更改

It is useful to separate the work ''δw'' done by the subsystem into the ''useful'' work ''δw_u'' that can be done ''by'' the sub-system, over and beyond the work ''p_R dV'' done merely by the sub-system expanding against the surrounding external pressure, giving the following relation for the useful work (exergy) that can be done:

It is useful to separate the work ''δw'' done by the subsystem into the ''useful'' work ''δw_u'' that can be done ''by'' the sub-system, over and beyond the work ''p_R dV'' done merely by the sub-system expanding against the surrounding external pressure, giving the following relation for the useful work (exergy) that can be done:

 

It is useful to separate the work δw done by the subsystem into the useful work δw_u that can be done by the sub-system, over and beyond the work p_R dV done merely by the sub-system expanding against the surrounding external pressure, giving the following relation for the useful work (exergy) that can be done:

It is useful to separate the work δw done by the subsystem into the useful work δw_u that can be done by the sub-system, over and beyond the work p_R dV done merely by the sub-system expanding against the surrounding external pressure, giving the following relation for the useful work (exergy) that can be done:

将子系统所做的功δw划分为子系统可以完成的有用功δw，除了子系统在周围外部压力下膨胀所做的功pR dV外，还可以给出以下可用功（放射本能）关系式:

将子系统所做的功δw划分为子系统可以完成的有用功δw_u ，除了子系统在周围外部压力下膨胀所做的功p_R dV外，<font color = 'red'><s>还可以</s></font>给出以下可用功（<font color = 'red'><s>放射本能</s></font>'''<font color = 'ff8000'>有用功 exergy</font>'''）关系式:

  <math> \delta w_u \le -d (U - T_R S + p_R V - \sum \mu_{iR} N_i )\,</math>

  <math> \delta w_u \le -d (U - T_R S + p_R V - \sum \mu_{iR} N_i )\,</math>

D (u-t r s + p r v-sum { iR } n i) ，/ math

<math> \delta w_u \le -d (U - T_R S + p_R V - \sum \mu_{iR} N_i )\,</math>

It is convenient to define the right-hand-side as the exact derivative of a thermodynamic potential, called the availability or exergy E of the subsystem,

It is convenient to define the right-hand-side as the exact derivative of a thermodynamic potential, called the availability or exergy E of the subsystem,

  <math> E = U - T_R S + p_R V - \sum \mu_{iR} N_i </math>

  <math> E = U - T_R S + p_R V - \sum \mu_{iR} N_i </math>

数学 e u-t r s + p r v- sum { iR } n i / math

<math> E = U - T_R S + p_R V - \sum \mu_{iR} N_i </math>

The Second Law therefore implies that for any process which can be considered as divided simply into a subsystem, and an unlimited temperature and pressure reservoir with which it is in contact,

The Second Law therefore implies that for any process which can be considered as divided simply into a subsystem, and an unlimited temperature and pressure reservoir with which it is in contact,

因此，第二定律意味着，对于任何可以简单地被视为分为一个子系统和一个与之接触的无限温度和压力储存器的过程,

因此，第二定律意味着，对于任何可以简单地被视为分为一个子系统和一个与之接触的无限温度和压力<font color = 'red'><s>储存器</s></font>'''<font color="#ff8000">热源 Reservoir</font>''' 的过程,

 

  <math> dE + \delta w_u \le 0 \, </math>

  <math> dE + \delta w_u \le 0 \, </math>

数学德 delta u  le 0，/ math

<math> dE + \delta w_u \le 0 \, </math>

i.e. the change in the subsystem's exergy plus the useful work done by the subsystem (or, the change in the subsystem's exergy less any work, additional to that done by the pressure reservoir, done on the system) must be less than or equal to zero.

i.e. the change in the subsystem's exergy plus the useful work done by the subsystem (or, the change in the subsystem's exergy less any work, additional to that done by the pressure reservoir, done on the system) must be less than or equal to zero.

也就是。子系统(火用)的变化加上子系统所做的有用功(或者，子系统(火用)的变化不包括任何功，除了压力贮存器所做的功之外，在系统中所做的功)必须小于或等于零。

也就是。子系统<font color = 'red'><s>(火用)</s></font><font color = 'blue'>有用能</font>的变化加上子系统所做的有用功(或者，子系统<font color = 'red'><s>(火用)</s></font><font color = 'blue'>有用能</font>的变化<font color = 'red'><s>不包括任何功，除了压力贮存器所做的功之外，在系统中所做的功</s></font><font color = 'blue'>减去除了'''压力热源'''外任何对系统做的功，</font>)必须小于或等于零。

 

In sum, if a proper infinite-reservoir-like reference state is chosen as the system surroundings in the real world, then the Second Law predicts a decrease in E for an irreversible process and no change for a reversible process.

In sum, if a proper infinite-reservoir-like reference state is chosen as the system surroundings in the real world, then the Second Law predicts a decrease in E for an irreversible process and no change for a reversible process.

