화학공학소재연구정보센터
Particulate Science and Technology, Vol.19, No.1, 45-65, 2001
Grain drying and aeration in a solar hexagonal silo
The processes involved in the drying and aeration of grain in a silo were studied. Experiments were performed on a model silo based on the design recently proposed by Hernandez-Cordero et al. (2000), capable of minimizing the dynamic stresses during the emptying process, therefore reducing the amount of grain losses due to mechanical damage during storage. This study addressed the second most important factor for grain losses, the grain loss resulting from lack of aeration and excess moisture. Air was injected into the interior of the model silo to study the grain drying time. The temperature of the air was controlled with an electrical heater that simulated a solar energy source. Day and night operating conditions were simulated by switching the heating on and off alternatively for periods of approximately 12 hours. The moisture of grain samples was monitored over time to obtain the rate of moisture decrease. The experimental results compared very well with the predictions of an established model. The mean difference between the experiments and the model was within in 1%. It is shown that a significant decrease in the drying time is achieved with the proposed system. A system operated with day solar heating achieved drying times 100% shorter than those obtained with a system with no heating. When, in addition to day heating, night aeration was used reductions of the order of 300% in the drying time were obtained. Comparisons between different operating conditions show that this system is a viable option to reduce the drying times and cost of operation for drying processes.