Research On Optimization Of Flow Channel Structure Of Plate Heat Exchanger

In order to achieve carbon neutrality as scheduled,in the face of my country’s energy utilization rate being less than 35%,plate heat exchangers,as the most common high-efficiency energy-saving equipment,have important research value in terms of energy saving and emission reduction.The size optimization of the plate heat exchanger is mostly based on the herringbone plate,which is biased towards the size design of the channel;the topology optimization of the plate heat exchanger still lacks the overall design of complete working conditions.Therefore,the size optimization and topology optimization of the plate heat exchanger were carried out.The main work and results are as follows:(1)First,optimize the size of the plate heat exchanger.Simplified modeling was carried out based on the structural characteristics of the plate heat exchanger,and the genetic algorithm was used to optimize it with multiple objectives.The optimization results were analyzed by single factor,response surface and sensitivity.The results showed that Nu,f increases with the increase of each structural parameter.PEC decreases with the increase of structural parameters;Fc increases with the increase of the welding hole radius R,and there will be a peak value under the action of the ellipse radius L,and the welding hole spacing P has no effect on it;each structural parameter has no effect on it.The sensitivity sequence of the objective function is: the radius of the weld hole R,the radius of the ellipse L,and the pitch P of the weld holes.A comparative analysis of the optimal results under different objective functions shows that the optimal structural parameters of the heat exchange plate are: R = 5.81 mm,L =5.02 mm,P’ = 32.00 mm.Compared with the existing concavo-convex plate heat exchanger,the optimized size structure increases the temperature difference between the inlet and outlet of the cooling water by 8.27% after the cooling water inlet speedis greater than 0.25 m/s,and the Nusselt number Nu is increased by up to 20.43%.Comprehensive heat exchange Performance improved by 2.3%～19.59%.(2)Using the MMA algorithm to optimize the topology of the plate heat exchanger,perform the optimal assessment of each parameter,and analyze the flow channel,thermal performance and hydraulic performance of the optimal structure.The results show that: when the filter radius is larger than the boundary size of the grid,it cannot play a filtering role.When the filter radius is less than 0.1 times the boundary size of the grid,it has a better filtering effect and can effectively eliminate grayscale and aliasing;high Under the Reynolds number,the performance advantage of the topology structure is more significant.With the increase of the Reynolds number,the number of branch flow channels in the topology structure increases,and the gray level gradually decreases;the solid area,high temperature area,and fluid flow velocity distribution in the design domain are uniform;finally,filter is selected the radius is 0.0001 m;the projection coefficient is 8;the grid is divided into 120×120,that is,the grid boundary length is 0.005 m.The two-dimensional topological structure is pulled up in three dimensions and numerical simulation is carried out.The simulation results are compared with the experiment of the herringbone heat exchanger.After the cooling water flow rate exceeds 0.3 m/s,the temperature difference increases by 24.29% ～30.6%,as the cooling water flow rate with the increase of,the Nusselt number Nu increases,and the heat transfer effect is strengthened.When the water flow velocity is(0.3 m/s,0.6 m/s),the comprehensive heat transfer performance increases by 12.73%～ 33.43%.(3)Numerically simulate the size optimization structure and topology optimization structure,build an experimental platform,conduct experimental investigations on the concave-convex plate heat exchanger and the herringbone heat exchanger,and compare the experimental results with the simulation results.The results show that: When it is greater than 0.25 m/s,the maximum absolute error of the temperature difference between the experimental value of the concave-convex plate heat exchanger and its simulated value is 3.12℃,and the relative error is less than19.37%.The comparison between the two simulated values shows that the temperature difference between the inlet and outlet of the cooling water has increased by less than8.27%.The maximum absolute error between the Nusselt number Nu simulation value and the experimental value is 97.45,and the relative error is less than 13.15%.Comparing the two simulated values,the Nusselt number Nu increases by up to 20.43%.Comprehensive heat transfer performance the maximum absolute error between the experimental value and the simulated value of the original concave-convex plate heat exchanger is 1.22,and the relative error is less than 22.42%.The overall heat transfer performance of the optimized size structure is increased by 2.3%～19.59%;the overall heat transfer performance of the topology structure has increased by 12.73%～33.43%;under the same cooling water flow rate,the topological optimization of the plate heat exchanger improves the heat transfer performance than the optimization of the size More significant.