SIMULATION BASED DEVELOPMENT OF THE SCR SPRAY PREPARATION FOR LARGE DIESEL ENGINES
In order to fulfil the requirements of the IMO-III regulation either a combination of internal engine technologies or external measures are required. Exhaust gas aftertreatment by Selective Catalytic Reduction (SCR) is a proven technology that basically allows any engine to fulfil the IMO-III regulation. The design of compact SCR systems remains a significant challenge for the developer. Besides a high efficient NOx-conversion on the catalysts, the main issue is the efficient spray preparation including the injection of a urea-water solution and the distribution of the reducing agent ammonia, generated by a thermolysis reaction. The uniformity of the ammonia at the catalyst inlet is decisive in order to achieve highest levels of NOx reduction and to avoid deposit formation. Therefore well adapted designs are mandatory to fulfil the system targets concerning emissions, durability and cost effectiveness. Due to the complex physical and chemical phenomena involved in the spray injection, CFD simulations are performed to provide valuable insight on the system behaviour. This assists the development in early phases of the development and enables an efficient optimization. Development time and costs are therefore reduced. The paper provides a survey over the physical and chemical models which have been developed for the description of all relevant phenomena involved in the spray preparation, including the spray evaporation and the thermolysis, the spray-wall interaction and the wall film formation. The developed models have been implemented into a commercial CFD code and validated by experimental investigations of the individual effects. The developed method is then applied for the investigation of the spray preparation and ammonia uniformity in SCR-systems as well as to evaluate the risk of deposit formation. The paper shows the CFD-aided development of an ultra-compact inter-turbine SCR system for a medium speed ship engine fulfilling IMO-III and describes the applied methods. The emphasis of the investigations was the optimization of the ammonia uniformity at the SCR-catalyst. Furthermore the spray behaviour and the risk of deposit formation in the exhaust pipes have been evaluated. Based on the results of the CFD-investigations and on the design of the SCR-System, engine tests will be performed to prove the performance of the SCR systems under real life conditions.
Moritz Frobenius Carsten Schmalhorst Rainer Fiereder Carsten Rickert Jan Dreves Michael Zallinger
AVL Germany,Germany AVL Deutschland,Deutschland AVL Deutschland,Germany Caterpillar Motoren,Germany AVL List GmbH,Austria
国际会议
上海
英文
1-9
2013-05-13（万方平台首次上网日期，不代表论文的发表时间）