A Novel Asymmetric Check Microvalve for Suppressing Flow Boiling Instability in Microchannels

Flow boiling in microchannels has attracted wide attention due to its excellent heat transfer capability, but flow boiling instability is a huge challenge limiting its application. Instability can lead to a series of problems, such as uneven flow distribution, temperature and pressure drop oscillations. This work proposes a novel asymmetric check microvalve (ACMV) structure, exhibiting high ratio of resistance between the reverse and forward flow. The results show the reverse pressure drop of the ACMV structure is 2.06 times that of the forward pressure drop, and the forward flow resistance of the ACMV structure is 16% smaller than that of the conventional inlet restrictor. In addition, bubble dynamics of an isolated bubble in the generated channel under dual outlet condition was numerically investigated. It is found that the bubble grows symmetrically in the rectangular channel upstream and downstream. The distance of bubble movement downstream in the microchannel with ACMV is three times that of the microchannel with inlet restrictor. The microchannel with ACMV can suppress the backflow of isolated bubble better than microchannel with inlet restrictor. Moreover, the growth of the bubble downstream extends the effective evaporation domain, which contributes to the enhanced bubble growth rate. The ACMV is expected to be a potential replacement for the conventional inlet restrictor, which provides a novel and efficient solution for future heat dissipation from high power devices.