A first-of-its-kind two-stage dew-point evaporative cooler with high energy efficiency and compact design

This research addresses the long-standing high working air ratio problem of conventional single-stage dew-point evaporative coolers (DPECs) by developing a first-of-its-kind two-stage DPEC. The system introduces a novel indirect cooling mechanism that distributes the cooling load across two sequential stages, significantly reducing the product air required for evaporation and enhancing energy efficiency. The key component of the cooler is a compact heat and mass exchanger capable of handling four fluid flows within a single unit, ensuring high performance and space efficiency. Tested under subtropical climate conditions, the developed two-stage DPEC demonstrated exceptional performance, preserving 88–90 % of the product air while maintaining its temperature below the wet-bulb and near the dew point. Additionally, it achieved a coefficient of performance (COP) of 15–17 under actual operating conditions, far surpassing conventional air conditioning systems. These results highlight its superior cooling capacity, energy efficiency, and compactness compared to existing single-stage M–cycle DPECs. The two-stage DPEC, with its high efficiency and compact design, is a scalable and sustainable cooling solution for real-world heating, ventilation, and air conditioning (HVAC) systems, offering significant energy savings and improved thermal comfort. This study underscores its potential as a transformative technology for reducing energy consumption and addressing cooling demands in subtropical and tropical climates.