Low Emission Research Articles

Machine learning driven building integrated photovoltaic (BIPV) envelope design optimization

By integrating renewable energy systems (RESs) into buildings, Building-Integrated Photovoltaics (BIPV) reshape the demand–supply relationship, offering substantial benefits such as reduced energy usage, lower greenhouse gas emissions, improved indoor comfort, and architectural enhancement. However, designing optimal BIPV systems involves balancing multiple parameters and conflicting objectives, making it a complex, computationally intensive process. This study proposes a data-driven optimization framework to enhance BIPV envelope design during the detailed design phase. The novelties of this research lie in 1) the use of Artificial Neural Networks (ANN) as a surrogate model for rapid prediction, and 2) a multi-objective optimization (MOO)framework tailored for BIPV design at the detailed design phase. The proposed framework integrates ANN-based predictive modelling with an NSGA-II optimization component to generate optimal BIPV configurations efficiently. Implemented in Python, this approach is validated through a benchmark case study in Melbourne, demonstrating its effectiveness in reducing computational demands while achieving balanced energy, economic, and indoor comfort performance. This research advances sustainable building design by addressing gaps in current optimization frameworks and providing practical tools for architects and designers, promoting the wider adoption of BIPV solutions with significant computational savings.

Using break-even analysis to explore the cost and carbon reduction benefits of solar and wind energy integration in microgrids for convenience stores

In response to the increasing demands for net-zero carbon emissions in Taiwan and globally, this study explores the feasibility of implementing microgrid technologies in convenience stores to reduce carbon emissions. The study utilizes the commercial simulation tool HomerPro to evaluate the performance of integrating solar and wind power into microgrid systems, aligning with Taiwan's current priorities in renewable energy development. The analysis incorporates carbon pricing scenarios, grid reliability considerations, and financial variables such as discount and inflation rates. We simulated 256 system configurations to identify the most economically viable solutions under various conditions. The results indicate that integrating solar and wind energy into microgrid systems can significantly lower energy costs and carbon emissions, especially in high carbon-price scenarios. These benefits provide strong incentives for businesses to adopt carbon-neutral strategies. These findings provide valuable insights for policymakers and businesses, highlighting the critical role of reducing green power purchase prices in improving economic feasibility. Future research explores the impacts of integrating other renewable energy sources, offering broader technical support for achieving carbon neutrality.

Aircraft performance of a novel SAF: Lower costs, lower environmental impact, and higher aircraft performance

Investing in Sustainable Aviation Fuel (SAF) is crucial for reducing the aviation industry’s carbon footprint and mitigating climate change. As global air travel demand increases, SAF offers a viable solution to significantly lower greenhouse gas emissions and enhance energy security, ensuring a more sustainable future for aviation. Additionally, converting biomass, particularly waste materials, into SAF adds value by turning potential environmental liabilities into valuable energy resources, promoting a circular economy and reducing overall waste. This study evaluates the aircraft performance of a novel sustainable aviation fuel (SAF) derived from multiple feedstocks in a hybrid biorefinery. SAF performance is compared to two conventional jet fuels, specifically a blend of 30% kerosene and 70% gasoline and JET-A1. The results demonstrated that the optimal SAF outperformed conventional fuels in terms of both thrust and range. Specifically, SAF exhibited a 17% increase in thrust and a 10% increase in range compared to conventional Jet A1 fuel. This novel fuel did not only mitigate CO2 emissions and achieve a cost reduction of 0.13 to 8.08%, but also exhibited superior aircraft performance. In addition, this fuel also meets the criteria of a “drop-in fuel” as it does not necessitate significant alterations to the currently existing CFM56-7B turbofan engine. This is due to its similar key thermodynamic indicators, such as heat capacities and combustion temperature, which are comparable to those of conventional jet fuels. In addition, this paper identifies the sensitivity of the CFM56–7B turbofan engine fuelled by the novel fuel.

A review of the application development and key technologies of rotary engines under the background of carbon neutrality

Rotary engines possess advantages such as light weight, high power density, and strong fuel adaptability, which are essential for powertrain systems. They hold great potential in the field of power machinery. However, the development of rotary engines has been constrained by increasingly stringent emission regulations. Despite this, numerous scholars and institutions continue to optimize rotary engines, leading to a proliferation of related research. It is necessary to synthesize these findings to guide future promotion and application efforts. This review examines the current applications and development status of rotary engines globally. It summarizes the development of key technologies such as sealing techniques, rotor configurations, and ignition devices, which have achieved lower energy consumption and emissions. The suitability of rotary engines for automotive and unmanned aerial vehicle applications has also been reported. To further reduce carbon emissions, researchers have explored zero-carbon fuel rotary engines. Hydrogen-fueled rotary engines have demonstrated higher combustion efficiency. By integrating EGR, load control strategies, and ignition system layouts, they have addressed issues such as NOx emissions, knock, and leakage. The development of ammonia-hydrogen hybrid fuels is also a potential effective solution. Continuous innovative research indicates that, with their inherent advantages and the integration of alternative fuels and advanced ignition technologies, rotary engines have the potential to meet future energy and environmental requirements. This positions them as strong contenders in future diversified power systems.

