Hasil untuk "Fuel"

Jing Zhu, Liangsheng Hu, Pengxiang Zhao et al.

Hydrogen fuel is considered as the cleanest renewable resource and the primary alternative to fossil fuels for future energy supply. Sustainable hydrogen generation is the major prerequisite to realize future hydrogen economy. The electrocatalytic hydrogen evolution reaction (HER), as the vital step of water electrolysis to H2 production, has been the subject of extensive study over the past decades. In this comprehensive review, we first summarize the fundamentals of HER and review the recent state-of-the-art advances in the low-cost and high-performance catalysts based on noble and non-noble metals, as well as metal-free HER electrocatalysts. We systemically discuss the insights into the relationship among the catalytic activity, morphology, structure, composition, and synthetic method. Strategies for developing an effective catalyst, including increasing the intrinsic activity of active sites and/or increasing the number of active sites, are summarized and highlighted. Finally, the challenges, perspectives, and research directions of HER electrocatalysis are featured.

N. Lewis

S. Anantharaj, Sivasankara Rao Ede, K. Sakthikumar et al.

Increasing demand for finding eco-friendly and everlasting energy sources is now totally depending on fuel cell technology. Though it is an eco-friendly way of producing energy for the urgent requirements, it needs to be improved to make it cheaper and more eco-friendly. Although there are several types of fuel cells, the hydrogen (H2) and oxygen (O2) fuel cell is the one with zero carbon emission and water as the only byproduct. However, supplying fuels in the purest form (at least the H2) is essential to ensure higher life cycles and less decay in cell efficiency. The current large-scale H2 production is largely dependent on steam reforming of fossil fuels, which generates CO2 along with H2 and the source of which is going to be depleted. As an alternate, electrolysis of water has been given greater attention than the steam reforming. The reasons are as follows: the very high purity of the H2 produced, the abundant source, no need for high-temperature, high-pressure reactors, and so on. In earlier days,...

R. Reitz, G. Duraisamy

This article covers key and representative developments in the area of high efficiency and clean internal combustion engines. The main objective is to highlight recent efforts to improve (IC) engine fuel efficiency and combustion. Rising fuel prices and stringent emission mandates have demanded cleaner combustion and increased fuel efficiency from the IC engine. This need for increased efficiency has placed compression ignition (CI) engines in the forefront compared to spark ignition (SI) engines. However, the relatively high emission of oxides of nitrogen (NOx) and particulate matter (PM) emitted by diesel engines increases their cost and raises environmental barriers that have prevented their widespread use in certain markets. The desire to increase IC engine fuel efficiency while simultaneously meeting emissions mandates has thus motivated considerable research. This paper describes recent progress to improve the fuel efficiency of diesel or CI engines through advanced combustion and fuels research. In particular, a dual fuel engine combustion technology called “reactivity controlled compression ignition” (RCCI), which is a variant of Homogeneous Charge Compression Ignition (HCCI), is highlighted, since it provides more efficient control over the combustion process and has the capability to lower fuel use and pollutant emissions. This paper reviews recent RCCI experiments and computational studies performed on light- and heavy-duty engines, and compares results using conventional and alternative fuels (natural gas, ethanol, and biodiesel) with conventional diesel, advanced diesel and HCCI concepts.

Xin Li, Jiaguo Yu, Jingxiang Low et al.

S. Habisreutinger, L. Schmidt‐Mende, Jacek K. Stolarczyk

Kenneth Holmberg, Peter Andersson, A. Erdemir

M. Schultz, J. Bendick, E. R. Holm et al.

Ying Huang, V. Yang

Chan-Chiao Lin, Huei Peng, J. Grizzle et al.

M. Kleiber

Chunmao Zhu, Takuma Miyakawa, Fumikazu Taketani et al.

Abstract Brown carbon aerosols (BrC) significantly contribute to regional climate warming in East Asia. However, their sources and atmospheric transformation remain poorly constrained due to limited observations. In this study, we clarified the seasonal dynamics of BrC and quantified the sources of relating carbonaceous components, at the gateway of the East Asian air outflow for seasonal variations. Our findings reveal that fossil fuel combustion dominates the sources of BrC containing carbonaceous components in winter, while biomass burning and local biogenic sources become more prominent in spring and summer, respectively. We provide benchmark optical properties of BrC for climate model simulations, demonstrating that the absorption coefficient and mass absorption cross-section of water-soluble fraction from land-originated air masses (0.47 Mm−1 and 0.53 m2 gC−1, respectively) are more than twice those of sea-originated air masses (0.11 Mm−1 and 0.21 m2 gC−1, respectively). Additionally, we show that BrC undergoes photochemical degradation during transport with a half-life of approximately 1.2 days. A significant reduction in BrC levels during the COVID-19 lockdown period highlights the potential of stringent emission controls to mitigate air pollution and its associated climate impacts. By shedding light on the seasonal dynamics, diverse sources, and atmospheric ageing of BrC, the study provides valuable insights for emission reduction strategies and improving BrC representation in climate models.

