【摘要】 研究兰炭颗粒在换热器内的流动特性,对于提高换热器的余热回收效率具有重要意义。基于离散单元法,建立了换热器内颗粒流动过程的离散单元法(DEM)模型,分析了换热器内的颗粒流动。结果表明:兰炭颗粒在换热器三个分区内均为整体流,内换热器间区域颗粒流动均匀性优于内外换热器间区域;流动过程存在着自换热器底部向上传递的速度波,颗粒竖直方向速度为不断脉动过程,且越接近料层顶部颗粒脉动幅度越大;颗粒流经内换热器横管时有明显绕流现象,横管下方形成无粒子区,颗粒流速增大。更多还原

【Abstract】 It’s of great significance to study the particle flow in the heat exchanger for improving heat recovery efficiency. A mathematical model based on the discrete element method( DEM) was developed to investigate the behaviors of particle in a multizone waste heat recovery exchanger. The flow characteristics of particle in the heat exchanger were studied. The results show that the particle flow model is all mass flow in three regions of heat exchanger. The flow uniformity of particle between the internal heat exchangers is better than the particle between internal and external heat exchangers. There is a velocity waves upward from bottom of the heat exchanger in the flow process. The vertical velocity of particles is always pulsating,and the amplitude of pulsation is larger with the height increasing. There is a clear flow around phenomenon when the particles flow through the horizontal tube,a region without particle is formed below the horizontal tube,and in this region the particles velocity increases.更多还原