Subtopic: Calculation of performance parameters – field capacity, efficiency, performance index, application rate and losses
Question Statement:
A tractor-mounted rotary tiller operates with a working width of $1.5\text{ m}$ at a depth of $0.10\text{ m}$. The forward operating speed is $v = 3.6\text{ km/h}$. The measured total PTO shaft power consumed by the rotavator during operation is $P_{\text{pto}} = 18\text{ kW}$. The specific energy consumption ($SEC$) of the rotary tiller in $\text{kJ/m}^3$ of tilled soil is ________ (round off to integer).
Answer Key:
120
Step-by-Step Solution & Explanation
```
Specific Energy Consumption (SEC):
SEC = Power / Soil Volume Rate
```
**Step-by-step Calculation:**
1. Forward speed in $\text{m/s}$:
$v = \frac{3.6 \times 1000}{3600} = 1.0\text{ m/s}$
2. Soil volume handled per second ($\dot{V}$):
$\dot{V} = \text{Width} \times \text{Depth} \times v = 1.5\text{ m} \times 0.10\text{ m} \times 1.0\text{ m/s} = 0.15\text{ m}^3/\text{s}$
3. Specific Energy Consumption ($SEC$):
$SEC = \frac{P_{\text{pto}}}{\dot{V}} = \frac{18\text{ kW}}{0.15\text{ m}^3/\text{s}} = \frac{18000\text{ J/s}}{0.15\text{ m}^3/\text{s}} = 120000\text{ J/m}^3 = 120\text{ kJ/m}^3$