AixLib.Utilities.Psychrometrics.TWetBul_TDryBulPhi

# .AixLib.Utilities.Psychrometrics.TWetBul_TDryBulPhi

Model to compute the wet bulb temperature based on relative humidity

## Information

This block computes the wet bulb temperature for a given dry bulb temperature, relative air humidity and atmospheric pressure.

If the constant `approximateWetBulb` is `true`, then the block uses the approximation of Stull (2011) to compute the wet bulb temperature without requiring a nonlinear equation. Otherwise, the model will introduce one nonlinear equation. The approximation by Stull is valid for a relative humidity of 5% to 99%, a temperature range from -20°C to 50°C and standard sea level pressure. For this range of data, the approximation error is -1 Kelvin to +0.65 Kelvin, with a mean error of less than 0.3 Kelvin.

Otherwise a calculation based on an energy balance is used. See #474 for a discussion. The model is validated in AixLib.Utilities.Psychrometrics.Examples.TWetBul_TDryBulPhi.

For a model that takes the mass fraction instead of the relative humidity as an input, see AixLib.Utilities.Psychrometrics.TWetBul_TDryBulXi.

#### References

Stull, Roland. Wet-Bulb Temperature from Relative Humidity and Air Temperature Roland Stull. Journal of Applied Meteorology and Climatology. Volume 50, Issue 11, pp. 2267-2269. November 2011 DOI: 10.1175/JAMC-D-11-0143.1

## Contents

Name | Description
--- | ---
Medium | Medium model

## Revisions

- June 18, 2024, by Michael Wetter:
  Added `start` and `nominal` attributes to avoid warnings in OpenModelica due to conflicting values.
  This is for IBPSA, #1890.
- March 6, 2023, by Michael Wetter:
  Added a constant in order for unit check to pass.
  See #1711 for a discussion.
- November 3, 2016, by Michael Wetter:
  Changed icon.
- May 24, 2016, by Filip Jorissen:
  Corrected exact implementation. See #474 for a discussion.
- October 3, 2014, by Michael Wetter:
  Changed assignment of nominal value to avoid in OpenModelica the warning alias set with different nominal values.
- November 20, 2013 by Michael Wetter:
  Updated model to use `AixLib.Utilities.Psychrometrics.Functions.saturationPressure()` and `AixLib.Utilities.Psychrometrics.Functions.saturationPressureLiquid()` as these functions have been moved from the medium to the psychrometrics package.
- October 1, 2012 by Michael Wetter:
  First implementation.

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