IMPROVED FLAT TUB WITH TEARDROP-SHAPED INdentATION

Abstract

The proposed useful solution involves a new actively machined flat tube configuration with teardrop-shaped indentations on the surface, aimed at improving heat transfer and heat-water efficiency in heat exchangers. The flat tube has a cross-sectional area of ​​axb mm, with a size ratio a / b = 0.4-0.6. The inner surface of the tube has teardrop-shaped indentations; each indentation has a relative length Ld / a = 1.0-1.5, a relative width dd / a = 0.4-0.6, and a relative depth hd / a = 0.1-0.2. The indentations have a rounded head and a tapered tail in the direction of flow. The indentations are distributed along the two flat surfaces of the tube, with a relative distance between them S / a = 2-4. The direction of the indentations is aligned with the main flow direction to reduce flow separation and limit the formation of vortices behind the tube. The tube configuration with teardrop-shaped indentations enhances heat transfer by 7.9-54.7%, and the maximum thermohydraulic efficiency reaches 1.035 when using a smooth tube as a reference.Therefore, this solution is a useful option that can be considered for application in pipe fabrication and in practical heat exchanger applications.