[yus310]

All,

I'm a engineering student, using ANSYS fluent, to model a solar cavity receiver device in order to capture, collect, and store solar energy into an heat exchanger. My design is as so (see attached).
anyway at the top (the blue), there is solar rays coming in (red), hence for the ANSYS simulations, I'm putting a heat flux at the (blue area). This blue area is a cylinder, with a circular cross section and thickness of 0.001 cm. Other than that (the green=heat exchanger), and black=entire receiver/container, that is all. The heat exchanger has a salt in it, so, that is why energy is being collected based on this salt.

I'm using S2S radiation model for this. I'm calculating the view factors via ANSYS fluent, and then assuming based on the science (radiation, convection, etc.), the will be exchange with other surfaces e.g. from the blue to green, green to black, black to blue, etc. as a result of the solar energy coming. Point is, I need most of the solar energy in to go into the heat exchanger.

Now when I run this for steady state, given a heat flux from solar rays at the blue part, nothing heats up from the initial system temp., other than the blue region. I've been trying to play around this, but it just shows the same result.

After further investigation on ANSYS, I learned that S2S radiation model cannot be used for symmetrical or non-periodic boundary conditions. Does anyone know what does that mean and it is applies to my problem?

Any suggestions why the ANSYS fluent refuses to exchange radiation among the varying surfaces?

Best,
yus310