Research On Working Characteristics And Heat Transfer Enhancement Of Shell And Tube Heat Exchanger Enhanced Composite Screw Insert

Shell-and-tube heat exchanger has the advantages of stable structure,high efficiency of waste heat recovery and a wide range of applications,so it is widely used in petrochemical,material processing,bulk material manufacturing,thermoelectric and nuclear power generation and other fields.However,due to the limitation of the manufacturing process and the easy scaling of the tube wall in the use process,the working performance of the shell-and-tube heat exchanger is reduced,which seriously affects the efficiency of the enterprise.Therefore,the active and passive enhanced heat transfer technology arises at the historic moment.However,the active heat transfer technology requires complex power structure and small scope of application,while the combined self-rotating and spiral twisted tape,which is widely used in passive heat transfer technology,also has some shortcomings,such as tedious installation,high cost,complex structure and so on.A new type of in-tube spoiler element-enhanced composite spiral plug-in is presented in this paper.The structure of the combined rotor is creatively combined with the structure of the rotary spiral twisted tape.The working characteristics and heat transfer performance of the enhanced composite spiral plug-ins with different structures are studied through the visualization device designed and built by ourselves and the shell-and-tube enhanced heat transfer test-bed of the research group.(1)Screw plug-in with single helix structure has higher rotational speed and lower resistance in the visualization tube.Under the same helix number,the working performance of the narrow blade screw plug-in is better.(2)Under the same experimental conditions,the heat transfer performance,resistance characteristics and comprehensive heat transfer performance of the plug-in with single helix structure are better,and the comprehensive heat transfer performance of the plug-in with wide blade is better under the same helix number.When the inlet section length is 150mm,the comprehensive heat transfer performance of the single helix wide blade reinforced composite helix plug-in achieves the best effect,which is 7.42%higher than that of the single helix wide blade plug with the inlet section length 50mm.(3)The structure of the spiral plug-in is optimized based on the above experiments.The experimental results show that the comprehensive heat transfer performance of the plug-in with a single spiral wide blade with a circular hole with a diameter of 5mm or 6mm is the best,which is 9.47%,6.58%and 6.73%higher than that of the ordinary spiral plug-in,respectively.