Dear all,
we are using the active layer model of EMPA, built in in type 56, to simulate a solar boiler of the type equal to floor heating. In our case we used the auto segmentation leading to 3 different segments of the active layer.
With 66 kg/h at 1,055 specific weight, inlet temperatures below 25 DC gave a fluent simulation at 15 minutes timestep. However, once simulating with higher inlet temperatures warmer climatic zones (e.g. Casablanca) fail at around 3400 hours in the simulation. In this case, we get a specific message that the inlet mass flow rate for the third part of the segmented roof requires a minimum mass flow rate that is higher than the input one. Opening the TRNBUILD file, the minimum is around 12 kg/h. The message in the list file mentions a minimum of over 30. A smaller timestep did not change the error.
Are we too close to the safety limits built in the EMPA model, or is there another thing we forgot to take into account?
Thanks already!
Leen