The effect of different Air Path based ATS thermal management strategy on a Non- EGR Medium Duty Diesel Engine’s performance and emissions.
Ajeet Kumar Sharma
AVL Technical Center Pvt. Ltd.
Abstract:
In view of BS6.2 emission norms implementation for medium duty diesel engine, the tail pipe emissions are not only confirmed in test bed conditions but also in real driving condition including different combinations of ambient temperature and pressure.
In modern non-EGR engine the Engine out emissions especially NOx emission is higher compared to EGR engine, therefore the tail pipe emissions are solely depending on conversion efficiency of After Treatment System (ATS). Hence meeting the stringent tail pipe emission, quick heating of ATS required. It became more challenging with a WHTC Cycle, where beginning of the cycle is not only having low load engine operations, but also cold ATS system followed by cold soaking. Further addition of DOC (Diesel oxidation Catalyst), DPF (Diesel Particulate Filter) and DOC front pipe installed prior to the SCR (Selective Catalytic Reduction) promote the heat loss generated from the engine. Therefore, efficient thermal management required to raise the ATS temperature to adequate level where the optimum performance of ATS can be ensured.
In BS6.2 emission norms, addition of Real Driving Emission (RDE) emphasizes on robust thermal management strategy that provide the adequate temperature for ATS against the different environment conditions.
Implementation of these thermal management has the negative impact on engine performances especially at fuel consumption. Hence in this paper the air path based different thermal management strategies including, ITV (Intake throttle valve), VEF (Variable Exhaust flap), Engine Brake Flap were discussed along with their effect on engine performance, fuel consumption and tail pipe emission in WHTC cycle as well as RDE cycle were also presented.
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Keywords: ATS Thermal Management, RDE, WNTE, Fuel Consumption, CO2 Reduction, ITV, VEF, Exhaust Brake, WHTC.