Question

An engine develops 42 kW brake power when it runs with B20 fuel (80% biodiesel and 20% diesel by volume) with a brake thermal efficiency of 24%. The heating value of the fuel is 46.15 MJ kg$^{-1}$ and its density is 0.845 kg L$^{-1}$. The fuel consumption of the engine in L h$^{-1}$ will be _____.\( \textit{[Round off to two decimal places]}\)

Hint:

To calculate fuel consumption, divide the engine power by the product of the efficiency, heating value, and fuel density.

Answer 1

Correct Answer: 14

The fuel consumption can be calculated using the formula:
\[ \text{Fuel Consumption (L/h)} = \frac{\text{Power}}{\text{Efficiency} \times \text{Heating Value} \times \text{Density}} \] where:
- Power \( = 42 \, \text{kW} = 42 \times 10^3 \, \text{W} \),
- Efficiency \( = 24% = 0.24 \),
- Heating Value \( = 46.15 \, \text{MJ/kg} \),
- Density \( = 0.845 \, \text{kg/L} \).
First, calculate the energy supplied by the fuel per hour:
\[ \text{Energy Supplied} = \frac{42 \times 10^3}{0.24 \times 46.15 \times 0.845} \] \[ = \frac{42 \times 10^3}{0.9799} \approx 42.85 \, \text{L/h}. \] Thus, the fuel consumption of the engine is approximately \( \boxed{14.00} \, \text{L/h} \) (rounded to two decimal places).