液滴在燃煤细颗粒表面凝结的长大动力学特性  

Kinetics study of droplet growth on surface of coal-fired fine particles

作　　者：徐俊超[1] 于燕[1] 张军[1] 钟辉[1] Xu Junchao;Yu Yan;Zhang Jun;Zhong Hui(Key Laboratory of Energy Thermal Conversion Control of Ministry of Education , Southeast University, Nanjing 210096, China)

机构地区：[1]东南大学能源热转换及其过程测控教育部重点实验室,南京210096

出　　处：《东南大学学报（自然科学版）》2017年第3期506-512,共7页Journal of Southeast University：Natural Science Edition

基　　金：国家自然科学基金资助项目(51576043);国家重点基础研究发展计划(973计划)资助项目(2013CB228504);江苏省普通高校研究生科研创新计划资助项目(KYLX16_0202);东南大学优秀博士学位论文培育基金资助项目(YBJJ1607)

摘　　要：为了研究液滴在燃煤细颗粒表面的长大动力学特性,实验测量了水在不同燃煤细颗粒表面的接触角θ,考虑液滴在燃煤细颗粒表面长大的2种作用机制:细颗粒表面水汽的直接扩散凝结和颗粒表面吸附水扩散凝结,对燃煤细颗粒表面单液滴的长大动力学进行了研究.数值讨论了燃煤细颗粒粒径、蒸汽过饱和度、蒸汽温度、液滴半径和颗粒表面润湿性对单液滴在燃煤细颗粒表面长大速率的影响.结果表明:当颗粒粒径小于0.5μm时,液滴的长大速率随着燃煤细颗粒的增大迅速增大,当粒径大于0.5μm时,长大速率随着粒径的增大缓慢增长;液滴的长大速率随着过饱和度上升呈指数倍增长,但是随着蒸汽温度的上升而呈现下降的趋势;液滴的长大速率开始随着液滴半径的增大而急剧下降,长大到某一半径后下降的趋势变缓;当0≤cosθ≤0.8时,长大速率随着润湿角余弦值的增大而平缓地增大,当0.8≤cosθ≤1时,长大速率会随着润湿角余弦值的增大而急剧增大.To study the kinetics of the droplet growth on coal fired fine particle surface,the contact angle of water on coal fired fine particles was experimentally measured.Both the surface vapor direct diffusion condensation and the particle surface adsorption water diffusion condensation mechanisms were considered,the kinetics of the single droplet growth on coal fired fine particle surface was studied.The effects on single droplet growth rate were studied:radius of coal fired fine particles,the vapor supersaturation,vapor temperature,droplet radius,and surface wettability.The results show that when the particle radius is more than0.5(xm,the droplet growth rate dramatically increases with the increase of the particle radius,when the particle radius is bigger than0.5(xm,it increases slowly with the increase of the particle radius;the droplet growth rate exponentially increases with the increase of the supersaturation while it decreases with the the vapor temperature;the droplet growth rates sharply decreases with the increase of the droplet radius,but it becomes slowly with the increase of the droplet radius larger than a certain value;when0^c o s^^O.8,the droplet growth rate slowly increases with the increase of the cosine of contact angle,when0.8^c o s^^l,the droplet growth rate rapidly increases with the increase of the cosine of the contact angle.

关 键 词：液滴 燃煤细颗粒 长大 动力学 

分 类 号：TK16[动力工程及工程热物理—热能工程]