibrium states.

在孤立的系统中,人们一直观察到,随着时间的推移,内部的重新排列会减少,并接近于稳定的条件。压力和温度趋于平衡,物质排列成一个或几个相对均匀的阶段。一个系统中的所有变化过程实际上已经完成,被认为处于热力学平衡状态。处于平衡状态的系统的热力学属性在时间上是不变的。平衡状态的系统比非平衡状态更容易以确定的方式描述。

For a process to be reversible, each step in the process must be reversible. For a step in a process to be reversible, the system must be in equilibrium throughout the step. That ideal cannot be accomplished in practice because no step can be taken without perturbing the system from equilibrium, but the ideal can be approached by making changes slowly.

For a process to be reversible, each step in the process must be reversible. For a step in a process to be reversible, the system must be in equilibrium throughout the step. That ideal cannot be accomplished in practice because no step can be taken without perturbing the system from equilibrium, but the ideal can be approached by making changes slowly.

要使一个过程是可逆的,该过程中的每一步都必须是可逆的。对于一个过程中的一个步骤是可逆的,系统必须在整个步骤中处于平衡状态。这一理想在实践中无法实现,因为没有一个步骤可以在不扰乱系统平衡的情况下进行,但可以通过缓慢地进行改变来接近这一理想。

Walls 壁

{ | class = “ wikitable” align = “ right”
Types of transfers permitted Types of transfers permitted
+ 允许转移的类型
by types of wall by types of wall
+ 按墙的类型排列 type of wall type of wall 墙的类型 type of transfer type of transfer 转移类型
Matter Matter 物质 Work Work 工作 Heat Heat
permeable to matter permeable to matter 无关紧要 Green tickY Red XN Red XN
permeable to energy but permeable to energy but 透过能量,但

impermeable to matter

impermeable to matter

不透物质

Red XN Green tickY Green tickY
adiabatic adiabatic 绝热的 Red XN Green tickY Red XN
adynamic and adynamic and 无名氏和

impermeable to matter

impermeable to matter

不透物质

Red XN Red XN Green tickY
isolating isolating 隔离 Red XN Red XN Red XN

A system is enclosed by walls that bound it and connect it to its surroundings.[7][8][9][10][11][12] Often a wall restricts passage across it by some form of matter or energy, making the connection indirect. Sometimes a wall is no more than an imaginary two-dimensional closed surface through which the connection to the surroundings is direct.

A system is enclosed by walls that bound it and connect it to its surroundings. Often a wall restricts passage across it by some form of matter or energy, making the connection indirect. Sometimes a wall is no more than an imaginary two-dimensional closed surface through which the connection to the surroundings is direct.

一个系统被壁所包围,这些壁约束着它,并将它与周围环境连接起来。[7][8][9][10][11][12] 通常情况下,壁限制了某种形式的物质或能量穿过它,使得这个连接是间接的。有时,壁不过只是一个假想的二维封闭表面,通过它与周围环境的联系是直接的。

A wall can be fixed (e.g. a constant volume reactor) or moveable (e.g. a piston). For example, in a reciprocating engine, a fixed wall means the piston is locked at its position; then, a constant volume process may occur. In that same engine, a piston may be unlocked and allowed to move in and out. Ideally, a wall may be declared adiabatic, diathermal, impermeable, permeable, or semi-permeable. Actual physical materials that provide walls with such idealized properties are not always readily available.

A wall can be fixed (e.g. a constant volume reactor) or moveable (e.g. a piston). For example, in a reciprocating engine, a fixed wall means the piston is locked at its position; then, a constant volume process may occur. In that same engine, a piston may be unlocked and allowed to move in and out. Ideally, a wall may be declared adiabatic, diathermal, impermeable, permeable, or semi-permeable. Actual physical materials that provide walls with such idealized properties are not always readily available.

壁可以是固定的(例如定容反应器)或可移动的(例如活塞)。例如,在一个往复式发动机中,一个固定的壁意味着活塞被锁定在其位置;然后,可能发生一个定容过程。在同一台发动机中,活塞可能被解锁并被允许进出。理想情况下,壁可以被认为是绝热的、透热的、不渗透的、可渗透的或半渗透的。而提供具有这种理想化特性的壁的实际物理材料并不总是现成的。

The system is delimited by walls or boundaries, either actual or notional, across which conserved (such as matter and energy) or unconserved (such as entropy) quantities can pass into and out of the system. The space outside the thermodynamic system is known as the surroundings, a reservoir, or the environment. The properties of the walls determine what transfers can occur. A wall that allows transfer of a quantity is said to be permeable to it, and a thermodynamic system is classified by the permeabilities of its several walls. A transfer between system and surroundings can arise by contact, such as conduction of heat, or by long-range forces such as an electric field in the surroundings.

