Environmental Progress & Sustainable Energy最新文献

Today, there is a desire to use low-carbon fuels and non-petroleum fuels in internal combustion engines. It is also important for energy diversity and security that countries use alternative fuels produced from local energy resources in energy production by blending them with fossil fuels. The purpose of this study is to investigate the effect of ignition timing on combustion parameters and knocking tendency by varying the initial flame kernel by varying the ignition timing ±5^oCA while using gasoline blends containing 30% alcohol by volume, which is a critical blend ratio for a spark ignition (SI) direct injection engine, and to analyze the data obtained. Based on the analysis, it was determined that retarding the ignition timing results in a drop in the cylinder gas pressure curve and a loss of engine power, as combustion takes place in a rapidly expanding cylinder volume. Ignition timing was found to have a direct effect on the magnitude and position of the cylinder gas pressure. Advancing the ignition timing increases the cylinder gas pressure for all fuels, while retarding the ignition timing reduces the cylinder gas pressure and moves it away from the top dead center. The knocking tendency of the engine is reduced when critical alcohol/gasoline blends are used. Significant reductions in NO_x and PM emissions have been achieved when using alcohol blends.

Solar Air Heaters (SAHs) face performance limitations due to inefficient heat transfer mechanisms. To address this, the current numerical study utilizes Computational Fluid Dynamics (CFD) to systematically optimize fin configurations. By first focusing on optimizing the fin tilt angle and subsequently refining the fin height, this methodology addresses key parameters influencing heat transfer efficiency and overall system performance. The systematic study of cooling effectiveness by varying the flow rate on the SAH, ranging from 0.0025 to 0.02 kg/s, is aimed at determining the optimal tilt angle and fin height to boost the thermal efficiency of the SAH within the radiation range of 400–1000 W/m². Remarkably, the investigation reveals that for a zero-tilt angle and a 0.01 kg/s mass flow rate, there is a notable enhancement in average thermal efficiency, reaching 42.18%. Additionally, the findings highlight that for a fin height of 15 mm and the same flow rate of 0.01 kg/s, the average thermal efficiency significantly improves, reaching 49.67%. These results signify the critical role of both tilt angle and fin height in optimizing the SAH thermal performance. The identified optimal configurations, such as the zero-tilt angle with an air flow rate of 0.01 kg/s and a fin height of 15 mm, underscore the potential for substantial improvements in SAH efficiency. These results offer insightful information for creating and enhancing SAHs, offering pathways to enhance their energy conversion capabilities and overall performance.

This research addresses two key questions related to Clean Development Mechanism (CDM) This research aimed to address two research questions related to CDM projects focused on energy generation in Latin America. The first question aimed to identify the most efficient projects carried out in this region, while the second question sought to identify their characteristics. These questions were proposed based on a clear gap identified in the scientific literature, particularly regarding these ventures developed in the region, which may be of interest to researchers, investors, and project managers alike. To answer these questions, a quantitative analysis was conducted using the database on CDM projects provided by the United Nations Framework Convention on Climate Change, employing two techniques. The first technique used was Data Envelopment Analysis, which generated an efficiency ranking for these projects. In this study, efficiency is considered as the results achieved by the project in terms of energy generation capacity and carbon emission reduction, relative to the resources invested in it. The second technique was the non-parametric Mann–Whitney test, which helped identify characteristics that exhibited significant differences in efficiency. Among the findings, three key characteristics were identified as relevant in explaining this difference: project scale, type, and country where they were developed. Large-scale projects—specifically those in the categories of Methane Avoidance, Landfill Gas, and Energy Efficiency Supply Side—as well as projects carried out in Mexico and Colombia, demonstrated significantly higher efficiency based on the model used in this research. Furthermore, Hydro and Biomass Energy projects were identified as having significantly lower efficiency compared to the others. The outcomes of this study hold significance in two aspects. Firstly, from an academic standpoint, it expands the understanding of project characteristics of these projects in Latin America by establishing a comparative analysis among them. Secondly, from a more practical perspective, the results can guide investors in defining a more suitable profile for energy-generating CDM projects, thereby reducing risks and increasing the likelihood of success. Moreover, these findings can lay the foundation for the formulation of public policies aimed at promoting projects with a more efficient profile. This is especially important given the waning interest in this crucial mechanism over the past decade, potentially spurring the execution of new projects and altering this reality.

