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Improvement of Fuel Consumption for SI Engines by Combing with Glow Plug Heated Sub-chamber and Lean Burn
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on November 30, 2020 by SAE International in United States
Lean burn gasoline engines can achieve noteworthy fuel consumption and power output. However, when the mixture becomes lean, the ignition delay increases, and the flame propagation speed becomes slow, which lead to increase the combustion fluctuation. The glow plug is usually used to solve the cold start problem in diesel engines, where the compression temperature might not be high enough to ensure the proper ignition of the injected fuel, resulting in instability combustion and increased exhaust emissions. Based on this point, the present study intends to install a glow plug to the sub-chamber. Experiments were conducted on a modified single cylinder four-stroke CI engine (YANMAR TF120V) to operate as SI engine with a higher compression ratio compared to the conventional SI engines, 15.1:1. The engine is operated at a constant speed of 1000 rpm for different equivalence ratios with different voltage of glow plug which creates the temperature variation inside the sub-chamber. COV_IMEP was calculated in order to ensure the engine’s cycle by cycle variation. According to the experimental results of different air-fuel ratios from 23.52 to 27.93, it was proved that stable combustion with a COV_IMEP of less than 7% can be achieved under the condition of air-fuel ratio is 27.34, which is the limit of lean burn. Also, the lean burn limit was improved by 3.32%, where the air to fuel ratio increased from 26.74 to 27.34, with the variation in the glow plug voltage. When compared to the condition without the glow plug, the specific fuel consumption of the engine was increased by 8.5% due to the temperature increase in the sub-chamber.