Study On Flow Heat Transfer Performance And Axial Thermal Conductivity Of Printed Circuit Board Type Gasifier

In recent years,with the rising global LNG production,the Floating Storage and Regasification Unit(FSRU)for offshore LNG is gradually being widely used.Printed Circuit Heat Exchanger(PCHE)is a new type of microfine channel plate heat exchanger with the advantages of high compactness,high heat transfer efficiency,small size,high safety and high pressure bearing capacity,so it has great prospect to apply PCHE to LNG-FSRU gasifier.In this paper,we mainly use theoretical analysis and numerical simulation to choose PCHE as the research object,and the working medium in the semicircular channel is supercritical LNG,to investigate the flow heat transfer performance and axial thermal conductivity effects of different channel printed circuit plate gasifier.Firstly,the flow and heat transfer performance of supercritical LNG in the PCHE channel is investigated in this paper.The three-dimensional two-channel physical models of the straight channel,Z-channel and sinusoidal channel printed circuit board gasifier are developed to study the flow and heat transfer performance of supercritical LNG in these three different channel structures.The effect of different mass fluxes on the flow and heat transfer performance of the three channel structures is mainly studied,and the performance evaluation index(PEC)is used to comprehensively evaluate the flow and heat transfer performance of supercritical LNG in the three channel PCHEs,and the results show that the sinusoidal channel has the best flow and heat transfer performance among the three channel structures.The results show that the temperature distribution of supercritical LNG in the three channel structures is mainly determined by the velocity distribution of supercritical LNG,and the temperature distribution and velocity distribution are basically similar,and the flow and heat transfer of supercritical LNG in Z-type channel and sinusoidal channel have periodic characteristics.Secondly,this paper also investigates the effect of axial thermal conductivity on the heat transfer performance of the printed circuit plate gasifier.By establishing a three-dimensional dual-channel physical model of a straight-through channel,sinusoidal channel printed circuit plate gasifier,we mainly investigate the effect of axial thermal conductivity on the heat transfer performance in the straight-through channel and sinusoidal channel printed circuit plate gasifier under different operating conditions by numerical simulation.The main influencing factors include Reynolds number,working pressure and cold side channel inlet temperature.The results show that when the average Reynolds number is small,the difference values of heat transfer performance are relatively large under the two models considering axial conduction and not considering axial conduction,and the influence of axial conduction on the heat transfer performance of straight-through channel and sinusoidal channel PCHE is relatively large,with the increase of the average Reynolds number,its influence gradually decreases,when the average Reynolds number is relatively When the average Reynolds number is large,the effect of axial thermal conductivity can be neglected;the inlet temperature of cold side channel in this paper ranges from 190 to 210 K.When the inlet temperature of cold side channel is 205 K,the heat transfer performance of straight-through channel and sinusoidal channel PCHE is the best;when the inlet temperature of cold side channel is 190 K,the heat transfer performance of straight-through channel and sinusoidal channel PCHE is the worst,and when the average Reynolds number is large,the different inlet temperatures of cold side channel have the best effect on the heat transfer performance of straight-through channel and sinusoidal channel PCHE.When the average Reynolds number is larger,the influence of different inlet temperatures of the cold side channel on the axial thermal conductivity in the straight channel and sinusoidal channel PCHE becomes smaller and smaller;The operating pressure range in this paper is 7 to 9MPa.The heat transfer performance of straight-through channel and sinusoidal channel PCHE decreases as the working pressure increases,and the effect of axial thermal conductivity on the heat transfer performance of straight-through channel and sinusoidal channel PCHE is smaller at higher working pressure.