The 155-C A/B/C heat exchangers, belonging to an olefins plant, which heat the water used in reboilers of some fractionation columns, have historically presented energy efficiency problems due to fouling by polymerization in the tubes, the side through which the process water passes. This was used as a basis for simulating different mechanical models in Aspen EDR, taking into account the fouling problem in the conceptual design criteria. The book contains a brief description of the plant process, with emphasis on the system to which the equipment in question belongs; a summary of the basic theoretical fundamentals of shell and tube heat exchanger design; and an introduction to the Aspen Exchanger Design & Rating simulation interface. The original design data, conceptual design criteria, simulation results and procedure are detailed.