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Biodiesel from Second-Generation Feedstock:
Published in Bhaskar Singh, Ramesh Oraon, Advanced Nanocatalysts for Biodiesel Production, 2023
Amjad Ali, Km Abida, Himmat Singh
For a BD sample, frequently studied physicochemical parameters along with prescribed test methods and corresponding ASTM D6751 and EN 14214 limits are provided in Table 3.6. Biodiesel produced from various feedstock sources must satisfy the prescribed specifications before their application in a diesel engine. The FAME content in the BD fuel must be > 96.5% and kinematic viscosity should be below 6 mm2/s as it affects the operation of the fuel injector, particularly at low temperatures.30 On the other hand, a low cetane number causes fuel knocking, which increases gaseous and particulate exhaust emissions due to incomplete combustion of biodiesel fuel. As indicated in Table 3.6, the BD produced from second-generation feedstock [such as jatropha oil (JO), karanja oil (KO), waste cooking oil (WO), and animal fats (AF)] meets the specified parameters and consequently would be safe to use in existing diesel engines in the form of a prescribed blend.145–147
Compression-Ignition Engine Combustion
Published in Kenneth M. Bryden, Kenneth W. Ragland, Song-Charng Kong, Combustion Engineering, 2022
Kenneth M. Bryden, Kenneth W. Ragland, Song-Charng Kong
Biodiesel is a mixture of fatty acid methyl esters (FAME), which are produced through the transesterification of triglycerides in vegetable oil. Triglycerides react with methanol by the use of a catalyst (e.g., sodium hydroxide or potassium hydroxide) to produce biodiesel and glycerin. The standard recipe uses 100 kg of oil with 21.7 kg of methanol and 1.5 kg of catalyst to produce 100 kg of biodiesel and 10.4 kg of glycerin with excess methanol. The source of oil can come from various agricultural products (e.g., soybean, rapeseed, sunflower, canola, palm, Jatropha, algae), restaurant waste oil, and animal fat. Mixtures of FAME can be easily produced, but only those that meet the biodiesel fuel standards can be certified as biodiesel. B20 is a mixture of 20% biodiesel by volume in diesel fuel. In general, biodiesel has better lubricity and a higher cetane number (~55) than regular diesel fuels. Combustion of biodiesel produces lower particulate, CO, and hydrocarbons emissions because it contains oxygen in the fuel molecules; however, it produces slightly higher NOX emissions, possibly because of higher combustion temperatures. Successful adoption of biodiesel for the fleet requires careful fuel management because certain fuel properties can deteriorate at low temperatures, causing negative effects on the fuel system.
Internal combustion engines and fuels
Published in J. F. Griffiths, J. A. Barnard, Flame and Combustion, 2019
J. F. Griffiths, J. A. Barnard
Diesel fuels are characterised by their cetane number, which is measured in a test similar in concept to the assignment of octane number to gasoline blends. The binary mixture scale used to characterise the cetane number is based on n-hexadecane (n-cetane, C16H34), assigned the cetane number 100, and α-methyl-naphthalene, assigned the cetane number 0. However, for practical reasons the binary mixture that is used in the comparative tests of commercial fuels is related to heptamethylnonane (an isomeric structure of cetane) at the lower end, with a cetane number of 15. Cetane numbers of some hydrocarbons are given in Table 13.5 [276]. The main but not necessarily the only parameter that is used to assess a diesel fuel performance in a test engine is the ignition delay, given by the time interval from initial injection to the maximum rate of pressure rise during combustion. The standardising binary mixture reflects the comparative ease of autoignition of the straight chain structure of n-hexadecane compared with its branched chain isomer. A high cetane number is compatible with very short ignition delay. A cetane number of 50 is typical for current diesel fuels.
A review on the production and physicochemical properties of renewable diesel and its comparison with biodiesel
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Rashi Koul, Naveen Kumar, R.C Singh
Cetane number is an index number of a diesel that tells us the quality of ignition of a diesel fuel. High cetane number leads to easy ignition of the fuel (Knothe 2010). Apart from improving the delay in the ignition, it is also a measure of speed. It tells how fast a fuel can autoignite on being injected into the diesel engine. It denotes the percentage of hexadecane by volume in an ignitable composition of hexadecane and 1-methylnaphthalene, whose characteristics match with those of a diesel fuel that is to be tested. The range of cetane index at which diesel engine operates well is between 40 and 55 (C. Liu et al. 2013a; Rêgo and Teixeira 2017; Xing-Cai et al. 2004). The same is shown in Table 1. The cetane number of biodiesel is not fixed, due to different vegetable oils considered as feedstocks. The biodiesel is made from various plant oil resources such as palm oil, karanja oil, jatropha oil, peanut oil, sunflower oil, rapeseed oil, and soybean oil. The CN is in the range of 68–94.8 (Table 1) and in case of animal fat it ranges in between 56 and 60. The number of C-atoms that make a long C-chain, the unsaturated bonds, and ester yield are some of the factors that decide the cetane number of the biodiesel (Araújo et al. 2017).
Comparison of different methods for producing bio oil from Egyptian jatropha seeds
Published in Biofuels, 2020
Said M.A. Ibrahim, K.A. Abed, M.S. Gad, H.M. Abu Hashish
The measured calorific values of jatropha oil for Soxhlet, solvent, screw press and hydraulic press processes were 39,135, 38,808, 39,128 and 39,201 kJ/kg, respectively, as presented in Table 6. The calorific value of fuel determines the availability of heat to produce the engine power. Therefore, calorific values are important in the choice of an alternative fuel for diesel engines for higher engine performance. The measured cetane number for jatropha oil extracted by Soxhlet, solvent, screw press and hydraulic press processes is 37.53, 37.62, 37.83 and 39.12, respectively. Cetane number is a measure of the combustion quality of a fuel in diesel engines, and is related to the volatility of the fuel and the ignition delay time. Ignition quality and cetane number affect engine performance, cold starting, warm up, and engine combustion roughness. A higher cetane number leads to shorter ignition delay and engine performance reduction. Flash points for jatropha oil extracted by screw press, hydraulic press, Soxhlet and solvent methods are 142, 146, 140 and 138 °C, respectively. Flash point temperature is critical for safe fuel handling and storage. Flash points of jatropha oil extracted by different extraction processes are higher than that of diesel oil, so handling and storage of these oils are relatively less hazardous as compared to diesel fuel, as recorded in Table 6.
Conversion of fatty acid distillates into biodiesel: engine performance and environmental effects
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Ramón Piloto-Rodríguez, Yosvany Díaz, Eliezer Ahmed Melo-Espinosa, Yisel Sánchez-Borroto, Leonardo Goyos, Laureano Canoira, Magín Lapuerta
The in-cylinder pressure measurements were analyzed through the first derivative with respect to crank angles, allowing the determination of the start of combustion. It was done for biodiesel obtained from FAD and compared to diesel fuel as is shown in Figure 3. As is observed, the curve representing biodiesel (dashed line) shows a slightly earlier start of combustion, associated to a higher cetane number of biodiesel from FAD. A higher cetane number leads to an advanced start of combustion that can influence the engine performance but also the exhaust emissions. This result is reported for biodiesel compared to diesel fuel (other feedstocks), associated to a higher oxygen content in biodiesel, which might ignition as well as splitting the heavier fatty acid into smaller compounds, causing earlier ignition (Hasan and Rahman 2017).