Numerical Simulation Of Low Temperature Flow And Heat Transfer Of Natural Gas In Sprial-wound Heat Exchanger

The sprial-wound heat exchanger is a shell and tube heat exchanger with a highly compact structure,high performance and a special internal structure.At present,most of them stay in experimental research.By constructing experimental models,analyzing experimental data,using some mathematical tools,fitting expressions with certain correlations,and numerical simulations of wound tubular heat exchangers are few.This is mainly because the shell-side structure of the spiral-wound heat exchanger is relatively complicated,and the winding bundles in the shell side are intertwined and closely arranged,and there is still no uniform and complete calculation method.In this paper,the numerical simulation method is used to simulate the numerical calculation of the tube and shell processes by establishing a single-layer multi-turn tube bundle model.The physical quantity cloud maps of velocity,temperature and pressure inside the field space are obtained,and verify the grid independence.The flow heat transfer formulas of tube test and shell test were established.The influence factors and change trends of Nusselt number,drag coefficient and comprehensive evaluation index PEC under different structural parameters were analyzed and compared.The winding tube side model was established.The velocity field and temperature field in the tube were simulated.It was found that the centrifugal force at the spiral elbow had a strong turbulence effect,forming a secondary flow and greatly enhancing the convective heat transfer inside the tube.The effects of different factors,tube diameter,winding diameter and pitch on single factor and multi-factors on the heat transfer performance in the tube were compared.The winding shell side model was established,and the velocity field,temperature field,pressure field and density field of the shell measurement space were simulated.It is found that the velocity distribution is uneven,the velocity near the pipe wall is large,and the velocity away from the pipe wall is small;the radial velocity gradient is large,and the axial mainstream velocity gradient is small.The effects of different speeds,center tube diameter,coil pitch and tube diameter on single factor and multi-factor flow heat transfer performance were analyzed.According to the simulation results,the orthogonal experimental method widely used at present is used to fit the flow-heat transfer correlation of the shell side.The shell-and-tube coupling model was established,and the interaction between the shell and the tube was analyzed,and the model of the medium phase transformation inside the tube was solved.