The effects of vegetable oil properties on injection and combustion in two different diesel engines

Abstract

Four different vegetable oils, each in at least 3 different stages of processing, have been characterized according to their physical and chemical properties, their injection and atomization characteristics, and their performance and combustion characteristics in both a direct‐injection and an indirect‐injection diesel engine. The injection and atomization characteristics of the vegetable oils are significantly different than those of petroleum‐derived diesel fuels, mainly as the result of their high viscosities. Heating the oils, however, results in spray characteristics more like those observed with diesel fuel. The 2 engine types demonstrated different sensitivities to the composition of the various oils. The combustion characteristics and the durability of the direct‐injection engine were affected by the oil composition. The indirect‐injection engine, however, was not greatly affected by composition. Two different preliminary specifications have been proposed: a stringent specification including compositional requirements for direct‐injection engines, and a less stringent specification for indirect‐injection engines. The specifications are discussed in terms of the data and the rationale used in their development. Some precautions concerning the application of the specifications are also presented.

Characteristics of vegetable oils for use as fuel in stationary diesel engines—Towards specifications for a standard in West Africa

“…It is easy to perform, even though some stabilization problems, due to high relative humidity, can be encountered during the rainy season in tropical countries. The water content of crude and refined vegetable oils can reach 600-1200 ppm in some cases [106]. The specifications for fuel oil in West African countries are 500 ppm, so lower than those proposed in the German pre-standard of 750 ppm.…”

“…Nevertheless, ash is not troublesome because there is 10 to 20 times less ash in SVOs than in petroleum products and it is always recommended to carry out safety filtration before injecting the oil into the combustion chamber. According to most published work, although the initial ash content of crude vegetable oil is about 300-2,300 ppm, it drops systematically to under 100 ppm when the oil is filtered [28,106]. As all SVO production processes require filtration, the ash content should always be below the limit of 100 ppm specified by both pre-standard DIN V 51605 and SONABHY.…”

“…But as for Ca and Mg , this is not a matter of concern for countries in West Africa (see section 5.2.1) The phosphorus content of seeds mainly depends on the process (expeller temperature) [30], but it is also highly variable from one species to another [113]. For example, it can reach 70 ppm for sunflower oil [106], 200 ppm for jatropha oil [114], 270 ppm for crude soybean oil and 620 ppm for crude cotton oil [106]. Current technical equipment used to filter oils in small-scale oil mills is not able to reduce the phosphorus content.…”

“…Acidity in vegetable oils can vary from 0.01% to 10% wt (which corresponds to 0.02 to 20 mg KOH/g oil) [37,106]. Free fatty acids have smaller molecular weights than the triglycerides they are derived from, which makes acidic vegetable oils more easily flammable.…”

Physiochemical and Phase Behaviour Study of Jatropha curcus Oil - Ethanol Microemulsion Fuels Using Sorbitane Fatty Esters

“…Therefore, vegetable oils have emerged as an alternative renewable source of green fuels globally [1][2][3]. Vegetable oils such as soybean, peanut, sunflower, rape, coconut, karanj, neem, cotton, mustard, jatropha, linseed and caster have shown a performance quite comparable to diesel fuels [4][5][6][7].…”