Subtopic: Calculation of power, torque, fuel consumption, heat load and power losses
Question Statement:
A 4-cylinder, 4-stroke diesel engine with bore $100\text{ mm}$ and stroke $120\text{ mm}$ runs at $2000\text{ rpm}$. The mean effective pressure during test is $750\text{ kPa}$. Calculate the indicated power of the engine in $\text{kW}$.
Answer Key:
47.12
Step-by-Step Solution & Explanation
Given:
- Bore $D = 0.10\text{ m}$
- Piston area $A = \frac{\pi}{4} D^2 = \frac{\pi}{4} (0.1)^2 = 0.007854\text{ m}^2$
- Stroke $L = 0.12\text{ m}$
- Mean effective pressure $P_m = 750\text{ kPa} = 750 \times 10^3\text{ N/m}^2$
- Speed $N = 2000\text{ rpm}$
- Power strokes per min $n = N/2 = 1000\text{ strokes/min} = \frac{1000}{60}\text{ strokes/s}$
- Number of cylinders $k = 4$
Indicated Power ($IP$):
$IP = \frac{P_m \times L \times A \times n \times k}{1000} = \frac{750 \times 0.12 \times 0.007854 \times (1000/60) \times 4}{1} \approx 47.124\text{ kW}$