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Future emission limits for off-highway application engines need advanced power train solutions to meet stringent emissions legislation, whilst meeting customer requirements and minimizing engineering costs. DI diesel engines with four valves per cylinder are widely used in off- highway applications because of the fundamental advantages of higher volumetric efficiency, lower pumping loss, symmetric fuel spray & distribution in combination with the symmetric air motion which can give nearly optimal mixture formation and combustion process. As a result, the fuel consumption, smoke levels and exhaust emissions can be considerably reduced. In particular, the four-valve technology, coupled with mechanical low pressure and electronic high pressure fuel delivery systems set different requirements for inlet port performance. In the present paper four valve intake port design strategies are analysed for off highway engine using mechanical fuel injection systems.

Air pollution in India and also global warming are two major concern in the country. To address this situation, India is moving from BS-IV to BS-VI for on-road applications with 90% reduction in NOx and 50% in PM with limit on particulate number. Also moving to Trem-IV and Trem-V for off-road applications subsequently. It needs higher efficiency after-treatment systems like SCR and DPF to achieve such lower emission levels. Addition of these complex after-treatment system, severely increase the cost of diesel power plant with heavy penalty on fuel economy. Hence, it is challenge to auto industry to reduce the complexity and cost, so that it requires an alternate solution to reduce NOx and PM emissions at source to reduce cost and system complexity. Low Temperature Combustion (LTC) is a potential concept to reduce the NOx and PM emissions simultaneously.

This paper focuses on assessment of different thermal management strategies for heavy duty Diesel(HDD) engine aftertreatment using semi-physical model for both engine and aftertreatment. Aftertreatment configuration of DOC, DPF and SCR is considered for six cylinder HDD engine. SCR reaction kinetics, ammonia adsorption and desorption parameters were calibrated with the data from synthetic test bench. Calibrated aftertreatment model is integrated with semi physical 6-cylinder HDD engine model to validate over steady state as well as transient measurement data. Engine model is modified for different thermal management strategies such as Intake, Exhaust throttle valve, start of main injection, Post injection and evaluated for their impact on performance and emission parameters. Results over operating point are analysed to select best strategy at cold operating zone.