Effect of nano-biodiesel blends on CI engine performance, emissions and combustion characteristics - Review

The situation of greenhouse gas emissions with the effect of severe decline in oil reserves and the increase in energy demand are among the alarming periods to be faced. For this reason, biodiesel is considered as an alternative that can be used in the transport sector. The main reason for this research is to review the Nano-biodiesel application in a diesel engine for the purpose of improving the fuel properties, combustion efficiency of the fuel and reducing the emission. This article critically and in-depth examines the impact of the different nano-biodiesel blends available, as well as highlighting their quality variations and their impact on engine outputs. The impact of Nano-metallic additives such as Al₂O₃, CeO₂, CNTs, CuO, GO, TiO₂ and others on fuel quality and combustion was analyzed. Selected and critically archived articles were reviewed. Significant enhancement is reported for nanoparticle-based disperse test fuels in term of brake thermal efficiency. Maximum improvement in BTE of up to 24.7 % with Jatropha biodiesel (B20) blend with 50 ppm Al₂O₃ nanoparticles was reported. Maximum percentage of 25 % reduction in BSFC was reported for Acacia concinna biodiesel blend with 150 TiO₂. The maximum percentages of emission level reduction were 70.94 % for HC, 80 % for CO and 30 % for NOx for methyl ester of waste cooking oil (B10) blend with 100 ppm TiO, JB20 blend with 20 ppm Al₂O₃ and B10 blend with combined 30 ppm Al₂O₃ and 30 ppm CeO, respectively. Therefore, it is recommended to further investigate several combinations of biodiesel blends with different metallic oxide nanoparticles at different concentrations. According to the assessment, future studies may focus on hybrid nanoparticles, which are composed of two or more nanoparticles in order to overcome the limitations of nanoparticles to one component, by improving the properties of the nanoparticle, achieving new properties that cannot be obtained by single nanoparticles.