Hasil untuk "Fuel"

Hideaki Kobayashi, A. Hayakawa, K.D. Kunkuma . A. Somarathne et al.

Abstract This paper focuses on the potential use of ammonia as a carbon-free fuel, and covers recent advances in the development of ammonia combustion technology and its underlying chemistry. Fulfilling the COP21 Paris Agreement requires the de-carbonization of energy generation, through utilization of carbon-neutral and overall carbon-free fuels produced from renewable sources. Hydrogen is one of such fuels, which is a potential energy carrier for reducing greenhouse-gas emissions. However, its shipment for long distances and storage for long times present challenges. Ammonia on the other hand, comprises 17.8% of hydrogen by mass and can be produced from renewable hydrogen and nitrogen separated from air. Furthermore, thermal properties of ammonia are similar to those of propane in terms of boiling temperature and condensation pressure, making it attractive as a hydrogen and energy carrier. Ammonia has been produced and utilized for the past 100 years as a fertilizer, chemical raw material, and refrigerant. Ammonia can be used as a fuel but there are several challenges in ammonia combustion, such as low flammability, high NOx emission, and low radiation intensity. Overcoming these challenges requires further research into ammonia flame dynamics and chemistry. This paper discusses recent successful applications of ammonia fuel, in gas turbines, co-fired with pulverize coal, and in industrial furnaces. These applications have been implemented under the Japanese ‘Cross-ministerial Strategic Innovation Promotion Program (SIP): Energy Carriers’. In addition, fundamental aspects of ammonia combustion are discussed including characteristics of laminar premixed flames, counterflow twin-flames, and turbulent premixed flames stabilized by a nozzle burner at high pressure. Furthermore, this paper discusses details of the chemistry of ammonia combustion related to NOx production, processes for reducing NOx, and validation of several ammonia oxidation kinetics models. Finally, LES results for a gas-turbine-like swirl-burner are presented, for the purpose of developing low-NOx single-fuelled ammonia gas turbine combustors.

P. Nigam, Anoop Singh

K. Gong, F. Du, Z. Xia et al.

M. Balat, H. Balat, C. Öz

M. Lapuerta, O. Armas, J. Rodríguez-Fernández

Andrzej Czernik, A. Bridgwater

Andrei Linde

H. Gasteiger, S. Kocha, Bhaskar Sompalli et al.

G. Knothe, J. Gerpen, J. Krahl

A. Demirbaş

M. Brooks, C. D’Antonio, D. Richardson et al.

D. Pimentel, T. Patzek

A. Aricò, P. Bruce, B. Scrosati et al.

Haonan Li, Elizabeth A. Holzhausen, Devendra Paudel et al.

Abstract This study investigates independent and joint effects of fine particulate matter (PM2.5) components on early childhood neurodevelopment and explores emission sources of key toxic components. We included 165 mother-infant dyads from Southern California. Annual average concentrations of 15 PM2.5 components, including carbonaceous components, secondary inorganic salts, and trace elements, were estimated for the birth year. Neurodevelopment across cognitive, language, motor, social-emotional, and adaptive behavior domains was assessed at age 2 using Bayley-III Scales. Mixture effects and key contributors were evaluated using weighted quantile sum (WQS) and Bayesian kernel machine regression (BKMR). Source inference was conducted through inter-component clustering and spatial analysis. Linear regression showed PM2.5, sulfate (SO4 2−), nitrate (NO3 −), ammonium (NH4 +), copper (Cu), nickel (Ni), lead (Pb), and vanadium (V) were inversely, while calcium (Ca) and zinc (Zn) were positively, associated with adaptive behavior scores (p < 0.05). WQS showed negative associations between the mixture and adaptive behavior (p = 0.02–0.06), with Ni, Cu, V, and SO₄²⁻ as key contributors. BKMR showed similar trends. Ni, V, and SO4 2− likely originate from heavy oil combustion, and Cu from brake wear. Findings suggest that PM2.5 components, particularly from traffic and marine fuel combustion, may adversely affect adaptive behavior in early childhood.

Feifan Liu, Lun He, Lvlv Ji et al.

ABSTRACT Due to a positive standard reaction Gibbs free energy (ΔrGmθ) of 237.1 kJ mol−1, electric energy input is indispensable for hydrogen production by conventional electrochemical water splitting. This energy requirement can be reduced by replacing the anodic oxygen evolution reaction to thermodynamic favorable small‐molecules oxidation reactions. In this work, anodic formaldehyde oxidation reaction (FOR) in alkaline media was paired with cathodic hydrogen evolution reaction (HER) in acidic media to establish a thermodynamically downhill system. The utilization of electrochemical neutralization energy in a hybrid alkaline‐acidic electrolyte configuration enables a further decrease in ΔrGmθ. Therefore, the resulting hybrid alkaline‐acidic formaldehyde‐proton fuel cell (FPFC) exhibits a significantly reduced ΔrGmθ of −101.5 kJ mol−1. A bifunctional Ru‐doped Cu catalyst (Ru─Cu NTs@CM) was designed and synthesized to simultaneously promote the kinetics of acidic HER and alkaline FOR, demonstrating superior catalytic activity and durability to pristine Cu and Ru catalysts. This catalyst enabled concurrent bipolar H2 production and electricity generation from the assembled FPFC, reaching a peak power density of 18.3 mW cm−2 at 53.4 mA cm−2. A combination of (quasi) in situ characterizations and theoretical calculations unveiled the important mechanistic role of Ru‐doping in enhancing the Cu catalyst's activity and stability.

Rashid Imran Ahmad Khan, Nabanita Ghosh, Zakaria Siddiqui et al.

