Calculation Of Water Vapor Pressure And Relative Humidity

Equations for calculation of Water Vapor Pressure and Relative Humidity

p_wv (mPa) = water vapor pressure at temperature T
T (K) = temperature
All Temperatures in degree Kelvin (K) = °C +273.15

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To determine relative humidity (RH),
1. Calculate p_wv for humidifier temperature, p_wv,humidifer
2. Calculate p_wv for the cell temperature, p_wv,cell
3. RH = p_wv,humidifer / p_wv,cell x 100%

This is done for the anode and cathode separately.
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Source: “Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam,” The International Association for the Properties of Water and Steam, Erlangen, Germany, September 1997