Air cooled heat sinks integrated with synthetic jets

This paper discusses the development of active air-cooled heat sinks using synthetic jet ejector arrays for high power dissipation electronics. The heat sinks typically consist of a plate fin heat sink augmented with a synthetic jet module such that each fin is straddled by a pair of synthetic jets thereby creating a jet ejector that entrains cool ambient air upstream of the heat sink and discharges it into the channels between the fins. The present work characterizes three configurations of active integrated heat sinks designed for around 100 W power dissipation levels with respect to power dissipation, thermal effectiveness and package weight and volume. The flexibility of adapting synthetic jets for different heat sink designs is demonstrated by changing the relative orientation of the entrained and discharged air flow for the different cooling module designs, indicating the potential for controlling and utilizing limited air flow in spatially constrained environments. The performance of the heat sinks is assessed using an Intel thermal die instrumented with thermocouples. Using air temperature and velocity measurements the thermal effectiveness of heat sinks is compared with an off-the-shelf heat-sink-fan combination as well as with a steady flow past the heat sink. The jets generate an airflow in the range of 3-5 CFM, resulting in ∼25 Watts/CFM for each device with a thermal effectiveness as high as 60-70%.