Development and Performance Evaluation of a Low-cost Winnower for Dry Coffee Cherry
Keywords:Air velocity, Coffea arabica L, Coffea canephora, cleaning efficiency, dry cherry coffee, winnower
The normal practice of coffee planters for cleaning dried cherry is time consuming, labourious, and totally depends on natural wind conditions. A low-cost power-operated dry cherry winnower was, therefore, developed at Central Coffee Research Institute, Karnataka. The dry cherry winnower consisted of a hopper, blower unit (exhaust fan), cherry outlet, and frame with an overall dimension of 1.28 (L) x 0.7 (W) x 1.63 (H) m. Arabica (Coffea arabica L) and robusta (Coffea canephora) cherry coffees were used for testing. During evaluation, cherry sample from main outlet, dried leaves and twigs from foreign materials outlet were collected to determine various parameters viz., percentage of blown cherry, cleaning efficiency, and output capacity. Air velocity of 4 m.s-1 was effective with lower percentage of blown cherry. Cleaning efficiency of arabica cherry was 99.85%, 99.73%, and 98.85% at 20, 25, and 30 kg.min-1 feed rate, respectively. Similarly, the cleaning efficiency of robusta cherry was 99.74%, 99.11%, and 98.53% at 20, 25, and 30 kg.min-1 feed rates. The output capacity ranged from 1,200 kg.h-1 to 1,807 kg.h-1 for arabica cherry, and 1,220 kg.h-1 to 1,821 kg.h-1 for robusta cherry. Higher cleaning efficiency of 99.85% and 99.74% were recorded for arabica and robusta cherry, respectively, at 20 kg.min-1 feed rate and 4 m.s-1 air velocity. The average power consumption was 0.375 kW.h. The cost of operation of the winnower was 105 `.h-1. The estimated cost of the winnower was `.16,000 per unit. The operational cost and time of winnowing could be reduced by 67% and 72%, respectively, by using the winnower when compared to conventional winnowing.