This section considers those parameters not involved in transfer processes within or between phases but which affect system performance, such as heat capacities and phase equilibria.
The saturation humidity may need to be known in modeling in order to calculate the water activity of the gas phase within an SSF bioreactor (awg), which is defined as:
where Pw is the vapor pressure (Pa) of water within the gas phase at a particular temperature and Psat is the saturation vapor pressure (Pa) of water at the same temperature.
The Antoine equation gives the saturation vapor pressure of water as a function of temperature (T, °C) (Reid et al. 1977):
For water vapor the constants are a=18.3036, b=3816.44, c=227.02, and d=133.322. The humidity at saturation (kg-vapor kg-dry-air-1) is then given by:
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