Roberto Fanigliulo, Daniele Pochi, Renato Grilli et al.

Subsoiling is a highly effective deep tillage method used to mitigate soil compaction in orchard rows, a condition frequently resulting from repeated passes of agricultural machinery. This compaction can reduce water infiltration into deeper soil layers, leading to excessive surface water stagnation and a subsequent reduction in soil fertility. Subsoiling restores the structure of compacted soil by creating a vertical cut and lifting the ground without inverting the soil layers. This action promotes stable soil porosity and enhanced drainage, effectively eliminating the plough sole, and consequently improving root growth and nutrient absorption. Despite its benefits, subsoiling is an energy-intensive practice. Vibrating subsoilers can significantly reduce the high traction force required by conventional subsoilers, thereby enabling the use of smaller, less powerful tractors. This study investigated the performance of a single-shank subsoiler equipped with an innovative oscillating working tool, focusing on its dynamic-energy requirements, tillage quality, and the whole-body vibrations (WBV) transmitted to the tractor driver. Comparative tests were conducted in a compacted poplar grove using two 4WD tractors of different power and mass, with the subsoiler’s oscillating tool alternately activated and deactivated. The results demonstrated that the oscillating tool reduced draft force, traction power requirement, fuel consumption, and tractor slip, while maintaining tillage efficiency, displacing a greater mass of soil. However, a comparison of the measured vibrations indicated that their level reached a hazardous condition for the driver of the lower-power, lower-mass tractor when the oscillating tool was active.

Houpeng Zhang, Zhen Lu, Tianyou Wang et al.

The micro-explosion of emulsion droplets plays an important role in promoting atomization, improving combustion efficiency, and reducing pollutant emissions. In this experimental study of the micro-explosion of emulsion droplets, we find that mist can be generated during the heating of emulsion droplets, and the mist generation is closely related to the micro-explosion process. Combined analysis from high-speed images, gas chromatography, and droplet temperature variation shows that the mist generation is due to the condensation of vapor into small droplets as the temperature decreases. Two micro-explosion modes are observed, intense micro-explosion with a large amount of mist and weak micro-explosion with a small amount of mist. Different emulsified fuels are tested, and mist can be produced for all the emulsified fuels. The mist is quantitatively analyzed via digital image processing. According to the mist concentration curve in the micro-explosion process, the micro-explosion mode can be distinguished. The effects of the water and surfactant contents in the emulsion droplets are studied, and the mists are used to characterize the micro-explosion. Increasing the water content can promote the vaporization of the water phase, increase the strength of micro-explosion, and result in a large amount of mist. Increasing the surfactant content can improve the stability of the emulsion droplet, reduce the probability of intense micro-explosion, and hence reduce the mist concentration.

M. M. Rahman, A. K. Das, S. Tabassum et al.

Saccharum spontaneum is a grass-type plant abundantly found in the Indian subcontinent, known for its beautiful, lustrous white flowers. Fibres were extracted from the flower and analyzed for their physical, mechanical, and chemical properties. The chemical composition of the fibre is 90.9% holocellulose, with a moisture content of 10.97%, and an average fibre length of 25 mm. FTIR spectra confirmed the presence of functional groups similar to those found in other natural cellulosic fibres. Additionally, the fibre exhibits a tensile strength of approximately 63 cN/tex, which is significantly higher than that of cotton and jute fibres. However, its crystallinity is relatively high at about 75%, resulting in a low elongation at break of 1.9%. FESEM analysis revealed a hollow structure in the fibre, indicating its potential suitability for applications requiring high thermal insulation, excellent moisture management, vapor permeability, and microbial fuel cell development.

Alejandro Uribe, Mariana Yepes, Juan Pablo González-Alzate et al.

The detrimental impact of fossil fuel dependence on the environment and human health needs a shift towards sustainable transportation solutions. Electric mobility, exemplified by electric vehicles (EVs), presents a promising solution to combat air pollution and address climate change concerns. However, the widespread adoption of EVs faces obstacles such as charging time and range anxiety. Battery Swapping (BS) stations have emerged as a potential remedy, facilitating quick battery exchanges to address these issues. This research proposes a method to determine charging policies for hybrid motorcycle fleets using mixed integer linear programming (MILP) and a simple greedy heuristic algorithm to minimize battery degradation and reduce the operating costs of a BS station designed for hybrid motorcycles. By employing these two solution techniques, we focus on evaluating the practicality of these stations and the impact of smart charging decisions on pricing. 10 unique instances were generated using six distinct values of time deltas, resulting in a total of 60 individual instances to evaluate various simulation scenarios, highlighting distinct operational dynamics for motorcycle and station management. Notably, objective function values were lower in the first 20 instances, with the heuristic outperforming the exact method by approximately 175,000 COP in the initial 10 instances. The models demonstrated greater cost efficiency at three and five-minute deltas, effectively capturing real dynamics and minimizing unexpected fluctuations. Simulation times varied significantly, with the heuristic method running between 0.001 and 0.005 s compared to the 50 to 200 s for the more complex exact method, which exhibited a broader range of results but also higher variability, indicating less consistency than the more stable heuristic approach.

