Evaluation of the Oxidation Stability of Biodiesel Produced from Moringa oleifera Oil

This research article published by ACS Publications, 2011Biodiesel is considered as an alternative fuel to petroleum-based conventional diesel fuel. Dependent upon the raw material, biodiesel can contain more or less unsaturated fatty acids in its composition, which are susceptible to oxidation reactions accelerated by exposure to oxygen and high temperatures. The present study evaluated the oxidative stability of biodiesel produced by methanolysis of Moringa oleifera oil, primarily available on the African continent. The evaluation was conducted by means of the Rancimat instrument, at a temperature of 110 °C, with an air flow of 10 L/h. Moringa oil methyl ester (MOME) displayed an oxidation stability of 5.05 h. Thus, MOME met the oxidative stability requirement in the American Society for Testing and Materials (ASTM) D6751 standard, which prescribes a minimum of 3 h, but did not meet the minimum requirement prescribed in the EN 14214 standard, which is 6 h. Also, this study evaluated the effectiveness of four antioxidants, 1,2,3-trihydroxybenzene [pyrogallol (PY)], 3,4,5-trihydroxybenzoic acid [propyl gallate (PG)], 2-tert-butyl-4-methoxyphenol [butylated hydroxyanisole (BHA)], and 2,6-di-tert-butyl-4-methylphenol [butylated hydroxytoluene (BHT)], on the oxidation stability of MOME. The result showed that the effectiveness of these antioxidants was in the order of PY > PG > BHA > BHT

Detailed modelling of the internal processes of an injector for common rail systems

In the last few decades exhaust emissions of road vehicles have decreased dramatically, owing to the more and more stringent emission standards issued by the legislative bodies of different countries, combined with the necessity of cleaner, better performing vehicles from society side. The introduction of Common Rail (CR) injection systems has been a great step towards achieving this target, thanks to its flexibility in fuel injection pressure, timing, and length, along variable engine load conditions. However, it is highly time and resource consuming to set up the injection system for all operating points of different engines, moreover, as the injection is a small scale, high speed process, the behaviour of the internal processes is challenging to measure. The best solution for these problems is to create a detailed model of the injector, where all the hydraulic, mechanic, and electromagnetic subsystems are represented, this way the internal working conditions can be analysed and resources can be saved. In this work, a detailed model of a first generation CR injector for commercial vehicles is presented and validated against needle lift data. The fluid dynamic and mechanic sub-systems are presented in details to thoroughly investigate the working principles of the injector internal parts. The fluid dynamic subsystem contains the chambers, holes, and throttles of the injector, while the mechanic subsystem models the motion and behaviour of the internal parts. The main features of the injector internal working conditions are described and analysed. Apart from the needle lift, these included solenoid anchor, pin and control piston lifts, the control chamber pressure and the mechanical force acting on the anchor. Five test cases were chosen on a medium duty test engine to represent a wide range of operation points from full load to idle and the simulated results were compared to the measured data. The simulated control piston movement accurately matched the measured curves in every test case