The system is delimited by walls or boundaries, either actual or notional, across which conserved (such as matter and energy) or unconserved (such as entropy) quantities can pass into and out of the system. The space outside the thermodynamic system is known as the surroundings, a reservoir, or the environment. The properties of the walls determine what transfers can occur. A wall that allows transfer of a quantity is said to be permeable to it, and a thermodynamic system is classified by the permeabilities of its several walls. A transfer between system and surroundings can arise by contact, such as conduction of heat, or by long-range forces such as an electric field in the surroundings.

系统由实际或名义上的壁或边界划定,守恒量(如物质和能量)或非守恒量的(如熵)量可以通过这些壁或边界进入和离开系统。热力学系统外的空间被称为周围环境、库或环境。壁的属性决定了哪些转移可以发生。能够允许一定数量转移的壁被认为具有渗透性,一个热力学系统是由它的几个壁的渗透性分类的。系统和周围环境之间的转移可以通过接触产生,如热量的传导,或通过长程力,如周围环境中的电场。

A system with walls that prevent all transfers is said to be isolated. This is an idealized conception, because in practice some transfer is always possible, for example by gravitational forces. It is an axiom of thermodynamics that an isolated system eventually reaches internal thermodynamic equilibrium, when its state no longer changes with time.

A system with walls that prevent all transfers is said to be isolated. This is an idealized conception, because in practice some transfer is always possible, for example by gravitational forces. It is an axiom of thermodynamics that an isolated system eventually reaches internal thermodynamic equilibrium, when its state no longer changes with time.

一个具有阻止所有转移的壁的系统被说成是孤立的。这是一个理想化的概念,因为例如通过引力,在实践中一些转移总是可能的。热力学的一个公理是,一个孤立的系统最终会达到内部热力学平衡,此时其状态不再随时间变化。

The walls of a closed system allow transfer of energy as heat and as work, but not of matter, between it and its surroundings. The walls of an open system allow transfer both of matter and of energy.[13][14][15][16][17][18][19] This scheme of definition of terms is not uniformly used, though it is convenient for some purposes. In particular, some writers use 'closed system' where 'isolated system' is here used.[20][21]

The walls of a closed system allow transfer of energy as heat and as work, but not of matter, between it and its surroundings. The walls of an open system allow transfer both of matter and of energy. This scheme of definition of terms is not uniformly used, though it is convenient for some purposes. In particular, some writers use 'closed system' where 'isolated system' is here used.

封闭系统的壁允许能量以热和功的形式在其与周围环境之间转移,但不允许物质的转移。开放系统的壁允许物质和能量的转移。[13][14][15][16][17][18][19] 这样的定义并没有被统一使用,尽管对于某些目的来说很方便。特别是,一些学者使用 "封闭系统",而这里使用的是 "孤立系统"来描述。[20][21]

Anything that passes across the boundary and effects a change in the contents of the system must be accounted for in an appropriate balance equation. The volume can be the region surrounding a single atom resonating energy, such as Max Planck defined in 1900; it can be a body of steam or air in a steam engine, such as Sadi Carnot defined in 1824. It could also be just one nuclide (i.e. a system of quarks) as hypothesized in quantum thermodynamics.

Anything that passes across the boundary and effects a change in the contents of the system must be accounted for in an appropriate balance equation. The volume can be the region surrounding a single atom resonating energy, such as Max Planck defined in 1900; it can be a body of steam or air in a steam engine, such as Sadi Carnot defined in 1824. It could also be just one nuclide (i.e. a system of quarks) as hypothesized in quantum thermodynamics.

任何穿过边界并影响系统内容变化的东西都必须在一个适当的平衡方程中加以说明。体积可以是单原子共振能量的周围区域,如马克斯·普朗克(Max Planck)在1900年的定义;可以是蒸汽机中的蒸汽或空气体,如萨迪·卡诺(Sadi Carnot)在1824年的定义。它也可以是一个核素(即一个夸克系统),正如量子热力学中所假设的那样。

Surroundings 周围环境

The system is the part of the universe being studied, while the surroundings is the remainder of the universe that lies outside the boundaries of the system. It is also known as the environment, and the reservoir. Depending on the type of system, it may interact with the system by exchanging mass, energy (including heat and work), momentum, electric charge, or other conserved properties. The environment is ignored in analysis of the system, except in regards to these interactions.

The system is the part of the universe being studied, while the surroundings is the remainder of the universe that lies outside the boundaries of the system. It is also known as the environment, and the reservoir. Depending on the type of system, it may interact with the system by exchanging mass, energy (including heat and work), momentum, electric charge, or other conserved properties. The environment is ignored in analysis of the system, except in regards to these interactions.

