The Adiabatic And Boiling Gas-liquid Flow Regime And Pressure Drop In A Serpentine Microchannel

Serpentine microchannels have an extensive application potential and increasing research value due to their compact structure and high heat transfer performance.Existing studies on flow regimes in serpentine channels mostly used conventional size channels and focused on curved sections.The analysis of flow regimes in serpentine microchannels cannot provide a complete theoretical explanation for practical applications.In the current study,flow regimes,flow pattern transition and two-phase pressure drop in a serpentine microchannel with a hydraulic diameter of 0.65 mm and curvature radii of 1.2 mm,1.8 mm and 2.4 mm are investigated experimentally.Experimental data is compared with existing flow regime maps and empirical pressure drop correlations,however,with poor agreement.The centrifugal force plays a key role in the two-phase flow pattern transition process in serpentine microchannels.The centrifugal force of bend sections causes multiple flow patterns transferring downstream in serpentine microchannels.The transition distance increases with increasing quality.Higher centrifugal force for the same mass flow rate leads transition zone of intermittent flow to annular flow in the flow regime map covering larger range of qualities.Surface tension and shear force at the gas-liquid interface tends to eliminate the effect of centrifugal forces spreading downstream.The two-phase flow patterns in a large serpentine heat exchanger are numerically simulated.The flow pattern transition processes are compared with that in the serpentine microchannel.Gravity and centrifugal force are the main forces dominating the flow pattern transition process in the large serpentine channel.