In this paper

the ε-NTU function of direct contact devices based on modified energy effectiveness definition was verified by 75 groups of countercurrent humidifier experimental data. The affection of pressure

water/air mass flow ratio

inlet water temperature and inlet air wet bulb temperature on heat capacity rate ratio and energy effectiveness were analyzed. The results show maximum relative-error of modified ε-NTU function is 27.7%

which can be used in engineering calculation. Heat capacity rate ratio change monotonically increase or decrease with operation parameters

while energy effectiveness curves has minimum inflection point at heat capacity flow being equal to 1. At fixed operating pressure

the affection of inlet air wet bulb temperature

water/air mass flow ratio and inlet water temperature on energy effectiveness of countercurrent humidifier decreases in turn.