PREDICTING HYGROSCOPIC LOADS IN GRAIN STORAGE BINS

A predictive model has been developed for hygroscopic (moisture-induce d) loads in grain storage bins. Swelling of a wetted grain kernel is a ssumed to be equal to the volume of water absorbed by the kernel. The volumetric strain of the grain bulk caused by moisture changes is calc ulated from swelling of individual grain kernels. Model predictions of hygroscopic strain are in close agreement (less than or equal to 3%) with an empirical correlation reported in the literature. Predicted hy groscopic pressure is 1.6 times higher than one of values observed by Dale and Robinson (1954) in model bin tests. For a hypothetical bin 6. 15 m high and 4.20 m in diameter, the model predicts hygroscopic overp ressure factors ranging from 5.0 to 8.6 for an increase of 10% db. (dr y basis) in grain moisture content for shelled corn with bulk densitie s between 681 and 771 kg/m(3).