Dynamic instabilities of flow boiling in micro-channels: A review

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As the heat dissipation requirements of micro-electronic component systems have increased by magnitude, scientists and engineers have shifted their focus from traditional single-phase heat transfer systems to systems that utilize phase change heat transfer. This review aims to review the literatures addressing gas-liquid two-phase flow boiling dynamic instabilities in micro-channels in theoretical and experimental aspects. Various methods to suppress instabilities were classified and summarized from the perspective of bubble dynamics. In theoretical studies, combined with bubble dynamics, the mechanism and criteria of dynamic instability are revealed. And some lumped models and models of pressure drop frequency and amplitude have been established, which are mainly for single or parallel straight micro-channels. Further theoretical studies on complex micro-channels and the suppression strategy of instabilities may be needed. In experimental studies, there is much experimental evidence for three primary dynamic instabilities called Density Wave Oscillations, Parallel Channel Instability, and Pressure Drop Oscillations in micro-channels. The effects of flow boiling instabilities on flow pattern, heat transfer coefficient, critical heat flux, and fluctuations in wall temperature and pressure were discussed. However, more work needs to be put into the identification of instabilities under different operating conditions in different micro-channel systems to avoid and suppress instability. At present, researchers tend to combine a variety of methods to suppress the occurrence of micro-channel instability.