The Analysis Of Plate Welded And Heat Transfer Characteristics In Laser Welded Plate Heat Exchanger

Heat exchanger in petroleum,chemical,smelting,and other fields have indispensable status.In order to enlarge the application range of heat exchanger,improve the efficiency of industrial production and economic benefit,need to develop suitable for different conditions of efficient heat exchanger.Welded plate heat exchanger with safe and reliable,pressure pipe heat exchanger performance advantages,at the same time with a removable plate heat exchanger efficiency advantages.But with thin plate type welded plate heat exchanger units,channel is more complicated,how to guarantee the welding process and the heat transfer efficiency,at the same time has been the industry's two big research problems.This paper established the simulation model of laser welding plate processing of the welding process of numerical analysis,emphatically discusses the welding time,welding power and spot diameter,welding path and the influence of environment temperature on the welding temperature regularly.Results show that at the beginning of the welding,the welding temperature is low,only about 1400 k,the melting point of 304 stainless steel has not been achieved,easy to cause welding phenomenon,but the laser welding heating speed is very fast,must control the heating time,avoid burning through the workpiece;The faster the welding speed,the lower the temperature of the center of the weld molten pool is,easy to lack of penetration,the opposite is easy to welding wear,when welding power of 3000 w,choose the speed of 5 mm/s is relatively appropriate;The change of temperature field of welding power influence is very big,too much is easy to weld penetration,welding power to overlay thickness of 1.6 mm artifacts,choose 2500 ~ 2500 w is suitable;The external environment of basic can not consider the influence of welding;Different spot radius has the effect of the welding heat affected zone size,the smaller the spot radius,the more concentrated the ability,energy utilization efficiency is high;When welding the shape of a circular track is better than spot welding performance.Based on the analysis of metallographic experiment and confined the microstructure characteristics and mechanical properties of laser weld joint.Research shows that: the faster the cooling rate after welding joint and the weld microstructure of present cellular austenite dendrite tendency;In the case of full welding,plate unit pressure can reach 3.0 MPa.The model of convection heat transfer is established,and the paper analyzes the plate corrugated parameters such as height,Angle,distance between the influence law of heat transfer characteristic of plate unit.Corrugated height change,will affect the distance between plates,the greater the height,the more powerful disturbance degree,the better the performance of heat transfer and resistance will increase,but height is 4 mm,the relatively appropriate;Corrugated directly affects the number of contact Angle and ripple spacing,the smaller the Angle,contact number,the more the greater the ripple spacing,the less contact number.Finally through to the welding type plate heat exchanger heat transfer performance test,the heat transfer coefficient,pressure drop along with the change of velocity curve,for practical engineering design of the heat exchanger,provides the reference.