1. The principle of fresh air system is that in a closed room, fresh air is sent into the room by special equipment on one side and then discharged to the outside by special equipment on the other side, and a "fresh air flow field" will be formed indoors, thus meeting the needs of fresh air ventilation in the room. At the same time of air supply, the air entering the room is filtered, disinfected, sterilized, oxygenated and preheated (in winter). When the exhaust air passes through the main engine, it exchanges heat with the fresh air, and most of the recovered energy is sent back indoors through the fresh air. Make use of the scheme of forming clean space on a large scale to ensure that the air entering the room is clean. In this way, indoor air can purify the environment.
2. Exhaust fan (also called negative pressure fan, negative pressure fan, etc.). ) Air convection is used to keep the room in a negative pressure state all the time, forming suction, continuously sucking in outdoor air and discharging indoor sultry air, thus achieving the effect of ventilation and cooling.