Abstract:
This study is related to the usage of energy for Bulk Virgina tobacco curing. The mathematical model of energy consumption was proposed. Also, direct measurements at tobacco curing station were made. The developed energy mathematical model was verified by comparing its results with the measured values. The research found that the hourly energy requirement wsa highly fluctuated. These unstable values were the result of ununiform air mixing properties at the entrance of tobacco curing shelves. However, the trend of energy requirements, predicted from the mathematical model and directed measurement, were found to be the same. It was also found that the total heat energy usage in the tobacco curing process, predicted from teh mathematical model, was highly accurate, with the error was less than 6 percent of the entire heat energy used in the curing test. This study found that the energy usage in the yellowing stage, color fixing and leaf drying stage as well as stem drying stage were 20%, 35% and 45% of total energy used in tobacco curing, respectively. For the efficient energy utilization, the bulk-curing barn with central hot-water heating, having 6 independent curing rooms, should be scheduled to start curing process with one day lagging for each barn in a row. As the result, the boiler that was currently used was found to have excess capacity enough for one additional curing room. This research also found that the pattern of controlled air properties for tobacco curing and the air circulation velocity through the packed tobacco were very important factors toward the energy usage in the curing process. Among the different curing patterns, it was found that the heat and electrical energy used for tobacco curing in the curing room with the capacity of 6,000 kgs., recommended by A.Hiran (1986), was less than that currently used at tobacco curing station by 161.9 MJ and 54 kW.h, respectively and the consumed curing time could be reduced by 20 hrs. Moreover it was found that air circulation velocity through the bulked tobacco at 0.19 m/s would consume the least energy usage.