Investigation of pinned Evaporation droplets under different wind velocity

doi:10.7523/j.ucas.2023.053

Abstract

Abstract: In order to study the sessile droplets evaporation under the shear flow, a closed loop wind tunnel that allows for high-quality optical observation was designed. Droplets were subjected to shear flow in the wind tunnel and the CCD cameras mounted horizontally and vertically were used to acquire the shape information to experimentally investigate the droplet evaporation. It is found that the droplet will experience three stages under the shear flow and airflow could enhance the evaporation rate significantly. For the droplet of 10µL, the evaporation rate is 168% higher in 2m/s wind speed than that without wind, However, increasing the wind speed can not improve the evaporation rate when the wind speed is high. The effect of airflow on the shape of droplet is mainly dependent on the Weber number and the dimensionless number k', which characterizes the ratio of wind force and adhesion force. The effect of shear flow on mass transfer at the gas-liquid interface was investigated, and the relationship between the dimensionless Reynolds number and the Sherwood numbers was determined. It was determined that the theoretical relationship between wind speed and evaporation rate is consistent with experimental data.

Key words: airflow, droplets, evaporation, mass transfer, Asymmetric droplet evaporation

CLC Number:

O361.3

LI Zilong, QIN Jun, TAO Yuequn, HE Naifeng, LIU Qiusheng, ZHU Zhiqiang. Investigation of pinned Evaporation droplets under different wind velocity[J]. Journal of University of Chinese Academy of Sciences, DOI: 10.7523/j.ucas.2023.053.

