• Energy Research

The energy conversion of nickel-impregnated coconut shells using supercritical water has not yet been explored. The impregnation process was conducted at room temperature and a pH of 5.80 for 72 h. Characterization of the prepared sample confirmed the presence of nickel nanoparticles with an average size of 7.15 nm. The gasification of control and impregnated samples was performed at 400–500 °C, biomass loading from 20 to 30 wt% and residence time from 20 to 60 min. The response surface methodology (RSM) approach, with a Box–Behnken method, was used to design the experiments. The optimization model showed that the non-catalytic process at 500 °C, 60 min and 20 wt% of biomass loading could promote an H2 yield of 8.8 mol% and gasification efficiency of 47.6%. The gasification of nickel-impregnated coconut shells showed significantly higher gasification efficiency (58.6%) and hydrogen yield (17.2 mol%) with greater carbon and hydrogen efficiencies (109.4 and 116.9%) when compared to the non-catalytic process. The presence of nickel particles in the biomass matrix as nanocatalysts promoted higher hydrogen production and supercritical water gasification efficiency.

The worldwide consumption of fossil hydrocarbons in the road transport sector in 2020 corresponded to roughly half of the overall consumption. However, biofuels have been discreetly contributing to mitigate gaseous emissions and participating in sustainable development, and thus leading to the extending of the commercial utilization of internal combustion engines. In this scenario, the present work aims at exploring the effects of alternative fuels containing a blend of 15% ethanol and 35% biodiesel with a 50% fossil diesel (E15D50B35) or 50% Fischer–Tropsch (F-T) diesel (E15FTD50B35) on the engine combustion, exhaust emissions (CO, HC, and NOx), particulate emissions characteristics as well as the performance of an aftertreatment system of a common rail diesel engine. It was found that one of the blends (E15FTD50B35) showed more than 30% reduction in PM concentration number, more than 25% reduction in mean particle size, and more than 85% reduction in total PM mass with respect to conventional diesel fuel. Additionally, it was found that the E15FTD50B35 blend reduces gaseous emissions of total hydrocarbons (THC) by more than 25% and NO by 3.8%. The oxidation catalyst was effective in carbonaceous emissions reduction, despite the catalyst light-off being slightly delayed in comparison to diesel fuel blends.

Les biocarburants ont été considérés à long terme dans des mélanges avec du diesel minéral visant à réduire les émissions de particules (PM) dans les moteurs diesel. Dans ce contexte, le biodiesel est l'un des biocarburants les plus prometteurs, bien que des additifs optimiseurs soient également considérés pour réduire davantage les émissions de particules. Ce travail présente les résultats d'une évaluation de la distribution du nombre et de la taille des particules (PSD) émises par un moteur diesel alimenté avec du diesel minéral, du biodiesel et un additif d'optimisation. Cet additif vise à réduire le nombre de particules émises, ce qui avantage l'utilisation du biocarburant dans un moteur diesel. Cette étude comparative a montré que l'ajout de biodiesel au diesel minéral induit une augmentation des émissions de particules de pointe et l'additif a pu réduire les émissions pour le mélange de biodiesel dans les conditions du moteur testées. Los biocombustibles se han considerado a largo plazo en mezclas con diésel mineral con el objetivo de reducir las emisiones de partículas (PM) en los motores diésel. En este contexto, el biodiésel es uno de los biocombustibles más prometedores, aunque también se consideran aditivos optimizadores para reducir aún más las emisiones de PM. Este trabajo presenta los resultados de una evaluación del número de partículas y la distribución de tamaños (PSD) emitidos por un motor diésel alimentado con diésel mineral, biodiésel y un aditivo optimizador. Este aditivo tiene como objetivo reducir el número de partículas emitidas, lo que beneficia el uso de biocombustible en un motor diésel. Este estudio comparativo ha demostrado que la adición de biodiésel al diésel mineral induce un aumento en las emisiones máximas de PM y el aditivo pudo reducir las emisiones de la mezcla de biodiésel dentro de las condiciones del motor probadas. Biofuels have been long term considered in blends with mineral diesel aiming to reduce particulate matter (PM) emissions in diesel engines.In this context, biodiesel is one of the most promising biofuels, although optimizer additives are also considered to further reduce PM emissions.This work presents the results of an evaluation of the particle number and size distribution (PSD) emitted by a diesel engine fueled with mineral diesel, biodiesel and an optimizing additive.This additive aims to reduce the number of particles emitted, which advantages the use of biofuel in a diesel engine.This comparative study has shown that the addition of biodiesel to mineral diesel induces an increase in peak PM emissions and the additive was able to reduce emissions for the biodiesel mixture within the engine conditions tested. تم النظر في الوقود الحيوي على المدى الطويل في الخلائط مع الديزل المعدني بهدف تقليل انبعاثات الجسيمات (PM) في محركات الديزل. في هذا السياق، يعد الديزل الحيوي أحد أكثر أنواع الوقود الحيوي الواعدة، على الرغم من أن إضافات المحسن تعتبر أيضًا لتقليل انبعاثات PM. يقدم هذا العمل نتائج تقييم عدد الجسيمات وتوزيع الحجم (PSD) المنبعث من محرك ديزل مزود بالديزل المعدني والديزل الحيوي ومادة مضافة محسنة. تهدف هذه المادة المضافة إلى تقليل عدد الجسيمات المنبعثة، مما يفيد استخدام الوقود الحيوي في محرك الديزل. أظهرت هذه الدراسة المقارنة أن إضافة الديزل الحيوي إلى الديزل المعدني يؤدي إلى زيادة في ذروة انبعاثات PM وتمكنت المادة المضافة من تقليل انبعاثات خليط الديزل الحيوي داخل ظروف المحرك التي تم اختبارها.

