Search Results (33)

This community-based participatory research (CBPR) study explored, using a Photovoice methodology, the lived expeiences of northeastern Black and/or African American youth and mothers who were currently experiencing the incarceration of their fathers and husbands. Grounded in critical theories of dual consciousness and comparative conflict, the findings provide valuable insights into how this population navigates the intersections of family, school, and community within the context of the criminal legal system, and, in the process, underscore the relevance of Abolitionist practice in capturing their theoretically lived experiences. Participants documented through photography and narrative reflections the multifaceted impacts of incarceration on fathers and husbands, including disrupted family dynamics, social stigma, and barriers to community resources. A focus group with the mothers of these youth highlighted the profound impact of incarceration on their family structure, revealing significant emotional burdens for caregivers as well as personal changes to parenting styles as a result of this project. A central theme that emerged was the development of a “double” or “dual consciousness”—an ability to see humanity and injustice in their circumstances, fueling a desire for systemic change. Overall, this CBPR project amplifies the voices of marginalized youth and mothers, illuminating how the criminal legal system perpetuates cycles of trauma, stigma, and disempowerment. The implications call for a radical reimagining of the role of social work in creating more equitable, restorative, and healing-centered communities, including an immediate embrace of Abolitionist practice concepts and interventions. Full article

Challenges associated with the homogeneous charge combustion ignition (HCCI) concept include combustion phasing control and a narrow operating window. To address the HCCI engine developmental needs, chemical kinetic solvers have been recently included in the commercial engine simulation toolchains like GT-Suite v2024 upward. This study investigates the feasibility of ammonia (NH₃) and hydrogen (H₂) as dual fuels in homogenous charge compression ignition (HCCI) engines, leveraging chemical kinetics modeling via GT-Suite software v2024. A validated baseline model was adapted with NH₃/H₂ injectors and simulated across varying blending ratios (BR), compression ratios (CR), air–fuel equivalence ratios (ER), and engine speeds. Results reveal that adding 10% H₂ to NH₃ significantly improves ignition. Optimal performance was observed at a CR of 20 and a lean mixture, achieving higher indicated thermal efficiency (about 40%), while keeping the intrinsic advantages of zero-carbon fuel. However, NOx emissions increased with higher ER due to elevated combustion temperatures. The study emphasizes the trade-offs between efficiency and NOx emissions under tested conditions. Finally, despite the single-zone model limitations in neglecting thermal stratification, this study shows that kinetic modeling has great potential for effectively predicting trends in HCCI, thereby demonstrating the promise of NH₃/H₂ blends in HCCI engines for cleaner and efficient combustion, paving the way for advanced dual-fuel combustion concepts. Full article

The increasing emphasis on environmental sustainability and stricter gas emissions regulations has made the optimization of fuel and emissions a crucial factor for marine propulsion systems. This paper investigates the potential to improve fuel efficiency and reduce emissions of LNG ship propulsion systems by using different load sharing strategies in Dual-Fuel Diesel-Electric (DFDE) propulsion systems. Using data collected from on-board cyclic measurements and an optimization model, the effects of different load sharing strategies for various types of fuel, such as HFO, MDO, and LNG, under different engine load conditions were investigated. The results of these strategies are compared with those of on-board power management systems (PMS), which evenly allocate power among the engines, irrespective of fuel usage and emission levels. The results show that load adjustments according to the optimization model can considerably increase fuel economy and contribute to the reduction of CO₂ and NO_x compared to standard practice at the equal load in different ship operating modes. Our approach introduces an innovative optimization concept that has been proven to improve fuel efficiency and reduce emissions beyond standard practices. This paper demonstrates the robustness of the model in balancing environmental and operational objectives and presents an effective approach for more sustainable and efficient ship operations. The results are in line with global sustainability efforts and provide valuable insights for future innovations in energy optimization and ship emission control. Full article

Marine two-stroke dual-fuel (DF) engines with a low-pressure gas concept normally face the problem of inferior fuel economy in diesel mode, mainly due to their lower compression ratio. To address this issue, a numerical study is performed to investigate the applicability of variable compression ratio (VCR) in a marine two-stroke DF engine, aiming at improving fuel economy in diesel mode. First, an engine simulation model is established and validated. Then, parametric investigation is performed to obtain insights on the effects of VCR on engine combustion, performance, and emissions. Finally, regression models of selected engine response variables are determined based on the response surface methodology (RSM), which are then optimized by particle swarm optimization (PSO) to obtain the optimal solution of engine setting parameters. The results show that with the application of VCR, the brake specific fuel consumption (BSFC) decreases by 9.65, 11.38, 11.13, and 11.27% at 25, 50, 75, and 100% maximum continuous rating (MCR), respectively. Meanwhile, the nitrogen oxides (NOx) emissions are maintained at the original levels, and the engine’s operating parameters are within specified limits. This study contributes to the delineation of the benefits and limits of VCR and provides a feasible method to facilitate the implementation of VCR in marine engines. Full article

