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Can someone identify what this graph is used for?

  1. Oct 26, 2016 #1
    Hi, I was asked by my senior to find out what this graph is and how to use it. No details were given as to where they found it.

    I know already that this is used to compare CSTRs and PFRs performance for first order reactions, but I can't deduce what the expressions Dd/(vxL) and kL/vx are for and what the variables represent.

    Thanks a lot!

  2. jcsd
  3. Oct 28, 2016 #2


    Staff: Mentor

  4. Oct 28, 2016 #3
    Hey, thanks for the response!

    Yeah, I'm familiar with nomographs. I just can't determine what the variables in the graph represent.

    But thanks a lot for this information! I really appreciate it!
  5. Oct 28, 2016 #4
    This graph is for a tubular chemical reactor in which there is axial mixing/dispersion. The velocity profile is assumed to be flat. The reaction is assumed to be first order decay. The dimensionless group ##D_d/v_xL## is a measure of the axial dispersion, and is the inverse of the Peclet number. The dimensionless group ##kL/v_x## is the ratio of the residence time in the tube to the characteristic decay time for the reaction.

    ##D_d## = axial dispersion coefficient
    ##v_x## = axial velocity
    L = length of tube
    k = first order reaction rate constant
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