Research On The Fluid Flow And Heat Transfer Performance Of Welded Plate Heat Exchanger

With the development of society and the improvement of productivity,people have higher requirements on energy utilization and conversion.Heat exchanger plays an increasingly important role.Plate heat exchanger,as a heat transfer equipment with superior heat transfer performance,is widely used in power,chemical,petroleum,light industry and other industries.However,due to the limitation of manufacturing and assembly,the welded plate heat exchanger is often not qualified for higher temperature and pressure conditions.Compared with Welding plate heat exchanger,welded plate heat exchanger can effectively improve the pressure and temperature,so it is applicable to a wider range.Therefore,it is of great significance to design and study the high efficiency welded plate heat exchanger for the improvement of energy utilization efficiency and energy saving in various fields.In this paper,the physical and mathematical models of air flow and heat transfer in welded plate heat exchanger are established.The heat transfer and resistance characteristics of fluid in a unit of welded plate heat exchanger were studied by numerical simulation.The influence of the Angle of the plate rib,the height of the channel and the air velocity on the air flow and heat transfer in the welded plate heat exchanger was analyzed.The results show that the heat transfer efficiency is the highest when the inclined rib Angle is 45°,which is about20%and 14%higher than 30°and 60°respectively.The influence of channel height on heat transfer is limited,but the Reynolds number is increased with the increase of channel height,so the velocity and turbulent kinetic energy of air in the cell channel will be increased.Cold side compression loss,inclined rib Angle from 30°to 45°increased significantly,but inclined rib Angle from 45°to 60°increased slowly;For the thermal lateral pressure loss,the inclined rib Angle decreased the pressure drop from 30°to 45°slowly,but the inclined rib Angle decreased the pressure drop from 45°to 60°significantly.With the increase of air flow rate,the heat transfer coefficient and air resistance loss were significantly increased.The heat transfer coefficient at the air flow rate of 12m/s was 28%higher than that at 8m/s.The results of numerical analysis can provide effective guidance for the serial design and development of subsequent products.In this paper,an experimental device for heat transfer and resistance performance of welded plate heat exchanger was established.Heat transfer elements with cross-flow structure were selected and the experimental medium was air.The data of fluid resistance and heat transfer characteristics in unit channel under different flow conditions were obtained through the experiment,and the total heat transfer coefficient of air and air in the heat exchanger was calculated.According to the experimental data,the change rule of air flow resistance with Reynolds number and convection heat transfer coefficient with Reynolds number is analyzed,and the relationship between air convection heat transfer coefficient and flow resistance coefficient in welded plate heat exchanger is concluded and fitted.The experimental results show that the K value of this cross-flow gas heat exchanger can reach 16W/(m~2K)at the lowest flow rate of 4m/s,and 42W/(m~2K)at the high speed of11m/s,and the heat transfer enhancement effect is obvious.