Heat exchangers are mainly made of materials such as aluminum foil, stainless steel foil, or polymers. When there is a temperature difference between the airflow isolated by aluminum foil and flowing in opposite directions, heat transfer occurs, achieving energy recovery. By using an air to air heat exchanger, the heat in the exhaust can be utilized to preheat the fresh air, thereby achieving the goal of energy conservation. The heat exchanger adopts a unique point surface combination sealed process, which has a long service life, high temperature conductivity, no permeation, and no secondary pollution caused by the permeation of exhaust gas.