并联竖直上升通道内二氧化碳流动不稳定性实验研究

Due to its compactness, high efficiency and flexibility, the potential applications of advanced supercritical carbon dioxide (S-CO₂) Brayton cycle in Generation III of Solar-thermal systems and Generation IV nuclear reactors are fantastic. The flow instability in the Brayton cycle system threatens the safe operation of the unit. To study the flow instability of CO₂ in parallel vertical upward channels, an experimental system is established, and the effect of operational parameters on the flow instability is obtained. A prediction model on CO₂ flow instability is established by introducing a dimensionless throttling coefficient. The predicted value is in good agreement with the experimental value (+20%). It is found that increasing the system pressure and the mass flow, and reducing the subcooling (∆T_sub-5~20 ℃) can increase the flow stability between parallel tubes. With the increase of outlet throttling, the flow stability between parallel tubes decreases, and the stability boundary of heat load gradually decreases.