The mall is densely populated, with obvious heat and moisture dissipation from the human body, and the display area of goods is prone to produce odors. If the ventilation system only provides simple air exchange, it is difficult to ensure the temperature and humidity balance between fresh air and indoor air. Plate heat exchangers can perform pre cooling or preheating treatment on fresh air, making the temperature of the fresh air close to the indoor temperature and avoiding discomfort for customers and employees caused by overcooling or overheating of the fresh air. At the same time, continuous and stable ventilation combined with efficient heat exchange can quickly remove indoor polluted air and odors, always keeping the air fresh, creating a comfortable shopping environment for customers, extending their stay time, and also creating good working conditions for employees, improving work efficiency.