Numerical Simulation of Solar Chimney

In this study, the numerical analysis on the performance of solar chimney is done using buoyantBoussinesqSimpleFoam.

The schematic of problem is displayed below.

schematic of solar chimney problem from Ref[1]

blockMesh


The grid is created with blockMesh. A fabulous feature in blockMesh which can be used to calculate mathematical paramters  is  #calc . look following examples:

1- theta is 30 degree, convert degree to rad :

#calc      "degToRad(30)"

2-use sin(theta) or cos(theta) functions :

 #calc     "sin(30)"

for simulation of 2d axisymmetric problem in OpenFOAM, special treatment is needed. The angle between planar front and back patch is  less than 5 degree and the type of BC is  considered wedge. The final grid is shown below:

grid generated with blockMesh for solar chimney
grid generated with blockMesh for axisymmetric simulation, baffle is created for fan BC

Boundary conditions


There is a turbine in solar chimney. It is modeled implicitly via fan BC. The fan boundary employs a pressure jump or drop consistent to the velocity crossing the patch. The fan is a sub-function of cyclic boundary condition. In order to create a cyclic BC along air flow, the OpenFOAM utility createBaffleDict is employed. The position of cyclic boundary is shown in above figure (fan_half0).

The  convection boundary condition  is taken into consideration for the roof of collector. This BC is employed with the aid of groovyBC as follow:

 type  groovyBC;
 variables "q=800;h=3;Tinf=300;Cp0=1.0035e03;rhoAir=1.127;kair=kappaEff*rhoAir*rhok*Cp0;";
 valueExpression "q/h+Tinf";
 gradientExpression "0";
 fractionExpression "1/(1+kair/(h*mag(delta())))";
 value uniform 300;

Result


The temperature and pressure contour is shown below:

temperature contour in solar chimney, simulation is done with buoyantBoussinesqSimpleFoam
dynamic pressure contour in solar chimney, simulation is done with buoyantBoussinesqSimpleFoam

 

Extra pictures from another simulation:

P.S:

fan BC in OpenFOAM-v5 does not support negative pressure jump, so groovyBCJump is another option.

Reference


1- Xu, G., Ming, T., Pan, Y., Meng, F. and Zhou, C., 2011. Numerical analysis on the performance of solar chimney power plant system. Energy Conversion and Management, 52(2), pp.876-883.

One Reply to “Numerical Simulation of Solar Chimney”

Leave a Reply

Your email address will not be published. Required fields are marked *