RESISTANCE OF COFFEE BEANS AND COFFEE CHERRIES TO AIR FLOW

Experimental were conducted to obtain information on the effect of airflow rates and bed depths on the resistance of coffee cherries and coffee beans available locally (Coffea Liberica). The airflow used were in the range of 0.06 to 0.6 cu. m/s-sq.m. The moisture content of the coffee cherries ranged from 10 % to 50% (wet basis) and that of coffee beans ranged from 12% to 30% )wet basis). Two methods of filling were used i.e. loose fill and packed fill. Pressure drops across the material bed in a vertical column were measured at several depths using inclined manometer. The pressure drop increased directly with air flow rate as well as bed depths. The effects of air flowrates and moisture contents on the resistance in terms of pressure drip per unit bed depth were analysed. The pressure drop per unit depth across the material bed varied slightly due to different depth. The resistance to airflow decreased with the increase in moisture content for loose fill. However, the effect of moisture content is not apparent for packed fill.