Andrew Balthrop, Justin T. Kistler, Yemisi Bolumole et al.

<i>Background:</i> Carbon pricing in the form of fuel taxes is an important tool for abating climate change. This study examines the impact and pass-through of fuel taxes in the truckload freight market. <i>Methods:</i> State-level truckload market data, integrated with retail diesel prices, are analyzed using fixed-effects regression modeling. <i>Results:</i> Taxes and fuel costs are not only passed on by diesel retailers to motor carriers; the results reveal the overshifting of diesel taxes from motor carriers to shippers. <i>Conclusions:</i> The findings are consistent with inelastic short-term demand for long-haul carriage, indicating that relatively large price increases will be necessary to reduce diesel consumption in the trucking industry.

Xiaoqing Wang, Fengzi Lu, Adnan Safi et al.

Determining the influence of climate policy uncertainty (CPU), fossil fuel dynamics, and renewable energy (REE) adoption on carbon market volatility (CTM) is essential for ensuring its stability and sustainable development. Therefore, this study captures the dynamic relationships among CTM, CPU, crude oil (COP), coal (COA) and REE across different time horizons utilizing a Time-Varying Parameter Structural Vector Autoregression with Stochastic Volatility (TVP-SVAR-SV) model. Results reveal that in the short term, shocks from CPU, COP, COA, and REE all significantly intensify carbon price fluctuations. In the medium term, the carbon market exhibits heightened sensitivity particularly to CPU and COA shocks, while the effects of all factors diminish over the long term. Furthermore, the analysis confirms pronounced time-varying characteristics, with the influence of oil prices on carbon price volatility notably strengthening over time. By comparing influence degree, CPU and COP emerge as the more influential and volatile drivers, whereas the impact of COA remains more stable. Finally, all shocks are significantly amplified during periods of major external disruption, especially during the Russia-Ukraine conflict. These findings highlight the importance of maintaining clear climate policy signals and stabilizing energy market dynamics to enhance the resilience and efficiency of carbon markets.

Abd Essamade Saufi, Hannah Bellenbaum, Martin Read et al.

We present the "First Light Advanced Ignition Model" (FLAIM), a reduced model for the implosion, adiabatic compression, volume ignition and thermonuclear burn of a spherical DT fuel capsule utilising a high-Z metal pusher. FLAIM is characterised by a highly modular structure, which makes it an appropriate tool for optimisations, sensitivity analyses and parameter scans. One of the key features of the code is the 1D description of the hydrodynamic operator, which has a minor impact on the computational efficiency, but allows us to gain a major advantage in terms of physical accuracy. We demonstrate that a more accurate treatment of the hydrodynamics plays a primary role in closing most of the gap between a simple model and a general 1D rad-hydro code, and that only a residual part of the discrepancy is attributable to the heat losses. We present a detailed quantitative comparison between FLAIM and 1D rad-hydro simulations, showing good agreement over a large parameter space in terms of temporal profiles of key physical quantities, ignition maps and typical burn metrics.

Chris J. Wright, Joel A. Thornton, Lyatt Jaeglé et al.

Aerosol interactions with clouds represent a significant uncertainty in our understanding of the Earth system. Deep convective clouds may respond to aerosol perturbations in several ways that have proven difficult to elucidate with observations. Here, we leverage the two busiest maritime shipping lanes in the world, which emit aerosol particles and their precursors into an otherwise relatively clean tropical marine boundary layer, to make headway on the influence of aerosol on deep convective clouds. The recent seven-fold change in allowable fuel sulfur by the International Maritime Organization allows us to test the sensitivity of the lightning to changes in ship plume aerosol size distributions. We find that, across a range of atmospheric thermodynamic conditions, the previously documented enhancement of lightning over the shipping lanes has fallen by over 40%. The enhancement is therefore at least partially aerosol-mediated, a conclusion that is supported by observations of droplet number at cloud base, which show a similar decline over the shipping lane. These results have fundamental implications for our understanding of aerosol-cloud interactions, suggesting that deep convective clouds are impacted by the aerosol number distribution in the remote marine environment.