# 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

http://ift.tt/1kRnyUQ

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