*3.2.1 Working fluids*

The right selection of coolant fluid is a critical factor in removing the generated heat and according to literature, the air-cooling systems have received more attention in the past. However, with advances in electronic technology and the miniaturization of devices, conventional (air) cooling systems cannot remove more than 100 W/cm<sup>2</sup> generated heat by electronic devices. Therefore, liquid cooling such as water due to high specific heat capacity, high thermal conductivity, and more availability is considered more than ever [85]. Nowadays, with advances in nanotechnology, researchers classified working fluids into two categories, (1) nanofluids and (2) phase change material (PCM) slurries. They reported that improved thermophysical properties and higher thermal conductivity could be the advantages of these liquid coolants [86].
