Abstract
The fuel qualities of several biodiesels containing highly saturated, mono, and poly unsaturated fatty acids, as well as their combustion and exhaust emission characteristics, were studied. Six biodiesel samples were divided into two groups based on their fatty acid composition, including group 1 (coconut, castor, and jatropha) and group II (palm, karanja, and waste cooking oil biodiesel). All fuels (in both groups) were tested in a single-cylinder off-road diesel engine. Castor and karanja biodiesel, both rich in mono-unsaturation level, have a high viscosity of about 14.5 and 5.04 mm2/s, respectively. The coconut and palm biodiesels are rich in saturation level with cetane numbers of 62 and 60, respectively. In both groups, highly saturated and poly-unsaturated methyl esters presented better combustion efficiency and less formation of polluted emissions than mono-unsaturation. At full load, coconut and palm biodiesel displayed 38% and 10% advanced start of combustion, respectively, which reduced ignition delay by approximately 10% and 3%, respectively. Mono-unsaturated methyl esters exhibited a higher cylinder pressure and heat release rate, which results in higher NOx gas emissions. The group II biodiesels showed about 10–15% lower exhaust emissions owing to an optimum level of fatty acid composition. Our study concluded that highly saturated and poly-unsaturated fatty acid performed better than mono-unsaturated biodiesels for off-road engine application.
Highlights
There has been a lot of focus on environmental pollution and rapid reduction in fossil fuel resources [1]
Biodiesel is an alternative sustainable source, which can be produced from plant seed oils, animal fats, and other long-chain fatty acid containing substances such as waste cooking oil [9]
A single cylinder variable compression ratio (VCR) diesel engine was used for testing (Table 2)
Summary
There has been a lot of focus on environmental pollution and rapid reduction in fossil fuel resources [1]. Zhang et al (2009) investigated the premixed combustion behavior of four carbon methyl esters in a research engine [15] They examined the impact of low-temperature fuel oxidation on exhaust gases at different compression ratios [15]. The aim of this study is to examine the combustion and emission behavior of the highly saturated, mono-unsaturated, and poly-unsaturated methyl esters in the same diesel engine. A single-cylinder stationary variable compression ratio diesel engine was use for the biodiesel test with varied saturation levels The objectives of this investigation are as follows: (i) to produce biodiesels with various levels of saturation; (ii) the measurement and comparison of the biodiesels’ fuel properties based on their saturation levels; (iii) to further understand the behavior of FAME compositions, investigating the combustion and Energies 2021, 14, x FOR PEER REVIEW. The combustion and emission qualities of biodiesels will be compared in order to determine the correlations between the various saturation levels
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