Effects of surface nanostructure and wettability on CO_(2)nucleation boiling:A molecular dynamics study  

作　　者：Yongfang Huang Xianqiang Deng Yongxiang Duan Chao Liu Xiaoxiao Xu 

机构地区：[1]Key Laboratory of Low-grade Energy Utilization Technologies and Systems,Chongqing University,No.174,Shazhengjie,Shapingba,Chongqing 400044,China

出　　处：《DeCarbon》2024年第3期73-84,共12页低碳科学(英⽂)

基　　金：supported by the National Natural Science Foundation of China(Grant No.52376001);Natural Science Foundation of Chongqing(Project No.cstc2021jcyj-msxmX0795);Graduate Student Research Innovation Project of Chongqing(Project No.CYB22022).

摘　　要：Nanostructured tubes hold great potential for enhancing heat transfer in refrigeration/heat pump systems.Therefore,it is essential to study the effects of nanostructured surface characteristics on refrigerant boiling heat transfer.In this paper,the nucleation boiling behavior of CO_(2)on the nanostructured surface is simulated using molecular dynamics.The effect mechanism of nanostructure size and surface wettability on CO_(2)bubbles nucleation and growth is investigated.At first,the nucleation boiling processes of both smooth surfaces and nanostructured surfaces featuring three different wide grooves are simulated.The results show that the local thermal aggregation effect is the key for nanostructures to promote CO_(2)bubble nucleation.The bubble nucleation efficiency is highest on the nanostructured surface with 5nm wide groove.Then,based on a 5nm wide nanostructured wall surface,the wettability effect on nucleation boiling is investigated by adjusting the potential energy factorα.The results show that the hydrophilic walls enhance the solid-liquid heat transfer and the collision of atoms within the liquid,resulting in boiling heat transfer capacity improvement between CO_(2)and the walls.The average temperature,average heat flux and critical heat flux in the liquid phase are also improved.A significant temperature gradient between the layers of CO_(2)liquid is noted on hydrophilic wall,where intermolecular forces and molecular advection dominate the heat transfer mechanism.In contrast,on hydrophobic wall,intermolecular forces dominate the heat transfer process.

关 键 词：CO_(2) Nanostructured surfaces Nucleation boiling Molecular dynamics simulation 

分 类 号：TG1[金属学及工艺—金属学]