Calculate enthalpy “Out Enthalpy” and absolute humidity “Out Abs. Humidity” as a function of air temperature, relative air humidity, and air pressure. Use Enthalpy with the Economy function.
The absolute humidity is calculated according to the following formula:
“Out Abs. Humidity” = 622,0 * (“In Rel. Humidity”/100 * SPWV) / (“In Air Pressure” – “In Rel. Humidity”/100 * SPWV)
SPWV is the saturation pressure of water vapour (in mbar):
SPWV= 2,8868 * Exp(8,02 * Ln(1,098 + (“In Outside Air Temp.” / 100)))
The enthalpy is calculated with the formula:
“Out Enthalpy”: = 1,004 * “In Outside Air Temp.” + “Out Abs. Humidity”/ 1000 * (2501,6 + (1,86 * “In Outside Air Temp.”))
Fig. 169. Wire-sheet Icon
Fig. 170. Property Sheet
Fig. 171. Slot Sheet
Table 115. Inputs
Inputs |
Type |
Functional description |
In Air Temp |
numeric |
outside air temperature in °C |
In Rel. Humidity |
numeric |
relative humidity in percent (0 through 100 %) |
In Air Pressure |
numeric |
air pressure (0,1 mbar …∞) |
In Enabled |
boolean |
If the input “In Enabled” is set to false disabled in the slot sheet, the output “Out” will be disabled and is set to the value “0”. |
Table 116. Outputs
Outputs |
Type |
Functional description |
Out Enthalpy |
numeric |
One analog output = dewpoint temperature |
Out Absolute Humidity |
numeric |
absolute humidity (0 - 100 g/ kg) |
No parameters