EFFECT OF SWIRL MOTION ON COMBUSTION AND EMISSIONS CHARACTERISTICS WITH DUAL-FUEL COMBUSTION IN COMPRESSION IGNITION ENGINE
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Donghyun Lim1, Jeongwoo Lee1,2, Hyungjin Shin1, Kihong Kim1, Sunyoung Moon1, Kyoungdoug Min1 |
1Seoul National University 2Jeonbuk National University |
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ABSTRACT |
In-cylinder flow motion is important for enhancing combustion in internal combustion engines. There are two major flow motions: tumble and swirl. Tumble enhances the flame propagation speed to spread throughout the entire cylinder. Swirl affects the behavior of diesel spray; an enhanced swirl ratio has been widely used in conventional diesel engines. Because dual-fueled combustion has the characteristics of premixed combustion from background fuels and mixingcontrolled combustion from directly injected fuels such as diesel, understanding the effect of in-cylinder flow motion on combustion characteristics in dual-fuel combustion is critical. In this research, the effect of swirl in gasoline and diesel dualfuel combustion was evaluated with different diesel injection timing conditions. As the dual-fuel combustion engine used in this research was driven by diesel spray, swirl was selected as the main flow motion rather than tumble. The effect of swirl with different diesel injection timings was investigated under low-speed and low-load conditions. The results demonstrate that increasing swirl intensity provokes fast-burning caused by the enhanced air-fuel mixture, decreasing the diesel fraction and allowing more exhaust gas recirculation (EGR) to be used for the reduction of engine-out nitrogen oxides (NOx) and smoke emissions, without reducing thermal efficiency.
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Key Words:
Dual-fuel combustion, Mass fraction burned 50 % (MFB 50), Premixed combustion, SCV (swirl control valve), Smoke, Swirl
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