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The inlet valve closing (IVC) timing plays a crucial role in engine combustion, which impacts engine performance and emissions. This study attempts to measure the potential to use n-butanol (Bu) and its blends with the neat diesel in a common rail direct injection (CRDI) engine. The computational fluid dynamics (CFD) simulation is carried out to estimate the performance, combustion, and exhaust emission characteristics of n-butanol-diesel blends (0%-30% by volume) for variable valve timings. An experimental study is carried out using standard valve timing and blends to validate the CFD model (ESE AVL FIRE). After validation, the CFD model is employed to study the effect of variable valve timings for different n-butanol-diesel blends. Extended coherent flame model-3 zone (ECFM-3Z) is implemented to conduct combustion analysis, and the kappa-zeta-f (k-ζ -- f) model is employed for turbulence modeling. The inlet valve closing (IVC) time is varied (advanced and retarded) from standard conditions, and optimized valve timing is obtained. Advancing IVC time leads to lower cylinder pressure during compression due to reduced trapped air mass. The brake thermal efficiency (BTE) is increased by 4.5%, 6%, and 8% for Bu10, Bu20, and Bu30, respectively, compared to Bu0. Based on BTE, optimum injection timings are obtained at 12° before the top dead center (BTDC) for Bu0 and 15° BTDC for Bu10, Bu20, and Bu30. Nitrogen oxide (NOx) emissions increase due to complete combustion. Due to IVC timing, further carbon monoxide and soot formation decreased with blends and had an insignificant effect. [ABSTRACT FROM AUTHOR]

Hydrogen fuel offers promising decarbonization pathways for hard-to-electrify transport sectors such as long-haul trucking, international maritime, and aviation. The internal combustion engine (ICE) is and will continue to be important in the transition to net zero emissions (NZE), especially in the transport sector. In this review, the research trend, hotspots, and evolutionary nuances of hydrogen-fuelled ICEs have been investigated. Our analysis reveals that while earlier research primarily focused on the performance and emission characteristics of hydrogen-fuelled ICEs, recent studies are increasingly paying more attention to combustion and emission control strategies. NOx emissions have received a lot of attention, as it is the most important pollutant from hydrogen engines. Several techniques, namely exhaust gas recirculation (EGR), water injection, and lean combustion, have been predominantly adopted and studied for controlling NOx emissions. Another major research area in the field has centered on combustion anomalies such as backfiring and knocking, which are key setbacks to the hydrogen-fuelled ICE. Owing to its ability to produce fewer emissions and greater performance than diesel-only operation, hydrogen in diesel engines as dual fuel has also become a major research hotspot in the field within the last decade. Our analysis also showed that there is a strong interest in this field where researchers are focusing on the use of hydrogen with other alternative fuels such as methane, biogas, biodiesel, ammonia, and methanol for optimal operation of the ICE. Finally, we provide some critical challenges and potential solutions related to the use of hydrogen as an ICE fuel. It is anticipated that the results from the present work will pave the way for the continuous development of hydrogen engine research for the ongoing fight to decarbonize the transport sector. [ABSTRACT FROM AUTHOR]

Currently, the vehicle industry is confronted with issues such as the depletion of fossil resources, an increase in crude oil costs, and stricter emission regulatory standards. In this scenario, the use of viable alternatives to diesel as a fuel is necessary. This study discusses the combined effects of injection time and exhaust gas recirculation (EGR) on neat algal biodiesel-powered diesel engines. The transesterification technique was used to extract algal oil methyl ester (AOME), and the majority of the fuel qualities of AOME were quite comparable to diesel. The practicality of neat AOME for diesel engines operating at varied injection timings such as 19º BTDC, 23º BTDC, and 27º BTDC was investigated. The results of the tests revealed that advanced injection timing has a 3.02% higher BTE than standard fuel injection timing at maximum load for the AOME. Compared to other injection timings at full load, the neat AOME at 27º BTDC has better combustion characteristics and lower exhaust emissions. At full load, however, NOx emissions were higher. NOx emission was reduced by 35.24% when AOME was burned at 27º BTDC combined with 10% exhaust gas recirculation (EGR) compared to 27º BTDC without EGR. [ABSTRACT FROM AUTHOR]

