Hi Ventsim
There appears to be a error in the calculation of radon progeny concentrations with time.
I have run this on version 5 and 6 and get the same error
Attached is a graph showing the theoretical growth of radon progeny per 1,000Bq/m3 Rn (1Bq/l Rn)
The maximum radon progeny concentration is about 5.6uJ/m3 after about 200minutes
This also gives you the equilibrium factor i.e. about EQF= 1 at 200 minutes. Slightly different if you include decay of Rn gas
I have tested this by putting 25,000Bq/s into 25m3/s in a 5m x 5m airway i.e. 1.0m/s - see model attached
I have then used different airway lengths to test the radon progeny concentrations e.g. 60m = 1min
The results show an ever increasing radon progeny concentration with time - see attached table
When I plot the Ventsim results with time against the theoretical values (Bateman Equations) I get the following. This indicates a divergence of theoretical v Ventsim after about 70mins.
This is a significant difference in air passing through old workings or cave piles. Could you take a look at this please
Thanks
Roy
Radon Test.vsm