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Hello everyone.
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I'm doing problem 51 from chapter 18.
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It tells us that there's some solar electric generating system, and it collects a certain amount of thermal energy, and it heats its collectors to a certain temperature, and then this is operating an electric generator.
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So it asks us, first of all, what is the maximum efficiency of this power plant, and it gives us the temperature of the cold reservoir.
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Okay, so whenever we hear maximum efficiency of some cycle or engine, we should think about the carnot cycle and its efficiency, which is 1 minus tc over th.
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And in fact, that's what we're going to use here.
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We need to be a little bit careful when we do this.
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We need to add 273 in to our celsius numbers in order to get them into kelvin roughly.
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And if you don't do that, you'll get the wrong thing because the ratio of two numbers in celsius is not the same as the ratio of those same numbers in kelvin.
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Earlier when we were using the change in temperature, the change in celsius is exactly the same as a change in kelvin, so it doesn't matter.
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But here when we're doing efficiency, we're concerned about the ratio, and so now it matters that you're in kelvin when you find these values...