Can someone identify what this graph is used for?

[Dong Aleta]

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 D_d/(v_xL) and kL/v_x are for and what the variables represent.

Thanks a lot!

 

[jedishrfu]

In general, these kinds of graphs are called nomograms or nomographs:

https://en.wikipedia.org/wiki/Nomogram

They were popular before the advent of personal computers and calculators.

What this particular one is, I'm not sure but I found this website with a similar chart:

http://slideplayer.com/slide/10044354/

 

[Dong Aleta]

In general, these kinds of graphs are called nomograms or nomographs:

https://en.wikipedia.org/wiki/Nomogram

They were popular before the advent of personal computers and calculators.

What this particular one is, I'm not sure but I found this website with a similar chart:

http://slideplayer.com/slide/10044354/

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!

 

[Chestermiller]

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