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Unformatted text preview: CE 111: Environmental Engineering MIDTERM EXAM #2 3 November 2010 SOLUTION 1. Concepts in environmental transport (a) J a = U × C ; J a = advective flux (g m-2 h-1 ); U = fluid speed (m h-1 ); C = concentration (g m-3 ) (b) The parameter ε is the turbulent diffusivity and it has units of L 2 T-1 (e.g., m 2 s-1 ). (c) It is the particle Reynolds number: Re p = d p U ρ p / µ . (d) The time required for acceleration is very short ( µ s to ms, commonly) compared with typical time scales to settle through distances of environmental significance. 2. Transformations in flow reactors (a) Write material balance expressions for each of the three species in the reactor and solve for the steady-state concentrations. (Or, use the MB approach for [A] and solve the rest by stoichiometry.) d(V[A])/dt = Q [A] in – Q [A] – k[A]V = 0 ⇒ [A] = [A] in (1/1+k θ ) = 2.5 mM d(V[B])/dt = Q[B] in – Q[B] – k[A]V = 0 ⇒ [B] = [B] in – [A] k θ = 7.5 mM d(V[C])/dt = Q[C] in – Q[C] + k[A]V = 0...
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This note was uploaded on 12/01/2011 for the course CE 13972 taught by Professor Chow during the Spring '09 term at Berkeley.
- Spring '09