A mathematical model of commodity wet-bulb temperature (CWBT) for grain storage applications

Commodity wet-bulb temperature (CWBT), which is the value of wet-bulb temperature of the interstitial air within a grain bulk, is an important insect control term in grain storage applications. However, due to difficulties in its measurement and also the need for iterative calculations, its application for aeration control has been limited in commercial grain industries throughout the world. In the present study, a remedy to these difficulties is introduced. A straightforward model was developed by applying dimensional analysis methods to the CWBT data obtained from iterative solutions of the original wet-bulb temperature equation. This model is capable of determining non-iteratively CWBT as a function of dry-bulb temperature and relative humidity inside the grain bulk. The values of coefficient of determination (R2), mean bias error (MBE), standard error (SE) and root mean square error (RMSE) for obtained CWBT model were 0.999, 4.71%, 0.015 °C and 0.319 °C, respectively, when compared with original data, which reflect accurate predictions. The model predictions were compared with available data from valid psychrometric charts. The mean relative deviation (MRD) was less than 1.85%. The model was further applied to determine the errors in calculation of CWBT as affected by uncertainties in dry-bulb temperature and relative humidity measurements. This enhanced the capability of the model to be applied in CWBT aeration controllers.