PHY2004 example test problem involving heat and gases

1. The problem statement, all variables and given/known data

A 500-MW electric power plant has an efficiency of 32%. It loses its waste heat in large cooling towers at 20◦C. If the plant operates at the maximum possible efficiency, what are the temperature of the hot reservoir (in ◦C) and the waste heat (in MJ) discharged per second respectively?

Given info:

Specific heat of water: c = 1cal/g·◦C
g = 9.80 m/s2
Density of water: ρw = 1 g/cm3
Density of air 1.20 kg/m3
Universal gas constant: R = 8.314 J/mole K
1atm=105 Pa
Heat of fusion for water: Hf = 80 cal/g
Heat of vaporization for water: Hv = 539 cal/g

2. Relevant equations

Could not even being this problem, my tutor and I had no idea what equation to use or how to even start.

3. The attempt at a solution

Couldn’t figure out how to even start the problem. The answer is 158, 1063 but I’d like to know the equations used and the steps

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