In tandem with the expansion of the amount of sewage treatment, the production of sludge has increased significantly, making sludge treatment suffer from environmental problems. Optimizing sludge drying technology to reduce pollutant emissions and improve treatment efficiency will garner widespread concern and attention. This study explores the efficacy of the moisture distribution, temperature, and thickness of three types of sludge (brewery sludge, printing and dyeing sludge, and municipal sludge) using thin-layer drying technology. Except for studying the three common moisture contents, it also expands on the influence of bound water on the drying process, and the addition of CaO primarily facilitates the conversion of a portion of interstitial water into free water. Additionally, multiple parameter combinations analysis of sludge drying illustrated that temperature has a more significant impact on the drying process of sludge than thickness, and increasing the temperature can mitigate the effects brought about by changes in thickness. Remarkably, under conditions of high temperature (200°C) and low thickness (0.5 cm), the drying curves of the three sludges showed little difference. Further, mathematical models of thin-layer drying were elaborated, and it was found that the Page model was quantitatively processed with a higher experimental relationship (R² = 0.9974) and a physical model was established to illustrate the role of CaO as a desiccant and conditioner to coordinate thin-layer drying. Therefore, the optimization of the drying characteristics of thin-layer sludge shows it is pivotal for adjusting the drying differences to reveal the drying behavior mechanism, as well as providing technical theoretical support.

A thin-film photocathode composed of Poly(2-mercaptoaniline)/Reduced Graphene Oxide Nanosheets (P2MA/rGO-NS) was synthesized through a two-step process involving the in situ chemical reduction of graphene oxide by the 2-mercaptoaniline monomer, followed by oxidative polymerization to form the conducting polymer matrix. The resulting hybrid structure exhibits a compact and homogeneous morphology, where P2MA particles (~140 nm) are uniformly distributed within rGO sheets (~100 nm), facilitating efficient charge transport and interfacial contact. Optical analysis confirms broadband light absorption with an optical bandgap of ~2.4 eV, as suitable for visible-light-driven photoelectrochemical applications. The photocatalytic efficiency of the P2MA/rGO-NS photocathode was assessed for hydrogen evolution using both natural Red Sea water and an equivalent synthetic seawater as electrolytes in a standard three-electrode configuration. At −0.72 V, the photocurrent densities reached −0.7 and −0.5 mA/cm² for natural and artificial seawater, respectively, correlating with an average hydrogen evolution rate of 18 μA per 10 cm² per hour. The wavelength-dependent photoresponse under monochromatic illumination demonstrated peak photocurrent densities of −0.63 and −0.57 mA/cm² at 340 and 440 nm, respectively, with a gradual decline to −0.54 mA/cm² at 730 nm, indicating broad-spectrum responsiveness. The excellent photocatalytic performance, combined with stable operation under chopped illumination, low-cost fabrication, and scalability, positions the P2MA/rGO-NS photocathode as a strong candidate for sustainable hydrogen production from seawater in industrial-scale application.

Transportation is one of the essential milestones for the economy. However, transportation is also one of the most environmentally damaging industries due to intense energy use. These contradictory effects should be balanced. In this regard, energy and economic efficiency in the transportation sector are significant targets in the European Union. To that purpose, first, we aim to assess the energy and economic efficiency of the EU members via the two-stage slack-based DEA. The results indicate that industrialized EU countries, namely Denmark, Netherlands, and Germany, perform efficiently throughout the analysis period in the developed countries group. This finding indicates that these efficient countries both use their energy sources effectively and transform these resources into economic value. Second, we perform the Tobit regression to explore the influencing factors, which are widely used to deal with censored variables. Tobit regression results indicate that economic growth, population, and foreign direct investments have a positive and significant effect on both energy and economic efficiency, whereas energy consumption structure negatively affects the efficiency of the EU countries. This study aims to contribute to the literature by integrating two-stage DEA with Tobit regression in the transportation sector, thereby presenting a comprehensive framework for analyzing efficiency and its influencing factors. Through considering results in a broader context, the research focuses on main issues for intervention, such as the necessity to instigate innovation, to form variety in energy production, as well as to reduce resource inefficiencies in the EU member states that are still in the stage of development.

