Model Reactors - PFR
3 important questions on Model Reactors - PFR
What are 2 assumptions you can make about a PFR?
- There is no 'back'-mixing, the fluid packages move through the reactor without exchange with other packages.
- Concentration changes along the reactor coordinate
Why is the average concentration in a PFR higher than in a CSTR?
In a PFR (Plug Flow Reactor), the average concentration is typically higher because:
- No mixing occurs along the flow direction.
- Reactants are converted as they move through the reactor.
- Concentration gradients exist, leading to higher concentrations near the inlet.
- Shorter residence times allow for less dilution compared to a CSTR.
- CSTRs have continuous mixing, leading to more uniform but lower average concentrations.
Why does a negative reaction order lead to a lower CSTR volume than a PFR?
A negative reaction order influences the design of reactors in several ways:
- Decreased substrate concentration increases reaction rate.
- CSTR operates at steady-state where mixing allows for uniform reaction.
- Lower required volume in CSTR due to continuous input and output.
- PFR requires higher volume for the same conversion due to a different flow pattern.
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