[Display omitted] • Presence of volatile impurities in sample A resulted in initial degradation at 348 °C. • DAP3 fuel exhibits a higher HRR compared to DAP1 and DAP2 fuels. • DAP3 resulted in an average reduction of ∼17.14% and 21.86% in CO and smoke. • DAP2 fuels emitted lower NOx than DAP1 due to slower oxidation reactions. • DAP1 and DAP2 showed large accumulation and coarse soot in the PM 10 form at ∼83 nm. Most research into the treats of plastic wastes have concentrated mainly on single-exposure pathways or products. These practices fail to acknowledge that the complications of carbon particles from engines are produced not only by diesel but by any plastic oils due to the vast amount of contaminants. With the potential to significantly weaken the impact of contaminants, the present study investigates the effects of dehalogenation and catalytic pyrolysis on plastic waste, as well as the risks associated with plastic oil blends on diesel engine. Different types of washing were conducted to effectively dehalogenate plastic waste. After pretreatment, odor compounds were analyzed using GC–MS. Subsequently, various types of pretreated plastic samples underwent catalytic pyrolysis with a 5:1 ratio of HDPE to Al 2 O 3 ·2SiO 2 ·2H 2 O. Differences in physico-chemical properties and hydrocarbon compounds of oils were determined. Experiments were performed using different fuel blends in a diesel engine under steady-state conditions, and their effects on combustion, emissions, morphology, and size particles were analyzed. The results show that sample B exhibited a lower toxicity level of 1,3-butadiene compared to other samples, while acetone and terpenes represented the second and third-highest emission levels in flakes, respectively. Sample C started to degrade at low temperatures (<300 °C) due to carbon addition from ethyl acetate solvent into the tertiary carbon chain of the flakes. DAP3 fuel achieved a higher reaction due to its degree of unsaturation and lower viscosity, resulting in the formation of smaller fuel droplets at high injection pressure and heat release rate (HRR). Higher emission levels were observed by DAP1 and D100, exceeding the Euro 5/6 standard limits. However, DAP3 fuel resulted in an average reduction of ∼17.14% and 21.86% in CO and smoke emissions, respectively, accompanied by a slight decrease in NOx and HC levels. Conversely, there were inconsistencies in the emission results observed with DAP2. Compared to D100, both DAP1 and DAP2 exhibited a significant accumulation and coarse particles in the PM 10 forms at a peak of ∼83 nm. Whereas the DAP3 showed a smaller mobility Dp with a low nucleation particle peak, which was prone to absorb the unburned HC soot and later change to accumulation mode particles. [ABSTRACT FROM AUTHOR]

[Display omitted] • HC and CO emissions decreases for Hy60 fuels, and increasing NOx with Hy40 fuels. • EC-soot slightly decrease compared to OC at all test fuels. • PAHs and n-alkanes turned out to be more less at higher nanoparticles concentrations. • In-cylinder pressure and HRR improve by 60 ppm hybrid nanoparticles. Due to little industrial use of plastic waste recycling, over 200 million tons are thrown in landfills and more than 15 million tons end up in the ocean every year. This study aimed to investigate the effect of waste plastic pyrolysis oil, n-butanol, hybrid (Al 2 O 3 and TiO 2) nanoparticles, and diesel fuel blends on combustion, gaseous emissions, and toxic particulates from CRDI diesel engine at steady-state mode. Experiments were carried out using different fuel ratios blended with hybrid nanoparticles at 20 ppm, 40 ppm, and 60 ppm through the ultra-sonification process. The most optimal blend was determined by Shannon entropy-weighted TOPSIS and PROMETHEE II, and was verified with the experimental results. The result shows that the overall fuels have a definite outline by naphthalene, which account for ∼42.67% of the total organic compounds. With n-bu15W30Hy60, n-bu20W40Hy40 and n-buW40Hy60 fuels, ∼54.9% significantly reduction was observed with n-alkane emissions. Low PAHs value found in particulate samples might reduce the effect of eyes irritants and cancers. Compared to EC, the variation in OC had unclear trend across all blend fuels, except for n-bu20W40Hy40 which averagely reduce by ∼89.47% across the Hy40 fuels. Reduction in CO and HC emissions were observed with Hy60 fuels, while the NOx of Hy40 tend to increase significantly than that of Hy20 and Hy60 by an average of 0.204 g/kWh and 0.401 g/kWh, respectively. However, almost equal pressure peaks were obtained with nano-fuels and their heat release became faster as the nanoparticles volume elevated. The MCDM results confirmed that significant benefit could be attained when the fuel mixtures are under the influence of nanoparticles at relatively higher concentrations. The short answer for waste plastic is to ban unnecessary uses of plastic, encourage alternative materials or fuels, and cut plastic production. [ABSTRACT FROM AUTHOR]