Enhancing Sustainable Subgrade Engineering Using Soil Tuff for Modifying Iron Tailings Sand: A Comprehensive Engineering Performance and Sustainability Analysis

Soil tuff, an industrial solid waste, can serve as a sustainable alternative to cement for modifying iron tailings sand (ITS). To substantiate this claim, the physical properties, durability and microstructure of soil tuff and cement-modified ITSs were analyzed at different modifier dosages, compaction degrees and maintenance ages, with a comprehensive comparison in the perspective of sustainable built environments. The results indicate that the physical properties of soil tuff-modified ITS (STM-ITS) were significantly enhanced in subgrade engineering applications compared with cement-modified ITS (CM-ITS). In addition, compared with CM-ITS, the hydration products of STM-ITS possessed a smaller amount of Ca(OH)2 and were cemented with surrounding binding products, which resulted in fewer cracks. STM-ITS featured a more stable C–S–H gel than CM-ITS due to a lower Ca/Si ratio, contributing to its higher corrosion resistance. Notably, a sustainability analysis demonstrated that incorporating STM-ITS has physical properties comparable to those of CM-ITS and can be obtained at a significantly lower cost, CO2 emission, and energy consumption. Therefore, this study highlights the potential of soil tuff as a promising eco-friendly option for subgrade engineering, promoting waste usage, improving built environments, and contributing to carbon-neutrality goals. These findings have significant implications for the construction industry and the pursuit of sustainable development.

Thermal performance analysis and optimization of air-supported membrane building envelope based on numerical simulation

Air-supported membrane (ASM) envelopes offer an effective solution for creating large interior spaces for buildings with lower energy consumption and carbon emissions. However, there is little research on the thermal performance of ASM envelopes, particularly regarding the natural convection within the air interlayer and its impact on thermal resistance. To address this gap, this study developed a numerical model of ASM envelopes and validated it through experiments. Subsequently, a numerical investigation was conducted to analyze natural convection and thermal resistance while considering factors such as indoor-outdoor temperature difference, membrane emissivity and air interlayer thickness. Results indicated that with the emissivity increased from 0.2 to 1, the thermal resistance of the air interlayer and the envelope decreased by 32.35% and 9.13%, respectively. Besides, the thickness of air interlayer also had evident effect on thermal resistance. When it increased from 5 mm to 35 mm, the thermal resistance of the air interlayer and the envelope increased by 156.19% and 14.74%, and further results in the heat transfer decreased by 13.85%. However, the convective heat transfer would remain constant when the thickness exceeded 35 mm. This study provided valuable reference for optimizing the design of ASM envelopes and accurately calculating their thermal resistance.

A multi-objective optimization framework for regional land-use allocation: Fully utilizing terrestrial vegetation to mitigate carbon emissions

Human-induced changes in land use and land cover (LULC) considerably impact the global carbon cycle. Rational LULC optimization with full utilization of terrestrial vegetation facilitates reconciling carbon reduction and socio-economic development. To this end, this study develops a multi-objective framework for low-carbon LULC spatial optimization that incorporates carbon suitability, historical suitability, and socio-economic needs. The framework is applied to Hubei Province, China. The key findings include: (1) Considering spatial variations in vegetation carbon sinks could lead to remarkable carbon reductions of 2.75 × 106 t C by 2030 and 7.68 × 106 t C by 2060. It would also lower carbon emissions per unit of gross domestic product (GDP) and enhance carbon sequestration per unit of vegetation by 2030, signifying enhanced carbon reduction efficiency. (2) Integrating carbon sequestration potential and historical suitability can considerably minimize emissions while sustaining socio-economic growth. Our method, compared with strategies based solely on historical development laws, can reduce carbon emissions by approximately 1.3–1.6 × 106 t C·a−1. (3) We also propose targeted low-carbon development suggestions for different LULCs. This study provides optimal spatial LULC allocations and strategic advice for regional LULC planning aimed at low-carbon development, demonstrating the feasibility of reconciling the tension between carbon reduction and socio-economic growth at the regional scale.

