Numerical study on flow and heat transfer characteristics of a novel centrosymmetric tube with bent inner fins based on experiment

Enhancing heat transfer within the tube is essential for minimizing the size of fire tube boilers, air preheaters, and solar collectors. A novel centrosymmetric tube with bent inner fins was proposed, and the tube inclues the flush and staggered structures. Numerical simulations based on experiment were conducted to investigate the impact of individual factors on flow and heat transfer characteristics. A genetic algorithm backpropagation neural network (GA-BP neural network) model was developed to analyze the interplay between multiple parameters. The fin thickness, fin bending angle, fin bending position, inlet fluid temperature, and average fluid Reynolds number were chosen as independent variables. Various flow and heat transfer indices were utilized to assess the thermal-hydraulic performance under constant wall temperature or constant heat flux conditions. The heat transfer enhancement mechanism of the bent inner fins was explored. The correlation formulas for the Nusselt number and friction coefficient were derived. The correlation error is below 10 %. Inlet fluid temperature, average fluid Reynolds number, and fin thickness were recognized as the primary factors affecting flow and heat transfer. The tube with the base structure can operate safely below 1173 K. The overall heat transfer performance of the inner finned tube is more than 1.7 times that of the plain tube. These findings are crucial for guiding the design and application of enhanced heat transfer tubes.