Effects of Biodiesel Saturation Degrees on NOx Emission and FTIR Spectroscopy

The Fourier Transform Infrared (FTIR) spectroscopic characteristics of biodiesel produced from vegetable oils with different saturation degree was investigated in this study. Unsaturation degree, usually determined by the Iodine Value (IV) indicates the sum of double bonds, triple bonds and/or rings. In this work, biodiesels were produced by canola oil, palm oil and coconut oil that have saturation degree of 7.0 wt%. 45.6 wt% and 81.5 wt%, respectively. Biodiesel blends of B10, B15 and B20 were tested in a direct injection diesel engine and the NOx emissions were measured with a flue gas analyser. The NOx emission was increased in all biodiesel cases, where the NOx emission seems to be proportional with the biodiesel unsaturation degree. The FTIR spectroscopy of each biodiesel was analysed with FTIR spectrometer. Each biodiesel produced different FTIR spectroscopy characteristics and the double bond of C=O was the most abundant in highly unsaturated canola oil methyl ester which suggested that FTIR spectroscopy can be suitable to analyse biodiesel characteristics

Detailed Examination on the Enhancement of Heat Release Rate in Inversed-delta-injected Diesel Spray Flame

Diesel engine will remain relevant even in the net-zero carbon society due to its high torque and high thermal efficiency characteristics. Inversed-delta injection rate shaping Diesel spray has been proven to increase Diesel engine thermal efficiency further. Although enhancement of heat release due to large scale vortices growth and development in the unstable inversed-delta-injected Diesel spray flame was observed, its impact on combustion duration reduction is much lesser than anticipated. In this study, apparent heat release rate derived from pressure history will be compared with the simultaneous high-speed images of OH* chemiluminescence and laser Schlieren; all the data were previously acquired in a constant volume combustion chamber CVCC experiment using a TAIZAC (TAndem Injector Zapping ACtivation) injector. MATLAB-based codes were employed for the flow velocity field turbulence intensity and the fuelair mixture spatiotemporal distributions analysis using Flame Imaging Velocimetry (FIV) analysis and Musculus-Kattke 1D model, respectively. Inversed-delta injection rate shaping exhibits enhancement of heat release throughout the diffusion combustion phase compared to that of conventional rectangle injection. Large scale vortices effect seems to be dominant factor in enhancing the heat release and OH* intensity in the inversed-delta injection rate shaping at the earlier stage of diffusion combustion phase. At the later stage, effects of high turbulence intensity coincide with fuel-air mixture availability at the spray tail marks by a larger OH* reacting area seems to be more pronounced in enhancing heat release rate for the inversed-delta injection. Regardless of the detected vortex and fuel-air mixture at the spray tail during the late combustion phase, no apparent OH* signal is observed in both injection cases suggesting that the mixture might be overly lean.</p