Research And Application On Heat Transfer Performance And Fluid Flow Resistance Of High Efficiency Self-support Twisted Tube Heat Exchanger

With the development of society, the energy crisis is getting worse. At the national policy of energy conservation promotion, high efficiency and energy saving technology have been developed rapidly. Heat exchangers are the key equipments in the thermodynamic processes and it is of great significance to apply Enhanced heat transfer technology to heat exchangers. As a New high efficiency heat exchanger, twisted tube heat exchanger is improved based on traditional tubular heat exchanger:with twisted tubes, pressed and twisted by smooth tube, instead of smooth round tubes in tube-side, self-supporting structure rather than the traditional baffle plate structure in shell-side. In this paper, performance tests were conducted on single twisted tube and twisted tube heat exchanger, and experimental results were compared with software simulation.On the steam-water heat test rig, heat transfer and flow resistance performance of 5 five twisted elliptical tubes with different screw pitch and round tube were tested. The experiment tests show that the twisted tubes can enhance heat transfer well. Compared with the round tube, the twisted tube can enhance the heat transfer by 5%～40% in test of Reynolds number range.On the basis of single tube research, A double tube shell heat exchanger was designed and manufactured, and was used to test the thermal performance of the twisted tube heat exchanger in different conditions.On the basis of single tube research, the relational correlation equations of Reynolds number, Nusselt number, Prandtl number were given respectively by the multiple regression; the obtained relationship of tube internal friction coefficient and Reynolds number also provide useful guidance for engineering design in tube type choice. With HTRI software to simulate the same structure under the traditional tubular heat exchanger, we compared the obtained experimental results with the traditional twisted heat exchanger tube-shell heat exchanger. It was found that pressure drop of twisted tube heat exchanger is only 15%～20% higher than that of traditional tubular heat exchanger in test of Reynolds number range,. This study perfected the heat transfer of twisted tube and twisted tube heat exchanger at higher Reynolds number, and provided helpful guidance for the optimized design of heat exchanger.