scholarly journals Numerical Study of Deposits Formation in SCR Systems Using Urea-Water Solution Injection

Author(s):  
Habchi C ◽  
Nicolle A ◽  
Gillet N
2012 ◽  
Vol 505 ◽  
pp. 175-179 ◽  
Author(s):  
R. Vikas ◽  
J.M. Mallikarjuna ◽  
V. Ganesan

Nowadays, due to the stringent engine emission norms, an efficient technique is required to reduce oxides of nitrogen (NOX) from automobiles especially from the lean burn engines. Although Urea Selective Catalytic Reduction (SCR) is capable of satisfying these norms, the ammonia slip nullifies its advantages. Ammonia slip is mainly due to the lack of uniformity of ammonia at the monolith entrance. The uniformity of ammonia distribution mainly depends upon the flow parameters of exhaust gas and the injection parameters of urea water solution. The current study addresses the effect of flow parameters, temperature and flow rate of exhaust gas on the injection pressure. The results obtained reveals useful guidelines for enhancing the uniformity of ammonia in Urea-SCR.


1998 ◽  
Vol 77 (2) ◽  
pp. 473-484 ◽  
Author(s):  
M. Sampoli, P. Benassi, R. Dell'Anna,

2020 ◽  
pp. 57-65
Author(s):  
Eusébio Conceiçã ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Jorge Raposo ◽  
Domingos Xavier Viegas ◽  
...  

This paper refers to a numerical study of the hypo-thermal behaviour of a pine tree in a forest fire environment. The pine tree thermal response numerical model is based on energy balance integral equations for the tree elements and mass balance integral equation for the water in the tree. The simulation performed considers the heat conduction through the tree elements, heat exchanges by convection between the external tree surfaces and the environment, heat exchanges by radiation between the flame and the external tree surfaces and water heat loss by evaporation from the tree to the environment. The virtual three-dimensional tree model has a height of 7.5 m and is constituted by 8863 cylindrical elements representative of its trunks, branches and leaves. The fire front has 10 m long and a 2 m high. The study was conducted taking into account that the pine tree is located 5, 10 or 15 m from the fire front. For these three analyzed distances, the numerical results obtained regarding to the distribution of the view factors, mean radiant temperature and surface temperatures of the pine tree are presented. As main conclusion, it can be stated that the values of the view factor, MRT and surface temperatures of the pine tree decrease with increasing distance from the pine tree in front of fire.


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