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Unformatted text preview: SECTION: NAME: CBE 320 December 19, 2006 Transport Phenomena Final Exam Part A: Short Answer 1. (5 pts.) What are the SI units of the following quantitities? a. n A b. c A c. j A d. q e. 2. (5 pts.) Express each of the following dimensionless groups as a ratio of forces or phenomena: a. Re b. ReSc c. RePr 1 3. (5 pts.) Most fluids have similar densities, but viscosities can vary over many orders of magnitude. Sketch a plot of the volumetric flow rate Q vs for flow through a circular pipe at constant P , , and R . Indicate regions of laminar and turbulent flow. 4. (5 pts.) List two different types of thermal energy production. For each, state the type of energy that is converted to thermal energy, and explain how the conversion occurs. 5. (5 pts.) Write Wiens displacement law. Provide definitions and dimensions for each term. 2 6. (5 pts.) A material ( A ) is diffusing (no convection) out of a porous sphere (radius R ) into a fluid ( B ). The concentration of species A within the sphere is c A ( r, , , t ) , and the diffusivity within the sphere is D A . Using this information, write an integral expression for the total rate of transport of species A from the sphere into the fluid (moles A /time). 7. (5 pts.) The mass transport of species A in a binary mixture of A and B can be written (for constant , D AB ) Dc A Dt = D AB 2 c A + R A . Simplify this expression for a stagnant liquid solution. 8. (5 pts.) Gas A dissolves in a beaker of stagnant liquid B , and reacts with B to form C ( R A = k 000 1 c A ). Sketch plots of c A as a function of z for both small and large k 000 1 . Here, z is the distance below the liquid/gas interface. 3 9. (5 pts.) Sketch k xm vs v for flow past a sphere (assuming all other parameters are constant). 10. (5 pts.) For turbulent flow in a tube of circular cross section, the logmean Nusselt number is given by Nu ln . 026 Re . 8 Pr 1 / 3 (assuming that physical properties are independent of temperature). What is the correlation for the dimension less mass transfer coefficient for a material that is slowly dissolving from the tube wall in turbulent flow?...
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 Fall '08
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