References

[1] Kandlikar S G, Steinke M E.Contact angles and interface behavior during rapid evaporation of liquid on a heated surface[J]. International Journal of Heat and Mass Transfer, 2002, 45(18): 3771-3780. DOI:10.1016/S0017-9310(02)00090-X.
[2] Preston D J, Mafra D L, Miljkovic N, et al.Scalable graphene coatings for enhanced condensation heat transfer[J].Nano Letters, 2015, 15(5): 2902-2909. DOI:10.1021/nl504628s.
[3] Singh M, Haverinen H M, Dhagat P, et al.Inkjet printing-process and its applications[J]. Advanced Materials, 2010, 22(6): 673-685. DOI:10.1002/adma.200901141.
[4] Lim T, Han S, Chung J, et al.Experimental study on spreading and evaporation of inkjet printed pico-liter droplet on a heated substrate[J]. International Journal of Heat and Mass Transfer, 2009,52(1/2):431-441. DOI:10.1016/j.ijheatmasstransfer.2008.05.028.
[5] Sartre V, Zaghdoudi M C, Lallemand M.Effect of interfacial phenomena on evaporative heat transfer in micro heat pipes[J]. International Journal of Thermal Sciences, 2000, 39(4): 498-504. DOI:10.1016/S1290-0729(00)00205-2.
[6] Langmuir I.The evaporation of small spheres[J]. Physical Review, 1918, 12(5): 368-370. DOI:10.1103/PhysRev.12.368.
[7] Cachile M, Bénichou O, Cazabat A M.Evaporating droplets of completely wetting liquids[J]. Langmuir, 2002, 18(21): 7985-7990. DOI:10.1021/la020231e.
[8] Hu H, Larson R G.Evaporation of a sessile droplet on a substrate[J]. The Journal of Physical Chemistry B, 2002, 106(6): 1334-1344. DOI:10.1021/jp0118322.
[9] Popescu M N, Oshanin G, Dietrich S, et al.Precursor films in wetting phenomena[J]. Journal of Physics: Condensed Matter, 2012, 24(24): 243102. DOI:10.1088/0953-8984/24/24/243102.
[10] Stauber J M, Wilson S K, Duffy B R, et al.Evaporation of droplets on strongly hydrophobic substrates[J]. Langmuir: the ACS Journal of Surfaces and Colloids, 2015, 31(12): 3653-3660. DOI:10.1021/acs.langmuir.5b00286.
[11] Picknett R G, Bexon R.The evaporation of sessile or pendant drops in still air[J]. Journal of Colloid and Interface Science, 1977, 61(2): 336-350. DOI:10.1016/0021-9797(77)90396-4.
[12] Bourges-Monnier C, Shanahan M E R. Influence of evaporation on contact angle[J]. Langmuir, 1995, 11(7): 2820-2829. DOI:10.1021/la00007a076.
[13] Wilson S K, D'Ambrosio H M. Evaporation of sessile droplets[J]. Annual Review of Fluid Mechanics, 2023, 55: 481-509. DOI: 10.1146/annurev-fluid-031822-013213.
[14] Khandekar S, Muralidhar K. Dropwise condensation on inclined textured surfaces[M/OL]. New York, NY: Springer New York, 2014(2013-09-06)[2023-02-08]. https://link.springer.com/10.1007/978-1-4614-8447-9. DOI:10.1007/978-1-4614-8447-9.
[15] 任东伟, 阳倦成, 倪明玖. 水平磁场作用下金属液滴撞击电解质液池表面的实验研究[J]. 中国科学院大学学报, 2021, 38(4): 442-449. DOI: 10.7523/j.issn.2095-6134.2021.04.002.
[16] 董泉润, 阳倦成, 倪明玖. 水平磁场作用下液态金属自由射流破碎特性的实验研究[J]. 中国科学院大学学报, 2022, 39(5): 577-585. DOI: 10.7523/j.ucas.2022.029.
[17] Bin L, Bennacer R, Bouvet A.Evaporation of methanol droplet on the Teflon surface under different air velocities[J]. Applied Thermal Engineering, 2011, 31(17-18): 3792-3798. DOI:10.1016/j.applthermaleng.2011.07.018.
[18] Buffone C.Evaporating sessile drops subject to crosswind[J]. International Journal of Thermal Sciences, 2019, 144: 1-10. DOI:10.1016/j.ijthermalsci.2019.05.018.
[19] Doursat C, Lecoq L, Laguerre O, et al.Droplet evaporation on a solid surface exposed to forced convection: Experiments, simulation and dimensional analysis[J]. International Journal of Heat and Mass Transfer, 2017, 113: 1234-1245. DOI:10.1016/j.ijheatmasstransfer.2017.05.110.
[20] Milne A J B, Amirfazli A. Drop shedding by shear flow for hydrophilic to superhydrophobic surfaces[J]. Langmuir, 2009, 25(24): 14155-14164. DOI:10.1021/la901737y.
[21] Madani S, Amirfazli A.Oil drop shedding from solid substrates by a shearing liquid[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014, 441: 796-806. DOI:10.1016/j.colsurfa.2013.04.058.
[22] White E B, Schmucker J A.A runback criterion for water drops in a turbulent accelerated boundary layer[J]. Journal of Fluids Engineering, 2008, 130(6): 1. DOI: 10.1115/1.2917429.
[23] Parekh S, Farid M M, Selman J R, et al.Solar desalination with a humidification-dehumidification technique—a comprehensive technical review[J]. Desalination, 2004, 160(2): 167-186. DOI:10.1016/S0011-9164(04)90007-0.
[24] Ahlers M, Buck-Emden A, Bart H J.Is dropwise condensation feasible? A review on surface modifications for continuous dropwise condensation and a profitability analysis[J]. Journal of Advanced Research, 2019, 16: 1-13. DOI:10.1016/j.jare.2018.11.004.
[25] Beér J M.High efficiency electric power generation: The environmental role[J]. Progress in Energy and Combustion Science, 2007, 33(2): 107-134. DOI:10.1016/j.pecs.2006.08.002.
[26] Eral H B, 't Mannetje D J C M, Oh J M. Contact angle hysteresis: A review of fundamentals and applications[J]. Colloid and Polymer Science, 2013, 291(2): 247-260. DOI:10.1007/s00396-012-2796-6.
[27] Antonini C, Carmona F J, Pierce E, et al.General methodology for evaluating the adhesion force of drops and bubbles on solid surfaces[J]. Langmuir, 2009, 25(11): 6143-6154. DOI:10.1021/la804099z.
[28] Acarlar M S, Smith C R.A study of hairpin vortices in a laminar boundary layer. Part 1. Hairpin vortices generated by a hemisphere protuberance[J]. Journal of Fluid Mechanics, 1987, 175(1): 1. DOI:10.1017/s0022112087000272.