Question

A four cylinder two- stroke cycle engine with a swept volume of 750 cm^3 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%

The question was asked in an interview for internship.

Asked question is from I.C Engine topic in chapter Internal Combustion Engine of Farm Machinery

Answer 1

Correct choice is (d) 36%

Easiest 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%.