Optimization of biodiesel fueled engine to meet emission standards through varying nozzle opening pressure and static injection timing

Abstract

The stationary diesel engines used for power generation in household and commercial applications also lead to twin crisis of fossil fuel depletion and environmental degradation due to exhaust emissions. In order to address these problems, in this study Mahua methyl ester (MME), a renewable biodiesel has been considered to be used as an alternate fuel in light of greener emissions compared to diesel. In order to optimize the use of MME in diesel engines, the performance and emissions of B20 blend of MME was investigated using a single cylinder diesel engine at various nozzle opening pressures (NOP) (225, 250, 275bar) and static injection timings (19°, 21°, 23°, 25°, 27° bTDC) in accordance with ISO 8178 D2 cycle, intended for homologation. The performance of B20 mahua bio-diesel was compared with diesel at manufacturers’ default NOP of 225bar and 23° bTDC static injection timing, whereas, the emissions were compared with the current regulatory norms for genset engines in India. The raw emissions measured in ppm were converted to composite emissions in g/kWh based on ISO 8178 D2 cycle, for their comparison with the norms. The NOx emissions were corrected based on the recommended correction factor by Fritz and Dodge to avoid any discrepancies arising due to different ambient conditions while testing. The results show that by either increasing the NOP to 275bar or by retarding the static injection timing to 21° bTDC, the stringent emission norms of Central Pollution Control Board (CPCB) stage I can be met with B20 mahua bio-diesel without compromising the performance against diesel. Eventually, on varying NOP and static injection timing, it was found that obtained emissions were lesser than CPCB limits by maximum of 5.7% and 11.8% for NOx, 91.5% and 90.0% for HC, 15.7% and 11.1% for CO, and 21.4% and 5.7% for smoke respectively.