The use of slow pseudo-first-order reaction to estimate the size of micro-mixed volume in a flow system
✍ Scribed by Soon-Jai Khang; Gary L. Fowler
- Publisher
- Elsevier Science
- Year
- 1989
- Tongue
- English
- Weight
- 533 KB
- Volume
- 44
- Category
- Article
- ISSN
- 0009-2509
No coin nor oath required. For personal study only.
✦ Synopsis
The pseudo-first-order hydrolysis reaction of acetic anhydride in water is employed as a chemically reacting tracer to measure the size of a flow system's micro-mixed volume. Unlike previous attempts to use chemical reactions for measuring the effectiveness of mixing, the present method is based on a relatively slow first-order reaction, with the reaction time and residence time distribution enabling an indirect evaluation of a micro-mixed volume without using any specific flow model. Using an electrolyte conductivity meter, a series of steady-state output concentrations of the reaction product, acetic acid, are measured at different operating temperatures. After plotting the conversion vs reaction rate constant, the slope at the zero reaction rate represents the space time that reactants spent in a micro-mixe$volume.
This method was demonstrated using a 0.0206 m i.d. pipe with commercial motionless mixer units inserted in the front section of the pipe. The results for Re = 5ooO showed that the fraction of micro-mixed region increased from 0.87 with no mixer unit to 0.96 with two mixer units, and to 1.0 with 14 mixer units, thus providing a valuable information on the extent of usage of the internal volume.