Thermal Modeling of POL Bulk Storage Tanks

A lumped-mass surface-temperature thermal model for POL (petroleum, oil, lubricants) bulk storage tanks is developed. The model utilizes twelve ordinary, coupled, first-order differential equations, obtained from energy balances, to describe the time-dependent variation of the surface temperatures (top and eight wall segments) of a partially filled POL tank. One-dimensional transient conduction in the soil is considered below the tank. Convective heat transfer and direct and diffuse irradiation are modeled as energy transfers into/out of the twelve lumped masses. The model is implemented in a computer simulation. Comparisons of the predicted tank surface temperatures with the available data show that the correct trends and salient features are predicted. In most instances predicted and measured temperatures agree within a few degrees centigrade. Preliminary model performance indicates that the technique incorporates much of the correct physics and is capable of being developed into a reliable predictive model. Recommendations are made for further development and validation.