Calculate the maximum efficiency of an engine operating between 120 degree C and 35 degree C

Maximum efficiency of an engine working between temperatures T₂ and T₁ is given by the fraction of the heat absorbed by an engine which can be converted into work is known as efficiency of the heat engine.

Mathematically,

Efficiency, η = (T₂ –T₁) / T₂

T₂ = 120o C = 120 + 273 = 393 K

T₁ = 35o C = 35 + 273 = 308 K

Therefore,

η = (T₂ – T₁) / T₂

  = (393 – 308) / 393

  = .21628 = 21.62%

Hence maximum efficiency of the engine is 21.62%