**A powerplant near a river- entropy question**
Hi, I am stuck on Termodynamics again (and I have an exam really soon)!
A typical coal-fired power plant generates 1000 MW of usable power at an overall thermal efficiency of 40%.
1. The river's temperature is 18.0 degrees celcius before it reaches the
power plant and 18.6 degrees celcius after it has received the plant's
waste heat. Calculate the river's flow rate, in cubic meters per second.
(the answer you should get is V =597 m^3/s )
2.By how much does the river's entropy increase each second?
(the answer is $\displaystyle \Delta S$ =5.15×106 J/K ).
I don't know how to start 1, please help. I am in a similar position with 2.
Usually I use $\displaystyle \Delta S=\int_{T_1}^{T_2} \frac{mcdT}{T}$
for this type of problem (as I can't find any other relevant formulas in my notes)
but as I don't know the mass of the river I don't this is not an option. Am
I missing something really obvious?
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Last edited by C.E; May 23rd 2009 at 07:58 AM.
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