A process synthesis modelling framework is proposed, based on the representation of synthesis alternatives via mass and heat transfer mechanisms. A simple, yet multipurpose mass/heat exchange module is introduced to represent the building block for any process operation involving mass/heat exchange process between two properly defined streams. A flowsheet hyperstructure is then developed comprising mass/heat exchange matches properly connected; conventional or non-conventional:units and process structures can be obtained from this representation through the minimization of a corresponding annualized cost.