Search Results (75)

Due to the limitations of current battery technologies—such as lower energy density and high cost compared to fossil fuels—electric vehicles (EVs) face constraints in applications requiring extended range or heavy payloads, such as refuse trucks. As a midterm solution, hybrid electric vehicles (HEVs) combine internal combustion engines (ICEs) and electric powertrains to enable flexible energy usage, particularly in urban duty cycles characterized by frequent stopping and idling. This study introduces a model-based energy management strategy using the Equivalent Consumption Minimization Strategy (ECMS), tailored for a retrofitted series hybrid refuse truck. A conventional ISUZU NPR 10 truck was instrumented to collect real-world driving and operational data, which guided the development of a vehicle-specific ECMS controller. The proposed strategy was evaluated over five driving cycles—including both standardized and measured urban scenarios—under varying load conditions: Tare Mass (TM) and Gross Vehicle Mass (GVM). Compared with a rule-based control approach, ECMS demonstrated up to 14% improvement in driving range and significant reductions in exhaust gas emissions (CO, NO_x, and CO₂). The inclusion of auxiliary load modeling further enhances the realism of the simulation results. These findings validate ECMS as a viable strategy for optimizing fuel economy and reducing emissions in hybrid refuse truck applications. Full article

This study examines the emissions generated by a tall ship of 81.36 m length under various operating conditions, focusing particularly on carbon dioxide emissions at different navigation speeds. The main purpose of the paper is to establish theoretical and practical methods for calculating and measuring the level of CO₂ emitted by the ship engines. Additionally, this article compares the results of carbon dioxide emission calculations based on theoretical methods with the results of real measurements. The paper verifies and assesses the carbon dioxide emission calculation methods compared to the emissions measured in real conditions for diesel engines. A comparative analysis of several methods for determining CO₂ emissions leads to much more accurate and conclusive results close to reality. The results obtained through empirical and theoretical methods for determining CO₂ emissions from the main engine demonstrate that the difference between these values is more accurate at lower engine loads but shows discrepancies at higher loads due to real-world inefficiencies, combustion variations, and model simplifications. The measured CO₂ emission values for auxiliary engines at 60% load demonstrate consistency and closely reflect real operating conditions, while analytical calculations tend to be higher due to theoretical losses and model assumptions. Stoichiometric values fall in between, assuming ideal combustion but lacking adjustments for real variables. This highlights the efficiency of the diesel generator and the importance of empirical data in capturing actual emissions more accurately. The investigation aims to provide a detailed understanding of CO₂ emission variations based on the ship’s operating parameters, including the study of these emissions at the level of the main diesel propulsion engine as well as the auxiliary engines. By analyzing these methods for determining engine emissions, conclusions can be reached about aspects such as the following: engine wear condition, efficiency losses, or incomplete combustion. This analysis has the potential to guide the implementation of new policies and technologies aimed at minimizing the carbon footprint of a reference ship, considering the importance of sustainable resource management and environmental protection in a viable long-term manner. Full article

Ammonia combustion has garnered increasing attention due to its potential as a carbon-free fuel. Globally swirling flow in a rectangular furnace generates flameless conditions by high flue gas recirculation. The reverse air injection (RAI) technique enabled stable swirling flameless combustion of pure ammonia without auxiliary methods. Experiments with pure ammonia combustion in a swirling flameless furnace demonstrated an operable equivalence ratio (ER) range of 0.3–1.05, extending conventional flammability limits of pure ammonia as a fuel. NO emissions were reduced by 40% compared to conventional combustion, with peak concentrations of 1245 ppm at ER = 0.71 and near-zero emissions at ER = 1.05. Notably, flameless combustion exhibited lower temperature sensitivity in NO formation; however, the ER has a serious effect. Developing a simplified reaction model for ammonia combustion is crucial for computational fluid dynamics (CFD) research. A reduced kinetic mechanism comprising 36 reactions and 16 chemical species was introduced, specifically designed for efficient and precise modeling of pure ammonia flameless combustion. Combustion simulation using the eddy dissipation concept (EDC) approach confirmed the mechanism’s predictive capability, maintaining acceptable accuracy across the operating conditions. Full article

