Numerical study on the cooling performance of various arrangements of medium-gap-medium for direct evaporative cooling systems

Medium is one of the most critical components in direct evaporative cooling systems. The current study is to investigate the effect of various arrangements of medium-gap-medium (MGM) on the performance of direct evaporative cooling systems, and to find the most practical MGM arrangement for engineering application. Different widths of medium 1 zone, gap zone and medium 2 zone are extensively studied by numerical simulation. Results indicate that: (1) the cooling efficiency and air-side pressure drop at air speed of 1.5 m.s(-1) increase from 79.8% to 91.9% and from 14.30 Pa to 14.76 Pa, respectively when the width of gap zone increases from 50 mm to 300 mm; (2) the cooling efficiency and air-side pressure drop at air speed of 1.5 m.s(-1) increase from 83.8% to 93.5% and from 14.42 Pa to 25.04 Pa, respectively when the width of medium 1 zone increases from 100 mm to 250 mm; (3) the cooling efficiency and air-side pressure drop at air speed of 1.5 m.s(-1) increase from 84.1% to 93.9% and from 14.40 Pa to 25.05 Pa, respectively when the width of medium 2 zone increases from 50 mm to 200 mm; (4) the cooling efficiency gradually tends to its maximum when the sum width (the total width of medium 1 zone, gap zone and medium 2 zone) reaches to 350 mm. Finally, the arrangement of 150 mm medium 1 zone, 100 mm gap zone and 100 mm medium 2 zone is found to be the most practical MGM arrangement.