This project is an investigation of heat transfer processes in very small channels with the goal of developing highly compact, high performance heat exchangers (heat transfer rates on the order of 105W/m2K, are feasible). Microfabrication techniques developed in the micro-electronic industry permit the fabrication of small size, high precision channels in silicon or other suitable materials. The proposed dimensions of the channels will range from a few microns to fractions of a millimeter in width and depth. The proposed lengths of the channel will be restricted to approximately 1-2 centimeters in the initial stages of the study. Large numbers of channels can be accommodated in extremely small volumes. Planar photolithographic technology provides a method for fabricating extremely complicated fins and extended surfaces suited to optimizing the heat transfer process. The proposed heat exchangers should be able to provide efficient heat transmission between two fluids or from a single fluid to the ambient. Other advantages of the proposed heat exchangers, aside from efficiency, are their very small mass, low inventory of working liquids, small supporting structures, low cost, and vibration-free character. This type of heat exchanger represents a class of thermal elements that have not been previously studied in the dimensional regime being considered here, suggesting that a fundamental inquiry into heat exchange in this mesoscale regime is desirable from a purely scientific viewpoint. The proposed research is interdisciplinary in nature as it addresses simultaneously heat transfer, materials, sensor elements for monitoring the heat transfer processes, and microfabrication issues.
