A large electrical power plant generates 1201 MW of electricity with an efficien

Question

A large electrical power plant generates 1201 MW of electricity with an efficiency of 34.8%.

(a) Calculate the heat input to the plant Qh in one day.
J

(b) How much heat Qc is exhausted in one day?
J

(c) If the cooling towers exhaust the heat in the form of 35.0°C air into the local air mass, which increases in temperature from 18.0°C to 20.0°C, what is the total increase in entropy due to this heat transfer?
J/K

(d) How much energy becomes unavailable to do work because of this increase in entropy, assuming an 18.0°C lowest temperature? (Part of Qc could, of course, be utilized to operate heat engines or for simple space heating, but it rarely is.)
J

Explanation / Answer

a. heat input in 1 day= 1201 x 10^6 x 24 x 3600/0.348=2.98 x 10^14 j

b.heat exhaust = heat input x (100-34.8)%= 2.98 x 10^14 x 65.2%= 1.94 x 10^4 J

c. change in entropy= 1.94 x 10^14/( 273 +35)=6.29 x 10^11 J/K

d. irreversible work = 6.29 x 10^11 x (273+18)= 1.83 x 10^14 J

available work = 1.94 x 10^14 - 1.83 x 10^14 = 0.11 x 10^14 J

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.