Condensation in Microchannels

Abstract

Abstract : Design of meso-scale energy systems, either for power production or heating/cooling, will require understanding of the thermodynamics of the proposed system as well as knowledge of the heat transfer and fluid dynamic characteristics associated with flow in microchannels. These proposed thermal energy systems require the exchange of significant amounts of heat and most take advantage of the large heat transfer rates accompanying phase change. Evaporators and condensers for meso-scale energy systems will most likely be constructed of microchannels due to the microfabrication constraints that limit most structures to two-dimensional planar geometries. Thus, forced convection boiling and condensation in horizontal microchannels will provide the mechanisms for heat exchange. Unfortunately, little is known about these two processes in microchannels. No work on condensation in microchannels has yet to be reported. For single-phase and phase-change heat transfer processes, knowledge of the heat transfer rates and pressure drops in microchannels is vitally important for the future design of complete meso-scale energy systems. Thus, design tools, such as analytical and numerical models and experimental correlations, that account for microscale effects must be available to engineers as they consider complete system design. This report summarizes the first steps taken to assess convection heat transfer in horizontal microchannels.