The effectiveness of multi-stage dehumidification—humidification for improving the cooling ability of evaporative air conditioning

Abstract

Evaporative cooling systems are commonly used because of their low initial and running cost. These systems have a great potential to provide thermal comfort in places where humidity is low; however, they are less efficient where air humidity is high. The present work proposes a system that can be used either in dry or humid climates by introducing a new concept: multi-dehumidification—humidification processes that can be coupled with evaporative cooling systems. The effect of this modification on the production of low temperature is investigated. To validate the model, the improvement carried out is quantified by comparing the performance of a classical evaporative cooling system and with the proposed single-step dehumidification—humidification system. It is found that increasing the number of dehumidification—humidification processes greatly reduces the air temperature and improves the performance of the system. In some cases, the reduction in the air temperature exceeds 20 °C in humid climates, a result that is comparable with those obtained by vapour-compression cooling systems. In conclusion, the proposed system delivers the low cost benefits of evaporative cooling systems with the high performance of conventional compression cooling systems.