Food Process Engineering & Operations

Transport phenomena analogies in chemical and food engineering:

• The classical transport phenomena analogies (Reynolds analogy, Prandtl analogy, and Chilton-Colburn $j$-factor analogy) establish direct mathematical and physical equivalence among the molecular and convective transport of momentum (fluid friction), heat (thermal conduction/convection), and mass (molecular/eddy diffusion).
• Temperature is a driving potential for heat transfer, not a transport quantity.
• Concentration is a driving potential for mass transfer.
• Pressure gradient is a driving potential for fluid momentum flow.

Bucket elevators are material handling systems engineered for vertical or steep inclined lifting of free-flowing bulk granular solids (grains, seeds, milled flour). While belt conveyors operate at gentle angles ($0-25^\circ$), elevators transport bulk materials vertically ($90^\circ$) or on steep inclines typically of $60-80^\circ$ to the horizontal.

Both statements are correct: A screw conveyor (auger conveyor) consists of a rotating helical screw blade inside a trough or tube. It is standard equipment for horizontal conveyance of bulk grains, seeds, and meals. Moreover, inclined screw conveyors are widely operated at angles up to $45^\circ$ to the horizontal (with appropriate pitch modification and reduced volumetric throughput capacity).