Comparison of the Axial Fan and Synthetic Jet Cooling Systems

Choosing the right cooling device is crucial for the proper operation of electronic equipment. A comparison of the two different cooling devices is presented in this paper: one with a standard axial fan and the other with a synthetic jet actuator. Two distinct sets of operating conditions of the fan and two different loudspeakers for the synthetic jet actuator were used. The experimental setup consisted of a radial heat sink mounted onto a round electric heater and two cooling systems: one with the axial fan and the other with a synthetic jet actuator. From the thermal balance in the specified control volume, the heat sink’s thermal resistance. as well as the coefficient of performance, were determined. The highest difference between the thermal resistance of both cooling systems occurred at a low input power of P = 0.5 W. The heat sink cooled with a synthetic jet had the thermal resistance of R = 0.39 K/W, while the same heat sink cooled with a fan achieved R = 0.23 K/W. Thus, the fan cooling exhibited almost 70% better performance than synthetic jet cooling. For a higher input power of P = 7.0 W, the relative difference in the thermal resistance decreased to the value of 42%. For the input power of P = 7.0 W, the fan-cooled heat sink dissipated the thermal power of Q˙HS=487 W under the temperature difference between the heat sink base and ambient air equal to 60 K. For the same input power and temperature difference, the synthetic jet cooling of the same heat sink dissipated a thermal power of Q˙HS=339 W. Under natural convection, the heat sink dissipated the thermal power of Q˙HS=57 W. Thus, the heat transfer enhancement with fan cooling relative to natural convection was equal to 8.5, while the enhancement with synthetic jet cooling relative to natural convection was equal to 6.0. The modified coefficient of performance and the heat transfer rate of the heat sink per unit temperature difference and unit volume of the cooling device ε are presented. The axial fan performed better in terms of both parameters under consideration. The ε of the investigated device with a fan was around four times higher than in the case of the synthetic jet actuator and eight times higher than in the case of natural convection.