Drop formation from flat tip nozzles in liquid-liquid system

Correct estimation of interfacial area for heat or mass transfer is of prim ary importance in liquid-liquid contacting systems. But the existing correl ations for the estimation of the sizes of drops formed by nozzles at low fl ow rate are based on experimental data using nozzles with tips filed down t o sharp or bevel or a very thin thickness, and the inside diameters are use d as the characteristic diameters. These correlations would underestimate t he size of aqueous drops formed from flat tip metallic nozzles considerably , because as the drops are detached from the nozzle tips, the liquid-liquid -solid contact lines are not just located at the inside edge of the opening . In this work, the formation of drops of aqueous., from flat tip stainless steel nozzles of various dimensions into solutions of NaCl and AlCl3 from flat tip stainless steel nozzles of various dimensions into a pool of n-dod ecane was studied experimentally. It was found that the deviation of the es timated drop sizes by the correlation of Kagan et al. differs only slightly from that of Scheele and Meister. The deviations of the estimated values a re not affected by the dissolved salts within the range of concentrations s tudied. And most importantly, the mean deviation of the correlation of Sche ele and Meister can be reduced to a few percents if different characteristi c diameters, d(n), are used in the computation: d(n)=O.D. for the cases of relatively large nozzles of about 1 cm O.D. with wall thickness between 0.0 98 and 0.170cm; d(n)=1.15xO.D. for small thin wall nozzles of O.D. < 0.35cm with wall thickness <0.036cm. (C) 2001 Elsevier Science Ltd.