Introduction to Chemical Engineering-II

A: The trap sits at the order of 10^2 Pa/m. Plugging into the viscous Ergun term gives ΔP/L = 150(1−ε)^2 μ v / (ε^3 dp^2). Using ε=0.4 and dp=0.006 m lands near 90 Pa/m. Many engineers jump to inertial dominance or mix density into the viscous term.

A: The key threshold is the simultaneous ΔP rise and temperature noise. Tube-side fouling increases hydraulic resistance and destabilizes heat transfer. Air binding doesn't raise tube ΔP, and valve stiction wouldn't explain the steady pressure increase.

A: The hard part is volume flow. 25 kmol/h at 373 K is roughly 0.19 m³/s. At 0.7 m/s allowable velocity, area is ~0.27 m², giving a diameter near 0.5 m. Oversizing usually comes from mixing liquid properties into vapor sizing.

A: The boundary here is laminar versus transitional. Re = ρvD/μ gives about 560, well within laminar flow. Most mistakes come from slipping a decimal in viscosity or diameter.