Passage arrangement design for multi-stream plate-fin heat exchanger under multiple operating conditions

As the development of heat exchangers from two streams and single operating condition to multi-stream and multiple operating conditions, passage arrangement becomes a key problem for heat exchanger design. In this paper, a new passage arrangement design method for multiple operating conditions is developed for multi-stream plate-fin heat exchangers. The integral-mean temperature differences method (IMTD) is expanded from three-stream to multi-stream plate-fin heat exchanger, and then the correlation model among heat transfer rate, passage arrangement and fin design parameters is constructed based on IMTD. Upon the maximum heat transfer rate under each operating condition, the passage arrangement coefficient of each condition and the passage arrangement design space of multiple operating conditions are calculated. As passage arrangements being design variables, the passage arrangement under multiple operating conditions is designed using hybrid particle swarm algorithm. Effectiveness of the passage arrangement design approach is verified through optimization design of a 24 streams heat exchanger, and the results show that the heat exchanger obtained by the proposed algorithm exhibit comfort heat transfer rates under multiple operating conditions. Finally, the method is used to design the passage arrangement of main heat exchanger in 80,000 Nm3 air separation unit.