An Experimental Study of Wheat Drying in Thin Layer and Mathematical Simulation of a Fixed-Bed Convective Dryer

Abstract

Drying of wheat (Algerian cultivar: Hadba03) in thin layers was studied and mass flux phenomenon was used to characterize the thin-layer drying process. Thin-layer drying of wheat was determined for drying air temperature range of 40-60 C, relative humidity of drying air from 10 to 30%, air velocity of 0.7 m/s, and initial grain moisture from 26 to 31% (dry basis). Equilibrium moisture content of wheat was determined using desorption isotherms obtained from the thin-layer drying data. An equilibrium model for a stationary deep bed with drying air moving vertically upward was developed using mass and energy balance between grain and drying air in the bed and drying air characteristics obtained from thin-layer drying experiments. The developed model was validated by drying wheat in a laboratory dryer using different drying air temperatures and initial moisture contents.

Assessment of the initial moisture content on soybean drying kinetics and transport properties

“…Many authors [3,4,5,6,7,8,9,10,11,12] have observed in agricultural products the absence of constant drying rate stage as well as a decrease on this rate value starting from the initial drying process. These results indicate that the material surface is not initially saturated with water, and the rate of internal moisture movement controls the drying rate during most of the process [13] .…”

“…Several studies have also revealed that air temperature has strong influence on drying rates enhancing their values [3,4,5,6,7,8,9,10,11,12,15,16,17,18] . However, drying processes at high temperatures can deteriorate the product quality by increasing temperature and moisture gradient leading to internal tensions, cracks, breakages, and fractures in the grain [16] .…”

A coupled mathematical model for simultaneous microwave and convective drying of wheat seeds

“…Mathematical models of convective drying of wheat were reported by Aregba et al (2006). Hemis et al (2009) used a coupled heat and mass transfer model for the prediction of drying characteristics of wheat under convective air drying. The MW drying model which was developed by Campanone et al (2001Campanone et al ( , 2005 was used by Hemis et al (2011) for wheat seeds.…”

Heat transfer characteristics on lignite thin-layer during hot air forced convective drying

“…Yet the validity of the deep-bed drying model is directly dependent on how accurately the thin layer drying kinetics behaved [11][12][13]. Celma et al [14] examined the thin-layer drying behavior of sludge at air temperature range of 20-80°C and air velocity of 1 m s À1 .…”