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Adiabatic meaning there's no heat involved, and we're going to see how that differs from the isothermal expansion and compression.
绝热意味着没有热量的传递，我们将看到它,与等温过程的区别。
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So then, going from the initial to final states with a red path, ou start with an isobaric processand then you end with an isothermal process.
因此沿着,这条红色路径，你从一个等压过程开始,以一个等温过程结束。
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PROFESSOR BAWENDI: So the question was, for an isothermal expansion, delta u does not change, therefore, The answer is that's true only for an ideal gas.
你的问题是，在等温过程中，内能是否，这只对理想气体成立。
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Instead of this reversible isothermal step, Let's make it an irreversible isothermal step.
不是可逆等温过程，而是不可逆等温过程。
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As long as it's reversible, you know what the efficiency has to be, and in principle, you could break it down into a bunch of steps that you could formulate as isothermal and adiabatic.
只要这个循环过程是可逆的，你们知道效率是多少，从理论上说，可以将总过程,分解成一系列绝热,和等温的小过程。
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For isothermal expansion, that means that delta u does not change, but delta q is equal to delta w?
在等温过程中，是不是内能不变，Δq等于Δw？
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PROFESSOR BAWENDI: So, for an ideal gas, the isothermal is the easy one because the energy doesn't change.
对理想气体，等温过程最简单,因为能量不变。
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OK, so we have constant temperature, because it's isothermal.
好，现在系统有恒定的温度，因为它是绝热的。
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If I want to compare it with the isothermal expansion, which is sitting here.
我们要将它与,这幅图中的等温线相比较。
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of the night what you say, isothermal process, what do you say?
等温过程，怎么回答？
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We've changed the external pressure slowly, and again this is isothermal.
我们慢慢改变外部压强，这个过程也是绝热的。
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Now let's talk about some simple observations on isothermal gas expansions.
接下来我们讨论几条,关于绝热膨胀的性质。
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Then we're going to have another isothermal step, a compression to some point four.
然后有另外一个绝热过程，绝热压缩到4点。
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We can have a different isothermal step.
这是一个不同的等温过程。
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STUDENT: Just a quick question on some of the constraints, like isothermal, isobaric, isovolumetric expansion.
学生：我有个关于,等温，等压，等容等约束条件的小问题。
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Now going from three to four right, so we have another isothermal process for an ideal gas, so I won't try to make you sing again so soon.
从第三点到第四点，这也是一个理想气体的,恒温过程，这次不用你们集体回答了。
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Therefore, if it's isothermal, the energy of the ideal gas doesn't change.
理想气体的，能量不变。
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So from one to two it's isothermal.
从一点到二点是等温过程。
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Constant temperature means isothermal, so this part means an isothermal process.
等温“指温度不变，这部分就是指一个等温过程。
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It's going to be an isothermal path that's going to connect them.
用等温过程,来连接。
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So it's, this is just the integral pdv And it's an ideal gas, isothermal, right.
从一点到二点的,的积分。，from，one，to，two，of，p，dV。,这是理想气体，恒温过程，好的。
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And you know, you could have a reversible engine with lots and lots of steps, but you could always break them down into some sequence of adiabatic and isothermal steps.
你们知道，我们可以设计一个由，很多很多个,循环步骤的热机，但是总可以把它分割成,一系列的绝热,和等温过程。
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u=0 Constant temperature isothermal delta u is zero.
对等温过程，Δ
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This is isothermal. This is adiabatic, there's no heat.
一个是等温，一个是绝热。
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These are all constant. It's isothermal.
它们都是常数，这个过程是绝热的。
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isothermal always means delta u equals zero.
理想气体。
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So this is an isothermal expansion.
这是个等温膨胀过程。
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It's an isothermal change.
这是恒温的变化。
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This is going to end up at a different temperature by the way. You saw this last time in a slightly different way. Last time what you saw is we compared isothermal and adiabatic paths that ended up at the same final pressure, and what you saw is that therefore they ended up in different final volumes.
末态温度是不一样的,上次你们看到的,和这个有一点不一样,上次我们比较的是末态压强,相等的等温过程和绝热过程,因此它们的末态,体积是不一样的。
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And here, in an isothermal expansion, The bath is putting back the energy that the gas is expanding or using to expand, and so the energy is flowing back into the gas through the environment in the isothermal expansion.
而在等温膨胀中，恒温环境将气体膨胀对外做功,而损失的能量又返还回来，在等温膨胀中,能量从环境,流向系统。
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