Book contents
- Frontmatter
- Contents
- Preface
- 1 The Global Perspective on Environmental Transport and Fate
- 2 The Diffusion Equation
- 3 Diffusion Coefficients
- 4 Mass, Heat, and Momentum Transport Analogies
- 5 Turbulent Diffusion
- 6 Reactor Mixing Assumptions
- 7 Computational Mass Transport
- 8 Interfacial Mass Transfer
- 9 Air–Water Mass Transfer in the Field
- APPENDIXES
- References
- Subject Index
- Index to Example Solutions
6 - Reactor Mixing Assumptions
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- 1 The Global Perspective on Environmental Transport and Fate
- 2 The Diffusion Equation
- 3 Diffusion Coefficients
- 4 Mass, Heat, and Momentum Transport Analogies
- 5 Turbulent Diffusion
- 6 Reactor Mixing Assumptions
- 7 Computational Mass Transport
- 8 Interfacial Mass Transfer
- 9 Air–Water Mass Transfer in the Field
- APPENDIXES
- References
- Subject Index
- Index to Example Solutions
Summary
Solving the diffusion equation in environmental transport can be challenging because only specific boundary conditions result in an analytical solution. We may want to consider our system of interest as a reactor, with clearly defined mixing, which is more amenable to time dependent boundary conditions. The ability to do this depends on how well the conditions of the system match the assumptions of reactor mixing. In addition, the system is typically assumed as one dimensional. The common reactor mixing assumptions are as follows:
Complete Mix Reactor – The complete mix reactor is also labeled a completely stirred tank reactor. It is a container that has an infinite diffusion coefficient, such that any chemical that enters the reactor is immediately mixed in with the solvent. In Example 2.8, we used the complete mix reactor assumption to estimate the concentration of three atmospheric pollutants that resulted from an oil spill. We will use a complete mix reactor (in this chapter) to simulate the development of high salt content in dead-end lakes. A series of complete mix reactors may be placed in series to simulate the overall mixing of a one-dimensional system, such as a river. In fact, most computational transport models are a series of complete mix reactors.
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- Introduction to Chemical Transport in the Environment , pp. 121 - 174Publisher: Cambridge University PressPrint publication year: 2007