Dual fuel combustion has gained attention as a cost-effective solution for reducing the pollutant emissions of internal combustion engines. The typical approach is combining a conventional high-reactivity fossil fuel (diesel fuel) with a sustainable low-reactivity fuel, such as bio-methane, ethanol, or green hydrogen. The last one is particularly interesting, as in theory it produces only water and NO_x when it burns. However, integrating hydrogen into stock diesel engines is far from trivial due to a number of theoretical and practical challenges, mainly related to the control of combustion at different loads and speeds. The use of 3D-CFD simulation, supported by experimental data, appears to be the most effective way to address these issues. This study investigates the hydrogen-diesel dual fuel concept implemented with minimum modifications in a light-duty diesel engine (2.8 L, 4-cylinder, direct injection with common rail), considering two operating points representing typical partial and full load conditions for a light commercial vehicle or an industrial engine. The numerical analysis explores the effects of progressively replacing diesel fuel with hydrogen, up to 80% of the total energy input. The goal is to assess how this substitution affects engine performance and combustion characteristics. The results show that a moderate hydrogen substitution improves brake thermal efficiency, while higher substitution rates present quite a severe challenge. To address these issues, the diesel fuel injection strategy is optimized under dual fuel operation. The research findings are promising, but they also indicate that further investigations are needed at high hydrogen substitution rates in order to exploit the potential of the concept. Full article

Under the global dual-carbon background, heightened public awareness of climate change and strengthened carbon taxation policies are increasing pressure on the steel industry to transition. Given the urgent need for carbon reduction, the exploration of low-carbon pathways in a blast furnace (BF) metallurgy emerges as crucial. Evaluating both asset retention and technological maturity, the development of low-carbon technologies for BFs represents the most direct and effective technical approach. This article introduces global advancements in low-carbon metallurgical technologies for BFs, showcasing international progress encompassing hydrogen enrichment, oxygen enrichment, carbon cycling technologies, biomass utilization, and carbon capture, utilization, and storage (CCUS) technologies. Hydrogen enrichment is identified as the primary technological upgrade currently, although its carbon emission reduction potential is limited to 10% to 30%, insufficient to fundamentally address high carbon emissions from BFs. Therefore, this article innovatively proposes a comprehensive low-carbon metallurgical process concept with the substitution of carbon-neutral biomass fuels at the source stage—intensification of hydrogen enrichment in the process stage—fixation of CCUS at the end stage (SS-IP-FE). This process integrates the cleanliness of biomass, the high-efficiency of hydrogen enrichment, and the thoroughness of carbon fixation through CCUS, synergistically enhancing overall effectiveness. This integrated strategy holds promise for achieving a 50% reduction in carbon emissions from BFs in the long processes. Critical elements of these core technologies are analyzed, assessing their cost-effectiveness and emission reduction potential, underscoring comprehensive low-carbon metallurgy as a pivotal direction for future steel industry development with high technological feasibility and emission reduction efficacy. The article also proposes a series of targeted recommendations, suggesting short-term focus on technological optimization, the medium-term enhancement of technology research and application, and the long-term establishment of a comprehensive low-carbon metallurgical system. Full article

Identifying and analyzing the engine performance and emission characteristics under the condition of performance decay is of significant reference value for fault diagnosis, condition-based maintenance, and health status monitoring. However, there is a lack of relevant research on the currently popular marine large two-stroke dual fuel (DF) engines. To fill the research gap, a detailed zero-/one-dimensional (0D/1D) model of a marine two-stroke DF engine employing the low-pressure gas concept is first established in GT-Power (Version 2020) and validated by comparing the simulation and measured results. Then, three typical types of turbocharger performance decays are defined including turbine efficiency decay, turbine nozzle ring area decay, and turbocharger shaft mechanical efficiency decay. Finally, the three types of decays are introduced to the engine simulation model and parametric runs are performed in both diesel and gas modes to identify and analyze their impacts on the performance and emission characteristics of the investigated marine DF engine. The results reveal that turbocharger performance decay has a significant impact on engine performance parameters, such as brake efficiency, engine speed, boost pressure, etc., as well as CO₂ and NOx emissions, and the specified limit value on certain engine operational parameters will be exceeded when turbocharger performance decays to a certain extent. The changing trend of engine performance and emission parameters as turbocharger performance deteriorates are generally consistent in both operating modes but with significant differences in the extent and magnitude, mainly due to the distinct combustion process (Diesel cycle versus Otto cycle). Furthermore, considering the relative decline in brake efficiency, engine speed drop, and relative increase in CO₂ emission, the investigated engine is less sensitive to the turbocharger performance decay in gas mode. The simulation results also imply that employing a variable geometry turbine (VGT) is capable of improving the brake efficiency of the investigated marine DF engine. Full article

