NUMERICAL STUDY ON HEAT TRANSFER AND FLOW RESISTANCE CHARACTERISTICS OF MULTI-HEAD TWISTED SPIRAL TUBE

A numerical calculation model of multihead twisted spiral tube was established. In the range of Reynolds number from 5000 to 35000, the influence of different twisted structure on the flow and heat transfer characteristics of the multihead twisted spiral tube was studied by numerical calculation. Numerical calculation results indicate that the Nusselt number and friction coefficient increase with the increase in the ratio of outside and inside diameter of the cross-section, the increase in the number of twisted nodes, and the increase in the number of twisted spiral tube heads. Under the condition of the same spiral structure and the same hydraulic diameter, the heat transfer performance of the multihead twisted spiral tube is better than that of the spiral smooth tube. In addition, through artificial neural network analysis, the ratio of outside and inside diameter of the crosssection, number of twisted nodes, and the number of twisted spiral tube heads were optimized to promote the comprehensive heat transfer performance. The performance evaluation criterion is the highest when the ratio of outside and inside diameter of the cross-section is 25/22.5, the number of twisted nodes is 3, and the number of twisted spiral tube heads is 3, which is 1.849 of the spiral smooth tube.