The vessel dispersion number (D/uL) for plug flow is_________________?
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Answer: A. 0
Explanation
An ideal plug flow reactor exhibits zero axial mixing or dispersion along the fluid path. The vessel dispersion number is a dimensionless parameter that quantifies axial mixing intensity in reactors. Plug flow assumes all fluid elements travel at identical velocities without mixing backward or forward. Axial dispersion measures the degree of backmixing occurring along the longitudinal axis of a reactor. A dispersion number of zero represents complete absence of backmixing in ideal plug flow systems. An infinite dispersion number represents complete backmixing characteristic of ideal continuous stirred tanks.
Tubular chemical reactors are designed to approximate plug flow conditions to maximize chemical conversion efficiency. Tracer injection experiments help engineers measure actual vessel dispersion numbers in industrial tubular reactors. Deviations from zero dispersion can significantly reduce conversion in high-order reversible chemical reactions. Values like 500 or 750 represent severe non-ideal dispersion states far removed from plug flow. An infinite dispersion number describes infinite backmixing found in ideal continuous stirred tank reactors. Negative dispersion numbers are physically impossible within standard fluid dynamics and reactor modeling.
- Subject
- Engineering
- Category
- Chemical Engineering
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- —
- Difficulty
- medium
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