Two dimensional model for multistream plate fin heat exchangers

•2-D numerical model is presented for multistream plate fin heat exchangers (PFHE).•Model takes care of axial heat conduction, property variations and heat in-leaks.•Based on present model, a numerical tool is developed for rating of PFHE.•Numerical model is validated against output from commercially available software.•Results are discussed for sample heat exchangers used in helium cryogenic systems. A model based on finite volume analysis is presented here for multistream plate fin heat exchangers for cryogenic applications. The heat exchanger core is discretised in both the axial and transverse directions. The model accounts for effects of secondary parameters like axial heat conduction through the heat exchanger metal matrix, parasitic heat in-leak from surroundings, and effects of variable fluid properties/metal matrix conductivity. Since the fins are discretised in the transverse direction, the use of a fin efficiency is eliminated and the effects of transverse heat conduction/stacking pattern can be taken care of. The model is validated against results obtained using commercially available software and a good agreement is observed. Results from the developed code are discussed for sample heat exchangers.