Question

The exhaust gases on leaving cylinders were passed through an exhaust gas calorimeter and raised the temperatures of 215kg of water from 15°c to 61°c.determin break thermo efficiency

Answer 1

Solution;

From the question,you are given;

Breaking torque =9Nm

Speed is 16rev/s =2π×16.5 rad/s

Fuel consumption is 2.5kg/hour

Calorific value of the fuel is 45500kJ/kg

To find the brake thermal efficiency;

Calculate;

Brake power=Torque × speed

$P_b=90×2π×16.5=9330.05J=9.33kJ$

Energy supplied by the fuel=mass of fuel×calorific value of the fuel.

$P_f=\frac{2.5}{3600}×45500=31.60kJ$

Hence;

$\eta_{t}=\frac{P_b}{P_f}=\frac{9.333}{31.59722}=0.29529$

Ans; 29.529%