My Professor just posted this on his website, because apparently a lot of other people are confused, too:
"In the last question, the engine is burning up the methane. Figure out how much heat (energy) this burning produces, using the enthalpy of the reaction. That gives you a total heat input...
So would I take T1 to be 773 Kelvin, T2 to be 293 Kelvin, and kappa to be 1.4? And then solve for v2? Or am I mixing my variables up? I think I might be. Which volume would correspond to 100 ft^3?
I think so, cause it says to use the ideal gas law. There's a whole proof for the volume ratio assumption, but it's super long. Do you think I should calculate the work using a different formula? I just can't think of how to do so without volume. And as for your first question - no, we're not...
Nope. Based on the ideal gas law, I believe there are 117.9 moles, but that's all I've got. Also, I simplified $$-n R \left(T_h ln\frac{v2}{v1}+T_c ln\frac{v4}{v3}\right)$$ because v2/v1 equals v3/v4 according to my textbook.
"A Carnot engine operates using a heat source at 500 °C, and a heat sink at room temperature (20 °C). Suppose that as a heat source, you use the combustion of 100 cubic feet of natural gas at room temperature and pressure (e.g. in a fuel cell of some kind). Under ideal conditions, what is the...