Subtopic: Calculation of performance parameters – field capacity, efficiency, performance index, application rate and losses
Question Statement:
The diameter of feed rollers of a conveyor type power chaff cutter is 100 mm and they are rotating at 90 rpm for cutting the dry fodder. The effective length of each feed roller is 250 mm and the average clearance between them is 15 mm. The compressed density of the material while passing through the feed rollers is 250 kg m⁻³. The throughput capacity of the chaff cutter in ton h⁻¹ is __________.
Official Answer Key:
1.55 to 1.65
Step-by-Step Solution & Explanation
• Peripheral (feeding) velocity of roller, v = πDN = π × 0.100 m × (90/60 rev/s) = π × 0.100 × 1.5 = 0.4712 m/s.
• Cross-sectional area of material stream between rollers = effective length × clearance = 0.250 m × 0.015 m = 3.75×10⁻³ m².
• Volumetric feed rate = v × A = 0.4712 × 3.75×10⁻³ = 1.767×10⁻³ m³/s.
• Mass feed rate = 1.767×10⁻³ × 250 kg/m³ = 0.4418 kg/s = 0.4418 × 3600 = 1590 kg/h ≈ 1.59 ton/h, inside the accepted range 1.55–1.65.
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