Question

In a certain process, water condensing at 420°C, transfers heat to water evaporating at 250°C. The resulting heat is used in a power cycle which rejects heat at 27°C. The fraction of the available energy in the heat transfer process at 420°C that is lost due to irreversible heat transfer at 250°C is ________.

Answer 1

The fraction of the available energy in the heat transfer process is given by formula

$m=\frac {T_0×(T_1-T_2)}{T_2×(T_1-T_0)} (1)$

In our case, we have

T₀=300 K, T₁=693 K, T₂=523 K

 Using (1) we got

m=0.25

Answer

0.25