Solar water heaters, solar stoves, solar dryers, and many other devices that use solar energy have been used by many people. These devices have a key part—the collector.
The role of the collector is to collect the scattered solar radiation energy. Common collectors are flat collectors and concentrating collectors. In the following, a flat plate collector widely used in solar water heaters is taken as an example to discuss the influence of the welding process on the heat transfer efficiency of the solar collector.
Ultrasonic welding and laser welding
Laser welding and ultrasonic welding are the two main processes currently used in solar collector welding.
Ultrasonic welding is the use of mechanical vibration energy of ultrasonic frequency (over 16KHz). Under pressure, the two metal surfaces are rubbed against each other to form a molecular layer infiltration. Close to cold working.
Laser welding is the use of high-energy laser pulses to locally heat materials in small areas. Energy is diffused into the interior of the material through thermal conduction, and the material is melted to form a specific molten pool to achieve the purpose of welding. Belongs to thermal processing.
Compared with ultrasonic welding, laser welding has the advantage that it does not need to apply pressure to the workpiece to be welded, so the overall deformation of the workpiece is small, and the integrity of the surface of the endothermic coating is maximized.
Effect of welding process on heat transfer efficiency of collector
The most direct judgment method for the performance of flat solar products is the heating efficiency of the water tank. The heating efficiency of the water tank is affected by a series of factors, and the heat absorption plate is the most important factor. Laser welding is used to weld the solar collector plate core runner with a highly selective endothermic coating. Weld a spot a few millimeters apart on the endothermic coating to combine strength and completeness of the endothermic coating. Makes the board core have higher heat absorption efficiency.