Characteristics of the ignition and combustion of biodiesel fuel spray injected by a common-rail injection system for a direct-injection diesel engine

Abstract

The effect of injection pressures at 100 MPa and 200 MPa respectively on the ignition and combustion characteristics of biodiesel fuel spray injected by a common-rail injection system for a direct-injection diesel engine was investigated. Two biodiesel fuels (namely biodiesel fuel from palm oil (BDFp) and biodiesel fuel from cooking oil (BDFc)) and JIS#2 diesel fuel were utilized in this research. The Mie scattering technique was used to characterize both the non-evaporating and the evaporating spray formation processes. The OH chemiluminescence technique was used to determine the ignition and the lift-off length of the combusting flame. Two-colour pyrometry was applied for the soot formation processes. At all injection pressures, the biodiesel fuels (especially BDFp) gave a longer spray tip penetration and a smaller spray angle under the non-evaporating conditions while the liquid-phase penetration length was longer for the biodiesel fuels than for diesel under the evaporating conditions. From estimation using a simplified model for air entrainment by the sprays, the BDFp and BDFc exhibited lower mass ratios of air to fuel than diesel did. The ignition delay was longest for the BDFc while it was shortest for the BDFp. Both the experimental and the predicted flame lift-off lengths for the BDFp were the shortest, indicating the least percentage of entrained stoichiometric air upstream. There was no significant difference between the integrated and averaged KL factors at 100 MPa injection pressure for the BDFc and diesel fuels. At 200 MPa, the BDFc presented much lower integrated and averaged KL factors than diesel did. The averaged flame temperatures of the BDFc were found to be lower than that of diesel. The oxygen content in the BDFc played a significant role in the soot formation in comparison with the oxygen from the percentage of stoichiometric air entrained upstream of the lift-off length.

Characterization of spray and combustion processes of biodiesel fuel injected by diesel engine common rail system

“…1, the constant volume vessel can produce typical thermodynamic conditions in the combustion chamber of a diesel engine. Description about this constant volume chamber can be found in previous works by the authors [14]. A manually operated high-pressure generator (High Pressure Equipment Co. model 37-5.75-60) as shown in Fig.…”

“…and Oxygen contents as shown in Table 2 , details about the parameters needed to obtain  x has been described in previous work by the authors [14].…”

Di̇zel Yakiti, Bi̇yodi̇zel Yakiti Ve Karişimlarinin İçten Yanmali Motorlara Etki̇leri̇ni̇n Teori̇k İncelenmesi̇

“…Şekil 5(a)'da püskürtme hızı BD yakıt ve yakıt karışımları için D yakıtına göre azalmakta olup en düşük değerleri BD yakıtı vermiştir. BD yakıtı ve BD20 ve BD40 yakıt karışımları kullanıldığında püskürtme basıncındaki düşüş söz konusu yakıtların yüksek yoğunluk ve viskoziteleri nedeniyle püskürtme basıncının azalmasından kaynaklanmaktadır [28][29][30]. Şekil 5(b) ve (c)'de sırasıyla yakıt demeti nüfuz derinliği ve yakıt demeti koni açısının Şekil 4.…”

A Review on Atomization and Sprays of Biofuels for IC Engine Applications

“…Significant reduction in soot production is observed in biodiesel spray combustion. It is believed that the presence of oxygen in biodiesel is mainly responsible for the soot reduction [63,66]. In the quasi-steady diffusion combustion phase, physical processes such as evaporation and mixing are observed to have a major effect on ignition and combustion processes.…”