Moisture Content and Temperature Variation Characteristics of Cut Tobacco During Variable Temperature Drying

The change of moisture content in and temperature of cut tobacco during variable temperature drying were determined at different hot air temperature combinations of first section at 120℃ and second section at 90℃(120&90℃),110&80℃ and 100&70℃,the determined results were analyzed and compared with those under constant temperature drying.The results showed that:1) Under variable temperature drying,the variation curves of moisture content and drying rate of tobacco before temperature changing were consistent with those under constant temperature drying at high temperature(100,110 and 120℃);after temperature changing,the curves gradually approached to those of constant temperature drying at low temperature(70,80 and 90℃).The dynamics of variable temperature drying could be described by the Midilli model.2) For variable temperature drying,the end temperature of cut tobacco was significantly lower than that of constant temperature drying at high temperature,and there existed a dehydration process at a relatively constant tobacco surface temperature around the point of temperature changing.3) The filling value of cut tobacco dried at different temperature combination was between that dried at high and low constant temperatures.However,the filling value of cut tobacco dried at 100&70℃ was close to that dried at the constant temperature of 100℃.