Solar heater flow rate, natural convection convergence
2 Attachment(s)
Hello there,
I find this forum very helpful and I will try to contribute more in the future. Meanwhile, I have a simple solar water heater problem and I'd appreciate if anyone could help. It's a natural convection flow inside an inclined rectangular cavity (see the attached picture for the result and boundary conditions). I have doubts in my solution for the following 2 reasons: 1) the solution did not properly converge after 8000 iterations (see picture). Gradually increasing gravity and reducing under-relaxation factors as suggested somewhere in this forum did not help either. 2) assuming that the achieved convergence is enough to get a rough estimate of the answer, the velocity inside the cavity is relatively high = 0.04 m/s (average), giving a mass flow rate of: m(dot) = rho*A*v = 1000*0.007*0.04=0.28 kg/s Thermosyphonic flow in the literature reaches around 0.02 kg/s, which is 10 times less. However, the examples that I refer to are using tubes with different area. If I calculate the velocity of 0.02 kg/s mass flow rate in the tube of 2.5cm diameter, the velocity is around 0.04 m/s, which is like the value that I get. Therefore, I am sort of right, saying that such mass flow rate is possible, considering a larger area of mine. However, the convergence makes me doubt my solution. Can I consider my simulation correct (at least within one order of magnitude)? Attachment 54870 Attachment 54871 Thank you in advance. |
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