The problem involves calculating the amount of coal required to generate 900 MW of power in a steam power plant, considering the efficiencies of two steam engines operating in sequence. The original poster presents the operating temperatures and the heat of combustion of coal, while also noting the efficiency of the engines as a fraction of the ideal Carnot efficiency.
The discussion is ongoing, with participants exploring different interpretations of the problem and attempting to clarify their understanding of the calculations involved. Some have provided guidance on how to relate the efficiencies of the engines to the total power output, while others are questioning their previous calculations and assumptions.
Participants are working under the constraints of a homework assignment, which may limit the information they can use or the methods they can apply. There is also a noted discrepancy in temperature values that affects the efficiency calculations, leading to further discussion about the correct values to use.
ideasrule said:I'm getting tired of pointing out careless mistakes.
In the first post you said the power plant puts out 900 MW of power. Alright, great. In post #17 you used 500 MW. In the answer in post #20, it's 600 MW. I mean, what the heck?
Also, I'm disappointed at the answer in post #20. It's wrong, period. They took into consideration the fact that the second engine is 0.65 times the Carnot efficiency, but didn't do the same for the first. I mean, what the heck?