Efficient operating parameters for bed dryers

The main aim for this presented work is to prove that higher efficiencies can be achieved when considering allotted drying time as a parameter of the drying cycle. This thesis explains how to theoretically calculate the most efficient drying parameters for wheat based on the ambient conditions and allotted drying time. Drying in the constant and falling rates will be discussed with mathematical models developed for each drying period. Drying air temperatures between 290 and 370 Kelvin, and drying air velocities between 0.3 and 5.3 meters per second will be explored. The wheat will be dried from a moisture content of 0.22 kilograms of water per kilograms of dry basis to a moisture ratio of 0.05. Energy and exergy efficiencies are utilized as a determining factor for most efficient drying parameters. The results prove that the dryer is most efficient when ran at 370 Kelvin and 0.3 meters per second when the allotted drying time is less than 21.7 hours. An allotted drying time between 21.7 and 25.4 hours would require a drying air temperature between 290 and 293 Kelvin, and a drying air velocity of 0.3 meters per second. If the allotted drying time is greater than 25.4 hours then ambient drying air temperature is most efficient due to no energy input. The mathematical models are compared to experimental results and show a good correlation with an average percent error of 5.9 percent.