An Experimental and Theoretical Study of the Effects of Excess Air Ratio and WasteGate Opening Pressure Threshold on Nox Emission and Performance in aTurbocharged CNG SI Engine

سال انتشار: 1393
نوع سند: مقاله ژورنالی
زبان: انگلیسی
مشاهده: 684

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شناسه ملی سند علمی:

JR_IJE-28-2_011

تاریخ نمایه سازی: 13 مرداد 1394

چکیده مقاله:

In this research, effects of excess air ratio and waste gate opening pressure threshold on NOx emissionand performance in a turbocharged CNG SI engine are experimentally studied at 13-mode ECE-R49test cycle. The engine power, boost ratio and charge air temperature are investigated experimentally atthe cycle for different waste gate pressure thresholds. A code is developed in MATLAB environmentfor predicting engine performance and NOx and the results are validated with the researchexperiments. The effects of excess air ratio on the engine indicated power and specific fuelconsumption as well as NOx emission are numerically investigated at WOT by the code. NOxemission of WOT is max at excess air ratio of 1.1. Simulation reveals that higher excess air ratio at arate of 20% decreases maximum indicated power 9% and improves minimum ISFC 7%. Experimentsindicate that brake power augments with increase of the pressure threshold especially at high loads andspeeds due to higher boost ratio. It is also found that changing the threshold from 165mmHg to 200and 265mmHg decreases total bsNOx at rate of 6 and 12%, respectively. The threshold increase to323mmHg augments total bsNOx. Therefore, the threshold of 265mmHg is optimum threshold amongthe four pressure thresholds experimented.

کلیدواژه ها:

Turbocharged CNG SI EngineNOx EmissionPerformanceECE-R49 Test CycleExcess Air RatioWaste Gated Turbocharger

نویسندگان

S Kharazmi

Center of excellence in energy conversion (CEEC), Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran

A.H Benisi

Center of excellence in energy conversion (CEEC), Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran

A Mozafari

Center of excellence in energy conversion (CEEC), Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran