The exhaust fan can be divided into partition type (both sides of the partition hole are free space, air exchange from one side of the partition wall to the other side), conduit exhaust type (one side enters from the free space, while the other side exhausts through the conduit), conduit intake type (one side enters through the conduit, while the other side exhausts from the free space), full conduit type (both sides of the exhaust fan are equipped with conduit, Intake and exhaust through ducts). According to the form of air flow, it can be divided into centrifugal type (air enters from the direction parallel to the rotating shaft and discharges from the direction perpendicular to the shaft), axial flow type (air enters from the direction parallel to the rotating shaft and still discharges from the direction parallel to the shaft) and cross flow type (air enters and discharges from the direction perpendicular to the shaft). There are three ways of air exchange for exhaust fan: exhaust type, suction type and combined type. The exhaust type enters the air from the natural air inlet and exhausts the dirty air through the exhaust fan; the suction type inhales the fresh air through the ventilation fan and exhausts the dirty air from the natural exhaust port; and the use type is that both the suction and the exhaust are completed by the ventilation fan. The exhaust fan belongs to a kind of axial flow fan. It is mainly used in negative pressure ventilation and cooling engineering and is called exhaust fan. The exhaust fan has the characteristics of super large air duct, super large blade diameter, super large exhaust air volume, ultra-low energy consumption, low speed, low noise, etc. Use together with cooling water curtain can solve the problem of ventilation and cooling at one stroke. During the operation of exhaust fan, a negative pressure environment will be formed in the room. If a cooling water curtain is installed on the other side of the air outlet of the exhaust fan, the exhaust fan will not only discharge the indoor hot air out of the outdoor, but also enter the indoor low-temperature air with rich water vapor through the cooling water curtain into the indoor intake, so as to achieve the effect of ventilation and cooling.
