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Enthalpy of evaporation of water #474
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When changing the value for for T=283.15 and RH=50% I find wet bulb temperatures:
however, an error still seems to remain? |
@Mathadon Recknagel, Sprenger, Schramek, 2006, lists specific enthalpy of vaporization as
As we use |
I found a mistake in my code. I forgot to take into account that we have a reference temperature of 273.15 K, so the code should be:
the wet bulb temperature for Tdry = 10 C and 50% RH is now 278.686, which is not equal to 278.85. However, based on the data in source (https://books.google.be/books?id=gniJE5lK0YAC&pg=PA233&lpg=PA233&dq=wet+bulb+dry+bulb+temperature+table&source=bl&ots=Bj2tyGoTUX&sig=Nhktcz_ydwD1Cd_f-GDY6jnVpLE&hl=nl&sa=X&ved=0ahUKEwjpz4Sd0fLMAhXLKsAKHUX9Awk4ChDoAQhQMAc#v=onepage&q=wet%20bulb%20dry%20bulb%20temperature%20table&f=false) I do get correct results for triplets (Tdry, Twet, RH): (29.4C, 21.1C, 48%) and (23.3C, 16.5C, 50%) from examples 17.1 and 17.2. So the new implementation seems to be correct whereas the on line calculators seem to be off. I'll make a pull request for the new implementation and update the unit tests and documentation. |
added validation test updated unit test for #474
…a/Annex60_Fluid_Sensors_Examples_TemperatureWetBulb.txt this is for #474
In
Annex60.Utilities.Psychrometrics.Constants
we currently havewhich seems to be inconsistent with the often quoted enthalpy of evaporation of 2260 kJ/kg. Is this correct?
Edit:
h_fg = 2501 kJ/kg is the enthalpy of evaporation at 100 degrees C. The specific enthalpy of saturated steam is 2257 kJ/kg. This is based on http://www.engineeringtoolbox.com/steam-vapor-enthalpy-d_160.html . So I think the value of h_fg is correct?
However, the example below then still gives different results. Is there possibly an error in the implementation of Annex60.Utilities.Psychrometrics.TWetBul_TDryBulPhi?
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