Numerical Analysis On Flow And Heat Transfer Characteristics Of Airfoil Printed Circuit Panel LNG Vaporizers

In recent years,Printed circuit heat exchangers(PCHE)have been often used in Floating Storage and Regasification units(FSRU)on offshore oil platforms.It can provides excellent safety and heat transfer performance,and keep high efficiency in high temperature and high pressure environment,unaffected by the shaking of offshore oil platforms,which is due to its compact structure,small footprint,and large heat transfer surface.The academic research on PCHE has a process from straight to Z type,then to S type,and the last is present airfoil.Airfoil is a new type of fin structure which is discontinuous,its thermal hydraulic performance is obviously better than Z type and S type when it is applied to PCHE.Nowadays,how to improve its thermo-hydraulic and heat transfer performance has become the academic research focus.The thermo-hydraulic performance of airfoil PCHE is analyzed comprehensively which combine the numerical study and theoretical analysis in this article,the working fluid in the micro channel is supercritical LNG.The influence of different arrangement and shape structure of airfoil fins in micro channels on flow and heat transfer performance is studied to explore the measures to enhance thermo-hydraulic performance.A three-dimensional numerical model of an airfoil PCHE has been established in this article,airfoil fins in micro channel are divided into parallel and staggered rows,the influence of different arrangement on the flow and heat transfer characteristics of SLNG is studied,the fluid-structure coupled mechanism and the influence laws of fin arrangement on the thermo-hydraulic performance of airfoil PCHE are revealed,and then the optimal finning arrangement is found out.On the basis of the above,by means of the bionics principle,we optimize the design of the airfoil fin into a shuttle shape,and comprehensively evaluate all the working conditions by using the comprehensive evaluation index.The results show the arrangement of airfoil fins has a great influence on the flow and heat transfer characteristics of SLNG,the thermo-hydraulic performance of airfoil PCHE is better when the fins are staggered,the finned interleaving distance Ls has little influence on the relative pressure drop of SLNG,but has great influence on the heat transfer characteristics,the finned vertical distance LV has a great influence on the hydraulic performance of PCHE,but little influence on the heat transfer.Considering the heat transfer performance and flow resistance comprehensively,when the finned vertical distance Lv=3mm and the interleaving distance Ls=3mm,Nu/Eu and J factors reach the maximum,in other words,the PCHE has the best thermo-hydraulic performance when 2Ls/Lh=1.On the basis of finding out the optimal arrangement of fins,the airfoil shape is optimized and designed into a shuttle shape from the perspective of bionics,The spindle head is sharp,the fluid is easy to flow through,the flow resistance is low,the velocity averaging is good,the flow heat transfer performance is better.Fluent software is used to simulate the flow and heat transfer of SLNG with different mass flow rates in different flow channels,the results show the larger the mass flow is,the better the heat transfer characteristics are when the mass flow is between 0.0005kg/s and 0.001kg/s.The research work lays a theoretical foundation for optimizing the industrial design and improving the operation efficiency of airfoil PCHE.