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Selective catalyst reduction systems are one of the most promising technologies to reduce NOx emissions from heavy-duty diesel engines. To meet the Euro VI regulations, the SCR system should achieve high NOx reduction efficiency. In the SCR system, NH3 is usually supplied by the injection of urea water solution (UWS), therefore it is important to improve the efficiency of UWS minimize urea deposits. In this systems deposit accumulations become one of the major problem to meet Euro 6 regulations. In this study, spray behaviors of the urea injectors are investigated on the hot gas test bench. Each parameters such as impingement angles, penetration length of the spray characterization were analyzed using high speed camera. Deposit accumulation tests were performed with different urea injection and exhaust mass flow rate. The deposit test show the amount of deposit accumulation are decreased above the 250 degree C. The deposit accumulation region was significantly influenced by the spray density and directions. Deposit weights and deposit localization zones on the exhaust system has a close relationship with spray properties. The UWS had formed with short spray penetration length. Spray and deposit tests showed that most of the deposit formations are directly related droplet size. After the tests, a new spray-based boundary condition map is created for reducing the deposit limits in the system.
