The effect of non-condensable gas on dynamic pressure induced by steam-water direct contact condensation

An experimental study was carried out to investigate the effect of non-condensable gas on dynamic pressure induced by steam-water direct condensation. Experiments were performed in a pool temperature range of 30-90 degrees C, a steam mass flux of 180 similar to 460 kg/m(2)-s, and an air fraction of 0 similar to 5%. The Condensation regime investigated in this study covers both the stable condensation (SC) and the condensation oscillation (CO) regime. All experimental data on dynamic pressure measured at the quench tank wall were evaluated in terms of both the pressure amplitude expressed by the R.M.S. value and its principal frequency defined as the peak frequency of the power spectrum. The principal frequency tends to decrease with an increase of the mass fraction of non-condensable gas. In the CO regime, the pressure amplitude tends to increase at first, then it decreases as the mass fraction of non-condensable gas becomes larger than 1 similar to 2 % until the mean temperature of the subcooled water pool reaches 70 degrees C. After that threshold pool temperature, the amplitude decreases slowly with pool temperature, and the peak dynamic pressure amplitude is observed when the mass fraction of non-condensable gas is 1 similar to 2%.