总之，如果选择一个合适的类似于无限库的参考状态作为现实世界中的系统环境，那么第二定律预测的不可逆性的 e 值会减少，而可逆过程的 e 值不会变化。

<font color = 'red'><s>那么第二定律预测的不可逆性的 e 值会减少，而可逆过程的 e 值不会变化。</s></font><font color = 'blue'>则第二定律预测不可逆过程的''E''值减少，可逆过程的''E''值不变。</font>

  <math>dS_{tot} \ge 0 </math> Is equivalent to <math> dE + \delta w_u \le 0 </math>

  <math>dS_{tot} \ge 0 </math> Is equivalent to <math> dE + \delta w_u \le 0 </math>

数学 d = 0 = 0 = 0 = 0 = 0

<math>dS_{tot} \ge 0 </math> Is equivalent to <math> dE + \delta w_u \le 0 </math>

This expression together with the associated reference state permits a design engineer working at the macroscopic scale (above the thermodynamic limit) to utilize the Second Law without directly measuring or considering entropy change in a total isolated system. (Also, see process engineer). Those changes have already been considered by the assumption that the system under consideration can reach equilibrium with the reference state without altering the reference state. An efficiency for a process or collection of processes that compares it to the reversible ideal may also be found (See second law efficiency.)

This expression together with the associated reference state permits a design engineer working at the macroscopic scale (above the thermodynamic limit) to utilize the Second Law without directly measuring or considering entropy change in a total isolated system. (Also, see process engineer). Those changes have already been considered by the assumption that the system under consideration can reach equilibrium with the reference state without altering the reference state. An efficiency for a process or collection of processes that compares it to the reversible ideal may also be found (See second law efficiency.)

This approach to the Second Law is widely utilized in [[engineering]] practice, [[environmental accounting]], [[systems ecology]], and other disciplines.

This approach to the Second Law is widely utilized in [[engineering]] practice, [[environmental accounting]], [[systems ecology]], and other disciplines.

This approach to the Second Law is widely utilized in engineering practice, environmental accounting, systems ecology, and other disciplines.

This approach to the Second Law is widely utilized in engineering practice, environmental accounting, systems ecology, and other disciplines.

===The second law in chemical thermodynamics===

===The second law in chemical thermodynamics===

For a spontaneous chemical process in a closed system at constant temperature and pressure without non-PV work, the Clausius inequality ΔS > Q/T_surr transforms into a condition for the change in Gibbs free energy  

For a spontaneous chemical process in a closed system at constant temperature and pressure without non-PV work, the Clausius inequality ΔS > Q/T_surr transforms into a condition for the change in Gibbs free energy  

对于一个封闭系统中的自发化学过程，在没有非 pv 功的情况下，在恒定温度和压力下，将克劳修斯不等式 s q / t sub surr / sub 转化为吉布斯自由能变化的条件

对于一个<font color = 'blue'>恒温恒压</font>封闭系统中的自发化学过程，在没有 non-PV 功的情况下，<font color = 'red'><s>在恒定温度和压力下，将</s></font>克劳修斯不等式Δ''S > Q/T_surr'' <font color = 'red'><s>转化为吉布斯自由能变化的条件</s></font>

  <math>\Delta G < 0 </math>

  <math>\Delta G < 0 </math>

数学 Delta g 0 / 数学

<math>\Delta G < 0 </math>

or dG < 0. For a similar process at constant temperature and volume, the change in Helmholtz free energy must be negative, <math>\Delta A < 0 </math>. Thus, a negative value of the change in free energy (G or A) is a necessary condition for a process to be spontaneous. This is the most useful form of the second law of thermodynamics in chemistry, where free-energy changes can be calculated from tabulated enthalpies of formation and standard molar entropies of reactants and products. The chemical equilibrium condition at constant T and p without electrical work is dG = 0.

or dG < 0. For a similar process at constant temperature and volume, the change in Helmholtz free energy must be negative, <math>\Delta A < 0 </math>. Thus, a negative value of the change in free energy (G or A) is a necessary condition for a process to be spontaneous. This is the most useful form of the second law of thermodynamics in chemistry, where free-energy changes can be calculated from tabulated enthalpies of formation and standard molar entropies of reactants and products. The chemical equilibrium condition at constant T and p without electrical work is dG = 0.

或者 dG 小于0。对于一个相似的过程，在恒定的温度和体积下，亥姆霍兹自由能的变化一定是负的，这是 Delta a 0 / math。因此，自由能(g 或 a)变化的负值是过程自发的必要条件。这是热力学第二定律在化学中最有用的形式，其中自由能的变化可以通过列表的生成焓和反应物及产物的标准摩尔熵来计算。在 t 和 p 不变的情况下，化学平衡条件是 dG 0。

或者 dG < 0。对于一个相似的<font color = 'blue'>恒温恒压</font>过程<font color = 'red'><s>，在恒定的温度和体积下</s></font>，'''<font color = '#ff8000'>亥姆霍兹自由能 Helmholtz free energy </font>'''的变化一定是负的， <math>\Delta A < 0 </math>。因此，<font color = 'blue'>一个负的</font>自由能(G 或 A)变化<font color = 'red'><s>的负值</s></font>是过程自发的必要条件。这是热力学第二定律在化学中最有用的形式，其中自由能的变化可以通过<font color = 'red'><s>列表的生成焓</s></font>'''<font color = '#ff8000'>表列生成焓 Tabulated Enthalpies of Formation</font>'''和反应物及产物的标准摩尔熵来计算。在<font color = 'red'><s>T 和 P </s></font><font color = 'blue'>温度和压力</font>不变的情况下，化学平衡条件是 dG = 0。

 

==History==

==History==