[esp-r] Re: Simulating solar sewage drying

[esp-r at h-rd.org]

Dear Oliver,

When trying to simulate drying in an enclosure, a very important aspect is the
ventilation regime.  Basically you need to know the humidity of the air in order
to calculate the evaporation.  That in turn requires a coupling with a flow
solver.  Naturally you need to calculate the radiation, too.
Also the properties of the sludge are very important:  the albedo, if it is
stirred or not, and other physical properties.

In designing such a system, I think you would need to consult with an expert on
the issue of sludge drying.  There are different specific models available,
although I do not know if they apply to your specific situation.

If you just want to model the mass of water to be extracted, you could try a
simple approach, calculating the potential evaporation, assuming "perfect"
ventilation and water like properties for the sludge.  Obviously such a model
would be valid only approximately for very wet sludge.  From the above it is
clear that I think it is not sufficient to use only weather and construction as
inputs.

yours sincerely,

Marc Hoffmann
esp-r at h-rd.org

Citeren Oliver Bucks <oliver.bucks at club-internet.fr>:

> Hello,
> The introduction :
> I Have been asked to simulate solar sludge drying. Given the answers I
> recieved
> previously on the same subject, it has been agreed that the exact behaviour
> of
> drying sewage sludge is not really the problem to be simulated. The aim is to
> model one or two designs (materials, thicknesses and orientations) in order
> to
> get the best. The aim is to design a decent envelope.
>
> However, the indicator chosen is the mass of water extracted from the sludge
> via
> evaporation per day as a function of simple weather and construction inputs.
>
> The question :
> Can someone please tell me how I can introduce an indoor, plane surface of
> water
> in a model so as the evaporations rates are automatically affected by the
> incoming solar radiation, water temperature and internal air temperature ?
>
> I saw a component calles "swimming pool" but am not experienced enough to
> understand how it might be put into use.
>
> Many thanks
>
> Olli Bucks
>
>
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Marc Hoffmann
esp-r at h-rd.org
http://www.h-rd.org