Nano Fluid in Heat Source Channel, Mixture Multiphase

Description

Nano Fluid Flows in a Heat Source Channel, Applying Mixture Multiphase Model, ANSYS Fluent Training

The present problem simulates the flow of an Al2O3-water nanofluid into a channel with a heat source using ANSYS Fluent software. This channel has a square cross-section and has ten obstacles inside.

Each of these obstacles has two diagonal plane barriers facing each other and a cylindrical barrier between them. Hence, the presence of these barriers determines the path of nanofluid flow through the channel.

Therefore, two different materials have been used water as the primary fluid and aluminum oxide (Al2O3) as the secondary fluid.

Aluminum oxide is defined as having a density of 3970 kg/m3, a specific heat capacity of 768 j/kg.K, a thermal conductivity of 40 W/m.K, and a viscosity equal to 0.000017894 kg/m.s and a molecular weight equal to 28.966 kg/kmol.

Also, the aluminum oxide particles defined as a secondary fluid have a diameter of 0.00001 m. In the lower part of this channel, there is a solid area of ​​aluminum.

The floor wall is under constant heat flux equal to 170,000 W/m2, which is responsible for transferring heat to the channel carrying the nanofluid. The simulation process is done in two steps.

At first, the simulation is performed in single-phase mode (pure water flow only). In this case, water flow enters the channel at a temperature of 300 K and a speed of 2.233 m/s. Then, the simulation is performed in a two-phase model (water flow containing aluminum oxide nanoparticles).

In this case, the nanoparticle of aluminum oxide enters the channel with the same water flow speed and temperature; Thus, the nanoparticle volume fraction is equal to 0.01.

The current model is designed in three dimensions using Design Modeler software. The model consists of a horizontal channel for the flow passage located on a solid object with heat flux.

The canal has a rectangular section with dimensions of 0.001 m * 0.0015 m, with ten obstacle categories. Each obstacle category consists of two diagonal plane barriers relative to each other and a cylindrical barrier between them.

The solid aluminum body under the channel has dimensions of 0.002 m * 0.02 m * 0.05 m. The following figure shows a view of the geometry.

The meshing of the present model has been done using ANSYS Meshing software. The mesh type is unstructured, and the element number is equal to 2160625.

Heat Source Methodology

To define the nanofluid, a mixture multi-phase model is used. The multi-phase mixture model is used when the mixing process occurs between a fluid and a solid particle. The boundary between the solute and the solvent is not accurately discernible.

Heat Source Conclusion

At the end of the solution process, two-dimensional and three-dimensional contours related to the mixing pressure, mixing temperature, and velocity of each of the water and Al2O3 phases are obtained. Two-dimensional contours are obtained in two sections of X_Z and Y_Z in the fluid flow region.

The fluid temperature increases as the fluid flow to the outlet section because of a heat source. At the same time, the nanoparticles enhance the temperature magnitude because of the more heat transfer.