Abstract
The experiments were conducted on a modified two-cylinder diesel engine to investigate the effects of excess-air coefficient (λ) and intake temperature (Tin) of different blending ratios (volume ratio of gasoline in the blends) on the combustion and emission characteristics of a Partially Premixed Compression Ignition (PPCI) engine. The results show that with the increase of gasoline blending ratio, the peak in-cylinder pressure (Pmax), the peak in-cylinder temperature (Tmax) and the peak heat release rate (HRRmax) of four test fuels all increase first and then decrease. When gasoline volume fraction is 10%, HC and CO emissions are the lowest. In addition, intake temperature (Tin) has a significant effect on the n-butanol/gasoline PPCI engine. With the increase of Tin, the in-cylinder Pmax and HRRmax of four test fuels gradually increase, the combustion phase advances and HC and CO emissions decrease, while NOx emissions increase slightly. Furthermore, as λ increases, the Pmax, Tmax and HRRmax of the four test fuels show monotonously reducing trend. At the same time, mixture concentration has basically no effect on start of combustion (CA10), the combustion duration (CD) gradually extends, and HC and CO emissions increase.
Highlights
Nomenclature CA10 Crank angle corresponding to 10% of accumulated heat release (@°CA) CA50 Crank angle corresponding to 50% of accumulated heat release (@°CA) combustion duration (CD) Combustion duration (°CA) COVPmax Coefficient of variation for peak in-cylinder pressure (%) heat release rate (HRR) Heat release rate n Engine speed (r/min) Pmax Peak in-cylinder pressure (MPa) Tin Intake temperature (°C) Tmax The maximum in-cylinder temperature (K) λ Excess-air coefficient
Tin was controlled at 120 °C, n was set at 1200 r/min, and the time of fuel direct injection in the cylinder was maintained at 20°CA after intake top dead center. λ was 2.0, 2.5 and 3.0, respectively
When gasoline blending ratio is greater than 10%, the evaporation and atomization effects of n-butanol/gasoline blends are better, and heating value of the blends increases, while the content of n-butanol in the blends decreases at this time, and the reduction in the amount of OH generated in low-temperature reaction stage is not conducive to oxidation of the blends, so that the combustion reaction rate decreases and HRR slows down, which causes Pmax and HRRmax to decrease, and at the same time, the corresponding crankshaft angle positions move backward
Summary
Nomenclature CA10 Crank angle corresponding to 10% of accumulated heat release (@°CA) CA50 Crank angle corresponding to 50% of accumulated heat release (@°CA) CD Combustion duration (°CA) COVPmax Coefficient of variation for peak in-cylinder pressure (%) HRR Heat release rate (kJ/°CA) n Engine speed (r/min) Pmax Peak in-cylinder pressure (MPa) Tin Intake temperature (°C) Tmax The maximum in-cylinder temperature (K) λ Excess-air coefficient. Under the condition of medium load 0.7 MPa BMEP and 1600 r/min, they found that NOx, soot, CO and HC emissions were 0.41, 0.032, 4.94 and 0.65 g/(kW·h), respectively Such low emissions results cannot be achieved with pure diesel. They compared the results of two injection pressures (100 MPa and 150 MPa) and found that the dependence of soot emission on injection pressure was greatly reduced with high degree of premixing blends. Kim et al.[8] conducted a multiple premixed compression ignition (MPCI) load expansion test of naphtha on a compression ignition engine They found that by optimizing injection parameters and intake control, the indicated mean effective pressure (IMEP) of naphtha MPCI mode could reach 1.4 MPa, which had high thermal efficiency, low emissions and low combustion noise. In terms of emissions, gasoline-type fuels are more suitable for compression ignition engines than diesel
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
