关键词: 传热, 多流股换热器, 状态空间超级结构, 模型, 优化设计, 系统工程

Abstract: Multistream heat exchanger (MHEX) has attracted attention in the process intensification field with its compact structure, high efficiency and low heat loss. However, the potential advantages of its process and equipment are still worth discussing. An improved State-space superstructure based on MHEXs process operator (PO) was proposed to convert the network synthesis into a super-exchanger design. Hierarchy matching MHEXs PO was constructed, and the strict heat transfer calculation among multiple streams was implemented through temperature coordinated effect between adjacent streams. Arbitrary splitting and mixing of any stream was achieved by corresponding mixers and splitters in distribution network (DN). The objective function was ameliorated by taking heat loss into consideration. Through introducing the cost of heat loss and thermal insulation material, the external surface envelope advantage of MHEX was presented clearly owing to coverage between adjacent heat-transfer surfaces. Then, a corresponding nonlinear programming (NLP) mathematical model was formulated for generating the optimal design of MHEXs network while synthesizing the utilities, equipment investment, heat loss and thermal insulation material simultaneously. At last, four case studies were performed to verify the feasibility and superiority of the methodology.

Key words: heat transfer, multistream exchanger, state-space superstructure, model, optimal design, systems engineering