| Elastic tube bundle heat exchanger uses fluid-induced tube vibration to realize passive enhanced heat transfer.Due to the structural characteristics of traditional planar elastic bundle tube,the heat transfer area per unit volume of heat exchanger is small and the comprehensive heat transfer performance is low,which makes the overall performance of the heat exchanger poor.Therefore,a helical elastic tube bundle heat exchanger was proposed.The effects of tube bundle structure parameters and fluid flow parameters on the vibration response and heat transfer characteristics of the helical elastic tube bundle were systematically studied by using a two-way fluid-solid coupling calculation method combined with rough calculation and actuarial calculation strategy.The structure of the helical elastic bundle heat exchanger was improved by adding hollow tube and baffle plate in order to obtain better heat transfer equipment with better heat transfer performance.The specific work is summarized as follows:(1)Based on the design concept of existing elastic tube bundle heat exchangers that effectively utilize fluid-induced vibration to enhance heat transfer,combined with traditional shell-and-tube heat exchangers and double-tube heat exchangers,a helical elastic tube bundle heat exchanger was proposed with miniaturization,light weight and compactness as the basic design criteria,which makes it efficient,reliable and flexible.(2)The geometric model of the helical elastic bundle and its uniform shell-side fluid domain was established,the internal mechanism of heat transfer enhancement by tube vibration induced by shell-side fluid is studied,and the effects of tube bundle structure parameters and fluid flow parameters on the vibration response of the tube were systematically studied.The results show that the synergy level in one vibration period increases by 6.38%.The tube vibration is mainly in the direction of gravity,and the vibration of the middle bundle is more severe.The increase of the helix diameter of the tube and the inlet velocity increases the vibration amplitude of the tube,but does not affect the vibration frequency.However,increasing the winding number and the number of tubes can increase the vibration amplitude of the tube and reduce the vibration frequency.(3)Based on the analysis of vibration response of the tube and the internal mechanism of vibration-enhanced heat transfer,the effects of tube structure parameters and fluid flow parameters on heat transfer characteristics of the helical elastic bundle were systematically studied.The results show that increasing the helix diameter of the tube can improve the heat transfer performance of the tube,while increasing the winding number and the number of tubes can reduce the heat transfer performance of the tube,but the performance of vibration-enhanced heat transfer can be improved.When the winding number of the tube is 5,7 and 9,the fluid-induced vibration improves the heat transfer performance of the tube by 1.93%,3.40% and3.59%,respectively,and the PEC value of the heat exchanger is 1.0258,1.0366 and1.0370,respectively.When the flow velocity increases in the range of 0.1-0.7 m/s,the heat transfer performance of the tube increases by 0.38%,0.89%,1.93% and13.65%,respectively,and the comprehensive heat transfer effect of the heat exchanger is better.(4)The structure of helical elastic bundle heat exchanger was improved by adding hollow tube and baffle plate in order to obtain better heat transfer equipment.The results show that when the helical elastic bundle in the heat exchanger is increased from one to two layers,the effect of fluid-induced vibration on enhanced heat transfer is better.After adding hollow tube and baffle plate,the vibration intensity and heat transfer performance of the tube are improved.The heat transfer performance of the tube is increased by 7.46% and 6.41% respectively due to fluid-induced vibration,and the PEC of the heat exchanger is increased by 5.49%and 7.35% respectively.Adding hollow tube and baffle plate in the heat exchanger is an effective measure to improve heat transfer performance of the helical elastic bundle heat exchanger.Figure [65] Table [11] Parameter [103]... |
