撞击流中颗粒碰撞传热理论模型研究

Theoretical Model Study on Impact Heat Transfer Between Particles in Impinging Streams

建立了考虑颗粒接触面导热的颗粒碰撞传热模型,相应完善了气固两相撞击流理论模型,并对不同条件的撞击流干燥过程进行了模拟。计算结果与实验结果非常吻合,从而验证了所建模型的正确性。本文还分析了颗粒碰撞传热、加料方式以及喷嘴间距对撞击流干燥性能的影响规律。结果表明:在本文所涉及的撞击流干燥过程中,颗粒碰撞传热对干燥性能的影响并不明显;单边加料时颗粒物料的降水幅度及撞击流装置的干燥强度都明显大于双边加料的工况;喷嘴间距较大时,物料的降水幅度及装置的干燥强度均较大。

A model for the inter-particle heat transfer through the contact surface was proposed. The theoretical model for gas-solid two-phase impinging streams （IS） was improved. And simulations were carried out for drying processes in IS under different conditions. The predicted results were in well agreement with the experimental data, which indicates the validity of the present model. The effects of the inter-particle heat transfer, the feeding mode and the distance between nozzles on the drying performance were analyzed. The results indicate that the inter-particle heat transfer has no significant effect on the drying performance. The dehydrating range and the drying intensity when loading particles with one nozzle are bigger than those with two nozzles. The increase in the distance between nozzles makes the dehydrating range and the drying intensity increase.