Volume 23 of "Advances in Chemical Engineering" covers the active field of process synthesis. There are currently three prevalent approaches to complex process synthesis strategies: heuristics-based selection, geometric representation, and optimization methods. This volume addresses a variety of these synthesis strategies for process subsystems, representing only a sample of the state-of-the-art of process synthesis research. The five papers in this volume address quite different process subsystems and application areas but still combine basic concepts related to a systematic approach. All five of the papers develop successful synthesis methods for their respective cutting-edge applications. As a group, the papers serve to highlight many unresolved issues in process synthesis and also provide guidelines for future research. It considers current approaches to process synthesis problems and examines areas of possible future research. The articles are written by leading experts in the field.