Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 128-129).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1963. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Typescript, etc.

The effect of drying parameters on the drying-rate constant, the diffusion coefficient, and the dynamic equilibrium moisture content was investigated using the Park variety of wheat. The initial moisture content of all the grain used in the drying tests was approximately 29 percent, dry basis. Air temperatures of 120, 100, 80 and 60 degrees Farenheit; air flow rates of 120, 80, 20 and 5 feet per minute and several relative humidities were employed as the drying conditions during the tests. A closed cycle, heated air dryer in which the air temperature and the relative humidity could be controlled to ± 2 degrees Farenheit and ± 5 percent respectively, was constructed for the investigation. It was assumed that the mechanism of internal flow of moisture within a kernel is that of diffusion. When the initial transition drying period was neglected, the drying-rate constant and the diffusion coefficient were found to be constant and the plot of log moisture ratio against time gave an excellent fit for each drying test. It was concluded that the falling-rate period in thin layer drying could be represented by a constant drying-rate constant and diffusion coefficient. The effect of air temperature on the drying-rate constant and diffusion coefficient was found to be inconsistent with an Arrhenius type equation. There was no observable effect due .to air flow rate and relative humidity of the drying air. The dynamic equilibrium moisture content increased with increased relative humidity of the air. A plot of log dynamic equilibrium moisture content versus log-log relative humidity gave a straight line relationship and satisfied Henderson's equation. The equilibrium constants were found to vary with the air temperature. The dynamic equilibrium moisture content was found to decrease with both the air temperature and air flow rate. The effect of air flow rate was quite small except at low' temperatures. When log air temperature was plotted against dynamic equilibrium moisture content, it followed a straight line, indicating that an exponential relationship between the two might exist. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

The use of fluidized beds of hot inert solids for drying wood is a relatively new concept. Recent investigations on fluidized bed drying of thin veneer (1,2) have shown that more rapid drying can be achieved by this method than by conventional means. In the present work, blocks of Western Hemlock wood, 2 in. x 4 in. x 1 ft. containing 70% to 100% moisture (dry-basis) were dried in a fluidized bed of -20 +30 mesh sand at four levels of bed temperature (175, 190, 204, and 217°F) and three air velocities. The drying time required to reach 15% moisture content (M.C.) was 14-15 hrs. for lumber dried at 204°F as against two or more days generally taken in Kiln drying. The quality of the wood dried at bed temperatures of 204°F and below was not adversely affected. Bed temperature had a strong inverse effect on drying time, while the fluidizing air flow rate had little effect. The diffusion equation was employed to describe the movement of moisture during the falling-rate period of drying and the heat conduction equation to describe the unsteady-state movement of heat inside the drying block of wood. Mathematically, drying was treated both as a one and a two-dimensional problem. The resulting equations were solved on a digital computer to predict the average moisture content and the average temperature of the drying block of wood, each as a function of time. The distribution of moisture content within the drying block was also computed. The calculated results showed a good agreement with experimental data. The economics of fluidized bed drying were estimated and compared with the cost of Kiln drying. The results showed that the capital cost of the fluidized bed system is considerably lower while the operating cost is similar to that for kiln drying. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

No description available.

No description available.

No description available.

No description available.

No description available.