The Study And Structure Adjustment Of Heat Transfer Characteristics In A Three Dimensional Finned Tube

With the increasingly severe energy situation in China,it is becoming more and more important to save energy and reduce emissions and encourage energy efficiency.In order to improve the efficiency of energy utilization,it is becoming more and more urgent to develop more efficient heat exchange equipment.And the intensified heat transfer of the heat exchanger has always been the key issue of the research.In this paper,the numerical simulation method is used to investigate the heat transfer characteristics of the three dimensional ribbed tube,and the structural adjustment of the size and layout of the ribbed tube inside the three dimensional ribbed tube is carried out,which provides a new idea for enhancing heat transfer in the tube of the heat exchanger.In this paper,the heat transfer characteristics of three dimensional ribbed tubes under different Reynolds numbers are simulated,and the simulation results are verified by experimental means.After comparing the eight sets of simulation results with experimental results,it is found that the accuracy of the calculation meets the requirements and the simulation results are reliable.The simulation results show that when the Reynolds number is less than 15000,the velocity of the air flow between the ribs is lower and the heat transfer resistance is increased,and the heat transfer effect is not as good as that of the normal tube.When the Reynolds number is greater than 15000,the velocity of the gas flow in the tube is increased and the boundary layer is destroyed,which can enhance the effect of heat transfer.Through the adjustment of the fin size and layout of the orthogonal design of 3-D IFT,found that the rib height is the main factor affecting the heat transfer effect,the small rib pipe flow,boundary layer thinner,smaller flow resistance,better effect of heat transfer;the main influence of rib circumferential spacing between the fins flow velocity,circumferential rib spacing increases,intercostal air velocity is enhanced,the better effect of heat transfer,and reduces the phase spacing increasing rib fin number,reduce the flow resistance;the heat transfer characteristics of rib width of 3-D IFT with little effect,increase the rib width can make the heat transfer coefficient increases,but at the same time the resistance increases,reducing the thermal coefficient of performance.The smaller the distance between the longitudinal ribs,ribs per unit length of the number of the more,the better effect of heat transfer,but the resistance increased,the thermodynamic performance coefficient of 3-D IFT is small.Through the structural adjustment of the orthogonal test,the optimum structure size of the three dimensional ribbed tube is 1mm height,rib width 1mm,rib circumferential distance 32.044 mm and rib longitudinal spacing 2mm.The dimensionless width of the rib B/D=0.0196,the dimensionless rib width H/D=0.0196,the dimensionless interribbed interphase distance S/D=0.6283,the dimensionless rib longitudinal distance Pt/D=0.1176.After structural adjustment,the heat transfer enhancement ratio of three dimensional internal ribbed tube is 1.1548,the ratio of resistance increase is 1.5419.