系统是正被研究的宇宙的一部分,而周围环境是位于系统边界之外的宇宙的其余部分。它也被称为环境和库。根据系统的类型,它可以通过交换质量、能量(包括热和功)、动量、电荷或其他守恒属性与系统进行互动。在对系统的分析中,除了这些相互作用之外,往往会忽略环境。

Closed system 封闭系统

In a closed system, no mass may be transferred in or out of the system boundaries. The system always contains the same amount of matter, but heat and work can be exchanged across the boundary of the system. Whether a system can exchange heat, work, or both is dependent on the property of its boundary.

In a closed system, no mass may be transferred in or out of the system boundaries. The system always contains the same amount of matter, but heat and work can be exchanged across the boundary of the system. Whether a system can exchange heat, work, or both is dependent on the property of its boundary.

在一个封闭的系统中,质量不得被转移而进出系统边界。系统总是包含相同数量的物质,但热量和功可以跨越系统的边界进行交换。一个系统是否可以交换热量、功或者两者都可以,取决于其边界的属性。


绝热边界——不允许任何热交换:一个热隔离的系统

刚性边界——不允许进行功的交换:一个机械隔离的系统

One example is fluid being compressed by a piston in a cylinder. Another example of a closed system is a bomb calorimeter, a type of constant-volume calorimeter used in measuring the heat of combustion of a particular reaction. Electrical energy travels across the boundary to produce a spark between the electrodes and initiates combustion. Heat transfer occurs across the boundary after combustion but no mass transfer takes place either way.

One example is fluid being compressed by a piston in a cylinder. Another example of a closed system is a bomb calorimeter, a type of constant-volume calorimeter used in measuring the heat of combustion of a particular reaction. Electrical energy travels across the boundary to produce a spark between the electrodes and initiates combustion. Heat transfer occurs across the boundary after combustion but no mass transfer takes place either way.

一个例子是流体被气缸中的活塞压缩。封闭系统的另一个例子是弹式量热计,这是一种用于测量特定反应的燃烧热的定容量热计。电能穿过边界,在电极之间产生火花并引发燃烧。燃烧后,热传递跨越边界,但没有任何质量转移的发生。

Beginning with the first law of thermodynamics for an open system, this is expressed as:

Beginning with the first law of thermodynamics for an open system, this is expressed as:

从开放系统的热力学第一定律开始,这可以表示为:

[math]\displaystyle{ \Delta U=Q-W+m_{i}(h+\frac{1}{2}v^2+gz)_{i}-m_{e}(h+\frac{1}{2}v^2+gz)_{e} }[/math]

[math]\displaystyle{ \Delta U=Q-W+m_{i}(h+\frac{1}{2}v^2+gz)_{i}-m_{e}(h+\frac{1}{2}v^2+gz)_{e} }[/math]



where U is internal energy, Q is the heat added to the system, W is the work done by the system, and since no mass is transferred in or out of the system, both expressions involving mass flow are zero and the first law of thermodynamics for a closed system is derived. The first law of thermodynamics for a closed system states that the increase of internal energy of the system equals the amount of heat added to the system minus the work done by the system. For infinitesimal changes the first law for closed systems is stated by:

where U is internal energy, Q is the heat added to the system, W is the work done by the system, and since no mass is transferred in or out of the system, both expressions involving mass flow are zero and the first law of thermodynamics for a closed system is derived. The first law of thermodynamics for a closed system states that the increase of internal energy of the system equals the amount of heat added to the system minus the work done by the system. For infinitesimal changes the first law for closed systems is stated by:

其中U是内能,Q是添加到系统中的热量,W是系统所做的功,由于系统中没有质量转移,涉及质量流的两个表达式都是零,封闭系统的热力学第一定律就可以被这样导出。封闭系统的热力学第一定律指出,系统内能的增加等于添加到系统的热量减去系统所做的功。对于无限小的变化,封闭系统的第一定律是这样表述的:

[math]\displaystyle{ \mathrm d U= \delta Q -\delta W. }[/math]

[math]\displaystyle{ \mathrm d U= \delta Q -\delta W. }[/math]



If the work is due to a volume expansion by dV at a pressure P then:

If the work is due to a volume expansion by dV at a pressure P then:

如果功是由于在压力P下体积膨胀dV而产生的,那么:

[math]\displaystyle{ \delta W = P\mathrm d V. }[/math]

[math]\displaystyle{ \delta W = P\mathrm d V. }[/math]

For a homogeneous system undergoing a reversible process, the second law of thermodynamics reads:

For a homogeneous system undergoing a reversible process, the second law of thermodynamics reads:

对于一个正在经历可逆过程的均质系统,热力学第二定律如下:

[math]\displaystyle{ \delta Q = T \mathrm d S }[/math]

[math]\displaystyle{ \delta Q = T \mathrm d S }[/math]



where T is the absolute temperature and S is the entropy of the system. With these relations the fundamental thermodynamic relation, used to compute changes in internal energy, is expressed as:

where T is the absolute temperature and S is the entropy of the system. With these relations the fundamental thermodynamic relation, used to compute changes in internal energy, is expressed as:

