During the food processing, steaming, baking and other processes generate a large amount of humid and hot air. If directly discharged, it will cause energy waste and may affect the surrounding environment. In the ventilation system of food processing plants, plate heat exchangers can recover heat from humid and hot exhaust air for preheating fresh air or heating production water. For example, in the bread baking workshop, plate heat exchangers are used to transfer the heat from the exhaust air to the fresh air entering the workshop, which not only ensures air circulation in the workshop but also reduces the energy consumption of heating the fresh air. In addition, in the ventilation of food cold storage, plate heat exchangers can prevent external hot air from directly entering, reduce the loss of cold storage capacity, maintain a low temperature environment in the cold storage, and reduce the operating costs of the refrigeration system.