Geometry of plate heat exchangers (PHE) is characterized by a complex net of narrow channels. It enhances turbulence and results in better heat transfer performance. Theoretically, larger number of channels (plates) should proportionally increase the PHE heat power capacity. In practice a nonuniform massflow distribution in consecutive flow channels can significantly deteriorate the overall heat exchange performance. The flow maldistribution is one of the most commonly reported exploitation problems and is present in PHE with and without phase-change flows. The presented paper investigates numerically a flow pattern in PHE with evaporation of R410A refrigerant. Various sizes of PHE are considered. The paper introduces a robust methodology to transform the complicated geometry of a real 3D PHE to its 2D representation. It results in orders of magnitude faster calculations and allows for fast evaluation of different geometrical changes of PHE and their effect on flow maldistribution.