Boiling and Condensation in Microchannels

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With the present trend towards miniaturisation of devices and development of microscale processes, there has arisen the need for microscale heat transfer equipment. For instance, in microelectronic processors, heat transfer is becoming the limiting factor in relation to increasing performance. Convective heat transfer with phase change offers significant performance improvements over single phase cooling systems. However, in microscale channels the mechanisms controlling the phase change and flow distribution differ from those at the macroscale. This project comprises an experimental study to solve some of the problems associated with phase change in microchannels and also the numerical modelling of boiling/condensation theory to both aid in design of experiments and develop design procedures for heat exchange processes based on two phase flow in microchannels.Development of novel experimental techniques (eg microsensor for heat flux and temperature measurement, fluid diode) will enable characterisation of local parameters in both boiling and condensation and active control of the boiling process.State-of-the-art numerical techniques will supplement the experimental investigation, enabling results to be applied to other systems. This combination of experimentation using innovative microsensors and control systems, developed using advanced microfabrication facilities, with numerical modelling offers a unique opportunity for the development of design procedures for such microscale heat transfer systems.