Water accumulation and countercurrent flow limitation in the upper plenum with a multi-hole plate

An experimental investigation was conducted to investigate the onsets of water accumulation and countercurrent flow limitation (CCFL) through perforated plates inside a vertical tank. 4-hole and 12-hole plates with the diameter of plate holes of 5 cm are used and the thicknesses of each plate are 1 cm and 4 cm. The effects of the number of holes, plate thicknesses, water injection method and the location of air vent line on the onset of water accumulation or on the onset of CCFL were examined. In addition, the influence of the location of air vent line on water level distributions was investigated. Experimental results show that the onset of water accumulation is promoted as the number of holes decreases and the water injection lines increase, while the plate thickness and the location of air vent line have a negligible effect on the onset of water accumulation. The location pf air vent line in the upper plenum does not affect the water level distribution on the UCSP and for a given water flow rate, the onset of CCFL occurs at the nearly same air flow rate regardless of the plate thicknesses of 1 cm and 4 cm. The present experimental results for the onsets of water accumulation and CCFL are compared with existing correlations and data. (author)