Enhancing the operational flexibility and environmental performance of coal-fired boilers under wide-load conditions presents a critical challenge in China’s low-carbon transition, particularly for low-quality coals (LQCs) with abundant reserves, poor combustibility, and high NO_x emissions. To overcome the intrinsically low reactivity of LQC, peak-shaving performance and combustion behavior were systematically investigated on an MW-grade pilot-scale test platform employing the fuel modification strategy in this study. Stable fuel modification was achieved without any auxiliary energy for LQCs and Shenmu bituminous coal (SBC) across a load range of 20~83% and 26~88%, respectively, demonstrating the excellent fuel reactivity and strengthened release control of volatile and nitrogenous species. The modified LQC exhibited ignition, combustion, and burnout characteristics comparable to Shouyang lean coal (SLC), enabling a “dimensionality-reduction utilization” strategy. The double-side fuel modification device (FMD) operation maintained axially symmetric temperatures (<1250 °C) in horizontal combustion chambers, while single-side operation caused thermal asymmetry, with peak temperatures skewed toward the FMD side (<1200 °C). Original NO_x emissions were effectively suppressed, remaining below 106.89 mg/m³ (@6%O₂) for LQC and 122.76 mg/m³ (@6%O₂) for SBC over broad load ranges, and even achieved ultra-low original NO_x emissions (<50 mg/m³). Distinct load-dependent advantages were observed for each coal type: SBC favored high-load thermal uniformity and low-load NO_x abatement, whereas LQC exhibited the inverse trend. These findings underscore the importance of a load-adaptive coal selection and FMD operation mode. This study provides both theoretical insights and engineering guidance for retrofitting coal-fired power units toward flexible, low-emission operation under deep peak-shaving scenarios. Full article

An alternative combustion technology to replace conventional start-up and flame stabilization using fuel oil or natural gas in pulverized coal-fired boilers has been investigated. In this study, a novel plasma burner design is proposed as a replacement for traditional auxiliary burners, operating by generating plasma through the ionization of air using microwave energy. The burner features an internal combustion system and a multi-stage ignition process to enhance flame stability, improve combustion efficiency, and enable more controlled pulverized coal burning within the plasma. Supported by a magnetron generating microwave energy at 915 MHz with a 75 kW output, the burner directly ignites approximately 22% of the coal–air mixture in the plasma zone, forming a stable flame that ensures complete combustion of the remaining coal. An experimental system was established, and tests were conducted by burning up to 3000 kg/h of pulverized coal in an industrial-scale setup at Unit-1 of the 22 MW_e Soma A Power Plant to optimize burner parameters. The specific microwave energy consumption was calculated as 0.055 kWh/kg of coal, demonstrating high energy efficiency and low operational cost. These results confirm that the microwave-assisted plasma burner is a technically viable, energy-efficient, and environmentally friendly alternative to conventional auxiliary burners. Full article

This study investigates the performance and combustion behavior of a spark ignition engine retrofitted to operate on compressed natural gas (CNG), with a focus on a newly developed stratified charge pre-chamber design. The engine was modified to include an auxiliary intake valve that enables partial enrichment of the pre-chamber mixture without the need for a dedicated fuel injector. This hybrid approach combines the mechanical simplicity of passive systems with the enhanced combustion control of active pre-chambers. Both experimental tests and computational fluid dynamics (CFD) analyses were carried out under partial load conditions (8 Nm) and engine speeds ranging from 900 to 1700 rpm. The results demonstrate improvements in indicated mean effective pressure (IMEP), combustion stability, and flame propagation speed—particularly at lower engine speeds where stratified combustion effects are more pronounced. However, increasing engine speed resulted in reduced volumetric efficiency and elevated exhaust temperatures, indicating potential for further optimization via turbocharging or advanced scavenging techniques. Overall, the findings validate the effectiveness of the proposed design in enhancing thermal efficiency and ignition stability in CNG-fueled engines, especially under urban driving conditions. Full article

