Current State and Perspectives on Transesterification of Triglycerides for Biodiesel Production

Triglycerides are the main constituents of lipids, which are the fatty acids of glycerol. Natural organic triglycerides (viz. virgin vegetable oils, recycled cooking oils, and animal fats) are the main sources for biodiesel production. Biodiesel (mono alkyl esters) is the most attractive alternative fuel to diesel, with numerous environmental advantages over petroleum-based fuel. The most practicable method for converting triglycerides to biodiesel with viscosities comparable to diesel fuel is transesterification. Previous research has proven that biodiesel–diesel blends can operate the compression ignition engine without the need for significant modifications. However, the commercialization of biodiesel is still limited due to the high cost of production. In this sense, the transesterification route is a crucial factor in determining the total cost of biodiesel production. Homogenous base-catalyzed transesterification, industrially, is the conventional method to produce biodiesel. However, this method suffers from limitations both environmentally and economically. Although there are review articles on transesterification, most of them focus on a specific type of transesterification process and hence do not provide a comprehensive picture. This paper reviews the latest progress in research on all facets of transesterification technology from reports published by highly-rated scientific journals in the last two decades. The review focuses on the suggested modifications to the conventional method and the most promising innovative technologies. The potentiality of each technology to produce biodiesel from low-quality feedstock is also discussed.

Experimental investigations on the performance and emissions characteristics of dual biodiesel blends on a varying compression ratio diesel engine

The present work discusses the performance and emissions characterization of dual biodiesel sample blends on a varying compression ratio diesel engine. The dual biodiesel blends were obtained by blending two biodiesels (Mahua and Jatropha) in equal proportions volume (1:1, v/v) with mineral diesel. The sample blends were obtained on a ‘percentage by volume’ basis and named B10, B20, B30, and B40 (B10 was a blend of 5% each biodiesel with 90% mineral diesel and similarly for all other sample blends). All the experiments were performed at a constant engine speed of 1500 rpm, 50% loading conditions (2.6 kW), and varying compression ratios of 13.5:1, 14.5:1, 15.5:1, and 16.5:1. The results revealed that the sample blends had slightly higher brake power and mechanical efficiency with sample blends B10 to B40 had (0.15–1.58%) higher brake power and (1.07–12.42%) higher mechanical efficiency as compared to mineral diesel at a compression ratio of 16.5:1. The In-cylinder peak pressure and exhaust gas temperature were observed to be lower than mineral diesel for the sample blends B10 to B40 by 0.15–0.36 bar and 11.1–69.8 ℃, respectively. Also, the emissions of carbon monoxide and hydrocarbons were lower by 33–62%, respectively, for the sample with the highest blend percentage. However, the carbon dioxide emissions were found to be higher by 42.85% than mineral diesel. From the overall performance and characterization, it is concluded that B20 had optimum properties and blend percentage to be a better substitute fuel for mineral diesel among all the tested samples.

Performance and emission characteristics of CNG-fueled compression ignition engine with Ricinus communis methyl ester as pilot fuel

Surge in petroleum prices, its drying sources and degradation in air quality focused interest on renewable energy sources as substitute for existing fuels for internal combustion engines. This study highlights the combustion, performance, and emission characteristics of diesel engines fueled with compressed natural gas (CNG) as primary fuel and castor (Ricinus communis) oil methyl ester (COME) as pilot fuel. COME was produced from non-edible grade Ricinus communis oil. The biodiesel fuel properties and characterization was done as per ASTM D6751 specifications. The CNG was inducted through inlet manifold fumigation at a consistent flow rate of 15 l/min under dual-fuel mode. It is evident from the test results that B20-CNG yields brake thermal efficiency of 23.6% when compared to 25 and 27% for D-CNG and diesel fuel, respectively. The peak cylinder gas pressure was lower in dual-fuel mode when compared to conventional diesel. The emission results show increase in NO_x emission by 24.5 and 28.4% for D-CNG and B20-CNG, respectively when compared to baseline diesel fuel at full engine load. There was increase in HC emission by 6.7 and 11% whereas CO emissions decreased by 31.6 and 37.4% for B20-CNG and D-CNG, respectively at similar operating conditions. Reduction in smoke opacity by 49.4 and 59.6% was achieved respectively for D-CNG and B20-CNG under dual-fuel mode. On the whole, COME exhibits a better pilot fuel choice for dual-fuel combustion mode in comparison to conventional fossil petroleum diesel in terms of combustion, performance, and emissions characteristics.

A, Mehta PS. Predicting surface tension for vegetable oil and biodiesel fuels

A unified methodology for predicting surface tension of oil and biodiesel is proposed. Effects of transesterification and compositional variations on surface tension of biodiesel are discussed and methods to address the variations are suggested.