颗粒性质对颗粒污垢成垢影响的数值模拟研究
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摘要
为了探究颗粒性质对换热面上颗粒污垢成垢过程的影响,本文建立了颗粒污垢沉积和剥蚀模型,采用计算流体力学(computational fluid dynamics,CFD)方法,借助Fluent软件,对不同颗粒性质条件下颗粒污垢的沉积过程进行了数值模拟。结果显示,颗粒污垢热阻先增加后平稳,一段时间后达到一个渐近值。随着颗粒密度的增大,结垢速率逐渐减缓,但由于物性参数不同,污垢热阻值呈现不同的变化规律;随着颗粒粒径的增大,结垢速率逐渐减缓,污垢热阻渐近值随之增大;随着颗粒浓度的增大,结垢速率逐渐加快,污垢热阻渐近值也随之增大。由数值模拟结果可知,减小颗粒浓度和粒径可减缓结垢速率,减小污垢热阻渐近值;颗粒种类对污垢热阻的影响较大。该方法对研究污水中多种颗粒沉积规律具有重要意义。
To study the influence of particle property to fouling forming,an deposition and scaling model is set up.A processing of particle fouling under conditions of different particle properties is simulated in Fluent with the method of CFD.The results showed that the thermal resistance of particle fouling increased firstly and then stabilized,and reached an asymptotic value after a period of time.With the increase of particle density,the scaling rate gradually slowed down,but because of the different physical parameters,the fouling resistance values have different variations.The fouling rate gradually slowed down with the increase of particle size,and the asymptotic value of fouling resistance increases.With the particle concentration increased,the fouling rate gradually accelerated which leads to increasing of the asymptotic value of fouling resistance.The calculated results indicate that the decrease of the particle concentration and particle size reduction can reduce the fouling rate and fouling asymptotic values,so the effect of particle types on the fouling resistance is large.It is very important to study the deposition law of various particles in the presence of sewage.
To study the influence of particle property to fouling forming,an deposition and scaling model is set up.A processing of particle fouling under conditions of different particle properties is simulated in Fluent with the method of CFD.The results showed that the thermal resistance of particle fouling increased firstly and then stabilized,and reached an asymptotic value after a period of time.With the increase of particle density,the scaling rate gradually slowed down,but because of the different physical parameters,the fouling resistance values have different variations.The fouling rate gradually slowed down with the increase of particle size,and the asymptotic value of fouling resistance increases.With the particle concentration increased,the fouling rate gradually accelerated which leads to increasing of the asymptotic value of fouling resistance.The calculated results indicate that the decrease of the particle concentration and particle size reduction can reduce the fouling rate and fouling asymptotic values,so the effect of particle types on the fouling resistance is large.It is very important to study the deposition law of various particles in the presence of sewage.
引文
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[14]史琳,昝成,杨文言.城镇二级出水换热表面混合污垢的成分及形貌[J].清华大学学报:自然科学版,2009,49(2):236-239.
[15]韩芸,巨姗姗,王志鹏,等.地表水及城市污水二级处理出水中颗粒性质及其混凝特性研究[J].西安建筑科技大学学报:自然科学版,2008,40(4):527-531.
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[18]徐志明,孙美,张一龙.静止流体中颗粒污垢沉积模型数值模拟[J].热能动力工程,2014,29(6):627-632.
[19]Kuppan T.钱颂文.换热器设计手册[M].北京:中国石化出版社,2004.
[2]孙卓辉.换热面上结垢过程数值模拟[D].东营:中国石油大学(华东),2008.
[3]Abd-Elhady M S,Rindt C C M,Wijers J G,et al.Minimum Gas Speed in Heat Exchangers to Avoid Particulate Fouling[J].International Journal of Heat&Mass Transfer,2004,47(17):3943-3955.
[4]李红霞,李冠球,李蔚.管内颗粒污垢特性分析[J].浙江大学学报:工学版,2012,46(9):1671-1677.
[5]张一龙,孙美,刘坐东,等.纳米与微米颗粒污垢沉积的表面特性及等效关系[J].化工进展,2015,34(1):266-272.
[6]徐志明,张敏霞,张一龙,等.微米颗粒污垢特性的数值模拟[J].化工机械,2015,42(6):828-834.
[7]徐志明,董兵,杜祥云,等.板式换热器颗粒污垢特性的实验研究[J].动力工程学报,2013,33(7):539-543.
[8]徐志明,王景涛,王磊,等.交叉缩放椭圆管颗粒污垢特性的实验分析[J].化工进展,2014,33(4):831-836.
[9]王景涛.交叉缩放椭圆管颗粒污垢特性的实验研究[D].吉林:东北电力大学,2014.
[10]张仲彬,谢飞帆,董兵,等.板式换热器内颗粒污垢表面分形特性[J].化工机械,2016,43(2):157-161.
[11]徐志明,王思源,王景涛,等.过冷流动沸腾状态下纳米氧化镁颗粒的污垢特性[J].化工进展,2017,36(3):839-845.
[12]徐志明,王景涛,王宇航,等.温度对纳米氧化镁颗粒污垢特性的影响[J].热科学与技术,2016,15(1):52-58.
[13]张冠敏,李冠球,李蔚,等.板式换热器内颗粒污垢预测模型与实验[J].工程热物理学报,2013,34(9):1715-1718.
[14]史琳,昝成,杨文言.城镇二级出水换热表面混合污垢的成分及形貌[J].清华大学学报:自然科学版,2009,49(2):236-239.
[15]韩芸,巨姗姗,王志鹏,等.地表水及城市污水二级处理出水中颗粒性质及其混凝特性研究[J].西安建筑科技大学学报:自然科学版,2008,40(4):527-531.
[16]陶文铨.数值传热学[M].西安:西安交通大学出版社,2003.
[17]董双岭,曹炳阳,过增元.颗粒在流体中所受的热泳冲力研究[C]//高等教育学会工程热物理专业委员会全国学术会议.扬州:高等教育学会工程热物理专业委员会,2015:134-141.
[18]徐志明,孙美,张一龙.静止流体中颗粒污垢沉积模型数值模拟[J].热能动力工程,2014,29(6):627-632.
[19]Kuppan T.钱颂文.换热器设计手册[M].北京:中国石化出版社,2004.