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Renewable fuels have received more attention in the last few decades since the fuel demand is constantly increasing. In this scenario, fuels from vegetable oils are emerging as an interesting alternative. In this study, biodiesel produced from used cooking oil was studied. Several concentrations of biofuel were tested to evaluate their performance and combustion characteristics i.e. 7% (B07), 17% (B17), 27% (B27), 52% (B52), 77% (B77) and 100% by volume of Biodiesel (B100) on conventional diesel. Tests were conducted in a single cylinder four-stroke compression ignition engine. A 1-D computational model was built and compared to experimental results. The biodiesel concentration in the blends had influence on engine performance by increasing fuel consumption due to its reduced lower heating value. In addition, larger fractions of biodiesel on conventional diesel presented higher peak of heat release.

Ethanol with high levels of hydration is a low cost fuel that offers the potential to replace fossil fuels and contribute to lower carbon dioxide (CO2) emissions. However, it presents several ignition challenges depending on the hydration level and ambient temperature. Advanced combustion concepts such as homogeneous charge compression ignition (HCCI) have shown to be very tolerant to the water content in the fuel due to their non-flame propagating nature. Moreover, HCCI tends to increase engine efficiency while reducing oxides of nitrogen (NOx) emissions. In this sense, the present research demonstrates the operation of a 3-cylinder power generator engine in which two cylinders operate on conventional diesel combustion (CDC) and provide recycled exhaust gas (EGR) for the last cylinder running on wet ethanol HCCI combustion. At low engine loads the cylinders operating on CDC provide high oxygen content EGR for the dedicated HCCI cylinder.

Low cost ethanol with high levels of hydrations is a fuel that can be easily produced and that offers the potential to replace fossil fuels and contribute to reduce greenhouse gas emissions. However, it shows several ignition challenges depending on the hydration level, ambient temperature compression ratio and other engine-specific aspects. Advanced combustion concepts such as homogeneous charge compression ignition (HCCI) have shown to be very tolerant to the water content in the fuel due to their non-flame propagating nature. Moreover, HCCI tends to increase engine efficiency while reducing oxides of nitrogen (NOx) emissions. In this sense, the present research demonstrates the operation of a 3-cylinder power generator engine in which two cylinders operate on conventional diesel combustion (CDC) and provide recycled exhaust gas (EGR) for the last cylinder running on wet ethanol HCCI combustion.

Biofuels for internal combustion engines have been explored worldwide to reduce fossil fuel usage and mitigate greenhouse gas emissions. Additionally, increased spark ignition (SI) engine part load efficiency has been demanded by recent emission legislation for the same purposes. Considering theses aspects, this study investigates the use of non-conventional valve timing strategies in a 0.35 L four valve single cylinder test engine operating with anhydrous ethanol. The engine was equipped with a fully variable valve train system enabling independent valve timing and lift control. Conventional spark ignition operation with throttle load control (tSI) was tested as baseline. A second valve strategy using dethrottling via early intake valve closure (EIVC) was tested to access the possible pumping loss reduction. Two other strategies, negative valve overlap (NVO) and exhaust rebreathing (ER), were investigated as hot residual gas trapping strategies using EIVC as dethrottling technique.

The prediction of ignition delay times is very useful during the development phase of internal combustion engines. When it comes to biofuels such as ethanol and its blends with gasoline, its importance is enhanced, especially when it comes to flex-fuel engines and the need to address current and future emissions legislations and efficiency goals. The ignition delay time measured as the angular difference between the spark discharge time, as commanded by the ECU and a relevant fraction of fuel mass burned (usually, 2, 5 or 10%). Experimental tests were performed on a downsized state-of-the-art internal combustion engine. Engine speed of 2500 rpm, with load of 6 and 13 bar IMEP were set for investigation. Stoichiometric operation and MBT or knock-limited spark timings were used, while valve overlap was varied, in order to address the effects of scavenging and residuals on ignition delay times.

Experimental aviation engines face numerous challenges, including the need for energy efficiency, alternative fuel sources, reduced weight and size, greater durability with reliability, emissions reduction, and integration with advanced control and monitoring systems. This study presents the performance of a two-stroke engine with a Uniflow scavenging system with a flathead valve concept, with lower specific fuel consumption than conventional two-stroke aircraft engines. The engine’s maximum speed is limited to 3000 rpm for better cylinder scavenging efficiency, which also eliminates the need for a reduction gearbox, simplifies the design, and reduces the engine’s total mass. 1D simulations were conducted to evaluate combustion and performance parameters using aviation.