A comprehensive review of recent advancements and developments in heat exchanger network synthesis techniques

The rapid development of computational technology and the increasing energy demand have improved heat exchanger network(HEN)synthesis.The HEN synthesis involves several optimizations of matches,distributions of heat loads,and stream splitting of heat units.Thus,obtaining good results at high efficiency has been the main standard for evaluating the techniques in the research area of HEN synthesis.This paper first summarizes and analyzes the main contributions of the existing HEN synthesis techniques.To compare related data quantitively,information on ten typical cases is presented in this paper.Furthermore,recently improved solutions for commonly encountered existing literature cases demonstrate the evolution and competition trends in the field of HEN synthesis.The comparison data presented in this paper not only provide a useful reference for future research but also present the optimization directions.Based on the findings of this study,it is noted that there is still a large room for improvement,and current approaches are incapable of dealing with all HEN cases.Moreover,it is still difficult to escape a local optimum and overcome structural constraints when seeking the global optimum.As a follow-up to the current work,the parallel computing mode and adaptively coordinating the ratio of global and local searching abilities are major development trends for future investigation.

Self-assembly of Blended PS-b-P2VP Block Copolymers

Directed Self-Assembly(DSA)of block copolymers(BCPs)is a promising technique for sub-10 nm nanofabrication,which is highly compatible with conventional lithography.DSA relies on the microphase separation of block copolymers to form nanostructures of different morphologies.The pitch size of the obtained nanostructure depends largely on the intrinsic properties of BCPs and is usually fixed when BCPs are produced.One effective way of tuning the pitch size of BCPs is by blending BCPs of different molecular weight.In this paper,we have demonstrated the pitch tuning capability by blending the triblock poly(2-vinyl pyridine-bpolystyrene-b-poly 2-vinyl)pyridine(P2VP-b-PS-b-P2VP)with another triblock P2VP-b-PS-b-P2VP or diblock copolymer(PS-b-P2VP)at various volume ratios by solvent annealing.The nanopatterns of blended BCPs after sequential infiltration synthesis(SIS)and plasma etching process,were characterized by scanning electron microscopy.It’s observed that the blended BCPs can form highly ordered lamellar nanostructures of different pitch sizes at different blending ratios.The method of blending BCPs of varying molecular weights greatly extends the functionality of existing BCPs,with the capability of fine-tuning nanopatterning pitch at nanometer resolution.

Facile Synthesis of N-Sulfonylcyclothioureas in Water

A sequential one-pot synthesis of N-sulfonylcyclothioureas from N-monosulfonyl diamines, CS2 and chloroace- tic acid at room temperature in water is described. In the absence of highly toxic thiophosgene and organic solvents, this method is environmentally benign. Simple reaction conditions, easy purification of the products, good yields and thioglycolic acid as the useful byproduct are also important attributes of this methodology. The plausible mechanism including tandem reactions is proposed.