A novel task-based ontology is proposed to improve the conceptual design at the level of a process unit for solution crystallization. The objective is to reduce the cost of resources and capital, and possibly lead to process intensification. The physical task concept is chosen to facilitate a more synthesis-focused, functional approach, as an alternative to the traditional way of thinking in geometric structures for existing equipment. The synthesis approach is to represent a crystallization unit as a structured set of basic functions (tasks), each of which transforms the physical state of matter from an initial state to some final desired target state by means of physical event(s). These tasks can be connected in a network to accomplish the transformation of the feed into the product within quality specifications. Because a task network is coupled with behavioral models of physical events, it can also be used in a process-modeling environment for synthesis, analysis, and optimization studies.