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Heat Integration with heat exchanger network (HEN) is a widely used way to save energy and improve efficiency. Varied types of heat exchangers and materials would influence the investment cost and affect the design of HEN retrofit. This paper critically reviews the features of various types of heat exchangers, their working conditions and investment costs, as well as the state-of-the-art of the current methods for HEN synthesis and retrofit, to introduce a framework for HEN retrofit which considers heat exchanger and material selection. The proposed framework divides the retrofit design process into two stages, diagnosis and optimisation. In the diagnosis stage, two graphical decision-making tools, the Shifted Retrofit Thermodynamic Grid Diagram with Shifted Heat Exchanger Temperature Range (SRTGD-SHTR) and Shifted Material Temperature Range (SRTGD-SMTR) are proposed for analysis and diagnosis of the existing HEN to determine feasible retrofit plans with pre-selected heat exchangers and materials. In the optimisation stage, the constrained particle swarm optimisation algorithm is applied to optimise the plans made in the first stage and minimise the total annual cost. A case study demonstrates a possible implementation of the proposed framework. The suitable types for new heat exchangers and their materials are selected, and the retrofitted design can reduce the utility cost by 8.9% compared with the existing HEN. This framework can be applied easily with a sound solution for HEN retrofit. • Development of a novel optimisation framework for the retrofit of HENs. • Consideration of the heat exchanger type and material selection in the design process. • Review of the features of various types of heat exchangers. • Review of the state-of-the-art of the current methods for HEN synthesis and retrofit. • Presentation of a case to verify the new optimisation framework. [ABSTRACT FROM AUTHOR]

In this study, diverse baffled longitudinal flow shell-and-tube heat exchangers (STHX) are contrasted with segmental baffle shell-and-tube heat exchanger (SG-STHX). Experimental data are obtained with municipal water served as the working fluid, and the shell-side volume flow rate ranges from 1.79 m3/h to 7.42 m3/h. The components of the shell-side pressure drop are discussed stand on different flow patterns. The maximum proportion of pressure drop in tube bundle section of rod baffle shell-and-tube heat exchanger (RB-STHX) is 12%, while it has nearly taken up 70% shell-side pressure drop for both SG-STHX and large-and-small hole baffle shell-and-tube heat exchanger (LSHB-STHX). The energy efficiency of three tested STHXs is deliberated from three perspectives, including entropy generation, exergy destruction, and efficiency evaluation criterion. The longitudinal flow pattern performed superior energy efficiency, particularly for RB-STHX with the least irreversible energy loss and the most available work. Grounded on the energy-saving potential of RB-STHX, further numerical simulations on the shell-side thermo-hydraulic performance of RB-STHX are conducted. The nexus between geometrical parameters of RB-STHX and its thermal-hydraulic performance are studied. The thermal-hydraulic performance and energy efficiency discussed in this study support further design and application of longitudinal flow STHX to retain inherent superiorities with advanced performance. • Only 12% of the total pressure drop in the shell-side of RB-STHX is derived from the tube bundle section. • RB-STHX performs 173%∼223% higher EEC than LSHB-STHX with the least irreversible energy loss. • Rod baffle shell-and-tube heat exchanger shows the best comprehensive performance. • Numerical investigation of the heat transfer enhancement. • Factors: tube arrangement, rod shape, baffle arrangement, and baffle number. [ABSTRACT FROM AUTHOR]