Experimental study on heat transfer characteristics of a heat sink with multiple-orifice synthetic jet

Abstract

Application of a synthetic jet is reasonably a novel approach for cooling of electronic components. The heat transfer enhancement using impinging multiple-orifice synthetic jet is investigated experimentally. A heat sink is mounted on the heat source and the resulting heat transfer characteristics are presented. The experiments are conducted for different configurations of multiple circular orifices. The input parameters such as excitation frequency, pitch circle radius (PCR) and axial distance from tip of the heat sink fin to orifice plate are considered in the study. The performance of the heat sink in terms of spatial-average heat transfer coefficient (havg) and thermal resistance is documented. While impinging on the heat sink, the maximum heat transfer coefficient obtained with multiple-orifice synthetic jet is 12% higher than a conventional single orifice synthetic jet and six times greater than the corresponding case with the bare heated surface. The PCR of the satellite orifices have a negligible effect on thermal resistance of the heat sink. The center orifice of the multiple-orifice arrangement plays a vital role in reducing thermal resistance of the heat sink. A synthetic jet-heat sink combination exhibits an identical thermal performance with that obtained with a conventional fan-heat sink mechanism. Thermal resistance of the heat sink shows decay with increase in input power to synthetic jet actuator. However, such behavior is not demonstrated by a fan. The minimum thermal resistance of the heat sink with multiple-orifice synthetic jet is found to be up to 10 times higher than the thermal resistance for natural convection. Empirical relations are developed from experimental data describing the variation in thermal resistance as a function of input power. Efficiency of synthetic jet with multiple-orifice arrangement is found to be marginally lower as compared to a standard commercial fan. However, multiple-orifice synthetic jet can emerge as an inexpensive cooling method in comparison with a fan. The results presented in this paper suggest that the synthetic jet is capable of replacing the fan in fan-heat sink mechanism employed for cooling of electronic devices.