Category Archives: Chemical Reaction Engineering

Please state dimensional units!

Chemical Reaction Engineering

I have been looking into developing a Web Lab simulation of a fluidized bed gasifier. Reaction rate equations are needed.

Trying to get rate equations from research papers has been frustrating because the dimensional units of terms in equations are often not stated.

To an editor or peer reviewer, it may look like the author has given all the required equations to duplicate their work, but you learn the truth when you try to use those equations, not just read them!

Please make sure you explicitly state the dimensional units for all terms in all equations, or example units if more than one set of consistent units can be used. Stating dimensional units is mandatory for equations with numerical constants. If equations are dimensionless, please state that.

Reviewers and editors, please check to make sure authors have done this.

On a related note, I ask that chemists reporting reaction rates please state for which type of reactor those rates and equations apply. Usually, a chemist is using a batch reactor, e.g., a test tube or flask but we should not have to assume that. Some chemists might even use a continuous stirred tank (beaker) reactor.

Space-time plot added to web lab

Chemical Reaction Engineering, Dynamics, Heterogeneous Catalysis, HTML5, Software Development, Web Labs

Space-time plots are a beautiful way to view dynamic reaction-diffusion systems. We added one to the Web Lab, “Dynamic diffusion and reaction in a porous solid catalyst.” Here is a static screen shot from the lab.

Adding this dynamic plot required learning how to program the HTML5 canvas element with Javascript – an exciting combination!

We prepared static plots of space-time data for our previous research work, e.g., at http://escholarship.org/uc/item/9bc7v3kv. We were inspired to make them dynamically by the fluid dynamics simulations of Oliver Hunt at https://nerget.com/fluidSim/ and Daniel Schroeder at http://physics.weber.edu/schroeder/fluids/. Those pages showed us that this was possible to do in a web page.

Web app experiment 3 posted – control of reactor T

Chemical Reaction Engineering, Dynamics, HTML5

Web app experiment 3 demonstrates feedback control of temperature during reaction in a continuous stirred tank reactor (CSTR). See the Resources tab, Web app experiments. Below is a static screenshot – click to enlarge.

web_app_3_image_4

At default conditions in manual control mode with constant inputs, the system oscillates. Do you know why the system oscillates? See the Resources tab, CRE Notes, 15 – CSTR thermal effects. Then put the system into Auto Control mode.

Chemical Reaction Engineering Notes posted

Chemical Reaction Engineering, Resources

See the RESOURCES tab above. Select the section “CRE Notes.” On that page there is a link to my Chemical Reaction Engineering (CRE) Notes.

The organization of these notes differs from most textbooks on CRE. These notes consider only Batch and Semi-Batch reactors at the start. Only after all the major topics (e.g., stoichiometry, change in gas density, thermal effects) are covered do they proceed to PFRs and CSTRs.

Why this organization? Some students told me that they got confused when they encountered a new topic (e.g., thermal effects) and lectures switched back and forth between the different types of reactors. I can understand their concern. I now think it is better to stick to Batch reactors until students learn them very well before switching to other reactors.