Numerical and Experimental Analysis of a Dew-Point Cooling System with a Psychrometric Energy Core

Indirect evaporative cooling (IEC) systems can decrease air temperature without increasing its moisture content and with water as the only fluid circulated. The performance of any evaporative cooling system is largely dependent on the structure and design of the heat and mass exchanger. By modifying the exchanger of the IEC system, air could be cooled below its wet bub temperature and towards the dew point temperature. In this study a numerical analysis is carried out for a dew point cooling system based on a psychrometric energy core (PEC) with a cross-flow heat and mass exchanger. A detailed mathematical model was developed for the energy core with the cross-flow exchanger using Matlab. The coupled heat and mass transfer equations were solved using a fully implicit accurate finite difference scheme to predict air temperature and humidity distributions throughout the dry and wet channels. The numerical model developed has been validated using published results. With an intake air of 30°C temperature and 50% RH and a working-to-intake air flow ratio of 0.33, the system attained a wet bulb effectiveness of 114.42% and a dew point effectiveness of 80.38% with 5 mm channel height and 0.8 m channel length. In addition, an experimental setup has been built and an indirect evaporative cooling unit with a cross-flow heat and mass exchanger employing dry and wet air channels has been tested to assess the feasibility of using such indirect evaporative cooling systems under various operational and ambient conditions.