其中T是绝对温度,S是系统的熵。有了这些关系,用于计算内能变化的基本热力学关系表示为:

[math]\displaystyle{ \mathrm d U=T\mathrm d S-P\mathrm d V. }[/math]

[math]\displaystyle{ \mathrm d U=T\mathrm d S-P\mathrm d V. }[/math]



For a simple system, with only one type of particle (atom or molecule), a closed system amounts to a constant number of particles. However, for systems undergoing a chemical reaction, there may be all sorts of molecules being generated and destroyed by the reaction process. In this case, the fact that the system is closed is expressed by stating that the total number of each elemental atom is conserved, no matter what kind of molecule it may be a part of. Mathematically:

For a simple system, with only one type of particle (atom or molecule), a closed system amounts to a constant number of particles. However, for systems undergoing a chemical reaction, there may be all sorts of molecules being generated and destroyed by the reaction process. In this case, the fact that the system is closed is expressed by stating that the total number of each elemental atom is conserved, no matter what kind of molecule it may be a part of. Mathematically:

对于一个简单的系统,只有一种类型的粒子(原子或分子),一个封闭系统相当于一个恒定数量的粒子。然而,对于正在进行化学反应的系统,可能会有各种分子在反应过程中产生和破坏。在这种情况下,“系统是封闭的”这一事实被表述为:每个元素原子的总数是守恒的,不管它可能是哪种分子的一部分。在数学上表示为:

[math]\displaystyle{ \sum_{j=1}^m a_{ij}N_j=b_i^0 }[/math]

[math]\displaystyle{ \sum_{j=1}^m a_{ij}N_j=b_i^0 }[/math]

where Nj is the number of j-type molecules, aij is the number of atoms of element i in molecule j and bi0 is the total number of atoms of element i in the system, which remains constant, since the system is closed. There is one such equation for each element in the system.

where Nj is the number of j-type molecules, aij is the number of atoms of element i in molecule j and bi0 is the total number of atoms of element i in the system, which remains constant, since the system is closed. There is one such equation for each element in the system.

其中Nj是j型分子的数量,aij是分子j中i元素的原子数量,bi0是系统中i元素的原子总数,由于系统是封闭的,所以这个数字保持不变。系统中的每个元素都拥有一个这样的方程。

Isolated system 孤立系统

An isolated system is more restrictive than a closed system as it does not interact with its surroundings in any way. Mass and energy remains constant within the system, and no energy or mass transfer takes place across the boundary. As time passes in an isolated system, internal differences in the system tend to even out and pressures and temperatures tend to equalize, as do density differences. A system in which all equalizing processes have gone practically to completion is in a state of thermodynamic equilibrium.

An isolated system is more restrictive than a closed system as it does not interact with its surroundings in any way. Mass and energy remains constant within the system, and no energy or mass transfer takes place across the boundary. As time passes in an isolated system, internal differences in the system tend to even out and pressures and temperatures tend to equalize, as do density differences. A system in which all equalizing processes have gone practically to completion is in a state of thermodynamic equilibrium.

孤立的系统比封闭的系统更具限制性,因为它不以任何方式与周围环境相互作用。质量和能量在系统内保持恒定,没有能量或质量转移发生在边界上。随着时间的推移,在一个孤立的系统中,系统的内部差异趋于平衡,压力和温度趋于平衡,密度差异也会趋于平衡。一个所有平衡过程实际上已经完成的系统,处于热力学平衡的状态。

Truly isolated physical systems do not exist in reality (except perhaps for the universe as a whole), because, for example, there is always gravity between a system with mass and masses elsewhere.[22][23][24][25][26] However, real systems may behave nearly as an isolated system for finite (possibly very long) times. The concept of an isolated system can serve as a useful model approximating many real-world situations. It is an acceptable idealization used in constructing mathematical models of certain natural phenomena.

Truly isolated physical systems do not exist in reality (except perhaps for the universe as a whole), because, for example, there is always gravity between a system with mass and masses elsewhere. However, real systems may behave nearly as an isolated system for finite (possibly very long) times. The concept of an isolated system can serve as a useful model approximating many real-world situations. It is an acceptable idealization used in constructing mathematical models of certain natural phenomena.

真正孤立的物理系统在现实中是不存在的(也许整个宇宙除外),因为,举例来说,在一个有质量的系统和其他地方之间总是存在着引力,[22][23][24][25][26] 然而,真实的系统可能在有限的(可能是非常长的)时间内几乎表现为一个孤立的系统。孤立系统的概念可以作为一个有用的模型,近似描述许多真实世界的情况。在构建某些自然现象的数学模型时,它是一种可接受的理想化模型。

In the attempt to justify the postulate of entropy increase in the second law of thermodynamics, Boltzmann's H-theorem used equations, which assumed that a system (for example, a gas) was isolated. That is all the mechanical degrees of freedom could be specified, treating the walls simply as mirror boundary conditions. This inevitably led to Loschmidt's paradox. However, if the stochastic behavior of the molecules in actual walls is considered, along with the randomizing effect of the ambient, background thermal radiation, Boltzmann's assumption of molecular chaos can be justified.

