Subtopic: Functional requirements, principles of working, construction and operation of manual, animal, tractor and renewable energy operated equipment for tillage, sowing, planting, fertilizer application, inter-cultivation, spraying, mowing, chaff cutting, harvesting and threshing
Question Statement:
A flywheel type power-operated chaff cutter has $z = 3$ cutting knives mounted on the flywheel rotating at $N = 360\text{ rpm}$. The feed throat opening has a width of $w = 20\text{ cm}$ and height of $h = 10\text{ cm}$. The length of cut set by the feed rolls is $L_c = 15\text{ mm}$. The bulk density of compressed green fodder passing through the throat is $\rho = 240\text{ kg/m}^3$. The theoretical fodder cutting capacity of the chaff cutter in $\text{tonnes/h}$ is ________ (round off to 2 decimal places).
Answer Key:
4.67
Step-by-Step Solution & Explanation
1. Throat cross-sectional area:
$A = 0.20\text{ m} \times 0.10\text{ m} = 0.02\text{ m}^2$
2. Total number of cuts per minute:
$\text{Cuts/min} = z \times N = 3 \times 360 = 1080\text{ cuts/min}$
3. Advance of fodder per minute:
$v = 1080 \times 0.015\text{ m} = 16.2\text{ m/min}$
4. Mass rate of fodder processed:
$\dot{m} = A \times v \times \rho = 0.02\text{ m}^2 \times 16.2\text{ m/min} \times 240\text{ kg/m}^3 = 77.76\text{ kg/min}$
$\text{Capacity per hour} = 77.76 \times 60 = 4665.6\text{ kg/h} = 4.6656\text{ tonnes/h} \approx 4.67\text{ tonnes/h}$