An experimental and numerical study on effects of exhaust gas temperature and flow rate on deposit formation in Urea-Selective Catalytic Reduction (SCR) system of modern automobiles

S. Sadashiva Prabhu, Nagaraj S. Nayak, N. Kapilan, Vijaykumar Hindasageri

Research output: Contribution to journalArticlepeer-review

56 Citations (Scopus)

Abstract

Urea Water Solution (UWS) is injected to generate NH3 in Selective Catalytic Reduction (SCR) system of modern automobiles. Thermal and fluid dynamic conditions such as temperature and Reynolds number of the flow favors ammonia generation in terms of heat transfer to UWS droplets by forced convection. During extremely cold weather conditions and low exhaust temperatures, the overdosing of UWS results in deposits of urea and its byproducts. As deposit depletion changes the stoichiometry of NOx/NH3, any predictive method becomes complementary to experimental studies on deposit formation. In the present work, we experimentally investigated deposit formation and its rate by a newer concept of usage of Stainless Steel (SS) foils considering temperature and flow rate as variables. According to numerical results, the droplet evaporation of UWS decreases as flow rate increases. For a fixed rate of UWS quantity of deposits decrease with increase in temperature and flow rate. Accordingly, structural changes are observed. Numerical values of time dependent deposit formation found slightly superior to the experimental values. The study revealed that deposit areas at low temperatures are comparable to numerical values. Phenomenological model is proposed to find deposit conversion factor for low temperatures (150–250°C), which helps in tuning of UWS dosage strategy to prevent NH3 slip.

Original languageEnglish
Pages (from-to)1211-1231
Number of pages21
JournalApplied Thermal Engineering
Volume111
DOIs
Publication statusPublished - 25-01-2017

All Science Journal Classification (ASJC) codes

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering

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