$22.$ Consider a mini channel with a gas$-$liquid flow where the mixture's mass flow rate is $0\mathrm{.}06$ kg$/$s$,$ with a $75\%-25\%$ mass split between the gas and liquid phases, respectively. Calculate the gas and liquid phase velocities, then estimate the void fraction.

$23.$ A three$-$phase flow in a column involves gas, solid, and liquid phases with volume fractions of $0\mathrm{.}2,0\mathrm{.}3,$ and $0\mathrm{.}5,$ respectively. Given that the column diameter is $0\mathrm{.}3$ m$,$ calculate the volumetric flow rate of each phase.

$24.$ In an agitated vessel handling a gas$-$solid$-$liquid mixture, with a gas holdup of $0\mathrm{.}05$ and solid holdup of $0\mathrm{.}1,$ calculate the average diameter of gas bubbles and solid particles assuming they have the same size.

$25.$ A packed bed with a cross$-$sectional area of $0\mathrm{.}5$ m operates under a liquid superficial velocity of $0\mathrm{.}02$ m$/$s and a solid particle size of $3$ mm$.$ Find the bed porosity and then estimate the pressure drop per meter of bed height.