A Hybrid System of Nocturnal Radiative Cooling and Indirect Evaporative Cooling to Augment Efficiency

In this paper, the results of an investigation on a hybrid system of nocturnal radiative cooling, cooling coil and indirect evaporative cooling is studied. During a night in summer, the nocturnal radiative cooling provides required chilled water for a cooling coil unit. The cold water is stored in a storage tank. During eight working hours of the next day, hot outdoor air is pre-cooled by means of the cooling coil unit and then it enters anindirect evaporative cooling unit. In this period, temperature variation of the conditioned air is investigated. Three sources provide secondary air ofindirect evaporative cooling. The sources are outdoor air, the air leaving the cooling coil and the air leaving the indirect stage (regenerative). The investigation is done for conditions of two cities of Tehran and Kerman. This hybrid system complements indirect evaporative cooling as if it consumes low energy to provide cold water and is able to fulfill the comfort conditions. The results obtained demonstrate that the hybrid system has a significantly higher efficiency than stand-alone indirect evaporative cooling in the both cities. Also, the regenerative model provides the best comfort conditions. Thus, this environmentally clean and energy efficient system can be considered as an alternative to the mechanical vapor compression systems.

Keywords:

Nocturnal cooling , Indirect evaporativecooling , Cooling coil , Hybrid cooling system