Question

A nuclear power plant operates at 80 percent of its maximum theoretical (Carnot) efficiency between temperatures of 600oC and 330°C. If the plant produces electric energy at the rate of 1.55 Giga-Watts, how much exhaust heat is discharged per hour?

Answer 1

The efficiency of a carnot engine operating between those temperatures is 1 - 330/600 = 45%

The power plant is operating at 80% of that, so its efficiency is
45 * .8 = 36%

So, work / heat energy entering the system = .36
Heat energy entering the system = work / .36
= 1.55 GW / .36
= 4.306 GW

Heat energy entering - work = Heat exhaust
Heat exhaust = 4.306 GW - 1.55 GW
= 2.756 GW
= 2.756 * 10 ^ 9 W = 2.756 * 10 ^ 9 J / s
= 2.756 * 10 ^ 9 J / s * 3600 s / hr
= 9.9216 * 10 ^ 12 J / hr