# finalf17.pdf - SECTION: NAME: CBE 320 Introductory...

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SECTION:NAME:CBE 320December 19, 2017Introductory Transport PhenomenaFinal ExamPart A: Short Answer1.(5 pts.) Give the SI units for the following quantities:a.νDABb.nAc.k′′′1(i.e., inRA=k′′′1cA)d.kTe.h(heat transfer coefficient)2.(5 pts.) Write the Planck distribution law. Provide a definition for each term.1
3.(5 pts.) A mass balance for speciesAin a mixture is written in one form below. Label each term,describing its physical significance.∂ρA∂t=(∇ ·ρAv)(∇ ·jA) +rA.4.(5 pts.) When an electric field is applied to a fluid containing ions, the ion speciesiexperiences anadditional contribution to the molar flux given byEqiciωi(Eis the electric field,qiis the charge onspeciesi,ciis the molar concentration of speciesi, andωiis the mobility of speciesi). Write downan expression for the modified Fick’s Law, describing thetotalmolar flux of speciesirelative to fixedcoordinates. Assume that everything else in the fluid constitutes species “B”.2
5.(5 pts.) A material (A) is diffusing (no convection) into a porous cylinder (radiusR, lengthL) from aflowing fluid (B). The concentration of speciesAwithin the fluidiscA(r, θ, z, t), and the diffusivitywithin the fluid isDAB.Using this information, write an integral expression for the total rate oftransport of speciesAfrom the fluid into the cylinder (molesA/time).You may assume thatAis dilute so that the total concentration is constant, and that transport at the cylinder ends may beneglected.6.(5 pts.) The mean Nusselt number for forced convection past a sphere is given byNum=hmDk= 2 + 0.60parenleftBiggDvρμparenrightBigg1/2parenleftBigghatwideCpμkparenrightBigg1/3.(1)

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