Experimental Studies for the Removal of Excessive Heat Originated from SCR Application in a Bus Powered by EPA10 Engine

SCR emission control system is the main adaptive system in order to achieve EPA10 emission levels in addition to the DPF+EGR system that is used commonly for EPA07 regulations. In this study, excessive heat of SCR system application in a 35 feet bus prototype is investigated. The application of the SCR system is done by means of new parts such as; a Diesel Exhaust Fluid (DEF) tank, a DEF supply pump, a DEF dosing module, SCR catalyst built-in catalytic substrates with isolation panels, DEF system lines, cooling and heating lines and additional NOx sensors and thermistors. SCR catalyst in the system has adverse effect as a heat source resulting 325 °C during normal operating conditions whereas 525 °C during failure mode conditions on the inlet and outlet surface. All the design parameters of the engine room are figured out according to these criteria. The layout is completely changed on the vehicle and isolation panels are added to the separation walls. Temperature tests are done by measuring 9 critical points on SCR system parts during regeneration, thermal camera measurements are done and temperature limits for the compartments are tested. Tests results have shown that excessive heat is originated from SCR application and by the experimental studies done on the structural design change, additional material isolation handling, enabling more air flow to the room. This excessive heat values are reduced to an extent and the effect on the vehicle is eliminated as proving by test results.