Study Of Multi-period Heat Exchanger Network Synthesis And Its Integration With Solar Thermal Energy

Heat exchanger network (HEN) is one of the well-developed scientific areas. However,as it has been proved to be an NP-hard problem, it is still hard to achieve the optimalnetwork. Multi-period heat exchanger network synthesis is an upgraded problem of singleperiod HEN problem. It should provide flexibility for different operation conditions, as wellas minimize the total economic cost. This thesis is focused on the methodology of MPHENand its implementation with solar thermal utilities.A multi-period extension of a one-step single-period MILP model presented byBarbaro in2005for grassroots design of heat exchanger network was proposed in thisthesis. The model is not based on the pinch analysis or decomposition of the synthesisproblem into sequential subproplems. The whole problem is handled simultaneously bylinear constraints and objective function. A special transportation–transshipment modelbased on temperature intervals is used in this model with potentials to obtain structuressuch as splitting, bypass, non-isothermal mixing, and some others. A benchmark was testedusing the proposed model. Total annualized cost was taken as the objective. Compared withresults using other methods, the proposed model is able to achieve reasonable MPHENcapable to operate in varying conditions satisfying temperature targets and heat loads withan economically optimal energy integration level.Maximizing heat recovery and increasing the share of renewables could significantlyreduce CO2emissions. Solar thermal technology is regarded as one on the promising toolsto meet this target. An integration methodology for implementing solar thermal collector inthe multi-period heat exchanger network is conducted in this thesis. Solar thermal collectoris considered an unsteady utility and integration in the MPHEN directly. A dairy factoryexample is used to illustrate the integration procedure.