Prediction Model for the Flow Boiling Instability of Cryogenic Fluids
A dynamic model for the flow boiling instability of liquid nitrogen is established to investigate the flow boiling instability of cryogenic fluids in channels.Based on the nonlinear stability theory,the flow boiling stability of liquid nitrogen is analyzed,and the flow instability criterion is obtained.According to the instability criterion and the flow boiling characteristics of liquid nitrogen,a new model consisting of dimensionless parameters is established to predict the occurrence of unstable flow.Compared with the experimental data reported in the literature,the proposed model successfully predicts the flow stability of 15 out of 17 experimental cases.Obviously,the presided results by the established model agree well with the experimental data with an accuracy of 88.2%,indicating that the model can be used to predict the boiling instability of liquid nitrogen.The analysis results reveal that,the acceleration pressure drop plays an importance role during the boiling instability of liquid nitrogen.For channels with the same length-diameter ratio,the stable/unstable flow boundaries almost coincide.Besides,increasing the saturation pressure can help suppress the flow instability.
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