Critical heat flux under flow oscillation of water at low-pressure, low-flow conditions Original Research Article

In this work, the effect of flow oscillations on critical heat flux (CHF) is investigated for water flow in vertical round tubes at low-pressure, low-flow (LPLF) conditions. An experimental study has been conducted to investigate the difference in CHF between forced and natural circulations, and between stable and oscillating flow conditions with three vertical round tube test sections (5.0 mm ID×0.6 m in length, 6.6 mm ID×0.5 m in length, and 9.8 mm ID×0.6 m in length) for mass fluxes below 400 kg m−2 s−1 under near atmospheric pressure. It is found that flow oscillations can drastically reduce the CHF, in particular for natural-circulation conditions. In addition to the experiments, CHF correction factors for flow oscillation effects are developed for forced and natural circulations, respectively, based on the experimental data of the present work and others.