Characterization of Heat Sink Flow Bypass in Plate Fin Heat Sinks

Experimental testing has been performed on two plate fin heat sinks in order to examine flow bypass phenomenon. The present study examines pressure drop and thermal resistance as well as flow velocities within the heat sinks. Tests are performed for bypass channel/fin height ratios of 0.25, 0.5, 0.75 and 1 with approach velocities from 2 to 8 m/s. By examining flow behavior within the heat sinks and the bypass channel, a model for predicting flow bypass is presented that incorporates only the significant pressure drop mechanisms that affect the flow path. This model allows for a simple prediction of flow bypass for plate fin heat sinks based solely on geometry. For all of the heat sinks tested the agreement between model and experimental data is ∓8%.