In the attempt to justify the postulate of entropy increase in the second law of thermodynamics, Boltzmann's H-theorem used equations, which assumed that a system (for example, a gas) was isolated. That is all the mechanical degrees of freedom could be specified, treating the walls simply as mirror boundary conditions. This inevitably led to Loschmidt's paradox. However, if the stochastic behavior of the molecules in actual walls is considered, along with the randomizing effect of the ambient, background thermal radiation, Boltzmann's assumption of molecular chaos can be justified.

在试图证明热力学第二定律中的熵增加的假设时,玻尔兹曼(Boltzmann)的H定理(H-theorem)利用方程,假定一个系统(例如,气体)是孤立的。也就是说,所有的自由度都可以被指定,把壁简单地当作像镜子一样的边界条件。这不可避免地导致了洛施密特悖论(Loschmidt's paradox)。然而,如果考虑到实际壁中分子的随机行为,以及环境、环境热辐射的随机效应,玻尔兹曼的分子混沌假设就可以得到证明。

The second law of thermodynamics for isolated systems states that the entropy of an isolated system not in equilibrium tends to increase over time, approaching maximum value at equilibrium. Overall, in an isolated system, the internal energy is constant and the entropy can never decrease. A closed system's entropy can decrease e.g. when heat is extracted from the system.

The second law of thermodynamics for isolated systems states that the entropy of an isolated system not in equilibrium tends to increase over time, approaching maximum value at equilibrium. Overall, in an isolated system, the internal energy is constant and the entropy can never decrease. A closed system's entropy can decrease e.g. when heat is extracted from the system.

孤立系统的热力学第二定律指出,不处于平衡状态的孤立系统的熵会随着时间的推移趋于增加,接近平衡状态的最大值。总的来说,在一个孤立的系统中,内能是恒定的,熵永远不会减少。一个封闭系统的熵可以减少,例如当热量从系统中被提取时。

It is important to note that isolated systems are not equivalent to closed systems. Closed systems cannot exchange matter with the surroundings, but can exchange energy. Isolated systems can exchange neither matter nor energy with their surroundings, and as such are only theoretical and do not exist in reality (except, possibly, the entire universe).

It is important to note that isolated systems are not equivalent to closed systems. Closed systems cannot exchange matter with the surroundings, but can exchange energy. Isolated systems can exchange neither matter nor energy with their surroundings, and as such are only theoretical and do not exist in reality (except, possibly, the entire universe).

需要注意的是,孤立的系统并不等同于封闭系统。封闭系统不能与周围环境交换物质,但可以交换能量。孤立系统既不能与周围环境交换物质也不能交换能量,因此其只是理论上的概念,在现实中不存在(可能除了整个宇宙)。

It is worth noting that 'closed system' is often used in thermodynamics discussions when 'isolated system' would be correct – i.e. there is an assumption that energy does not enter or leave the system.

It is worth noting that 'closed system' is often used in thermodynamics discussions when 'isolated system' would be correct – i.e. there is an assumption that energy does not enter or leave the system.

值得注意的是,在热力学讨论中经常使用 "封闭系统",而 "孤立系统 "才是正确的——即此时存在一个假设,能量不会进入或离开该系统。

Selective transfer of matter 物质的选择性转移

For a thermodynamic process, the precise physical properties of the walls and surroundings of the system are important, because they determine the possible processes.

For a thermodynamic process, the precise physical properties of the walls and surroundings of the system are important, because they determine the possible processes.

对于一个热力学过程来说,系统的壁和周围环境的精确物理特性是十分重要的,因为它们决定了可能发生的过程。

An open system has one or several walls that allow transfer of matter. To account for the internal energy of the open system, this requires energy transfer terms in addition to those for heat and work. It also leads to the idea of the chemical potential.

An open system has one or several walls that allow transfer of matter. To account for the internal energy of the open system, this requires energy transfer terms in addition to those for heat and work. It also leads to the idea of the chemical potential.

一个开放系统有一个或几个壁,并允许物质的转移。为了说明开放系统的内能,除了热和功之外,还需要用以描述能量转移的术语。这也引出了化学势的概念。

A wall selectively permeable only to a pure substance can put the system in diffusive contact with a reservoir of that pure substance in the surroundings. Then a process is possible in which that pure substance is transferred between system and surroundings. Also, across that wall a contact equilibrium with respect to that substance is possible. By suitable thermodynamic operations, the pure substance reservoir can be dealt with as a closed system. Its internal energy and its entropy can be determined as functions of its temperature, pressure, and mole number.