Gas evolution in lithium-ion batteries represents a pivotal yet underaddressed concern, significantly compromising long-term cyclability and safety through complex interfacial dynamics and material degradation across both normal operation and extreme thermal scenarios. While extensive research has focused on isolated gas generation mechanisms in specific components, critical knowledge gaps persist in understanding cross-component interactions and the cascading failure pathways it induced. This review systematically decouples gas generation mechanisms at cathodes (e.g., lattice oxygen-driven CO₂/CO in high-nickel layered oxides), anodes (e.g., stress-triggered solvent reduction in silicon composites), electrolytes (solvent decomposition), and auxiliary materials (binder/separator degradation), while uniquely establishing their synergistic impacts on battery stability. Distinct from prior modular analyses, we emphasize that: (1) emerging systems exhibit fundamentally different gas evolution thermodynamics compared to conventional materials, exemplified by sulfide solid electrolytes releasing H₂S/SO₂ via unique anionic redox pathways; (2) gas crosstalk between components creates compounding risks—retained gases induce electrolyte dry-out and ion transport barriers during cycling, while combustible gas–O₂ mixtures accelerate thermal runaway through chain reactions. This review proposes three key strategies to suppress gas generation: (1) oxygen lattice stabilization via dopant engineering, (2) solvent decomposition mitigation through tailored interphases engineering, and (3) gas-selective adaptive separator development. Furthermore, it establishes a multiscale design framework spanning atomic defect control to pack-level thermal management, providing actionable guidelines for battery engineering. By correlating early gas detection metrics with degradation patterns, the work enables predictive safety systems and standardized protocols, directly guiding the development of reliable high-energy batteries for electric vehicles and grid storage. Full article

Double-base (DB) propellants, renowned for their superior performance and cost-effectiveness, are extensively utilized in both rocketry and artillery applications. During the 3D printing process of double-base propellants, auxiliary solvents play a crucial role in plasticizing the DB propellant mixtures. Consequently, the printed propellants are prone to significant shrinkage and dimensional instability as a result of solvent evaporation post-printing. To address these challenges, we have innovated a UV-assisted material extrusion 3D printing technique that preserves the intended geometries of the DB propellant. The results of our printing trials indicate that incorporating an energetic UV-curable resin as a modifier into the DB propellant paste is highly effective. Ultimately, we successfully fabricated a porous propellant cylinder featuring a periodic woodpile structure. Additionally, the internal structure, mechanical properties, combustion characteristics, and in-barrel ballistic performance of the printed propellants have been thoroughly characterized. Our findings underscore that the UV-assisted material extrusion additive manufacturing process confers exceptional properties to the DB propellant. Full article

Waste heat recovery is one of the most investigated solutions for increasing the efficiency of powertrains in the transportation sector. A major portion of thermal energy is wasted via exhaust gases. Almost one third of fuel energy is lost, and its recovery as propulsion energy is a promising goal. Moreover, this enables the increased electrification or hybridization of powertrains, assuming the energy recovered is converted into electrical form and used to fulfill different vehicles’ needs. The present study focuses on a dual-stage energy recovery system designed to enhance the efficiency of internal combustion engines (ICEs) in heavy-duty vehicles (HDVs). The system combines a turbocompound unit for direct heat recovery (DHR) and an organic Rankine cycle (ORC) for indirect heat recovery (IHR). These technologies aim to exploit waste heat from exhaust gases, converting it into electrical energy. In this regard, electrical energy can be stored in a battery for it to be available for the energy needs of powertrains that use hybrid propulsion and for driving pumps and compressors on board, following recent technologies of auxiliaries on demand. The proposed setup was modeled and analyzed under off-design conditions to evaluate energy recovery potential and engine performance impacts. From this point of view, in fact, any device that operates on exhaust gas introduces a pressure loss, increasing engine backpressure, whose effect is an increase in specific fuel consumption. An estimate of this negative effect is presented in this paper based on experimental data measured in a F1C IVECO™ engine. An average net recovery of 5–6% of engine power has been demonstrated, with an important prevalence of the turbocompound with respect to the ORC section. The results demonstrate the viability of integrating DHR and IHR stages, with implications for advancing sustainable transportation technologies. Full article