The global move towards a circular economy, as well as that of achieving the United Nations Sustainable Development Goals (SDGs), has necessitated the search for several sustainable solutions in various sectors. Given this, the provision of sustainable waste management and electricity systems constitute a significant part of the SDGs, and the waste-to-energy (WtE) concept has recently become a key topic given that it can potentially help reduce the dependence on fossil fuels for energy generation, as well as minimizing the need to dispose of waste in landfill. However, to date, the sustainability assessments of WtE generation technologies have been limited in scope concerning the three-dimensional sustainability framework (economic, environmental, and social). Life Cycle Sustainability Assessment (LCSA) has been proposed as a potential approach that could comprehensively address these three pillars of sustainability simultaneously based on life cycle thinking. LCSA, as a holistic method, could also potentially deal with the complexity associated with decision-making by allowing for the consideration of a full range of possible sustainability consequences. LCSA is an analytical tool that integrates the Life Cycle Assessment (LCA), Life Cycle Costing (LCC), and Social Life Cycle Assessment (sLCA) methodologies, which already exist and continue to be developed. Individually, these life-cycle approaches tend to be used to point out particular ‘hotspots’ in product or service systems, and hence focus on direct impacts in a given sustainability domain, neglecting the indirect ones. LCSA aims for a more holistic sustainability perspective and seeks to address the associated challenge of integrating these three pillars of sustainability into an overall and more comprehensive sustainability assessment. This need for harmonization within the LCSA methodology is a major challenge in its operationalization. In recent years there has been steady progress towards developing and applying LCSA, including for WtE. The aim of this paper is to review the most recent trends and perspectives in developing countries, especially regarding how LCSA could help inform decision-making. The paper also analyses the LCSA literature to set out the theoretical and practical challenges behind integrating the three methods (LCA, LCC, and sLCA). The review was conducted via a search of keywords such as LCSA, waste, and energy in the Web of Science databases, resulting in the selection of 187 publications written in English. Of those, 13 articles operationalized LCSA in specific waste and WtE related case studies. The review provides a review of the application of LCSA for researchers, technological experts, and policymakers through published findings and identifies perspectives on new research. These include uncertainty, subjectivity in weighting, double-counting, the low maturity of sLCA, and the integration of the interconnection between the three dimensions (environmental, economic, and social dimensions) of LCSA results in decision-making. In addition, gaps (such as the integration of the interconnection between the three dimensions) that need to be addressed via further research are highlighted to allow for a better understanding of methodological trade-offs that come from using the LCSA analytical approach to assess the sustainability of WtE generation technologies, especially in developing countries. It is hoped that this study will be a positive contribution to environmental and energy policy decisions in developing countries faced with the dual problems of waste management and electricity supply along with their sustainable development goals. Full article

To meet climate targets, a global shift away from fossil fuels is essential. For sectors where electrification is impractical, it is crucial to find sustainable energy carriers. Renewable methanol is widely considered a promising fuel for powering heavy-duty applications like shipping, freight transport, agriculture, and industrial machines due to its various sustainable production methods. While current technological efforts focus mainly on dual-fuel engines in shipping, future progress hinges on single-fuel solutions using renewable methanol to achieve net-zero goals in the heavy-duty sector. This review examines the research status of technologies enabling methanol as the sole fuel for heavy-duty applications. Three main categories emerged from the literature: spark-ignition, compression-ignition, and pre-chamber systems. Each concept’s operational principles and characteristics regarding efficiency, stability, and emissions were analyzed. Spark-ignition concepts are a proven and cost-effective solution with high maturity. However, they face limitations due to knock issues, restricting power output with larger bore sizes. Compression-ignition concepts inherently do not suffer from end-gas autoignition, but encounter challenges related to ignitability due to the low cetane number of methanol. Nonetheless, various methods for achieving autoignition of methanol exist. To obtain stable combustion at all load points, a combination of techniques will be required. Pre-chamber technology, despite its lower maturity, holds promise for extending the knock limit and enhancing efficiency by acting as a distributed ignition source. Furthermore, mixing-controlled pre-chamber concepts show potential for eliminating knock and the associated size and power limitations. The review concludes by comparing each technology and identifying research gaps for future work. Full article