A wall selectively permeable only to a pure substance can put the system in diffusive contact with a reservoir of that pure substance in the surroundings. Then a process is possible in which that pure substance is transferred between system and surroundings. Also, across that wall a contact equilibrium with respect to that substance is possible. By suitable thermodynamic operations, the pure substance reservoir can be dealt with as a closed system. Its internal energy and its entropy can be determined as functions of its temperature, pressure, and mole number.

一面只对纯物质有选择性渗透的壁可以使系统与周围环境中的纯物质库有扩散性接触。那么,就有可能出现该纯物质在系统和周围环境之间转移的过程。另外,透过物质的壁,与该物质有关的接触平衡的发生是可能的。通过适当的热力学操作,纯物质库可以作为一个封闭系统来看待。它的内能和熵可以被确定为其温度、压力和摩尔数的函数。

A thermodynamic operation can render impermeable to matter all system walls other than the contact equilibrium wall for that substance. This allows the definition of an intensive state variable, with respect to a reference state of the surroundings, for that substance. The intensive variable is called the chemical potential; for component substance i it is usually denoted μi. The corresponding extensive variable can be the number of moles Ni of the component substance in the system.

A thermodynamic operation can render impermeable to matter all system walls other than the contact equilibrium wall for that substance. This allows the definition of an intensive state variable, with respect to a reference state of the surroundings, for that substance. The intensive variable is called the chemical potential; for component substance it is usually denoted . The corresponding extensive variable can be the number of moles of the component substance in the system.

一个热力学操作可以使除该物质的接触平衡壁之外的所有系统壁对物质不渗透。这就允许为该物质定义一个相对于周围环境的参考状态而言的强度量。这个强度量被称为化学势;对于组分物质 i ,它通常表示为 μi 。相应的广延量可以是系统中这个组分物质的摩尔数。

For a contact equilibrium across a wall permeable to a substance, the chemical potentials of the substance must be same on either side of the wall. This is part of the nature of thermodynamic equilibrium, and may be regarded as related to the zeroth law of thermodynamics.[27]

For a contact equilibrium across a wall permeable to a substance, the chemical potentials of the substance must be same on either side of the wall. This is part of the nature of thermodynamic equilibrium, and may be regarded as related to the zeroth law of thermodynamics.

对于透过物质的壁的接触平衡,物质的化学势在壁的两边必须是相同的。这是热力学平衡性质的一部分,可被视为与热力学第三定律有关。[27]

Open system 开放系统

模板:Expand section

In an open system, there is an exchange of energy and matter between the system and the surroundings. The presence of reactants in an open beaker is an example of an open system. Here the boundary is an imaginary surface enclosing the beaker and reactants. It is named closed, if borders are impenetrable for substance, but allow transit of energy in the form of heat, and isolated, if there is no exchange of heat and substances. The open system cannot exist in the equilibrium state. To describe deviation of the thermodynamic system from equilibrium, in addition to constitutive variables that was described above, a set of internal variables [math]\displaystyle{ \xi_1, \xi_2,\ldots }[/math] that are called internal variables have been introduced. The equilibrium state is considered to be stable. and the main property of the internal variables, as measures of non-equilibrium of the system, is their trending to disappear; the local law of disappearing can be written as relaxation equation for each internal variable

In an open system, there is an exchange of energy and matter between the system and the surroundings. The presence of reactants in an open beaker is an example of an open system. Here the boundary is an imaginary surface enclosing the beaker and reactants. It is named closed, if borders are impenetrable for substance, but allow transit of energy in the form of heat, and isolated, if there is no exchange of heat and substances. The open system cannot exist in the equilibrium state. To describe deviation of the thermodynamic system from equilibrium, in addition to constitutive variables that was described above, a set of internal variables [math]\displaystyle{ \xi_1, \xi_2,\ldots }[/math] that are called internal variables have been introduced. The equilibrium state is considered to be stable. and the main property of the internal variables, as measures of non-equilibrium of the system, is their trending to disappear; the local law of disappearing can be written as relaxation equation for each internal variable

在一个开放系统中,系统与周围环境之间存在着能量和物质的交换。在一个开放的烧杯中存在的反应物,就是一个开放系统的例子。这里的边界是一个包围烧杯和反应物的假想表面。如果边界对物质来说是不可穿透的,但被允许以热量的形式传递能量,则被称为是封闭的;如果没有热量和物质的交换,则被称为孤立的。开放系统不能在平衡状态下存在。为了描述热力学系统偏离平衡的状态,除了上面描述的变量外,还引入了一组变量[math]\displaystyle{ \xi_1, \xi_2,\ldots }[/math],称为内部变量。平衡状态被认为是稳定的。而内部变量作为系统非平衡的度量,它们呈现消失趋势;而局部的消失规律可以写成每个内部变量的松弛方程:

