Single droplet impingement of urea water solution on heated porous surfaces. (December 2021)

• Record Type: Journal Article
• Authors: Kuhn, C.; Schweigert, D.; Kuntz, C.; Börnhorst, M.
• Is Part Of: International journal of heat and mass transfer. Volume 181(2021)
• Publication Date: 2021-12
• Subjects: Droplet impingement -- Porosity -- Regime map -- Wetting boundary -- Splash; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2021.121836
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Additional regimes: Partial rebound and partial rebound with breakup. Leidenfrost point is shifted to higher temperatures with increasing pore diameter. The wetting boundary is highly dependent on K. Splash boundary is dependent on surface roughness and topography. Graphical abstract: Abstract: The droplet/wall interaction of urea water solution on surfaces with varying properties is one decisive element for the detailed understanding of liquid film formation in the exhaust gas system of diesel-powered engines. An experimental study was conducted on the single droplet impingement of urea water solution on porous steel surfaces. The outcome of droplet impact was investigated under variation of droplet momentum, wall temperature and surface properties such as pore diameter and surface roughness. Droplet impact is recorded by high-speed shadowgraphy. The results allow the development of regime maps describing the hydrodynamic and thermal phenomena deposition, splash, boiling induced breakup, total rebound and rebound with breakup as a function of dimensionless parameters. Based on systematic investigations the influence of surface properties on the transition boundaries can be shown. The porosity of the sample leads to a significant shift of the wetting boundary to higher temperatures, as the evolving vapour between droplet and surface can escape through the pores. The regimes partial rebound with breakup and partial rebound are introduced to describe the single droplet impingement on porous surfaces. The experimental results serve as database for modelling the droplet/wall interaction in the selective catalytic reduction system.