Question

A steam engine develops 600 kW at 180 r.p.m. The coefficient of fluctuation of energy is found to be 0.5 and the fluctuation of speed is required to be kept within ±1% of the mean speed. The maximum fluctuation of the energy during operation is given by:
1. 150 kN-m
2. 50 kN-m
3. 100 kN-m
4. 120 kN-m

Answer 1

Correct Answer - Option 3 : 100 kN-m

Concept:

The maximum fluctuation of the energy during operation is given by:

ΔE = Work done per cycle × C_E

Work done per cycle = \(P×\frac{60}{N}\)

where C_E = Coefficient of fluctuation of energy, P = Power, N = Speed in r.p.m

Given:

Calculation:

P = 600 kW, N = 180 r.p.m, CE = 0.5

Work done per cycle = \(P\;×\;\frac{60}{N}\) = \(600\;×\;\frac{60}{180}\) = 200 × 10³ Nm.

ΔE = Work done per cycle × CE

ΔE = 200 × 10³ × 0.5 = 100 kN-m.