Comparison of gas hold-up in impeller agitated water and high viscosity liquids

Gas hold-up in water and Castor oil, which were agitated separately by four disc type impellers, is compared on the basis of equal specific power diss ipation (P-G/V). It is noted that unlike in water, gas hold-up in Castor oi l is time dependent, and also strongly influenced by impeller design. Furth er, the gas hold-up values in Castor oil are generally higher than those ob served in water, and unlike in water, decrease with increasing (P-G/V). The se observations, which appear anomalous in the context of some earlier publ ications, are explained by considering the hold-up in Castor oil in terms o f contributions from large and tiny bubbles.