Convective Flow of Nanofluid and Nanoencapsulated Phase Change Material Through Microchannel Heat Sink for Passive Cooling of Microelectronics

In this work, a microchannel heat sink (MCHS) of dimension 40 mm × 40 mm × 14 mm with a circular copper tube (ID 0.8 mm) is designed, mimicking microelectronic component. The MCHS is subjected to a constant temperature condition which is mitigated via convective flow of single-phase fluid and different nanofluids. The investigation focused upon the heat transfer characteristics of all the coolants and to elucidate the effect of non-spherical nanoparticles in nanofluid. Here, the fluid flow and heat transfer parameters of the MCHS are focused experimentally at a constant Reynolds number of 1170 (velocity 1.19 m/s). Four coolants were used to study the heat transfer characteristics of the MCHS which was subjected to constant surface temperature of 125 °C, namely de-ionized (DI) water (hereafter abbreviated as water), Water + 0.0005% (v/v) CuO, Water + 0.0005% (v/v) multi-wall carbon nanotube (MWCNT) and DI water + 0.0005% (v/v) wax-intercalated MWCNT (WICNT). The wax is the phase change material (PCM) in this context which was encapsulated within MWCNT via self-sustained diffusion. Carbon nanotubes had an aspect ratio of 200. During the experiment, the temperature of particular depth within the MCHS from the surface was monitored. The maximum allowable limit of that particular point, aka the part of the integrated circuit (IC), was fixed between 70 and 50 °C, while the lower one is considered safe, whereas the upper one is critical for IC. It was seen that over a long period of unsteady-state investigation, the effect of WICNT was more pronounced in reducing the time required to lower the temperature to the safe operating limit. The cooling time of MCHS is reduced by 11.54% and 20.77% using Water + 0.0005% (v/v) multi-wall carbon nanotube and wax-intercalated MWCNT, respectively, over water which explains that WICNT enhances the heat transfer which is beneficial to increase the total operation time or computation time at the same memory usage rate.