A four cylinder two- stroke cycle engine with a swept volume of 750 cm³ per cylinder gives a specific fuel consumption of 0.25 kg KW^-1 h^-1. When developing a brake mean effective mean pressure 650 kPa at 1500 rpm. What is the brake thermal efficiency, if the calorific value is 40 MJ kg^-1?
a) 9%
b) 18%
c) 32%
d) 36%

Answer: d
Explanation:
Brake power = \(\frac{pLAN*n}{60000} \)
B.P. = \(\frac{650∗750∗10^{−6}∗1500∗ 4∗10^3}{60000} \)
B.P. = 48.75 KW
Brake thermal efficiency = \(\frac{B.P.*60}{Wf*Cf} \)
B.T.E. = \(\frac{48.75∗60}{0.203∗40∗10^3} \)
B.T.E. = 36%.