Correct Answer - Option 2 : 120 kW
Concept:
Mechanical efficiency is defined as the ratio of brake power (delivered power) to the indicated power (power provided to the piston).
It can be defined as the ratio of the brake thermal efficiency to the indicated thermal efficiency.
\({\eta _m} = \frac{{bp}}{{ip}} = \frac{{bp}}{{bp + fp}}\)
Calculation:
Given:
Indicated power = 150 kW, Mechanical efficiency = 80%
\(\eta_m = {Brake~ power\over Indicated ~power}\)
\(0.8 = {Brake~power\over 150}\)
Brake power = 120 kW.
