Going below the wet-bulb temperature by indirect evaporative cooling: Analysis using a modified ε-NTU method

► A method to achieve sub-wet bulb temperature by indirect evaporative cooling. ► Main idea lies in indirectly pre-cooling the working air. ► A modified model is developed based on the effectiveness-NTU method (ε-NTU). ► Results are in agreement with other numerical and experimental results. ► Ultimate temperature for such a process is the dew-point temperature.