This work presents a steady state model based on the multi-zone method, developed to simulate Brazed Plate Heat Exchagers working as condensers and evaporators, employing empirical correlations in order to determine heat transfer coeficients and friction factors. Given calculation inputs are refrigerant temperatures and pressures at condenser and evaporator inlet, super-heating and sub-cooling degrees, heat transfer fluids inlet conditions, as well as heat exchangers specification. Simulation outputs are refrigerant conditions at heat exchangers outlet, heat transfer fluids temperature at outlet, heat rate and thermal exchange area. In general terms, the model outputs have good convergence to experimental data, Payne et al. Exceptions are the thermal exchange area to condenser and evaporator, which do not agree to experimental values. Due to that model validation becames infeasable, although, it can be freely used to first estimations.