Effect of fall in sink on efficiency of a heat engine
Consider a reversible heat engine is operating between a source at T1 and a sink at T2. If T2 decreases, the efficiency of the heat engine ______
a. decreases
b. increases ---
c. remains constant
d. none of the above
Correct Answer: b. increases
Explanation:
The efficiency of a reversible heat engine is operating between a source at T1 and a sink at T2 is given by,
η = Work done / Heat supplied
ηrev = ηmax = ( T1 – T2 ) / T1
ηrev = 1 – (T2/T1)
From the above equation, as T2 decreases the efficiency increases and tends towards 100%
