Spray evaporation of urea–water solution: Experiments and modelling

Lieber, Christian; Koch, Rainer; Bauer, Hans-Jörg

Abstract:
Selective catalytic reduction is a key technology for reducing nitrogen oxide ($NO_x$) emissions of diesel engines, which requires the injection of urea–water solution (UWS) into the hot exhaust gas. The main objective of this paper is the development of a methodology for predicting the evaporation of urea-water sprays. For this reason a generic experiment was conducted in order to provide validation data under realistic operating conditions. The configuration is based on a twin-fluid atomiser, which is used to inject UWS into a hot pipe flow. Microscopic imaging was applied in conjunction with particle tracking velocimetry to record droplet size and velocity distribution profiles. Using this approach, droplets of a diameter as small as 4 μm were successfully detected at operating conditions of the gaseous phase of up to 773 K and 0.24 MPa. The analysis of droplet data at different positions downstream of the atomiser revealed details of the evaporation characteristics of UWS. In particular, a characteristic droplet size is proposed, which may serve to characterise the overall progress of UWS spray evaporation. Using this criterion, the comparison of experimental results to numerical predictions is straightforward. ... mehr

 Zugehörige Institution(en) am KIT Institut für Thermische Strömungsmaschinen (ITS) Publikationstyp Zeitschriftenaufsatz Publikationsmonat/-jahr 08.2020 Sprache Englisch Identifikator ISSN: 0894-1777 KITopen-ID: 1000118162 Erschienen in Experimental thermal and fluid science Band 116 Seiten Article: 110108 Schlagwörter Spray analysis; Microscopic imaging; AdBlue preparation: Evaporation model; Urea–water solution; Selective catalytic reduction Nachgewiesen in ScopusWeb of Science
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