Wood Veneer dryers can be classified based on heat transfer methods, veneer conveying methods, and the circulation direction of hot air. Below are the detailed classifications:
1. Classification by Heat Transfer Method
- (1) Air Convection Type: Heat is transferred to the veneer through circulating hot air.
- (2) Contact Type: Heat is transferred to the veneer directly through contact with a heated plate.
- (3) Combined Type: Combines convection heat transfer with other heat transfer methods to transfer heat to the veneer. Common combinations include:
- Convection-contact type
- Infrared-convection type
- Microwave-convection type
2. Classification by Veneer Conveying Method
- (1) Mesh Belt Dryer: The wood veneer is conveyed using a mesh belt, suitable for thinner veneers, such as face and back veneer.
- (2) Roller Dryer: The veneer is conveyed using rollers, suitable for thicker veneers or specific drying requirements, such as core veneers.
3. Classification by Hot Air Circulation Direction
- (1) Longitudinal Ventilation Dryer
- Hot air circulates along the length of the veneer dryer.
- If the airflow direction is the same as the veneer’s movement, it is referred to as co-current flow; if opposite, it is called counter-current flow.
- Characteristics:
- The circulation path is long, resulting in significant airspeed loss along the path and uneven airflow, leading to poor drying efficiency.
- (2) Cross Ventilation Dryer
- Hot air circulates along the width of the dryer.
- Airflow can move parallel to the veneer surface or be sprayed perpendicularly onto the veneer surface.
- Characteristics:
- The circulation path is shorter, airspeed loss is smaller, and airflow is more uniform, resulting in better drying efficiency.
- Optimal Design:
- High-speed airflow sprayed perpendicularly onto the veneer surface from both directions (cross circulation) can break through the boundary layer, accelerating drying and achieving the best results.
