余热发电系统双S型旋流片喷嘴内部闪蒸过程数值研究  

Numerical investigation of the flash evaporation process inside a nozzle with two S-shaped internal vanes in a waste heat power generation system

作　　者：季璨 刘志刚 吕明明 JI Can;LIU Zhi-gang;LÜ Ming-ming(Energy Research Institute,Qilu University of Technology (Shandong Academy of Sciences), Jinan 250014, China)

机构地区：[1]齐鲁工业大学(山东省科学院)山东省科学院能源研究所,山东济南250014

出　　处：《山东科学》2021年第6期77-82,105,共7页Shandong Science

基　　金：国家自然科学基金(52076113);山东省科学院青年基金(2019QN0021,2019QN0019);山东省科学院科技发展基金(科基合字2019第2号,2020KJC-GH04);山东省重点研发计划(2019GSF109074)。

摘　　要：闪蒸是液体经历压力突降时的快速汽化现象,在高耗能行业余热回收领域具有广阔的应用前景。针对闪蒸余热发电系统喷嘴内部流动与相变现象研究相对缺乏的问题,以典型的双S型旋流片喷嘴为研究对象,展开内部闪蒸问题的数值研究。基于耦合的流体体积函数模型与降压相变模型构建喷嘴内部闪蒸流动的数学描述,并利用CFD软件进行数值求解。结果表明,流体流经S型旋流片时开始旋转加速,在旋流片下游呈现中间旋转程度低、周围旋转程度高,随后经流道收缩段加速喷出。旋流片下游压力降低引发内部闪蒸现象,流体最终以气液混合物状态离开喷嘴。此外,从改善雾化效果、减轻积垢、增加通流能力的角度提出一种改进的喷嘴结构,能够促进喷雾闪蒸充分快速进行,有助于进一步提升闪蒸余热发电系统效率。Flash evaporation refers to the abrupt vaporization of liquid when it undergoes a sudden pressure drop.It has broad application prospects in the field of waste heat recovery in energy-intensive industries.Motivated by the lack of research on internal flow and phase-change phenomena inside the nozzle in a waste heat power generation system,in this work,we conduct numerical research on the internal flashing in a typical nozzle with two S-shaped internal vanes.The mathematical description of this problem is given by coupling the Volume of Fluent model and the pressure-driven phase-change model,and a numerical solution is obtained using CFD software.Results show that the fluid starts to rotate and accelerate when it flows through the S-shaped vanes.Downstream the vanes,the rotation speed is low in the middle and high near the wall.After that,the fluid accelerates and ejects through the contraction section of the nozzle.Pressure drop downstream the vanes leads to flash evaporation inside the nozzle,and fluid leaves the nozzle as a liquid-vapor mixture.In addition,a modified nozzle structure is proposed from the perspectives of improving atomization,reducing fouling,and enlarging passage area.The proposed structure can promote the complete and rapid progress of spray flash evaporation and help to further improve the efficiency of the waste heat power generation system.

关 键 词：闪蒸 数值模拟 两相流 相变 

分 类 号：TK124[动力工程及工程热物理—工程热物理]