Energy and exergy analysis applied to the evaporative cooling process in air washers

This paper presents a study on the performance of the evaporative cooling process in air washers with the use of mass balances, energy and exergy equations. Usually, the performance of these devices is described in terms of their saturation effectiveness based on energy analysis. This method, however, is inappropriate to identify the main sources of irreversibility within the process. It is also unsuitable to give the optimum conditions for operating the system with a proper use of energy resources. Thus, an exergy analysis was developed to complement the energy analysis of the process. A mathematical model based on mass and energy balances was used to determine the water and air properties in the washer. The influence of the humidity and temperature of the air and water at the inlet, the washer length in the saturation effectiveness, and the second law efficiency was investigated. The results showed that the best condition of the intake air for obtaining thermal comfort does not coincide with the best condition for the thermodynamic performance of the system. The energy and exergy analyses were carried out simultaneously to generate the conditions required for optimum performance with minimal exergy depletion.

► A model based on energy and exergy is proposed for the study of the air washers.
► The efficiency is investigated in terms of saturation effectiveness and second law efficiency.
► The temperature and humidity are based on an analytical model.
► The effect of five parameters on the performance of the system is investigated.