| Enhanced heat transfer technology is mostly used in the power,chemical,and smelting industries,among which the Research field of enhanced convection heat transfer is Relatively extensive.It is mainly to improve the efficiency performance of the heat exchange equipment,which is conducive to the full use of energy,and also plays an important role in ecological environment protection.In recent decades,research scholars have made in-depth research in this field of heat exchangers,such as the development and application of various Reinforced special-shaped tubes,which have a significant effect on improving the heat transfer efficiency.However,with the development of human society and the urgent need for efficient use of energy,various Reinforcement methods have emerged.Electro-Hydro-Dynamics(EHD)strengthening,as an active strengthening method,has the advantages of obvious strengthening effects,simple equipment,and low energy consumption.It is one of the new methods and new methods that are currently being studied.Because its strengthening mechanism is more complicated,further research is needed.This article innovatively combines the active strengthening of electric field(EHD)and the passive strengthening of different shaped tubes,uses the user interface UDF provided by FLUENT,writes the electric field equation in C language,and imports the model into FLUENT to Reynolds number(Re=600?1800)and Reynolds number(Re=12000?36000)under two flow conditions for numerical simulation.The velocity distribution,temperature gradient distribution and pressure gradient distribution in the heat exchange tube under different electric field voltage,flow rate and other parameters are obtained.And the field synergy theory is used to analyze the synergy of electric field,flow field and thermal field.The synergistic relationship between the heat flow,mass flow,and fluid flow driving force in the convection heat transfer field of the circular tube,transverse tube,and corrugated tube by the electric field and the enhanced heat transfer mechanism reflected by the electric field are obtained.The following conclusions are obtained:The electrodes are arranged in the three heat exchange tubes to apply an electric field.The electric field force generated by the electric field acts on the fluid in the tube to enhance the disturbance and form a small vortex.The vector velocity and the temperature gradient synergy angle ? in the flow field of the heat exchange tube are reduced,the synergy is enhanced,and the convection heat exchange efficiency in the tube is significantly improved.At the same time,the pressure drop in the tube increases,the synergy angle ? between the vector velocity and the pressure gradient increases,the synergy deteriorates,and the flow resistance in ?e tube increases.By simulating the convective heat transfer in two flow states of the heat exchange tube,the Nusselt number Nu and the flow resistance coefficient f are obtained.The electric field strengthening coefficient Sf and the comprehensive evaluation coefficient PEC are calculated.The heat transfer effect is enhanced under both,and the convective heat transfer,at a lower Reynolds number has a better strengthening effect while the fluid with a higher Reynolds number has greater inertial force,and the electric field force increases the resistance of the fluid,and the strengthening effect is not obvious.From the perspective of heat exchange only,the electric field strengthening coefficient Sf of the bellows can reach a maximum of 6.36,and the transverse rib tube can reach 5.73.Comprehensive evaluation of the heat exchange effect of the three heat exchange tubes,the heat transfer effect of the transverse tube is the best,under certain conditions,the PEC is between 1.1 and 5.75;the second is the PEC of the plain tube,which is between 0.99 and 4.76;the corrugated tube heat transfer effect of the bellows.At the same time,the increase in flow resistance is also very large,with PEC between 0.67 and 4.19. |
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