For many years evaporative micro-channel systems have been considered for the cooling of high power electronics due to large surface area per unit volume and efficient heat transfer. However, in applications, evaporative micro-channels using water encountered severe flow instabilities. This is the reason why a growing bubble is severely squeezed in the narrow channel and expands towards both upstream and downstream simultaneously.;The importance of the Bond number was revealed to describe physics in a micro-channel. Using the Bond number, improved micro-channel correlations of pressure drop and heat transfer were first established. To assist the general design of complex micro-channel systems, a network computational scheme was developed based on accurate micro-channel correlations. Furthermore, the theories of the channel as well as system instabilities were established. Both the general correlation of two-phase pressure drop and the channel and system instability criteria of evaporative micro-channels have been experimentally validated satisfactorily.;Various designs to reduce both channel and system instabilities were adopted based on the guidance of a theoretical model. To reduce channel instability, installation of an inlet orifice at the upstream, or making the micro-channel expand at the downstream were found to be effective. On the other hand, to reduce the system instability, it was found that the applying of cross-cutting grooves on the parallel straight micro-channels or the utilization of radially expanding micro-channels is effective. Experiments were conducted on evaporative micro-channel systems of water and the advantages of these new designs were validated. Based on present research, accurate and stable thermal-fluids designs of evaporative micro-channel systems could be accomplished.
展开▼
