Tobacco Moisture, Equilibrium Desorption of Water Vapor on Tobacco

Abstract

The equilibrium desorption moisture contents of air-cured (burley and Maryland), heatcured (bright), and sun-cured (Turkish) tobaccos have been determined over a temperature range of 80°to 140°C. and a relative humidity range of 10 to 80%. The isosteric net heats of desorption varied from about 9000 to 16,000 B.t.u. per pound-mole in the region of 1% moisture to about 700 to 1 800 B.t.u. per pound-mole in the 20% moisture region, depending on the type of tobacco. Apparatus and procedure are described which permit rapid isosteric (constant moisture content) determination on materials, such as tobacco, which are easily damaged by prolonged contact with excessive moisture or heat.

Thermophysical Properties of Plant Leaves and Their Influence on the Environment Temperature

“…These measurements have reported values of the thermal conductivity in the range from 0.2 W · m −1 · K −1 to 0.5 W · m −1 · K −1 for different species of plant leaves. Although a few papers reporting the thermal conductivity of leaves have appeared in the literature, fewer studies on the specific heat or thermal diffusivity could be found [9]. On the other hand, no direct measurements of the thermal effusivity could be found in the literature.…”

Specific Surface Area and Specific Pore Volume Distribution of Tobacco

“…(5), the constant term 511.9 [cm 2 /g] gives the specific surface area of the larger pores more than 300 A in diameter. Since it was below 8 % of the total specific surface area, it can be concluded that the specific surface area oftobacco is mostly due to the micropores smaller than 300 A in diameter.…”

“…Since it was below 8 % of the total specific surface area, it can be concluded that the specific surface area oftobacco is mostly due to the micropores smaller than 300 A in diameter. By assuming that the pores are connected each other to make a uniform long cylinder, the specific surface area S [cm 2 /g] and the specific pore volume Vg [cm 3 /g] can be given as following. cylinder of pores is crossing over at places, the above calculation gives a larger value of d than the actual diameter of the cylinder.…”

Heat Transfer during a Flash Drying Process

“…The chemical composition of tomato leaf is described in the literature (Mathan and Cole, 1964). The drying curve (Chang, 1970;Chenikov and Krasivski, 1972) and the thermal diffusivity (Locklair, et al, 1957) for a leaf having a porous-colloidal structure (Luikov, 1966) have been reported. However, the flow pattern found in a pneumatic duct and resulting slip velocity have rather general character and are factors independent of the properties of the material used.…”

“…The amount of heat transferred from the gas to the particles was evaluated by measurements of the amount of water evaporated from the particles plus the calculated heat absorbed during the heat-up period. The oven method (forced heating of the samples at 212°F) was used to determine the initial and final moisture level in the particles (Locklair, et al, 1957).…”