This research investigates the effects of a synthetic diesel-like fuel (Fischer-Tropsch diesel) and biofuels (ethanol and biodiesel) fuel blends on the energy-exergy efficiencies and gaseous exhaust emissions characteristics of a compression ignition engine. Two blends of alternative fuels denoted as E15B35FTD50 (15% ethanol, 35% biodiesel, and 50% Fischer-Tropsch diesel) and E15B35D50 (15% ethanol, 35% biodiesel, and 50% diesel) were experimentally studied on a single-cylinder diesel engine and compared to diesel fuel. The results show that the energetic and the exergetic efficiencies of the alternative fuels are comparable to those of the engine fueled with diesel fuel. The unburnt HC, NO, N2O, and NH3 emissions were reduced for the two alternative fuel blends compared to diesel, while CO emissions increased. The light HC species were found to slightly increase for the alternative fuel blends in comparison with diesel fuel. However, the total HC was considerably reduced by the combustion of E15B35FTD50 not only when compared to the diesel fuel combustion, but also when compared to E15B35D50. Overall, these results may contribute to identifying advantages and limitations in terms of energetic-exergetic analysis and emissions for the new generation of conventional diesel and hybrid electric vehicles that aim to achieve future emissions regulations.

Biofuels provide high oxygen content for combustion and do modify properties that influence the engine operation process such as viscosity, enthalpy of vaporization, and cetane number. Some requirements of performance, fuel consumption, efficiency, and exhaust emission are necessary for the validation of these biofuels for application in engines. This work studies the effects of the use of diethyl ether (DEE) in biodiesel-ethanol blends in a DI mechanical diesel engine. The blends used in the tests were B80E20 (biodiesel 80%-ethanol 20%) and B76E19DEE5 (biodiesel 76%-ethanol 19%-DEE 5%). Fossil diesel (D100) and biodiesel (B100) were evaluated as reference fuels. The results revealed similar engine efficiencies among tested fuels at all loads. The use of B100 increased CO and NOx and decreased THC compared to D100 at the three loads tested. B80E20 fuel showed an increase in NOx emission in comparison with all fuels tested, which was attributed to higher oxygen content and lower cetane number. THC and CO were also increased for B80E20 compared to B100 and D100. The use of B76E19DEE5 fuel revealed reductions in NOx and CO emissions, while THC emissions increased. The engine efficiency of B76E19DEE5 was also highlighted at intermediate and more elevated engine load conditions.

In recent decades, many kinds of research have been conducted on alternative fuels for compression ignition (CI) engines. Low/zero-carbon fuels, such as bioalcohols and hydrogen, are the most promising alternative fuels and are extensively studied because of their availability, ease of manufacturing, and environmental benefits. Using these promising fuels in CI engines is environmentally and economically beneficial. The most common alcohols are methanol, ethanol, isopropanol, propanol, butanol, n-butanol, tert-butanol, iso-butanol, and pentanol. The primary objective of this review paper is to examine the impact of bioalcohols and their blends with conventional diesel fuel in CI engines since these fuels possess characteristic properties that impact overall engine performance and exhaust emissions. This research also indicated that alcohols and blended fuels could be used as fuels in compression ignition engines. Chemical and physical properties of alcohols were examined, such as lubricity, viscosity, calorific value, and cetane number, and their combustion characteristics in compression ignition engines provide a comprehensive review of their potential biofuels as alternative fuels.