Numerical Study Offlow And Heat Transfer On Printed Plate Exchanger

With the improvement of design method and manufacturing process,In recent years,Printed Plate Exchanger have been widely concerned and recognized for their small size and high heat exchange efficiency.Especially in aeronautics and astronautics,ship engineering and petrochemical industries have great application prospects.This paper takes Printed Plate Exchanger as the research object,the flow and heat transfer characteristics between sea water and natural gas are studied numerically based on the numerical simulation method of gas thermal coupling.It includes the influence of different heat transfer channel geometric dimensions and matching modes on temperature,pressure and density,the distribution of temperature and pressure in each area of heat exchanger,the structure of heat exchanger was optimized on this basis.Major innovations include: Consider the variation of natural gas density,specific heat and viscosity with temperature,accurately simulate the flow and heat transfer process in the pipeline;Based on the numerical simulation method,obtain the total pressure recovery coefficient and temperature characteristic curve of a real heat exchanger,obtain a better structural paramenters of heat exchanger tubes.The numerical simulation results were compared with the experimental date,verify the reliability of calculation method and result,lays a foundation for optimal design of heat exchanger.The main findings are as follows:Research shows that the flow rate can increase the heat exchange capacity between the fluid inside the tube of printing plate heat exchanger and the environment outside.It also can reduce the total pressure loss,decrease the corresponding pump work,and need a lees strength requirement of heat transfer tube.The reduction of the bend angle of the heat transfer tube makes the heat exchange area increasing within the same pipe length,and along with the periodic bending of the heat transfer pipe,the mixing between the mainstream fluid and the boundary layer fluid is enhanced,so as the heat exchange is also increased.With the increase of the roughness of the pipe wall,the heat exchange capacity of the pipe is enhanced,but the friction between the fluid and the pipe wall is increased.In addition,the total pressure recovery efficiency decreases as the pipe wall roughness increased,reducing by 10% compared with the smooth pipe while the roughness is 12.5?m.As the cooling medium flow increases with the diameter of the heat transfer tube,the heat exchange capacity also increases with the diameter of the tube.Through the study of three A/B/C pipe types and different flow rate matching methods,all the schemes can meet the designed heat exchanging requirements,and the temperature drop of natural gas at the inlet and the outlet increased 5% compared with design value.However,due to the large inlet speed of scheme A,the pressure loss of the seawater pipeline can reach 318540 Pa.In the other two schemes,the pressure loss research 88180 Pa after reducing the seawater flow rate,which meets the design pressure loss requirement of less than 1 bar.From the perspective of the internal heat transfer characteristics of the heat transfer pipe,the heat exchange between natural gas and seawater is mainly concentrated in the former 50% part from natural gas inlet.The temperature of natural gas in this region can be reduced to over 80 K,while the temperature in the second half of the pipe falls by less than 30 K.By reducing the diameter of the natural gas pipe,the height of the equipment can be effectively reduced.When the diameter of the pipe is decreased from 2mm to 1.5mm,although the pressure drop in the natural gas pipe is slightly increased,the heat exchange capacity and pressure drop could meet the design requirements.Considering the heat exchange and pressure drop requirements comprehensively,this scheme is optimal solution in this paper.