Perforated Air Distributor for Laterally Aerated Moving Bed (LAMB) system

Description

Perforated tubes are widely used in industry for numerous applications such as drainage system, bioreactor fermentation, commercial buildings for aesthetic purpose, drilling of crude oil, dryer, etc. Core design of the LAMB dryer (Laterally Aerated Moving Bed) is its inner tube, or also known as its radial revolution aerator. This aerator is a perforated tube which functions to uniformly distribute the air radially to surrounding medium. The arrangement of this inner tube has given the LAMB a major advantage in terms of low pressure drop, in another word, a less energy consumption design.

In this project the geometry is generated in Spaceclaim and meshed in ANSYS Meshing  producing 2,983,355 cells for instance for the case with 4[mm] holes distance.

Methodology

One of the essential goals when designing vertical perforated tube is to uniformly distribute fluid in all orifices then we expect that simulating design of perforated tube will be done with proper result and will reach to our major purpose that is maintain desire distances of air flow through perforated tube. We simulated a perforated pipe with 0.025 [m] diameter containing  holes in three rows around it by equal distance between. The pipe is surrounded by a cube with 1.7 m length as the domain around. All surfaces of the cube are defined as the outlet, except for the one considered as adiabatic wall in front of the air inlet. Also the outlet of the tube is set as wall.

To investigate the effect of  holes distance and inlet velocity, we considered different designs. In the The first one the tube with 3 [mm] diameter is simulated finding effect of varying velocity in 0.3, 1 and 3 [m/s]. Then we changed the distance between the holes to 4 and 5 [mm] so that we could observe how these parameters affect the results such as flow distribution uniformity. The air with 2.25% moisture and 300 [k] temperature enters the tube. The problem is solved steadily and turbulence of the flow is simulated by RNG k-e model. Also to see how species are transported and seeing mass fraction of them in the flow coming out of the pipe holes, the Species model is activated.

conclusion

As shown in results, the velocity contours for created planes on the tube holes radially and axially, the fluid is distributed uniformly exiting the holes. Also the mass fraction of the species are visible in the contours.