Most active electronics cooling modules are cooled by forced flow driven by a rotating fan. Recently, a piezoelectrically-driven plate driven in a flapping mode has been proposed as a replacement. This fan gives both flow movement and agitation. To raise effectiveness, reduce size, and otherwise meet the demands of future electronics cooling devices, better methods are continually being sought. The present research explores the possibility of using a piezoelectric stack to oscillate blades in a translational mode to agitate the flow in a heat sink channel, thus enhancing heat transfer on the channel walls. The aim is to disrupt the thermal boundary layer while introducing strong pressure gradients and channel vorticity. In the present cooling module design, this agitation is used in conjunction with a rotating fan which provides through-flow. The dimensions of actual heat sink channels are small, making detailed heat transfer measurements difficult and inaccurate. Only global averages can be measured. Thus, a Large Scale Mock-Up (LSMU) heat sink channel was created to document agitation enhancement of heat transfer. The LSMU is a single channel arrangement which simulates one channel of a 26-channel heat sink being developed. Results from it complement actual-scale experiments in single and multiple channels. With the LSMU, the effect of frequency and amplitude of agitation on heat transfer along different sections of the channel are assessed. At lower velocities of agitation, the heat transfer coefficient is mainly governed by the velocity of agitation (frequency times amplitude) irrespective of the value of frequency or amplitude. However, at higher velocities, amplitude seems to be somewhat more important than frequency in enhancing heat transfer. The results of the present study show strong effectiveness of plate agitators.

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