Performance evaluation of a solar powered solid desiccant evaporative cooling system with different recirculation air ratios

The evaporative cooling technology (ECT) has been regarded as an effective alternative to conventional vapour compression systems due to its energy saving and eco-friendly features. Moreover, when integrating with a solid desiccant unit, ECT can further extend its application in hot and humid environments. This paper proposed and evaluated a solar-assisted solid desiccant Maisotsenko cycle (M−cycle) based indirect evaporative cooling (IEC) system with different recirculation air ratios. Three other cooling systems, including stand-alone Direct Evaporative Cooling (DEC), stand-alone M−cycle IEC, and conventional solid desiccant evaporative cooling system (SD-DEC), were also simulated and compared with the proposed system under various ambient conditions. These systems were assessed in terms of supply air temperature, indoor relative humidity ratio, water consumption rate, coefficient of performance (COP) and solar fraction in this study. A case study of the proposed system was carried out under two typical Australian climates, Darwin and Melbourne. The results indicated that the solar-assisted solid desiccant cooling system integrated with M−cycle IEC had the best cooling performance compared with the other three systems, particularly in hot and humid areas. When increasing the recirculation air ratios from 0% to 60%, a maximum reduction of 23.1% and 41.9% could be observed in the system’s supply air temperature and humidity ratio, respectively. The highest COP was 0.89 when the inlet air temperature was 30 °C, and the COP value would vary as the inlet air temperature and humidity ratio increased. However, a higher water consumption rate was also observed, 31.36% to 57.94% more water would be consumed. This indicates that it requires selecting a proper recirculation air ratio for different climates to achieve the best performance.