$13.$ Which factor does not affect the performance of a fluidized bed reactor?

A$.$ Particle size

B$.$ Fluid velocity

C$.$ Reactor diameter

D$.$ Ambient temperature

$14.$ In pneumatic conveying, the solid loading ratio is defined as:

A$.$ The velocity of solids to the velocity of air

B$.$ The mass flow rate of solids to the mass flow rate of air

C$.$ The density of solids to the density of air

D$.$ The pressure of air to the pressure of solids

$15.$ The modification of the drift flux model for liquid$-$liquid and gas$-$liquid flows in mini channels primarily considers:

A$.$ The effect of channel size on flow dynamics

B$.$ The impact of temperature on fluid properties

C$.$ The influence of solid particles

D$.$ The viscosity of the liquid phase

$16.$ What is the primary challenge in modeling three$-$phase flows?

A$.$ Simplifying the equations of motion

B$.$ Ignoring the effects of gravity

C$.$ Accounting for the interactions between all three phases

D$.$ Determining the single$-$phase flow properties