超亲水表面喷雾冷却强化尿素钢带造粒换热性能研究

Heat Transfer Enhancement of Urea Steel Strip Granulation Process by Spray Cooling with Super-hydrophilic Surface

尿素钢带造粒工艺引入超疏水表面后可显著提高尿素颗粒球形度,改善壁面粘附现象,但同时减小了熔体与钢带接触换热面积和导热,导致造粒过程移热效率下降。在钢带正面进行超疏水改性同时,将背面改性为超亲水表面构成超疏水/超亲水双面不对称钢带,结合喷雾冷却技术,可有效增大喷雾微小液滴捕获效率、铺展速率和面积,显著提升液滴蒸发吸热效率,快速降低钢带及周边环境温度,并利用该技术实现了大颗粒尿素快速固化得到合格产品。

The introduction of superhydrophobic surface into the urea steel strip granulation process can significantly improve the sphericity of urea granules and avoid the wall adhesion phenomenon,but reduces the contact heat transfer area between the melt droplet and the steel strip and lowers the heat conduction of the steel strip,at the same time,resulting in a decrease in the heat transfer efficiency of the steel strip granulation process and solidification rate of urea granules.Superhydrophobic modification was carried out on the front of the steel strip,and the back surface,which did not contact with urea melt,was modified into a superhydrophilic surface to form a super-hydrophobic/super-hydrophilic combined double-sided asymmetric super-wetting steel strip.Combined with spray cooling technology,the capture efficiency,spreading rate and area of sprayed micro-droplets can be effectively increased,significantly improving the heat absorption efficiency of droplet evaporation phase change,quickly reducing the temperature of steel strip and surrounding environment.The intensification of heat transfer in the steel strip granulation process was achieved,realizing the rapid cooling and solidification of large urea granules,and obtaining qualified products.