WUFI

Hello,


I am a user of WUFI V.2.5.3.0.

I would like to know how to calculate Natural/Mechanical ventilation that I can only input ACH in WUFI because I simulate underground parking place with opening, and I should consider outer air flows into the space.

I am not sure whether that can be taken into account infiltration or ventilation.

Anyway, as far as I've found the formula to calculate that, it might be calcuated through same equation as 'Thermal Loads', Chapter 16, Ventilation and Infiltration in ASHRAE Fundamental. (ex, q(W)=QρcpDeltaT)

If the thermal transport part as above is correct, what is the vapor transport part(kg/m2s)?

Hello,

for a zone, in the ventilation treenode you can define the natural ACH (for infiltration and/or natural ventilation). Then the heat flow is calculated = air mass flow rate * (specific enthalpy of inner air - specific enthalpy of outer air). Considering that only the outer air with its moisture content is heated or chilled from the outer air temperature to the inner air temperature the specific enthalpy change is calculated: (hi - he) = (1006 + moisture content of outer air * 1840) * (inner air temperature - outer air temperature).

the moisture flow is = (moisture content of outer air - moisture content of inner air) * air mass flow rate.

the mechanical ventilation is calculate quite similar, except the possible added heat- or moisture recovery rate.

in the result graphs you will get the calcuated heat and moisture flows hourly or monthly.

However, this is calculated if you define the ACH. if you set it zero, you can set your calculated heat- or moisture flows as internal loads per shedule, or from an external file...

Hi,

if I consider the moisture recovery efficiency = 0 (and no control) in the mechanical ventilation does the model apply exactly the same equation for natural ventilation for moisture exchange?

If I set both natural infiltration and natural ventilation, in the results the moisture exchange by infiltration is the sum of the two elements?

Thank you