A burr mill grinds sorghum at 200 kg/h from 4 mm to .336 mm using7.2 kW. At another gap the product is .306 mm with the same feed. Use Kick’s law to find power in kW, to two decimals.
Kick’s specific-energy law is proportional to $\ln(D_f/D_p)$. At unchanged mass rate, $P_2/P_1=\ln(4/.306)/\ln(4/.336)$. Thus $P_2=7.2(1.0377587)=\mathbf{7.47}$ kW. Feed rate cancels in the ratio; the finer product requires slightly more energy.
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