Reactivity-controlled compression ignition (RCCI) combustion is considered one of the most promising low-temperature combustion (LTC) concepts aimed at reducing greenhouse gases for the transportation and power generation sectors. RCCI combustion mode is achieved by combining different fuel types with low and high temperatures. The aim of this study is to investigate combustion characteristics and reduce nitrogen oxide (NO_x) and carbon dioxide (CO₂) emissions. In this experimental study, the effects of the RCCI strategy using methanol/diesel fuel on combustion characteristics (ignition delay, combustion duration), engine performance (brake-specific fuel consumption and brake-specific energy consumption), and emissions were examined in a four-cylinder, turbocharged, dual-fuel engine. The experiments were conducted at a constant speed of 1750 rpm at partial loads (40 Nm, 60 Nm, 80 Nm, and 100 Nm). The test results obtained with diesel fuel were compared with the test results obtained with methanol at different mass flow rates. When the results were examined, the minimum ignition delay (ID) occurred at 40 Nm torque, 5.63 crank angle (CA) with M12 fuel, while the maximum ID occurred with M26 fuel at 80 Nm torque, showing an increasing trend as engine load (EL) increased. The highest combustion time (CD) was achieved with M26 fuel at 100 Nm torque, whereas the lowest was achieved with the same fuel (M26) at 40 Nm. While the minimum brake-specific fuel consumption (bsfc) was 45.9 g/kWh for conventional diesel fuel at 40 Nm, the highest bsfc was 104.88 g/kWh for 100 Nm with M26 fuel. Generally, bsfc tends to increase with increasing load. Brake-specific energy consumption (bsec) had the lowest value of 1950.58 kJ/kWh with conventional diesel fuel at 40 Nm and the highest value of 4034.69 kJ/kWh with M26 fuel at 100 Nm. As the methanol content increased, significant improvements were observed in (NO_x) and (CO₂) emissions, while hydrocarbon (HC) and oxygen (O₂) emissions increased as well. Smoke emissions decreased at low loads but tended to increase at high loads. Full article

Acidic deep eutectic solvents (DESs) have been considered desirable extractants and catalysts for desulfurization. However, their hydrogen bond donors (HBDs) are usually sole organic acids, which are not conducive to efficient green catalysis. Herein, a novel inorganic–organic dual-acid DES (DADES) was reported for efficient extractive and oxidative desulfurization. Benefiting from the physical interaction among the three components in a DADES, a transparent homogeneous liquid can be obtained even though inorganic acid (boric acid, BA) and organic acid (acetic acid, AA) can be immiscible. Furthermore, the dual-acid HBD can increase the acidity of the DADES and reduce its viscosity, accelerating its mass transfer efficiency and enhancing its catalytic activity. With 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as the hydrogen bond acceptor, [Bmim]Cl/BA/0.3AA effectively activated hydrogen peroxide and achieved sulfur removal of 96.6% at 40 °C. Furthermore, the universality of the synergistic effect in various DADESs was confirmed by the modulation of the types of organic acids. This study not only motivates the construction of more intriguing novel DESs based on the DADES concept but also highlights their potential in clean fuel production. Full article

Reactivity-Controlled Compression Ignition (RCCI) combustion is considered one of the most promising Low-Temperature Combustion (LTC) concepts aimed at reducing greenhouse gases for the transportation and power generation sectors. Due to the spontaneous combustion of a lean, nearly homogeneous mixture of air and low-reactivity fuel (LRF), ignited through the direct injection of a small quantity of high-reactivity fuel (HRF), RCCI (dual-fuel) shows higher efficiency and lower pollutants compared to conventional diesel combustion (CDC) if run at very advanced injection timing. Even though a HRF is used, the use of advanced injection timing leads to high ignition delays, compared to CDC, and generates high cycle-to-cycle variability, limited operating range, and high pressure rise rates at high loads. This work presents an experimental analysis performed on a heavy-duty single-cylinder compression ignited engine in dual-fuel diesel–natural gas mode. The objective of the present work is to investigate and highlight the correlations between combustion behavior and pollutant emissions, especially unburned hydrocarbons (HC) and oxides of nitrogen (NOx). Based on the analysis of crank-resolved pollutants measurements performed through fast FID and fast NOx systems under different engine operating conditions, two correlations were found demonstrating a good accordance between pollutant production and combustion behavior: Net Cyclic Hydrocarbon emission—cyclic IMEP variations (R² = 0.86), and Cyclic NOx—maximum value of the Rate of Heat Released (R² = 0.82). Full article

