| 초록 |
The stringent emission regulation for diesel engines results in changes on emissions measurement methods(NEDC→ WLTP), as per the Euro-6 standard. To satisfy such a strict regulation standard, Urea-SCR devices are most frequently used to ensure NOx reduction. Under a certain temperature(-11 °C), a urea-water solution, which is a reducing agent, becomes frozen and is present in the form of a solid state inside the urea water tank. This makes it impossible to operate the gear pump and to cause problems in the entire Urea-SCR system, including high emissions during cold starts. Thus, to secure a stable supply within the urea-water solution system, heating modules must be introduced to undertake a thawing phenomenon. In this study, a three dimensional, unsteady numerical analysis of the process of thawing the frozen urea was performed by using the ANSYS Fluent. The urea flow path was investigated during the thawing phenomenon with respect to the heat transfer characteristics in the urea tank. Finally, the thawing performance of the two different models was compared in terms of thawing periods with the flow path and the frozen urea area inside the pump by changing the material and its property. |
