Wear of Rice in an Abrasive Milling Operation, Part II: Prediction of Bulk Temperature Rise

The phenomenon of abrasion of rice grains during milling operations was analysed in Part I. This part includes modelling of the temperature rise and energy utilisation in an abrasion milling operation and its effect on milling quality of grain. Medium grain brown rice was milled in an abrasive polisher. The rise in the bulk temperature was modelled by energy balance, on the basis of abrasion wear theory. The head rice yield was correlated with the final temperature of the grain and was found to decrease steadily with increase in the bulk temperature of the grain. The developed model accurately predicted well the bulk temperature rise in the rice grains with milling time. Energy utilised for milling was found to be about 33%, whereas, about 10% of the energy was utilised to raise the temperature of the grains, and 55–60% of the total energy was utilised in running the machine in idle conditions.