Heat exchanger network retrofit through heat transfer enhancement

Many design methods for the retrofit of heat exchanger network (HEN) have been proposed during the last three decades. The conventional methods used to solve retrofit problems often involve too many topology modifications and are limited by the size and complexity of retrofit problems. Moreover, practical implementation of the additional area in retrofit problems can be difficult due to topology, safety and downtime constraints. Heat transfer enhancement (HTE) can increase heat transfer coefficient so as to make exchangers smaller. The application of HTE provides an opportunity to avoid high capital costs for replacing equipments and pipelines in topology modification and the difficulties of additional area implementation in retrofit design. This paper presents a novel design approach to solve HEN retrofit problems based on HTE. An optimisation method based on simulated annealing has been developed to find the appropriate heat exchangers to be enhanced and augmentation level of enhancement. The new methodology allows enhancement to be added to tube-side or shell-side or both, which depends on the heat transfer control side. The application of this new methodology can bring a significant energy saving in retrofit design without any topology modification, or investment reduction in retrofit design with topology modifications. Copyright © 2011, AIDIC Servizi S.r.l.