Heat transfer mechanism of cross-type multi-stream plate-fin heat exchanger (MPFHE) was analyzed and the mathematical model by finite volume method was established based on the research of parallel-counter type MPFHE

and then the distance between fins was separated with cell size by reasonable assumption

expanding the application of former mathematical model. Besides

discussion about choice of cell size was conducted for the airborne cross-type three-stream plate-fin heat exchanger; while the analysis of transverse heat transfer of flow within a cell on the same channel was applied to demonstrate the possibility of ignoring the transverse heat transfer in this direction

so as to increase calculation efficiency under the constant computational accuracy; moreover

experiment of different inlet flow rates or temperatures was carried out to verify the veracity of numerical method. The calculation uncertainty is less than 7.9% compared with the test record

thus proving the rationality of numerical method.