Phase-Change Materials for Transient Cooling of a Heater Array in a High Aspect Ratio Channel in the Presence of Mean Flow

This paper explores the effectiveness of phase-change material (PCM) for cooling of a discrete array of heat sources in low form factor channels in the presence of mean flow. The alkane n-Eicosane was chosen as the material for this work. A parametric experimental study was conducted on an array of heaters that simulate the heat dissipating components in a low form factor portable electronic device. The effects of the clearance at the top of the devices, thickness/volume of the PCM, as well as the mean flow velocity were studied under uniform and nonuniform patterns. It was found that the cooling effect of the PCM in the time frame considered reduces with increase in the mean flow Reynolds number due to its delayed melting. Thus, the cooling effect in a natural convection environment is higher compared to one with mean flow. The thickness of the PCM increases its effectiveness for a certain threshold value beyond which we reach a region of diminishing returns. The results are presented as design curves in terms of nondimensional parameters. The use of thin spreader inside the PCM pack improves its cooling effectiveness due to better lateral spreading. However, the cooling time for the n-Eicosane is not negligible and can be a potential challenge under repeated cyclic loads.