Analysis On The Effect Of The Perforated Baffle On Performance Of Heat Exchanger

Shell-and-tube heat exchangers have occupied dominant position among the heat transfer device,in which single segment baffle heat exchanger has been widely adopted with the advantages of its simple structure,convenient manufacture and maintenance, good heat transfer, etc. However, the structure is easy to produce dead zone in back of the baffle, which is not conducive to heat transfer, and with fluid repeatedly washed bundles, it is easy to produce the vibration and distribution to heat exchange tube. Perforated baffle can solve this problem in a certain extent. But, studies on the impact of single segmental baffle trepanning on the shell features are relatively few. This paper will use methods with experimental and numerical simulation to study the effect about heat exchanger performance with the perforated baffle.In the experimental part, a new PIV technique was used for a large amount of experimental study. A large number of experimental studies using a new PIV method with different opening models as a means to study its effect on the shell side flow. The study found that velocity changes with y position, it goes with the similar conic distribution trend.The flow properties of shell side flow field was illustrated with the average vorticity,the greater the average vorticity, the greater the velocity gradient, the more prone to deadzones. Different trepanning solutions were researched and different regional averagevorticities had been calculated. It is found that the average vorticity increases with theincrease of baffle spacing, and decreases along with the increase of flow rate, the bestperforated baffle had been obtained during the same flow and same spacing.In numerical simulation, the experimental model of shell side fluid properties had been carried on the contrastive analysis from the velocity contours and velocity section by using fluent software to simulate, velocity contours and velocity section had also been analyzed.The numerical simulation results agree with the results of the PIV test. The velocity of the section also goes with the similar conic distribution trend.Finally, the numerical simulation on the effect of perforated baffle heat exchanger under actual working conditions had been researched. Making a comparison between the best perforated one and non-perforated baffle, it shows that the heat transfer coefficient becomes a slightly lower when the baffle is perforated, but the pressure drop has a big reduce. It is found that the heat transfer coefficient can be enhanced when the baffle is perforated. It shows a result which can be used to the industrial design for heat exchanger, which can enhance the heat transfer.