Mounting environmental repercussions stemming from persistent fossil fuel reliance have catalyzed the exploration of renewable energy alternatives, with biodiesel emerging as a prominent alternative. This work aims to validate a low-cost, waste-derived calcium oxide (CaO) catalyst (from postconsumer eggshells) for scalable biodiesel production across castor, Brassica napus, and waste soybean oils (WSO) by optimizing transesterification. Despite the well-documented catalytic efficacy of nano-structured heterogeneous systems, their synthesis complexity and elevated cost structures frequently inhibit industrial-scale translation. To circumvent these limitations, this study employs CaO derived from postconsumer eggshells, an agro-waste source, as an economical, bio-originated catalyst for transesterification. Comprehensive characterization of the catalysts was carried out using Scanning Electron Microscope (SEM), energy-dispersive X-ray spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction, Brunauer Emmett Teller (BET), and particle size analysis. Under optimized reaction conditions (12:1 methanol-to-oil molar ratio, 5 wt% catalyst loading, 65 °C, and 2.25 h), conversion efficiencies of 90.53% (castor oil [CO]), 89.05% (Brassica napus oil [BN]), and 92.14% (WSO) were achieved, confirming the catalyst’s adaptability and robustness across diverse lipid matrices. FTIR analysis substantiated successful ester formation. The fuel properties conformed to American Society for Testing and Materials (ASTM) standards, while cost estimations revealed favorable economics at $1.10/L (CO), $1.04/L (BN), and $0.21/L (WSO). These outcomes underscore a scalable, low-cost approach for biodiesel synthesis from readily available agro-based residues, with strong implications for decentralized, resource-constrained production landscapes.

Varničić Miroslava M., Sentić Milica N., Mihailović Marija D.

Fuel cells, batteries, and supercapacitors represent the most efficient and promising technologies for electrochemical energy conversion and storage. However, their production and practical application are primarily constrained by the high cost of materials (65% - 75%), such as noble metals, including platinum, which is commonly used as an electrocatalyst for the oxygen reduction reaction (ORR). Therefore, the investigation of novel materials is crucial for the development of alternative solutions that can compete with existing technologies. The main objective of this study is to investigate ORR electrocatalysts based on cobalt/lanthanum oxides (Co/La material) as alternatives to noble metals for the cathodic reaction. The synthesized material was fabricated as an electrode on a graphite disk with a surface area of 0.196 cm² and tested for the oxygen reduction reaction using standard electrochemical techniques, namely cyclic and linear sweep voltammetry. The results indicate that the hybrid material is a promising electrocatalyst for ORR, achieving a current density of -3.5 mA cm-². The calculated number of exchanged electrons for the Co/La material suggests a four-electron oxygen reduction mechanism and high electrocatalytic activity towards ORR.

Wenli Xie, Bin Cui, Desheng Liu et al.

The rational design of high-performance catalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is essential for the development of clean and renewable energy technologies, particularly in fuel cells and metal-air batteries. Two-dimensional (2D) covalent organic frameworks (COFs) possess numerous hollow sites, which contribute to the stable anchoring of transition metal (TM) atoms and become promising supports for single atom catalysts (SACs). Herein, the OER and ORR catalytic performance of a series of SACs based on TQBQ-COFs were systematically investigated through density functional theory (DFT) calculations, with particular emphasis on the role of the coordination environment in modulating catalytic activity. The results reveal that Rh/TQBQ exhibits the most effective OER catalytic performance, with an overpotential of 0.34 V, while Au/TQBQ demonstrates superior ORR catalytic performance with an overpotential of 0.50 V. A critical mechanistic insight lies in the distinct role of boundary oxygen atoms in TQBQ, which perturb the adsorption energetics of reaction intermediates, thereby circumventing conventional scaling relationships governing OER and ORR pathways. Furthermore, we established the adsorption energy of TM atoms (Ead) as a robust descriptor for predicting catalytic activity, enabling a streamlined screening strategy for SAC design. This study emphasizes the significance of the coordination environment in determining the performance of catalysts and offers a new perspective on the design of novel and effective OER/ORR COFs-based SACs.

Joshua Kanaabi Muliira, Eilean Rathinasamy Lazarus, Prossy Nandawula

<b>Background/Objective:</b> This review explored the literature on Missed Nursing Care (MNC) in inpatient oncology settings to gain insights on how to enhance the quality of nursing care for hospitalized patients with cancer and survivors. The aim was to identify the common MNC and the factors associated with MNC in inpatient oncology units. <b>Methods:</b> A scoping review approach was used, in which a five-stage methodological framework informed the process. Five databases were searched for relevant studies (EMBASE, Medline, SCOPUS, CINAHL, and PsycINFO) published from January 2013 to June 2025. Other search methods were conducted using Google Scholar, Trove, and ProQuest Dissertations for records focusing on the topic. The review included qualitative and quantitative articles. Thomas and Harden’s three-step method for thematic synthesis was followed to summarize data into themes. <b>Results:</b> Fifteen studies were selected and included in the scoping review. Three themes were generated: the commonly MNC; reasons for MNC; and factors associated with MNC. The common categories of MNC were related to basic patient care, documentation, and communication with patients or family members. The common factors associated with MNC were job satisfaction, patient load, and staffing adequacy. <b>Conclusions:</b> MNC is common in inpatient oncology settings and presents a key challenge to the safety of cancer patients and their health outcomes. Efforts to curtail MNC, such as integration of evidence-based policies, clinical guidelines, and standards in oncology nursing care, are needed. Interventional studies are needed to provide insight into effective remedies to the factors that fuel MNC, such as staffing, work overload, communication, work environment, and nurses’ skills. Studies from pediatric oncology settings, Africa, and other resource-limited settings where the future global burden of cancer will be highest are also needed.

G. Soete