Heated Air Drying of Garlic Bulb in Air-Bag Type Dryer (Part 1)

Water·Heat Balance and Energy Efficiency for Various Static Pressures in Drying Chamber

Abstract

Experiments with positive, negative and zero static pressures were carried out to determine the static pressure suitable for heated air drying of garlic bulb in an air-bag type drying chamber. Under positive pressure the air current was in turbulent state and was partly pushed outside through lower part of air-bag wall. The thermal efficiency was 30.5%, and the energy efficiency was 142.6MJ/kg. Under negative pressure the air current was in a stable state and sucked in ambient air. The thermal efficiency was 8.4%, and the energy efficiency was 128.6MJ/kg. Under zero static pressure the air current was in the most stable state with minimal air leak. Thermal efficiency was 12.2% and the energy efficency was 198.4MJ/kg. It was concluded that heated air drying of raw garlic bulb using an air-bag type is suitable under negative static pressure because it produces stable air current and low energy consumption. Then water and heat balance equations were represented under three static pressures to express the characteristics of air-bag type dryer.