The internal combustion engine has done useful work equal to 27.6 MJ and consumed 3 liters

The internal combustion engine has done useful work equal to 27.6 MJ and consumed 3 liters of gasoline. Calculate the efficiency of the engine.

Initial data: Ap (useful work of the internal combustion engine) = 27.6 MJ = 27.6 * 10 ^ 6 J; V (volume of consumed gasoline) = 3 l = 3 dm ^ 3 = 7.5 * 10 ^ -3 m ^ 3.

Constants: ρ (gasoline density) = 710 kg / m ^ 3; q (specific heat of combustion of gasoline) = 4.6 * 10 ^ 7 J / kg.

The efficiency of an internal combustion engine is calculated by the formula: η = Ap / Q = Ap / (q * m) = Ap / (q * ρ * V).

Let’s make a calculation: η = 27.6 * 10 ^ 6 / (4.6 * 10 ^ 7 * 710 * 3 * 10 ^ -3) = 0.281 or 28.1%.

Answer: The efficiency is 28.1%.