Solar air heaters are widely used in low-temperature applications such as drying, heating, etc. The growth of the laminar sub-layer under the absorber plate in conjunction with flowing air leads to lower convective heat transfer and, thereby, low performance. In this present work, the conventional solar air heater is reconfigured using transverse wire ribs with variable gaps to break the laminar sub-layer. The experiment was performed under actual outdoor weather conditions in Jagdalpur, India. The important design and control variables used are relative roughness height (e/D) of 0.043, relative roughness pitch (p/e) of 10, gap width (g) of 4 mm, rib roughness diameter (e) of 2 mm, the number of gaps (Ng) varying from 1 to 4 (in 4 steps) and Reynolds number in the range of 2000–16,000 (in 8 steps). The experimental result indicates that the maximum Nusselt number and friction factor are achieved for Ng = 2 compared to all the gaps. Ng = 2 configuration outperforms both continuous rib and smooth duct configurations. The findings show that the maximum augmentation in heat transfer and fluid friction compared to smooth ducts is 3.04 and 3.03, respectively. The optimal parameters identified as p/e = 10, e/D = 0.043, e = 2, g = 4, and Ng = 2 resulted in the highest enhancement in heat transfer across all cases studied. The heat transfer found in the present study outperforms that of prior investigations in the field of solar air heaters, which utilized similar rib configurations but did not incorporate variable gaps.

Concentrated sugarcane juice is a raw material used to manufacture a number of value-added products. At present, the sugar industry ingests the maximum amount of fuel for obtaining concentrated sugarcane juice, which in turn leads to degradation of the environment. This study addresses the unexplored application of aluminum nanoparticle-enhanced beeswax, a sustainable bio-PCM, in solar still systems (SSS) for sugarcane juice evaporation, evaluating its thermal performance using simple and modified collectors to enhance energy efficiency and promote eco-friendly distillation in rural settings, at a flow rate of 25 mL/min. Among the tested systems, the stepped solar still having nanoparticle mixed beeswax and a modified collector is found to be the most economical, thermally more stable, and eco-friendlier. This system produces a maximum distillate output (4930.2 g) with the most concentrated sugarcane juice having a brix value of 32.8°B. The average convective heat transfer coefficient is found to be maximum for the stepped solar still having nanoparticle mixed beeswax and a modified collector, which is 14.29 to 57.96% higher than the other developed units. This system is also found to lead other systems with maximum values of carbon credit earned ($1137.1), CO₂ mitigation (56.85 tons), total productive cost ($0.96), thermal efficiency (64.8%) and exergy efficiency (3.91%). This study concludes that the stepped solar still having nanoparticle mixed beeswax and a modified collector might be an affordable and environmentally friendly tool to evaporate water from sugarcane juice, which could help the NCS industry in attaining the sustainability goal.

Peat is abundant and can be used to produce biomethane, a clean energy source that helps reduce greenhouse gas emissions and drive the energy transition. Yet, its natural methane yield is low, making scientific pretreatment crucial for boosting biomethane output. Microwave and ultrasonic pretreatment technologies can promote biomethane production from biomass. Microwave and ultrasonic pretreatment applications in peat methane production need to be explored. The effects of microwave and ultrasonic pretreatment on biomethane production from herbaceous peat were systematically investigated using daily biomethane production, total biomethane production, methane content, humic acid content, glucose content, and acetic acid content. Results showed that the total biomethane production employing microwave and ultrasonic pretreatment was 25.16 and 21.79 mL/g, 2.75 and 2.38 times that of the control group, respectively. Furthermore, compared with the control group, the peat biomethane fermentation system after microwave and ultrasonic pretreatment had a higher methane content (p ≤ 0.05), higher glucose content (p > 0.05) and higher humic acid content (p ≤ 0.05), while a lower acetic acid content (p > 0.05). These findings demonstrated that microwave and ultrasonic pretreatment facilitated peat biomethane fermentation. Particularly, microwave pretreatment presented a more significant enhancement in biomethane production. This is because microwave and ultrasonic pretreatment can improve the specific surface area of peat, which increases the effective contact area between microorganisms and peat. Meanwhile, microwave pretreatment of peat can reduce the crystallinity of cellulose. The proposal of this study provides a new idea for the green, sustainable conversion of peat resources.

The treatment of distillery wastewater by microalgae is a promising low-carbon green technology for wastewater treatment. A key aspect of this process is the selection of appropriate microalgal strains. In this study, based on anaerobically treated distillery wastewater, Chlorella sorokiniana M7 with high decontamination efficiency was screened from Wuliangye wastewater treatment plant. This strain demonstrated superior decontamination efficiency compared to both Chlorella sp. (FACHB-30) and Tetradesmus obliquus (FACHB-12). Chlorella sorokiniana M7 exhibited optimal nitrogen and phosphorus removal efficiency at the carbon dioxide concentration of 2.5% and unsterilized wastewater, the removal rates for NH3-N and TP reached up to 100% and 90.39%, respectively. The findings from high-throughput sequencing suggested that as the duration of wastewater treatment with Chlorella M7 extends, there was a corresponding increase in the abundance of Fimbriimonadaceae, which played a pivotal role in enhancing the growth of Chlorella.