In order to achieve lower emissions and extensive load in the homogeneous charge com- pression ignition (HCCI) engine system, a novel fuel design concept that high-octane number fuel and high-cetane number fuel are mi...In order to achieve lower emissions and extensive load in the homogeneous charge com- pression ignition (HCCI) engine system, a novel fuel design concept that high-octane number fuel and high-cetane number fuel are mixed real-time to con- trol HCCI combustion is proposed in this study. HCCI combustion fueled with iso-octane/n-heptane mix- tures controlled real-time on a single-cylinder HCCI combustion engine is studied. The test results show that the equivalence ratio of n-heptane in mixtures decides ignition and controls the combustion phase of HCCI combustion. The addition of iso-octane ex- tends knocking limit in equivalence ratio somewhat, but knocking occurrence mainly depends on the total concentration of mixture. Although operating range in equivalence ratio becomes narrow with the increas- ing proportion of iso-octane, the maximum load of HCCI combustion fueled with iso-octane/n-heptane mixtures controlled real-time is increased about 80% more than that of pure n-heptane. When iso-octane/ n-heptane mixtures are controlled in optimized method, it is proved that the load of HCCI combustion can be fully extended and emissions can be de- creased remarkably, while at the same time the higher indicated thermal efficiencies are obtained over the extensive operation range.展开更多
Agricultural biomass presents a promising feedstock, which may contribute to a transition to low carbon fuels. A significant amount of research has identified a number of challenges when combusting agricultural feedst...Agricultural biomass presents a promising feedstock, which may contribute to a transition to low carbon fuels. A significant amount of research has identified a number of challenges when combusting agricultural feedstock, related primarily to energy value, ash, emissions, corrosion and combustion characteristics. The mitigation of such challenges can be addressed more cost effectively when dealing with large or utility scale combustion. The costs associated with harvesting, conversion, transportation and ultimately, market development all create additional roadblocks for the creation of an agricultural biomass industry. Nova Scotia, an Eastern Canadian province, has significant land resources, however it is prone to wet spring and as yet does not have a supply chain established for such an industry. The main components of supply, processing and conversion and demand simply do not yet exist. This research addresses one aspect of this supply chain by attempting to develop a fuel suitable for a) existing markets (local residential wood and wood pellet stoves and b) a scale that will support industry engagement. The outcomes of this research have determined that such a venture is possible and presents empirical preprocessing conditions to achieve a competitive agricultural fuel.展开更多
Homogenous charge compression ignition （HCCI） engines feature high thermal efficiency and ultralow emissions compared to gasoline engines. However, unlike SI engines, HCCI combustion does not have a direct way to tr...Homogenous charge compression ignition （HCCI） engines feature high thermal efficiency and ultralow emissions compared to gasoline engines. However, unlike SI engines, HCCI combustion does not have a direct way to trigger the in-cylinder combustion. Therefore, gasoline HCCI combustion is facing challenges in the control of ignition and, combustion, and operational range extension. In this paper, an active fuel design concept was proposed to explore a potential pathway to optimize the HCCI engine combustion and broaden its operational range. The active fuel design concept was realized by real time control of dual-fuel （gasoline and n-heptane） port injection, with exhaust gas recirculation （EGR） rate and intake temperature adjusted. It was found that the cylinder- to-cylinder variation in HCCI combustion could be effectively reduced by the optimization in fuel injection proportion, and that the rapid transition process from SI to HCCI could be realized. The active fuel design technology could significantly increase the adaptability of HCCI combustion to increased EGR rate and reduced intake temperature. Active fuel design was shown to broaden the operational HCCI load to 9.3 bar indicated mean effective pressure （IMEP）. HCCI operation was used by up to 70% of the SI mode load while reducing fuel consumption and nitrogen oxides emissions. Therefore, the active fuel design technology could manage the right fuel for clean engine combustion, and provide a potential pathway for engine fuel diversification and future engine concept.展开更多
基金This work was supported by the National Basic Research Program(Grant No.2001CB209208)the Key Project of the National Natural Science Foundation of China(Grant No.50136040).
文摘In order to achieve lower emissions and extensive load in the homogeneous charge com- pression ignition (HCCI) engine system, a novel fuel design concept that high-octane number fuel and high-cetane number fuel are mixed real-time to con- trol HCCI combustion is proposed in this study. HCCI combustion fueled with iso-octane/n-heptane mix- tures controlled real-time on a single-cylinder HCCI combustion engine is studied. The test results show that the equivalence ratio of n-heptane in mixtures decides ignition and controls the combustion phase of HCCI combustion. The addition of iso-octane ex- tends knocking limit in equivalence ratio somewhat, but knocking occurrence mainly depends on the total concentration of mixture. Although operating range in equivalence ratio becomes narrow with the increas- ing proportion of iso-octane, the maximum load of HCCI combustion fueled with iso-octane/n-heptane mixtures controlled real-time is increased about 80% more than that of pure n-heptane. When iso-octane/ n-heptane mixtures are controlled in optimized method, it is proved that the load of HCCI combustion can be fully extended and emissions can be de- creased remarkably, while at the same time the higher indicated thermal efficiencies are obtained over the extensive operation range.
文摘Agricultural biomass presents a promising feedstock, which may contribute to a transition to low carbon fuels. A significant amount of research has identified a number of challenges when combusting agricultural feedstock, related primarily to energy value, ash, emissions, corrosion and combustion characteristics. The mitigation of such challenges can be addressed more cost effectively when dealing with large or utility scale combustion. The costs associated with harvesting, conversion, transportation and ultimately, market development all create additional roadblocks for the creation of an agricultural biomass industry. Nova Scotia, an Eastern Canadian province, has significant land resources, however it is prone to wet spring and as yet does not have a supply chain established for such an industry. The main components of supply, processing and conversion and demand simply do not yet exist. This research addresses one aspect of this supply chain by attempting to develop a fuel suitable for a) existing markets (local residential wood and wood pellet stoves and b) a scale that will support industry engagement. The outcomes of this research have determined that such a venture is possible and presents empirical preprocessing conditions to achieve a competitive agricultural fuel.
文摘Homogenous charge compression ignition （HCCI） engines feature high thermal efficiency and ultralow emissions compared to gasoline engines. However, unlike SI engines, HCCI combustion does not have a direct way to trigger the in-cylinder combustion. Therefore, gasoline HCCI combustion is facing challenges in the control of ignition and, combustion, and operational range extension. In this paper, an active fuel design concept was proposed to explore a potential pathway to optimize the HCCI engine combustion and broaden its operational range. The active fuel design concept was realized by real time control of dual-fuel （gasoline and n-heptane） port injection, with exhaust gas recirculation （EGR） rate and intake temperature adjusted. It was found that the cylinder- to-cylinder variation in HCCI combustion could be effectively reduced by the optimization in fuel injection proportion, and that the rapid transition process from SI to HCCI could be realized. The active fuel design technology could significantly increase the adaptability of HCCI combustion to increased EGR rate and reduced intake temperature. Active fuel design was shown to broaden the operational HCCI load to 9.3 bar indicated mean effective pressure （IMEP）. HCCI operation was used by up to 70% of the SI mode load while reducing fuel consumption and nitrogen oxides emissions. Therefore, the active fuel design technology could manage the right fuel for clean engine combustion, and provide a potential pathway for engine fuel diversification and future engine concept.