[math]\displaystyle{ {{NumBlk|:|\lt math\gt {{ NumBlk | : | \lt math \gt \frac{d\xi_i}{dt} = - \frac{1}{\tau_i} \, \left(\xi_i - \xi_i^{(0)} \right),\quad i =1,\,2,\ldots , \frac{d\xi_i}{dt} = - \frac{1}{\tau_i} \, \left(\xi_i - \xi_i^{(0)} \right),\quad i =1,\,2,\ldots , 1} ,左(xi-xi-xi _ i ^ {(0)}右) ,quad i = 1,,2,ldots, }[/math]

 

 

 

 

(1)


where [math]\displaystyle{ \tau_i= \tau_i(T, x_1, x_2, \ldots, x_n) }[/math] is a relaxation time of a corresponding variables. It is convenient to consider the initial value [math]\displaystyle{ \xi_i^0 }[/math] are equal to zero.

where [math]\displaystyle{ \tau_i= \tau_i(T, x_1, x_2, \ldots, x_n) }[/math] is a relaxation time of a corresponding variables. It is convenient to consider the initial value [math]\displaystyle{ \xi_i^0 }[/math] are equal to zero.

其中 < math > tau _ i = tau _ i (t,x _ 1,x _ 2,ldots,x _ n) </math > 是对应变量的松弛时间。我们通常考虑初始值 < math > xi _ i ^ 0 </math > 等于零。


The essential contribution to the thermodynamics of open non-equilibrium systems was made by Ilya Prigogine, when he and his collaborators investigated systems of chemically reacting substances. The stationary states of such systems exists due to exchange of both particles and energy with the environment. In section 8 of the third chapter of his book,[28] Prigogine has specified three contributions to the variation of entropy of the considered open system at the given volume and constant temperature [math]\displaystyle{ T }[/math] . The increment of entropy [math]\displaystyle{ S }[/math] can be calculated according to the formula

The essential contribution to the thermodynamics of open non-equilibrium systems was made by Ilya Prigogine, when he and his collaborators investigated systems of chemically reacting substances. The stationary states of such systems exists due to exchange of both particles and energy with the environment. In section 8 of the third chapter of his book, Prigogine has specified three contributions to the variation of entropy of the considered open system at the given volume and constant temperature [math]\displaystyle{ T }[/math] . The increment of entropy [math]\displaystyle{ S }[/math] can be calculated according to the formula

伊利亚·普里高津(Ilia Prigogine)对开放的非平衡系统的热力学做出了重要贡献,当时他和他的合作者研究了化学反应物质的系统。这种系统的静止状态由于粒子和能量与环境的交换而存在。在他的书的第三章第8节中,普里高津在给定体积和恒定温度下,对所考虑的开放系统的熵的变化的研究做出了贡献 。熵的增量 [math]\displaystyle{ S }[/math]可以根据公式来计算:

[math]\displaystyle{ {{NumBlk|:|\lt math\gt {{ NumBlk | : | \lt math \gt T\,dS = \Delta Q - \sum_{j} \, \Xi_{j} \,\Delta \xi_j + \sum_{\alpha =1}^k\, \mu_\alpha \, \Delta N_\alpha. T\,dS = \Delta Q - \sum_{j} \, \Xi_{j} \,\Delta \xi_j + \sum_{\alpha =1}^k\, \mu_\alpha \, \Delta N_\alpha. T,dS = Delta q-sum { j } ,Xi { j } ,Delta Xi _ j + sum _ { alpha = 1} ^ k,mu _ alpha,Delta n _ alpha. }[/math]

 

 

 

 

(1)


The first term on the right hand side of the equation presents a stream of thermal energy into the system; the last term—a stream of energy into the system coming with the stream of particles of substances [math]\displaystyle{ \Delta N_\alpha }[/math] that can be positive or negative, [math]\displaystyle{ \mu_\alpha }[/math] is chemical potential of substance [math]\displaystyle{ \alpha }[/math]. The middle term in (1) depicts energy dissipation (entropy production) due to the relaxation of internal variables [math]\displaystyle{ \xi_j }[/math]. In the case of chemically reacting substances, which was investigated by Prigogine, the internal variables appear to be measures of incompleteness of chemical reactions, that is measures of how much the considered system with chemical reactions is out of equilibrium. The theory can be generalized,[29][30] to consider any deviation from the equilibrium state as an internal variable, so that we consider the set of internal variables [math]\displaystyle{ \xi_j }[/math] in equation (1) to consist of the quantities defining not only degrees of completeness of all chemical reactions occurring in the system, but also the structure of the system, gradients of temperature, difference of concentrations of substances and so on.

