In this study, a correlation for predicting the thermal performance of PCHEs which are subject to counterflow, parallel flow, and crossflow condition, is presented. The analytic expressions for conduction and convection thermal resistances and resulting equation for predicting the overall heat transfer coefficient are derived based on 3D numerical analysis. The convection thermal resistances of the PCHEs are estimated based on the pre-existing correlation for the combined entry length flow condition. Based on the equation for the overall heat transfer coefficient, the correlation for effectiveness of the PCHE is developed. The developed correlation is shown to predict the experimental data well, and can be widely utilized for designing and analyzing the thermal performance of PCHEs which is a key component in future compact energy systems.