Mathematical modeling of infrared radiation thin layer drying of onion slices

An infrared dryer was developed and infrared radiation thin layer drying of onion slices was carried out at infrared power levels of 300, 400 and 500 W, air temperatures of 35, 40 and 45 °C and air velocities of 1.0, 1.25 and 1.5 m/s. The drying occurred in the falling rate of drying period. Drying rate increased with increase in infrared power at a given air temperature and velocity and thus reduced the drying time. The drying time increased with increase in air velocity at a given infrared power and air temperature because of the increased cooling effect at the surface of the product. Eight available moisture-ratio models were fitted to the drying data. Page's model had a higher correlation coefficient and low chi-square value and thus predicted drying behaviour of the onion slices more accurately.