A technique for quantitative temperature visualization of single-phase liquid flows in silicon (Si) microchannels using infrared thermography is presented. This technique offers a new way to measure, non-intrusively, local variations in wall temperature, or fluid temperature at the fluid-wall interface, in a microchannel fabricated entirely of silicon. The experimental setup and measurement procedure required to obtain a high desired signal-to-noise ratio is elaborated. A single 13-mm long and 50 μm wide by 135 μm deep Si microchannel is used in this study. Experiments were performed with a constant electrical heat input to the heat sink surface for four fluid flow rates between 0.6 g/min and 1.2 g/min, corresponding to a Reynolds number range from 200 to 300. Temperature profiles of water in contact with the visualized wall of the microchannel indicate a monotonically increasing trend from the channel inlet for all cases, which is expected of a hydrodynamically and thermally developing flow. The estimated experimental fully developed Nusselt number matches the solution provided in literature for laminar flows. Measurements of the heat sink surface temperature are performed to determine axial variation in heat flux to the visualized channel wall. Results indicate that axial non-uniformity can be significant for the larger Peclet number flows.

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