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.

blockMesh

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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:

Boundary conditions

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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

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The temperature and pressure contour is shown below:

 

Extra pictures from another simulation:

P.S:

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

Reference

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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.