Perma Pure FC Humidifier performance is characterized by Approach Temperature and Approach Dew Point. They are defined as follows:
Approach dew point: the difference in dew point between the recycled gas used for humidification (fuel cell: cathode exhaust inlet) and the resultant humidified outlet gas
Approach Temperature: the difference in temperature between the recycled gas used for humidification and the resultant humidified outlet gas
See the graph above for more detail.