Simulation-based performance analysis of residential direct evaporative coolers in four climate regions of Iran

Abstract

In this paper, the effect of direct evaporative cooling (DEC) system design parameters, including the cooling pad saturation efficiency, the airflow rate, and the thermostat set-points on the system electricity and water consumption, is evaluated in four different climates of Iran according to Köppen-Geiger classification. EnergyPlus is used to perform the simulations for a typical residential apartment. The results show that using pads with a 30% higher saturation efficiency can significantly decrease the electricity and water consumption by up to 50.0% and 29.6%, respectively, because of the working time reduction. The maximum impact is in Esfahan city in cold desert climate as its wet-bulb temperature is lower than other investigated climates. Besides, increasing the airflow rate from 3000 m3/h to 6000 m3/h leads to 43.4%–55.2% reduction in electricity consumption in different climates, although the water consumption increases by 20.5%–58.8%. According to the results, by using the DEC system with 80% saturation efficiency and 6000 m3/h airflow rate, the average indoor relative humidity and CO2 concentration is 42.3%–48.5%, and 450 ppm–470 ppm, respectively, in different climates, which can provide acceptable indoor air quality. Increasing the saturation efficiency or decreasing the airflow rate increases the indoor relative humidity and CO2 concentration. The results are also compared with a typical packaged terminal air conditioner (PTAC). The total hours when the indoor relative humidity is out of comfort zone in the DEC system, with 60% saturation efficiency, are about 92% lower than the PTAC system, on average. Moreover, with 24/26 °C thermostat set-points, the PTAC system consumes 234%–265% more electricity than the DEC one with 80% saturation efficiency in different climates.