Hybrid indirect and regenerative evaporative cooling design for enhanced cooling density

Indirect evaporative coolers (IEC) enable low-energy cooling of air without humidification. While a conventional IEC is limited to cooling incoming air down to its wet-bulb temperature, a regenerative IEC (M-cycle) can cool air further, approaching its dew point. In this study, a hybrid IEC-M-cycle design is proposed and evaluated for enhanced cooling, with initial cooling in the IEC portion, followed by subsequent cooling in the M-cycle section. Such a hybrid design produces the same product air temperature as a stand-alone M-cycle with 12-18 % lower heat transfer area. At a fixed system size, around 20 % higher cooling rate is achieved with the hybrid system while achieving the same product air temperature by optimizing the area fraction of the IEC section, and the recirculation flow rate. Overall, the proposed hybrid design enables improved indirect evaporative cooling at lower system sizes.