Problem Spray drying is process where a suspension or slurry is sprayed through a number of nozzles in order to create small droplets i.e. particles to reduce the liquid content of the individual particles. The small size of the particles combined with the "large" distance between the particles enhances the evaporation of the liquid solvent and the its transfer to the gas phase that may be stationary of moving. The concentration, temperature, and the overall efficiency of the particles is controlled by the residence time. Your objective is to derive an analytical expression that describes the position of a particle over time within this device.