This study presents the design and computational fluid dynamics (CFD) analysis of a mini demonstrator for a dual fluid reactor (DFR). The DFR is a novel concept currently under investigation. The DFR is characterized by the implementation of two distinct liquid loops dedicated to fuel and coolant. It integrates the principles of molten salt reactors and liquid metal cooled reactors; thus, it operates in a high temperature and fast neutron spectrum, presenting a distinct approach in the field of advanced nuclear reactor design. The mini demonstrator serves as a scaled-down version of the actual reactor, primarily aimed at gaining insights into the CFD analysis intricacies of the reactor while minimizing computational costs. The CFD modeling of the MD intends to add valuable data for the purpose of modeling validation against experiments to be conducted on the MD. These experiments can be used for DFR licensing and design optimization. The coolant and fuel utilized in the mini demonstrator are of low Prandtl number (Pr = 0.01) liquid lead, operating at two distinct inlet temperatures, namely 873 K and 1473 K. The study showed a rapid increase in turbulence due to intense mixing and abrupt changes in flow areas and directions, despite the relatively low inlet velocities. Hot spots characterized by elevated temperatures were identified, analyzed, and justified based on their spatial distribution and flow conditions. Flow swirling within pipes was identified and a remedy approach was suggested. Inconsistent mass flow rates were observed among the fuel pipes, with higher rates observed in the lateral pipes. Although lower fuel temperatures were observed in the lateral pipes, they consistently exhibited higher heat exchange characteristics. The study concludes by giving physical insights into the heat transfer and flow behavior, and proposing design considerations for the dual fluid reactor to enhance structural safety and durability, based on the preliminary analysis conducted. Full article

To meet stringent fuel sulfur limits, together with NO_x limits, ships are increasingly utilizing dual-fuel (DF) engines operating with liquified natural gas (LNG) as the primary fuel. Compared to diesel, LNG combustion produces less CO₂, which is needed in targeting the reduction of the shipping impact on the climate; however, this could be significantly interfered with by the methane emission formation. In this study, the methane emissions, together with other emission components, were studied by measurements onboard a state-of-the-art RoPax ferry equipped with two different development-stage engines. The results from the current standard state-of-the-art DF engine showed methane levels that were, in general, lower than what has been reported earlier from onboard studies with similar sized DF engines. Meanwhile, the methane emission from the DF engine piloting the new combustion concept was even lower, 50–70% less than that of the standard DF engine setup. Although the CO₂ was found to slightly increase with the new combustion concept, the CO₂ equivalent (including both methane and CO₂) was smaller than that from the standard DF engine, indicating that the recent development in engine technology is less harmful for the climate. Additionally, lower NO_x and formaldehyde levels were recorded from the new combustion concept engine, while an increase in particle emissions compared to the standard DF engine setup was observed. These need to be considered when evaluating the overall impacts on the climate and health effects. Full article

With increased interests in affordable energy resources, a cleaner environment, and sustainability, more objectives and operational obligations have been introduced to recent power plant control systems. This paper presents a verified load frequency model predictive control (MPC) that aims to satisfy the load demand of three practical generation technologies, which are wind energy systems, clean coal supercritical (SC) power plants, and dual-fuel gas turbines (GTs). Simplified state-space models for the two thermal units were constructed by concepts of subspace identification, whereas the individual wind turbine integration was implicated by the Hammerstein–Wiener (HW) model and then augmented from the output to simulate the effect of a wind farm, assuming similar power harvesting from all turbines in the farm. A practical strategy of control was then suggested, which was as follows: with a changing load demand, the available harvested wind energy must be fully admitted to the network to cover part of the load demand with the free energy, and the resultant load signal will then be instructed to the MPCs designed for the coal and gas units for the coordination of generation. The load signal, after being penetrated by wind, has more transients and faster changes, and needs a more sophisticated control in order to follow the load demand of the flexible coal and gas units. Furthermore, as the level of wind penetration increases, the power system frequency excursions are higher. The simulation results show an acceptable performance for linear MPCs embedded to the GT and coal units, with around a 90 MW share of wind without exceeding the safe restrictions of the plants and allowable reasonable frequency excursions. The complete simulation framework can be used to facilitate wind energy penetration in such power systems and train the operators and future engineers with subsequent power system frequency simulation studies. Full article