In the present work, heat transfer and fluid flow in square pin fin heat sinks are analyzed through experimental methods. For an experimental analysis, 20 aluminum square pin fin heat sinks having a 101.43 mm × 101.43 mm base size are tested with inlet velocity ranging from 1 m/s to 5 m/s. In each test, the heat sink is heated uniformly at the bottom. Effects of the ratio of spacing between the adjacent fins to the fin pitch on the pressure drop across the heat sink and the base temperature distributions are investigated. From the experimental study, effects of the height of the heat sink and the ratio of spacing between the adjacent fins to the fin pitch on the pressure drop across the heat sink and the thermal resistance of the heat sink are investigated. A compact model is suggested using a porous medium approach for predicting the thermal performance of an in-line square pin fin heat sink In this model, correlations for the variables such as K, $C_E$ and $K_{eff}$ which represent the thermal and hydrodynamic characteristics of the heat sinks are determined.
