The optimal design for multi-stream plate-fin heat exchanger with differential model was investigated. An effective method for the passage arrangement was presented

together with the corresponding calculation program. With this program

many conditions with different initial lengths and slice thicknesses were calculated. From the calculation results

the initial length almost had no effect on the final divergent length

but the slice thickness had great influence on the final result. A numerical example shows the feasibility and effectiveness of the proposed method.