Gas hold-up, the amount of gas retained in the column at a given time, is one of the key variables that determine how intense the contact between gas and liquid is. It can reach a stationary value or can vary periodically. Together with size and form factors, the actual throughputs, feed distribution, and whether or not there is a packing or additional mixing, hold-up values determine the extent of the interfacial area, as well as the flow regimes; these in turn determine transport efficiency (heat & mass).
Gas hold-up, the amount of gas retained in the column at a given time, is one of the key variables that determine how intense the contact between gas and liquid is. It can reach a stationary value or can vary periodically. Together with size and form factors, the actual throughputs, feed distribution, and whether or not there is a packing or additional mixing, hold-up values determine the extent of the interfacial area, as well as the flow regimes; these in turn determine transport efficiency (heat & mass).