HAMT Model: Water Content goes way beyond 100% RH

[germolinal]

Issue overview

I am performing some simulations using the HAMT algorithm and I noticed that—in some cases—the water content reported reported by EnergyPlus goes way beyond what would be 100% RH.

For example, take the following material:

MaterialProperty:HeatAndMoistureTransfer:SorptionIsotherm,
    TI 135 U,
    10,
    0.0,0.0,
    0.8,0.7,
    0.93,1.8,
    0.97,3.8,
    0.99,5.6,
    0.995,7.4,
    0.999,13.9,
    0.9995,18.1,
    0.9999,32.9,
    1.0,372.0;

And in the results, after some unit conversions, I get the following relationship between RH and Water Content.

Expected Behaviour

Shouldn't the material—at some point—just stop accumulating water? Maybe the water that has no place could be accounted for in a "runoff water" or something like that...? I wonder how this affects the drying behaviour; I mean, drying from 10,000kg/m3 to is quite different to drying from 390kg/m3.

Note:

This particular simulation seems to have numerical stability issues. Yet, I would expect this behaviour not to happen.

Details

Some additional details for this issue (if relevant):

• Running on EnergyPlus 9.5

[griffincherrill]

Hmm, this is a very curious issue as the weight of water at 1 cubic meter is only 1,000kg. I don't know a huge amount of the HAMT algorithm, but have you entered other details about the suction, redistribution and diffusion? It seems as though water is accumulating but has no way of escaping.

[germolinal]

have you entered other details about the suction, redistribution and diffusion? It seems as though water is accumulating but has no way of escaping.

I did! But the point is that, at some point, the material should not allow any more water to come in at all