Transient wall temperature measurements of two-phase slug flow in a microchannel

A High frequency wall temperature measurement approach at the microscale is demonstrated. This experimental approach was implemented to study the transient effect of bubbles in a slug flow regime. Air stream was injected into liquid water flow in a 210 μm deep and 1.5 mm wide horizontal microchannel to form a slug flow regime (with bubble frequency of ~280 Hz) and the associated wall temperature variations were recorded using the embedded resistance temperature detectors (RTDs) inside the channel-on the heater area. Synchronized images of the two-phase flow were simultaneously recorded by a high speed camera, and the recorded footage was used to interpret the observed trends. Three different regions with different heat transfer characteristics were identified for each cycle of bubble/liquid-slug passage.