微通道内表面活性剂溶液的流动沸腾特性

The flow boiling characteristics of aqueous solutions of surfactant Sodium Dodecyl Sulfate (SDS) with solute concentration of 0—800 mg/kg were investigated in flat and tree-shaped microchannels of 0.8 mm hydraulic diameter. The results showed that SDS significantly enhanced the heat transfer effect of both structures, the maximum heat transfer coefficients of 1.5×10⁵ W/(m²·K) and 6×10⁴ W/(m²·K) can be achieved in flat and tree-shaped microchannels, and the aqueous solutions of 400 mg/kg and 200 mg/kg increased the maximum heat transfer coefficients by more than 40%, respectively. As SDS significantly increased the number of nucleation points, many bubbles agglomerated and moved as a whole, and many activated bubbles interfered with the main flow movement during the process of fluid flow and friction with the wall, which enhanced the convective heat transfer. For the flat microchannel, the flow was fully developed, and local dry spots were easily observed in the unstable boiling phase, and more homogeneous mixing of the gas-liquid phase occurred in the tree-shaped microchannel, resulting in smaller fluctuation of pressure drop. The pressure drop in the single-phase flow was significantly reduced by SDS, and the effect on the pressure drop in the boiling phase decreased as the volume flow rate increased, the change in pressure drop at a volume flow rate of 150 mL/min was less than 6%.