Abstract:The numerical simulation was performed to study the flow boiling heat transfer characteristics in the sinusoidalwavy microchannel by volume of fluid (VOF) model and userdefined functions(UDF). The variation of bubbles behaviors, the effect of flow boiling heat transfer and the reliability in the horizontal straight microchannel were compared with those in the wavy microchannel, and the influences of wave structure on flow boiling heat transfer characteristics were analyzed. The comparisons show that the wave structure can promote bubbles detachment with maintained nucleate boiling and avoid local dryness of heating wall to ensure the reliability of vaporliquid twophase flow. The flow boiling heat transfer in the microchannel can be enhanced by increasing the wave amplitude or decreasing the pitch of waves. Increasing the wave amplitude by 4 times from 20 μm to 80 μm can increase the boiling heat transfer coefficient by 26.5%, and the pressure drop of the twophase flow is increased by 24.0% in the meantime. While decreasing the pitch of waves by 4 times from 2.0 mm to 0.5 mm can increase the boiling heat transfer coefficient by 16.0%, and the pressure drop is increased about 40.0%. The wave amplitude has great influence on the flow boiling heat transfer coefficient, while the pitch of waves has great influence on the flow resistance. However, too big wave amplitude or too small pitch can result in heat transfer deterioration, which is not good for stable and reliable heat transfer in microchannel.