Study on the impact of water spraying parameters on the performance of polypropylene film-based indirect evaporative cooling equipments

The performance of an indirect evaporative cooler (IEC) is affected by the water distribution method and droplet parameters. This study combines numerical simulations with experimental validation to analyze the impact of factors like spraying method, droplet size, and initial velocity on the cooling efficiency of a polypropylene film-based IEC core. The simulation shows that the air temperature in the channel drops when a vertical directly upper spraying method with 1 mm droplets and an initial velocity of 1.5 m/s is used. Specifically, the temperature stabilizes at 28.2 °C in the directly upper spraying area and 26.6 °C in the directly lower spraying area (with 0.1 mm droplets and 1.5 m/s velocity). The directly lower spraying method reduces the outlet temperature by 1.6 °C, achieving a 23.71 % improvement in cooling performance. The 45° inclined spraying method shows a slight increase of 0.2 °C compared to vertical directly upper spraying, with a 2.5 % decrease in cooling efficiency; in terms of droplet size, the directly upper spraying method works better with 0.8 mm droplets than with 1 mm ones. Larger droplets (1.5 mm or 2.0 mm) lead to an uneven temperature distribution. For the directly lower spraying method, 0.05 mm droplets perform better than 0.08 mm droplets, with larger droplets (0.1 mm or 0.2 mm) causing an uneven distribution. The initial droplet velocity has minimal impact on cooling performance. Overall, the lower vertical spraying method achieves the best cooling performance for the IEC.