Flooding in small-scale passages

Experimental flooding data are compiled that have been obtained by various authors in six recent investigations on reflux condensation as well as on adiabatic countercurrent gas-liquid flow in different vertical small-scale passages. The hydraulic diameter of the flow channels varies between 3 and 8.3 mm. The test sections consist either of a small diameter tube or of a corrugated plate or plate-fin arrangement. Air-water is used in the adiabatic experiments. For the reflux condensation experiments R134a, n-pentane/nitrogen and steam are used as the working fluids. It has been found that even in case of similar small hydraulic diameters the type of the flow channel and fluid properties have a strong effect on the flooding point. The experimental data are compared with values predicted by correlations that are often used in process industry to predict the flooding point in reflux condensers. Each set of experimental data can be fitted by a correlation but there is not yet a general correlation that reasonably predicts data for all geometries and all physical properties. (C) 2002 Elsevier Science Inc. All rights reserved.