Commercial success of a new spray dryer investment depends upon the dryer meeting its specified performance in all respects, and this puts great importance on the scale-up procedures used in the projecting of the new spray dryer. Scale-up still relies heavily on the experience of the designer. However, as the applications and specifications become more and more complex, so does the need for improved test work in pilot plants, and computational fluid dynamics simulations become more important, so that better scale-up tools are available to minimize the possibility for personal errors that may lead to the new dryer investment becoming an unsuccessful commercial venture.