Cold start emission and CO_2 reduction by engine idle combustion quality improvement in dedicated CNG pick-up truck

摘要

Recently at Tata Motors Ltd., a 2.1L Gasoline engine is converted for CNG operation for pick-up truck application. However undesirable vibrations are perceived at driver's seat due to idle instability of engine. This combustion inconsistency is quantified using statistical parameters like COV and LNV. From literature we understand that internal EGR during valve-overlap is a dominant factor affecting idle. Hence the gas exchange processes are studied computationally and valve overlap is re-optimised for stoichiometric (Lambda=1) CNG operation. The optimised overlap camshaft configuration resulted in smooth idle operation. With re-calibration of ECU and reduced idle speed, 10% CO_2, 89% HC and 45% NO_x reduction is achieved at cold-start idle.