In order to explore the influence of pilot structure on the lean ignition characteristics in a certain type of internally staged combustor, the current study was conducted on the effects of the auxiliary fuel nozzle diameter, the rotating direction of the pilot swirler, and the swirl number on the lean ignition fuel–gas ratio limit, combining numerical simulation and experimental validation. The optimization potential of the mixing structure of this type of internally staged combustor was further explored. It indicated that the lean ignition fuel–gas ratio limit was significantly influenced by the diameter of the auxiliary fuel nozzles the swirl number of the pilot swirler and the combination of the same rotating direction for both pilot swirlers, while the mass flow rate of air was constant. Increasing the diameter of the auxiliary fuel path nozzles (0.4~0.6 mm) and having excessively higher or lower swirl numbers of the pilot module primary swirlers are not conducive to broadening the lean ignition boundary. Compared with the two-stage pilot swirler with the same rotation combination, the fuel–gas ignition performance of the two-stage pilot swirler with the opposite rotation combination is better. Under the typical working conditions (the air mass flow rate is 46.7 g/s and the ignition energy is 4 J), for a pilot swirler with a rotating direction opposite to the main swirler, the diameter of the auxiliary fuel nozzles is 0.2 mm, the swirl number of first-stage of pilot swirler is 1.4, and the lean ignition fuel–air ratio was reduced to 0.0121, which is 32.78% lower than the baseline scheme, which further broadens the lean ignition boundary of the centrally staged combustion chamber. Full article

The continuous expansion of the vehicle fleet contributes to escalating emissions, with the transportation sector accounting for approximately 21% of CO₂ emissions, based on 2023 data. Focused on reducing emissions and reliance on fossil fuels, the study observes the shift from internal combustion vehicles to electric and hybrid models since 2017. Despite advancements, these vehicles still lack optimal efficiency and suffer from limited range, deterring potential buyers. This article aims to evaluate the range-extending technologies for electric vehicles, emphasizing efficiency, low pollution, and integration compatibility. An algorithm incorporating equations representing mechanical or electrical component curves is developed for Extended-Range Electric Vehicles, facilitating insight into potential range extender behavior. The core objectives of this study involve optimizing the entire powertrain system to ensure peak efficiency. Experimental tests demonstrate that integrating an auxiliary power unit enhances range, with an internal combustion engine generator configuration extending the travel distance by 35.35% at a constant speed. Moreover, with the use of an Equivalent Consumption Minimization Strategy control, the distance traveled increases up to 39.28% on standard driving cycles. The proposed methodology, validated through practical implementations, allows for comprehensive energy analyses, providing a precise understanding of vehicle platform performance with integrated range extenders. Full article

Due to high greenhouse gas emissions, countries worldwide are stepping up their emission reduction efforts, and the global demand for new, carbon-free fuels is growing. Ammonia (NH₃) fuels are popular due to their high production volume, high energy efficiency, ease of storage and transportation, and increased application in power equipment. However, their physical characteristics (e.g., unstable combustion, slow flame speed, and difficult ignition) limit their use in power equipment. Based on the structural properties of the power equipment, NH₃ fuel application and emissions characteristics were analyzed in detail. Combustion of NH₃ fuels and reduction measures for NO_x emissions (spark plug ignition, compression ignition, and gas turbines) were analyzed from various aspects of operating conditions (e.g., mixed fuel, fuel-to-exhaust ratio, and equivalence ratio), structure and strategy (e.g., number of spark plugs, compression ratio (CR), fuel injection, and ignition mode), and auxiliary combustion techniques (e.g., preheating, humidification, exhaust gas recirculation, and secondary air supply). The performance of various NH₃ fuel cell (FC) types was analyzed, with a focus on the maximum power achievable for different electrolyte systems. Additionally, the application and NO_x emissions of indirect NH₃ FCs were evaluated under flame and catalytic combustion conditions. The system efficiency of providing heat sources by burning pure NH₃, anode tail gas, and NH₃ decomposition gas was also compared. Based on a comprehensive literature review, the key factors influencing the performance and emissions of NH₃-powered equipment were identified. The challenges and limitations of NH₃-powered equipment were summarized, and potential strategies for improving efficiency and reducing emissions were proposed. These findings provide valuable insights for the future development and application of NH₃ FCs. Full article

