Dual-fuel Compression Ignition Combustion Research Articles

Effects of Varying Equivalence Ratios on the Combustion Efficiency Characteristic of a Dual-Fuel Compression Ignition Engine by Changing Intake Pressures and Exhaust Gas Recirculation Rates

In general, a leaner mixture condition improves combustion efficiency in compression ignition (CI) combustion using diesel. However, in the case of leaner air–fuel mixture conditions, it disturbs flame propagation in spark ignition combustion using gasoline, i.e., low reactivity fuel, causing a decrease in combustion efficiency. Since dual-fuel combustion in a CI engine typically involves the use of high- and low-reactivity fuels together, the differing reactivity conditions in the cylinder become as important as the local equivalence ratio in the cylinder. Thus, there is a need to verify the effect of a leaner mixture condition on combustion efficiency in dual-fuel CI combustion. For this reason, this study experimentally evaluates the effects of varying equivalence ratios on the combustion efficiency of gasoline/diesel dual-fueled CI combustion in a 0.4-L single-cylinder engine under low-speed (1500 rpm) and low-load (total LHV 570 J/str) conditions. To vary the equivalence ratios, intake pressures and exhaust gas recirculation (EGR) rates were, respectively, changed under the part-load condition. The results emphasize that as the equivalence ratio becomes leaner by increasing the intake pressure, combustion efficiency worsens due to the low reactivity properties and certain flame propagation modes of gasoline combustion. On the contrary, increasing the EGR rate did not significantly influence combustion efficiency, but it effectively helped reduce nitrogen oxide (NOx) emissions. Based on these results, it is concluded that optimizing dual-fuel CI combustion to suppress NOx emissions is better achieved using EGR, rather than creating a leaner mixture condition.

Laboratory Control and Measurement System of a Dual-Fuel Compression Ignition Combustion Engine Operating in a Cogeneration System

Electrical energy production from renewable energy sources is currently one of the key directions of conducted research. This paper describes a developed laboratory control system for the operation of a dual-fuel compression ignition engine in which the main fuel charge is fed in the form of biogas with variable composition, it also describes a system enabling the measurement of waste heat from this engine.

Throttleless and EGR-controlled stoichiometric combustion in a diesel–gasoline dual-fuel compression ignition engine

Stoichiometric Diesel and Gasoline Dual-fuel (Dieseline) Compression Ignition (SDCI) combustion using three-way catalyst (TWC) after-treatment is a promising technology to address the challenge issues of fuel consumption and emissions in future internal combustion engines. The authors use EGR instead of the throttle to control the load of the dual fuel compression ignition combustion engine. In order to investigate the fuel consumption and emission characteristics of SDCI combustion, a series of experiments were conducted in a modified single cylinder diesel engine using gasoline with a small portion of diesel for ignition enhancement. The experimental results show that SDCI combustion can achieve high indicated thermal efficiencies in a relatively wide range of loads (IMEP 4.3–8.0bar) because of a higher compression ratio, shorter combustion and smaller pumping losses. An attractive indicative specific fuel consumption (ISFC) of 190.8g/kWh has been achieved at a medium load without any boosting and the PM emissions are lower than for conventional diesel combustion. Different diesel percentages in the dual fuel supply have shown a significant impact on the ignition process and provide a wider available time range for combustion phase control. Diesel direct injection (DI) timing has a greater effect on PM emissions than the fuel ratio. Late DI timing reduces the thermal efficiency and results in higher PM emissions. Early DI timing and less diesel are preferable in order to reduce or avoid the diffusion combustion stage, which may lead to high PM emissions in the stoichiometric combustion.