Flow And Heat Transfer Characteristics And Parameter Optimitization Of A Printed Circuit Board Heat Exchanger With A Tesla Valve Channel Structure

The printed circuit heat exchanger(PCHE)is a high-efficiency compact heat exchanger.Its distinctive feature is that it adopts the two core manufacturing processes of "chemical etching" and "vacuum diffusion",security and other advantages,have received extensive attention from scholars at home and abroad.At present,PCHE has great potential in the fields of supercritical carbon dioxide power generation,nuclear energy,heat pump,hydrocarbon gas and natural gas liquid processing,and fine chemicals.Since the structure and form of the internal channel of PCHE have a very important influence on its performance,many scholars at home and abroad have carried out a lot of research on the structure of the PCHE channel,mainly discussing how to change the internal structure of the PCHE to achieve good heat transfer performance while maintaining lower pressure drop.The proposed PCHE channel structures are almost all positive and negative,that is,the flow characteristics and heat transfer characteristics of the fluid do not change significantly compared with the forward flow and the reverse flow.In the practical application of PCHE,the pressure involved is often very high.To ensure the safe operation of the system,the PCHE is usually connected with a check valve.It is of great significance to improve the safety of the PCHE application system to study and design a PCHE that can not only ensure the overall heat transfer effect but also have obvious one-direction flow characteristics.First,based on the Z channel combined with the Tesla valve structure,the physical model of the PCHE with the Tesla valve channel structure(referred to as TV-PCHE in this paper)is designed through Solidworks.The rationale for the design:The use of inertial flow in physics allows fluids to pass easily in one direction while exhibiting significant resistance to the opposite flow.Secondly,to understand the flow,heat transfer,and one-direction flow characteristics of TV-PCHE,numerical simulation is carried out in this paper with supercritical CO2 as the flow working medium under the Reynolds number operating condition,and the counter-flow arrangement is used for the forward flow respectively.In-depth study of flow and reverse flow.The results show that:in terms of flow,in the forward flow,the Tesla valve diversion area does not play the role of diversion,and the internal fluid is almost stagnant;in the reverse flow,due to inertia,it shows significant resistance;in terms of heat transfer,in the forward flow,the overall convective heat transfer is similar to the Z-type PCHE,and in the reverse flow,the convective heat transfer is improved,but at the expense of several times the pressure loss;from the perspective of one-direction flow characteristics,TV-PCHE showed good one-direction flow characteristics.After that,through the analysis of structural parameters,it is found that the corner a has a significant effect on the flow friction loss,while the effect on the heat transfer performance is relatively weak.Therefore,to have better performance of TV-PCHE,the corner should be reduced;for the flow channel.The design of width should balance heat transfer and friction loss as much as possible;the size of TV-PCHE pitch has no strong correlation with the performance of TV-PCHE.When designing TV-PCHE,it can be adjusted according to industrial needs;and TV-PCHE The splitting pitch has a great influence on the heat transfer performance.To have better heat transfer for TV-PCHE,the splitting pitch should be reduced;the arc diameter of TV-PCHE has a great impact on one-direction flow characteristics.The channel conductivity can be appropriately increased by increasing the diameter of the arc.Finally,five parameters of TV-PCHE interaction were investigated by the Taguchi method:corner(α),channel width(B),pitch(L),split pitch(Lp),and arc diameter(D).The results show that:α is the parameter that has the greatest influence on heat transfer and frictional loss(in which a has a significant influence on frictional loss according to the size of the weight),and D is the parameter that has the greatest influence on one-direction flow characteristics.Based on the results of the noise performance statistics(NPS),three optimal designs are proposed to achieve the maximum Nusselt number,the minimum Fanning factor,and the maximum one-direction flow characteristics parameter.The geometric characteristics are:α=20°,B=0.8mm,L/B=14,Lp/L=0.26,D/B=4;α=20°,B=2mm,L/B=20,Lp/L=0.26,D/B=4;α=30°,B=1.6mm,L/B=16,Lp/L=0.32,D/B=4.In addition,according to the size of the weight,five parameters were analyzed to sort the Nusselt number,the Fanning factor number,and the primary and secondary influence of the one-direction flow characteristics parameter,respectively:α>Lp/L>B>D/B>L/B;α>B>Lp/L>L/B>D/B;D/B>α>B>L/B>Lp/L.