An engine with 30% efficiency drives a refrigerator having COP of 5. What is the heat input into the engine if 10 MJ of heat is removed from the cold body by the refrigerator? -

Mumbai university > MECH > SEM 3 > THERMO

Marks: 6M

Year: May 2014

Given: Q3 = 10MJ, η = 0.3, COP = 5

For Refrigerator,

$COP = (\frac{Q_3}{W_{in}})$

$5 = (\frac{10}{W_{in}})$

$W_{in} = 2MJ$

For Engine,

$η = (\frac{W_e}{Q_1})$

$0.3 = (\frac{2}{Q_1})$

$Q_1 = 6.667 MJ$

For Engine,

$Q_1 = W_e + Q_2$

$Q_2 = 4.667MJ$

For Refrigerator,

$Q_4 = W_e + Q_3 = 12 MJ$