Effective decarbonization of the power generation sector requires a multi-pronged approach, including the implementation of CO₂ capture and storage (CCS) technologies. The Graz cycle features oxy-combustion CO₂ capture in a power production scheme which can result in higher thermal efficiencies than that of a combined cycle. However, the auxiliary consumption required by the air separation unit to provide pure O₂ results in a significant energy penalty relative to an unabated plant. In order to mitigate this penalty, the present study explores the possibility of chemical looping combustion (CLC) as an alternative means to supply oxygen for conversion of the fuel. For a midscale power plant, despite reducing the levelized cost of electricity (LCOE) by approximately 12.6% at a CO₂ tax of EUR 100/ton and a natural gas price of EUR 6.5/GJ and eliminating the energy penalty of CCS relative to an unabated combined cycle, the cost reductions of CLC in the Graz cycle were not compelling relative to commercially available post-combustion CO₂ capture with amines. Although the central assumptions yielded a 3% lower cost for the Graz-CLC cycle, an uncertainty quantification study revealed an 85.3% overlap in the interquartile LCOE range with that of the amine benchmark, indicating that the potential economic benefit is small compared to the uncertainty of the assessment. Thus, this study indicates that the potential of CLC in gas-fired power production is limited, even when considering highly efficient advanced configurations like the Graz cycle. Full article

With the recent conversion of internal combustion engines to electric vehicles, new noise issues have arisen, and among them, the noise generated by internal vehicle auxiliary systems is being considered. This study introduces an electronic filter designed with a motor model featuring vibration components, aiming to minimize the noise and vibrations generated by a Brushed DC (BDC) motor commonly employed in vehicle internal systems. It introduces a method to identify the connectors and internal parameters used in the motor for the matching of the model and experimental motor, and to measure and estimate these parameters. The model is separated and executed to ensure convergence, and it is validated by comparing the analysis results with the measured values. A filter is designed using the model to reduce current oscillations in the motor, confirming a subsequent reduction in noise and vibration. This research suggests the potential to attenuate noise and vibration in already produced motors by attaching only a filter without modifying the internal motor structure. Moreover, it is anticipated that a filter can be designed to predict and mitigate the noise and vibration components of the motor based on changes in load. Full article

In this paper, a new preparation technology is developed to make high-alumina coal gangue (HACG) auxiliary cementitious admixture by calcining HACG–Ca(OH)₂ (CH) mixture. HACG powders mixed with 20 wt.% CH were calcined within a temperature range of 600–900 °C, and the thermal transformation and mineral phase formation were analyzed. The hydration reaction between activated HACG–CH mixture and cement was also investigated. The results showed that HACG experienced a conventional transformation from kaolinite to metakaolin at 600 °C and finally to mullite at 900 °C, whereas CH underwent an unexpected transformation process from CH to CaO, then to CaCO₃, and finally to CaO again. These substances’ states were associated with the dehydroxylation of CH, the chemical reaction between CaO and CO₂ generating from the combustion of carbon in HACG, and the decomposition of CaCO₃, respectively. It is the formation of a large amount of CaO above 800 °C that favors the formation of hydratable products containing Al₂O₃ in the calcining process and C-A-H gel in the hydration process. The mechanical properties of HACG–cement mortar specimens were measured, from which the optimal calcination temperature of 850 °C was determined. As compared with pure cement mortar specimens, the maximum 28-d flexural and compressive strengths of HACG–cement mortar specimens increased by 5.4% and 38.2%, respectively. Full article