What is Plug flow reactor (PFR)?

A model reactor in which gas moves along a tube like a plug, reacting as it goes, without mixing forwards or backwards.

It shows how temperature and composition change along a tube — in tubular reactors, long ducts or the post-flame region — step by step.

Think of toothpaste squeezed from a tube: what goes in first comes out first, with no overtaking or mixing along the way.

Give the length, cross-section area and inlet gas (temperature, pressure, composition, mass flow). Laplaxian returns the outlet state, temperature and species profiles, and the residence time. Pressure is assumed constant.

A steady, constant-pressure PFR is equivalent to a constant-pressure batch reactor that follows a parcel of gas. Position x and time t are linked by:
\frac{dx}{dt} = u = \frac{\dot{m}}{\rho A}
Laplaxian integrates this way and reports the state at the outlet x = L.

Axial diffusion, heat loss and pressure drop are not included.

• Chemical equilibrium
• Residence time
• Reaction mechanism

• Cantera documentation