Air cooler (evaporative air conditioner) cooling principle is: when the fan runs into the cavity to generate negative pressure, the wet curtain makes the external air flow through the porous surface wet curtain to force the air dry bulb temperature to the wet bulb temperature close to the air outside, the outlet of fan dry bulb temperature than the outdoor dry bulb low temperature of 5-12 DEG C (dry areas up to 15 DEG C), the air is dry, the temperature difference is bigger, the cooling effect is better. Because the air is always introduced from outside (now called positive pressure system) so as to keep the indoor air fresh; at the same time as a result of this machine use evaporative cooling principle, it has double functions of cooling and humidification (relative temperature up to about 75%), used in the textile and knitting workshop, not only can improve the cooling and humidification the conditions, but also purify the air, reduce the process of knitting needle fracture rate, improve the quality of textile products. Air cooler (evaporative air conditioner) are arranged around the use of special materials like wet curtain, has a large surface area, through the water circulation system of wet curtain continuous humidification; in the wet curtain cooling fan with high efficiency and low noise energy-saving fan, when the fan is running, wet curtain cooling fan to generate negative pressure that makes the external air flowing through the porous moist wet curtain into the machine, because the heat absorption of the wet curtain of water evaporation, forcing the wet curtain air cooling system. At the same time, because the water on the wet curtain evaporates from the air flowing through the wet curtain, the humidity of the air is increased.