An Experimental and Numerical Analysis of Heat Transfer Paths in Urea-Water Dosing Modules for SCR Systems

The international regulations are challenging automotive industry to further develop efficient systems for reducing NOx emissions from diesel engines. Selective Catalytic Reduction sys-tems represent a possible effective solution. SCR systems are already on the market, firstly developed for heavy duty diesel engine applications, while it is beginning the spreading to light automotive applications. The urea-water solution dosing module may be subjected to strong heat transfer; an efficient heat dissipation is consequently crucial to avoid severe damages to the injector. In order to limit system complexity and costs, the air cooling of the dosing module should to be preferred to the liquid cooling. To obtain an efficient heat dissipation from the injector holder unit can represent an hard task, when some critical operating and ambient conditions occur simultaneously, as high engine load, diesel particulate filter regeneration, high temperature of the ambient air, low vehicle speed. A careful design of the dosing module is consequently needed. In this paper the first steps are presented of an activity, performed at the Industrial Engineering Department of the University of Perugia in cooperation with Magneti Marelli Powertrain, for the set up of a methodology aimed to quickly design, analyse and develop different prototypes of air-cooled heat sinks for urea-water solution dosing modules.