Introduction to the results:

The evaporator heat exchange tube with a composite cavity structure surface jointly developed by our school and Jiangsu Province is machined on the outer surface of the tube to form a composite cavity structure composed of fins with transverse fins, which is used to strengthen the outer surface of the heat exchange tube. Boiling heat exchange is especially suitable for boiling and vaporizing the liquid immersed in it on the outer surface of the tube, or evaporating the liquid flowing through the outer surface of the tube. Currently, it is mainly used in flooded refrigeration evaporators. This invention is proposed based on the evaporation theory of liquid micro-layers at the bottom of the bubble and the phenomena found in low-level boiling heat transfer experiments. A machining method is used to form a composite cavity structure composed of fins with transverse fins on the outer surface of the tube to suppress the free growth of bubbles and change the shape of the bubbles, thereby expanding the area of the liquid micro-layer at the bottom of the bubble, and significantly improving the boiling heat transfer coefficient between the outer surface of the heat exchange tube and the liquid outside the tube. The product is suitable for current domestic and foreign central air-conditioning system evaporators, and breaks through foreign technical blockade in this field, improves the ability of local central air-conditioning companies to participate in international competition, and promotes the export of local central air-conditioning units.

Main performance indicators:

1. The outer diameter of the pipe is 18~25mm, and the number of teeth per inch is 42~58;

2. Eddy current flaw detection: Comply with GB/T5248 standard; airtightness test: 2.8MPa air pressure test;

3. Tensile strength: ≥205MPa; yield strength: ≥62MPa; elongation: ≥40%; grain size: ≥0.015

4. Boiling heat transfer coefficient: 20kW/m2K.