Resilient heat exchanger network design

Most of the recent automated heat exchanger network synthesis programs have been developed by using optimization techniques. Although the optimization approach is more rigorous, it is limited by knowledge and insight. In this dissertation, a heuristic design approach is used. An automated HEN synthesis program via a rule-based system is developed. A new resilient HEN design method is presented wherein specified resiliencies are directly achieved.; The published HEN design heuristics are analyzed and they are organized into a number of match operators by discriminating the position of a match, the comparative heat loads and the heat capacity flowrates. The match operators for a match of two streams without splitting is complete. Match operators for split match and other special case matches are also devised. The rule-based system found solutions for most of the HEN synthesis problem solutions without or with few backtrackings.; The network resiliency is directly incorporated at the network structure generation level. When incorporated with the 'tick-off' and pinch heuristics, the network design by using this new design method will feature (i) minimum number of matches, (ii) maximum energy recovery, and (iii) specified resilience.; The new design method, called the disturbance propagation (DP) technique, employs physical knowledge and causal logic, e.g. the disturbance of the residual stream is the sum of its original disturbance and the propagated disturbance. Two classes of resilient HEN problems are demonstrated: (i) no pinch jump and (ii) pinch jump due to temperature or flowrate variations. A new problem partitioning procedure is devised in order to cope with the drastic structural change of a network when the pinch is moved. The match operator classes are identified for their resilience properties. The DP method is incorporated with the match operator technique and a design state concept in order to find a solution in a most efficient and systematic way. It is shown that the new method is straightforward and insightful.