Two-Phase Boiling Flow in Microchannels: Instabilities Issues and Flow Regime Mapping

The design, fabrication, and evaluation of forced convection boiling two-phase flow, micro scale heat exchanger are described. The micro heat exchanger consist of a heater, and 16 mm long multiple parallel triangular micro channels, with hydraulic diameter ranging from 50 μm to 200 μm. The system allowed simultaneously visualizing the flow regime, to measure the resistor temperature distribution, the pressure drop, and input power levels. Experiments were conducted using water with mass flow rate of 1–10 ^g/_min and heat fluxes ranging from 10–60 W/cm² in order to better understand the flow mechanism associated with micro scale forced convection boiling two-phase flow. The pressure drop, temperature, fluctuation and flow regimes map were obtained. The results are consistent with newly reported studies and show that flow fluctuation at that scale is exaggerated with respect to conventional size channels. A unique flow regime was observed and was named “rapid bubble growth”.