Parametric study of particle distribution in tube bundle heat exchanger

• Adoption of Eulerian multiphase fluid model for simulation of particle distribution
• Uniformity of particle distribution was improved in the velocity greater than 1.2 m∙ s − 1.
• Great diameter or density of particle was unfavorable to particle distribution.
• Prevailing resistance in particle fluidization caused the particle maldistribution.
• Good agreement of simulation result with the experimental one

Fluidized particles in liquid–solid fluidized bed exchangers are able to remove deposits from walls and thus are able to prevent fouling or scaling. Particle distribution is an important parameter for the performance of fouling prevention. In this paper, the Eulerian multiphase fluid model was adopted to simulate the particle distribution in the fluidized bed heat exchanger incorporating tube bundle arranged in parallel. The porous media model was applied in the zone of the tube bundle to analyze the pressure loss through the vertical tube. Factors influencing the particle distribution including the velocity, volume fraction of the solid phase and the property of the particle were discussed respectively. Particle distribution became more uniform in the high velocity due to the full fluidization of particle in each tube. With the increase in density or diameter of particle, particle maldistribution took place because the sedimentation velocity of these particles was so great that particles could not run into the tubes on both sides. With the increasing of volume fraction of solid phase, particle distribution became slightly more uniform. However increment of particle would bring about greater flow resistance and reduce the usage life of particle and devices. Therefore amount of injected particle should be adjusted according to parameters such as effect of fouling prevention, pressure drop etc. A comparison of the simulation results with the experimental measurements was carried out, showing good agreement.

When particle density was increased up to 2300 kg/m3, particle maldistribution occurred in the tubes of heat exchanger, where the fouling was easy to form and the heat transfer efficiency was reduced. It was because the great sediment velocity was unfavorable for particle to flow into the side tubes of heat exchanger.Figure optionsDownload as PowerPoint slide