Determination of Static and Dynamic Injection Characteristics of a Common-Rail Direct Injection Diesel Engine Fuelled by CME-Diesel Blends

Much interest is given to the research in biodiesel these days. It is renewable and has similar properties to conventional diesel. Biodiesel is also generally seen to produce less emissions, hence it is seen as an attractive and a greener alternative source of energy. Biodiesels are also referred to as Fatty Acid Methyl Esters (FAME). They are obtained from the transesterification of oils from organic products such as animal fat or vegetable oil. Common biodiesel feedstocks are soybean (USA), rapeseed (Europe), palm, and coconut (Asia). The Philippines, being one of the largest producers of coconut in the world, should have a substantial interest in this. Biodiesel in the Philippines is obtained from coconut oil and is commonly called Coconut Methyl Ester (CME). There is a number of research works available that study the effects of biodiesel when used to run diesel engines, although there is notably less studies on CME and particularly Philippine-CME available. This work aims to show the fuel injection timing and duration of a Common Rail Direct Injection (CRDI) engine run by CME-diesel with neat diesel as baseline. There are two sets of injection parameters that describe the injection behaviour of an engine. The static injection parameters refer to the electronic commands given out by the Electronic Control Unit (ECU) while the dynamic injection parameters refer to the actual physical injection happening in the fuel injector nozzle. Knowledge of these information may help explain possible differences in performance and/or emissions observed in biodiesel-fed engines. The static injection commands were obtained by tapping into the solenoid signal wire from the ECU. The dynamic injection parameters were estimated from line pressure signals in the fuel injection line. All the tests were done on the AVL Eddy Current Engine Dynamometer in the University of the Philippines Vehicle Research and Testing Laboratory. Baseline data were recorded from 100% neat diesel, then volumetric blends B10 (10% CME biodiesel and 90% neat diesel) and B20 (20% CME biodiesel and 80% neat diesel) were mixed for the tests. The CRDI engine was ran at full load, sweeping the operating range at 400 RPM increments from 800 to 4000. The results showed no significant difference in the static injection parameters of the CME-diesel blend-fed engines as compared to being ran with neat diesel. As for the dynamic injection parameters, there were some significant differences observed in the higher engine speeds starting at 2800 RPM. The observed changes were attributed to the differences in the physiochemical properties of CME biodiesel as compared to neat diesel.