The first term on the right hand side of the equation presents a stream of thermal energy into the system; the last term—a stream of energy into the system coming with the stream of particles of substances [math]\displaystyle{ \Delta N_\alpha }[/math] that can be positive or negative, [math]\displaystyle{ \mu_\alpha }[/math] is chemical potential of substance [math]\displaystyle{ \alpha }[/math]. The middle term in (1) depicts energy dissipation (entropy production) due to the relaxation of internal variables [math]\displaystyle{ \xi_j }[/math]. In the case of chemically reacting substances, which was investigated by Prigogine, the internal variables appear to be measures of incompleteness of chemical reactions, that is measures of how much the considered system with chemical reactions is out of equilibrium. The theory can be generalized, to consider any deviation from the equilibrium state as an internal variable, so that we consider the set of internal variables [math]\displaystyle{ \xi_j }[/math] in equation (1) to consist of the quantities defining not only degrees of completeness of all chemical reactions occurring in the system, but also the structure of the system, gradients of temperature, difference of concentrations of substances and so on.

方程式右边的第一项代表了进入系统的热能流; 最后一项ーー进入系统的能量流,伴随着粒子流进入系统,粒子流可以是正的也可以是负的。第一部分的中期描述了由于内部变量的松弛而引起的能量耗散(产生熵)。在化学反应物质的情况下,由普利戈金研究,内部变量似乎是测量不完全的化学反应,也就是测量多少考虑的体系与化学反应是不平衡的。该理论可以推广,[29][30] 将任何偏离平衡态的情况视为一个内变量,因此我们认为方程(1)中的一组内变量不仅包含了体系中发生的所有化学反应的完全程度,而且包含了体系的结构、温度梯度、物质浓度差等。

方程右边的第一项是进入系统的热能流;最后一项是进入系统的能量流与物质的粒子流 [math]\displaystyle{ \Delta N_\alpha }[/math] ,可以是正的或负的,[math]\displaystyle{ \mu_\alpha }[/math] 是物质的化学势 [math]\displaystyle{ \alpha }[/math]。方程(1)中的中间项描述了由于内部变量[math]\displaystyle{ \xi_j }[/math] 的松弛而产生的能量耗散(熵产生)。在普里高津研究的化学反应物质的情形下,内部变量似乎可以表示不完全的化学反应,也就是衡量所考虑的有化学反应的系统失去平衡的程度。这个理论可以被推广,将任何偏离平衡状态的情况都视为内部变量,因此我们认为方程(1)中的内部变量集 [math]\displaystyle{ \xi_j }[/math] 不仅定义包括系统中发生的所有化学反应的完整程度的量,而且包括系统的结构、温度的梯度、物质浓度的差异等。

The Prigogine approach to the open system allow describing the growth and development of living objects in thermodynamic terms.

The Prigogine approach to the open system allow describing the growth and development of living objects in thermodynamic terms.

普里高津的开放系统方法允许用热力学语言描述生命体的生长和发展。

Adiabatic system 绝热系统

An adiabatic system is the one which doesn't allow any heat to be transferred into or out of the system. The [math]\displaystyle{ PV^\gamma = constant }[/math] equation is only valid for an adiabatic system which is also undergoing a reversible process provided it is a closed system having an ideal gas. If it fails to satisfy any of these conditions then only [math]\displaystyle{ dQ=0 }[/math] is true and it cannot be represented in an equation like [math]\displaystyle{ PV^\gamma = constant }[/math] .

An adiabatic system is the one which doesn't allow any heat to be transferred into or out of the system. The [math]\displaystyle{ PV^\gamma = constant }[/math] equation is only valid for an adiabatic system which is also undergoing a reversible process provided it is a closed system having an ideal gas. If it fails to satisfy any of these conditions then only [math]\displaystyle{ dQ=0 }[/math] is true and it cannot be represented in an equation like [math]\displaystyle{ PV^\gamma = constant }[/math] .

绝热系统就是不允许任何热量,进出系统的系统。这个方程只适用于绝热系统,而且绝热系统也在经历可逆过程,前提是它是一个有理想气体的封闭系统。如果它不能满足这些条件中的任何一个,那么只有 < math > dQ = 0 </math > 是正确的,它不能用 < math > PV ^ gamma = constant </math > 这样的方程来表示。


绝热系统是一个不允许任何热量传入或传出系统的系统。[math]\displaystyle{ PV^\gamma = constant }[/math] 方程只对绝热系统有效,该系统也同时经历着一个可逆过程,前提是它是一个具有理想气体的封闭系统。如果它不能满足这些条件中的任何一个,那么只有[math]\displaystyle{ dQ=0 }[/math]是正确的,它不能用[math]\displaystyle{ PV^\gamma = constant }[/math] 这样的方程表示。

See also 参见

References 参考资料

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