The PSI-Cell model is used to predict flow patterns and drying rates for laboratory-scale spray dryers. The liquid feed is water, with atomization producing a spectrum of droplet sizes. An analysis of the cause-and-effect relationships determining droplet trajectories, temperature fields, the location and magnitude of the backflow recirculation effect, and drying rates provides insight into the factors governing spray-air contacting and dryer performance. Independent effects are assessed for spray angle, dryer column diameter, initial droplet size distribution and droplet velocity (separately and as linked through atomizer pressure), air/water flow ratio, and liquid volatility. Inferences are made for effective dryer design, selection of operating conditions, and logic for scale-up.