D. Fans series industrial fan is a new type of HVLs energy-saving super large industrial fan independently developed by King ventilation based on aerodynamic principle. It has low speed, large air volume and no dead angle air circulation, and pushes the effect of class 1-3 similar to natural wind. It can eliminate high temperature and muggy, balance air humidity, improve space oxygen content, smoke exhaust and dust removal and reduce bacterial concentration, It can effectively solve the problems