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The reactivity controlled compression ignition (RCCI), which belongs to dual fuel mode (DFM) combustion has been considered as a promising way to achieve high fuel conversion efficiency and low emissions. By this strategy, a fuel reactivity gradient is formed in the combustion chamber which offers the probability of controlling combustion phasing. In this study, the role of fuel reactivity gradient was examined numerically by comparing a DFM (i.e., RCCI) combustion with other hypothetical cases under one specific load condition. Firstly, a chemical reaction mechanism was developed aiming at a modelling study on dual fuel and blend fuel combustion in internal combustion (IC) engines fueled by gasoline/diesel and gasoline/biodiesel. Ignition delays were validated for 100% diesel, 100% gasoline and 100% biodiesel under 102 conditions in total. Subsequently, the validated reaction mechanism which consists of 107 species and 425 reactions was implemented in coupled KIVA4-CHEMKIN code. Three dimensional validations were further conducted under 3 conditions including pure diesel combustion, and gasoline/diesel DFM combustion with both single and double injection strategies in the engine. To investigate the fuel reactivity gradient, the gasoline/diesel DFM combustion with single injection was compared with other three hypothetical cases, one of which was DFM without fuel reactivity gradient, two were the blend fuel mode but with different start of injection (SOI) timings. The results showed that the fuel reactivity gradient could retard the ignition timing, reduce heat release rate, and ease peak pressure rise rate. In addition, low levels of NOx and soot emissions were observed for the DFM combustion. The gasoline/biodiesel reaction mechanism will be employed in future work.

Decal transfer is an effective method for fabricating membrane electrode assemblies (MEAs), due to its low interfacial resistance and applicability for mass production. Here we introduce a modified decal method which makes it possible and convenient to achieve complete decal transferring. The composition of catalyst inks, drying process and transfer pressure are optimized in detail. During catalyst ink preparation, the viscosity is adjusted by altering the composition of the solvents to obtain catalyst layers (before transfer) with continuous thickness. In addition, MEAs whose catalyst layers (before transfer) were dried in four different ways are tested for application in a proton exchange membrane fuel cell. The transfer pressure is also optimized on the basis of the two previous conditions and the MEAs fabricated by this modified method show simplicity to achieve complete transfer in decal method, good repeatability and improvement in cell performance.

The present study aims to bridge the gap on hydrogen assisted biodiesel combustion, and to investigate its impacts on the engine performance, combustion and emission characteristics. Simulations were conducted on a diesel engine fueled by biodiesel with supplementary hydrogen inductions of 0.5%, 1%, 2% and 3% vol of H2 in air. A skeletal reaction mechanism was developed to include the reaction kinetics of biodiesel and hydrogen, with the CO, NOx and soot formation mechanisms embedded. The developed reaction mechanism was validated by performing the ignition delay calculations against the detailed biodiesel reaction mechanism, as well as the 3D numerical simulations against the experimental results. Good agreements in terms of ignition delay, cylinder pressure and heat release rate predictions were obtained. Key simulation results review that with the increase of hydrogen induction, a substantial increase in the peak cylinder pressure and heat release rate can be obtained under 50% and 100% load conditions, indicating an improved performance. But a reduced performance is observed at light load (10% loads) conditions due to the poor ignition and combustion processes. In terms of emissions, a general decreased trend is observed for both CO and soot emissions at all the engine speeds and loads, and a more remarkable reduction is found at 100% engine load conditions. Furthermore, due to the enhanced combustion, NOx emissions are increased slightly at 50% and 100% engine loads.

A blend of 20% (v/v) ethanol/methyl soyate was prepared and added to diesel fuel as an oxygenated additive at volume percent levels of 15 and 20% (denoted as BE15 and BE20). We also prepared a blend containing 20% methyl soyate in diesel fuel (denoted as B20). The fuel blends that did not have any other additive were stable for up to 3 months. Engine performance and emission characteristics of the three different fuels in a diesel engine were investigated and compared with the base diesel fuel. Observations showed that particulate matter (PM) emission decreased with increasing oxygenate content in the fuels but nitrogen oxides (NOx) emissions increased. The diesel engine fueled by BE20 emitted significantly less PM and a lower Bosch smoke number but the highest NOx among the fuel blends tested. All the oxygenate fuels produced moderately lower CO emissions relative to diesel fuel. The B20 blend emitted less total hydrocarbon (THC) emissions compared with base diesel fuel. This was opposite to the fuel blends containing ethanol (BE15, BE20), which produced much higher THC emission.