**3.2 Microscale heat transfer**

The study of fine scale heat transfer was done with various channel configurations. 3D flow and heat transfer were examined in microchannels [29]. Theoretical analysis for heat transfer in laminar flow between two parallel plates separated by a very small space in micron range was conducted. The momentum and energy equations are solved for the hydraulic and fully developed thermal flow in the microchannel [30]. This method was also used to simulate rarefied gas flow and heat transfer in microchannels in a particular Knudsen number range [31]. Water was used as the working fluid in microchannel of rectangular shaped heat sinks, and computational studies were carried out [32]; also, their thermal performance was optimized minus water [33]. Convective heat transfer of fully developed flow both thermally and hydrodynamically in a rectangular microchannel is investigated [34]. A simulation model of low-power microchannel thermal reactor was presented [35]. Fractal branching used for the cooling of electronic chips was investigated [36]. Slotted microchannels were studied analytically on the basis of conduction and convection [37]. The performance of thermal fluid in a small capillary was studied experimentally [38].