Integrated rather than organic farming history facilitates soil nitrogen turnover and N2O reduction in a green rye – silage maize cropping sequence

AbstractSoil gross mineral N production and consumption processes are crucial regulators of plant productivity and N loss from croplands. Substituting synthetic fertilizers by integrating legumes in cultivation systems is common in organic farming, but research on its long-term impact on dynamics of gross soil N transformation and associated environmental N loss is scarce. In particular, studies at a temporal resolution that allows for a mechanistic understanding of long-term effects of organic farming are missing. Therefore, we determined gross N turnover rates of ammonification, nitrification, and ammonium and nitrate immobilization at monthly temporal resolution during a full green rye-maize cropping sequence. Measurements were carried out at sites with same pedo-climatic background but organic farming (OF) and integrated farming (IF) history. During green rye growing, N turnover rates for OF and IF were low and not significantly different, likely owing to low temperatures. During silage maize growing, IF exhibited significantly higher average N turnover rates of 1.86, 4.46, and 5.57 mg N kg⁻1 dry soil d⁻1 for gross ammonification, ammonium immobilization, and nitrate immobilization, respectively, compared to OF values of 1.11, 1.80, and 2.90 mg N kg⁻1 dry soil d⁻1. The significantly higher N turnover rates were likely due to higher soil organic C, N and microbial biomass which result from different long-term management practices. Especially the increased immobilization potential on the IF site contributed to significantly lower area-scaled N₂O emissions (1.45 vs. 4.36 kg N ha⁻1) during periods of high nitrification. This shows that for low SOC soils, integrated farming history with high C return enhances soil N cycling and reduces the risk of N losses in the form of N2O emission.

A coupled plasma-thermal model for hollow cathode power decomposition and parametric analysis

Abstract A 2D axisymmetric transient coupled plasma-thermal model is developed to simulate the plasma behavior during the self-sustained discharge of hollow cathodes, which presents a complete hollow cathode structure and energy transfer processes in multiphysics fields. The model has been validated by quantitative agreement between the simulation results and experimental data on the plasma and emitter temperature at the NSTAR cathode. The effects of thermal protection design, operating conditions, and geometric design on the cathode performance are analysed through electric and thermal power decomposition. The parametric analysis shows that the optimal thermal protection design is to use a 1/3 thickness cathode tube with 4 layers of radiation shielding close to the tube, which reduces 43.7% conductive and 61.1% radiative heat dissipation, respectively. Increasing the inlet flow rate counter-intuitively reduces the emitter temperature due to the potential reversal in the diffusion electric field dominated region, revealing that the flow rate can be traded for the dual optimisation of lifetime and power consumption. Under high current conditions, the IAT effect dominates the plume resistance to increase the discharge voltage after an inflexion point, which is the main factor limiting the cathode performance. A large internal radius gives a uniform low emission and helps to prolong life, while the orifice length should be avoided to be longer than 4 times the orifice radius due to the significantly enhanced Joule heating in the narrow orifice. The orifice radius determines the power deposition due to electron and ion bombardment through potential penetration. For high-current discharger cathodes dominated by electron bombardment, large or through-orifice designs are preferred, while for low-current neutralizer cathodes dominated by electron bombardment, small-orifice designs are recommended.

An Experimental and ANN Analysis of Ammonia Energy Integration in Biofuel Powered Low-Temperature Combustion Engine to Enhance Cleaner Combustion

In the pursuit of global net-zero emissions targets and cleaner combustion technologies, researchers are increasingly turning to innovative solutions. Ammonia, as a carbon-free fuel, holds promise for achieving low emissions and efficient combustion. This study explores the potential synergies of various ammonia shares (20%, 40%, and 60%) combined with Citronella biofuel in a Low-Temperature Combustion (LTC) Reactivity Controlled Compression Ignition (RCCI) engine. Comparative analysis between a 40% ammonia blend Citronella biofuel (A40) and a Standard Diesel (SDL) in an RCCI engine demonstrates significant reductions in oxides of nitrogen (by 17%), carbon dioxide (by 6.6%), and smoke (by 9.8%), along with a notable enhancement in Brake Thermal Efficiency (BTE) by 5.4% for A40. The validation of results using an Artificial Neural Network (ANN) model shows robust coefficients of determination (97%), high R values (0.9945 to 0.9995), and low Root Mean Square Error values (ranging from 0.0219 to 0.0483). These findings strongly support the efficacy of the A40 blend, positioning it as a promising and viable alternative fuel for achieving cleaner combustion in LTC-RCCI engines.

Energy Transition Analysis and Climate Action Strategy in the Power Sector: A Case Study of the Java-Bali System

Abstract The transformation of societies over time has led to a marked shift in energy consumption patterns. In the face of rapid industrial growth and a burgeoning population, Indonesia confronts the multifaceted challenge of achieving a balance among energy trilemma: energy security, economic affordability, and environmental sustainability. This study assesses the feasibility of low-carbon energy systems in Indonesia, evaluating current policies and proposing a roadmap for net-zero emissions. Utilizing the Low Emissions Analysis Platform (LEAP) and the Next Energy Modeling System for Optimization (NEMO), the study explores multiple scenarios—namely, Business-as-Usual (BAU), Carbon Capture and Storage Mitigation (CCSM), and New and Renewable Energy Mitigation (NREM). Of these, the NREM scenario, emphasizing the integration of innovative and renewable energy sources, achieves the most substantial reduction in greenhouse gas emissions while maintaining economic viability. This strategy advocates for the comprehensive adoption of new and renewable energy, aiming to approximate zero emissions by 2060. The peak direct cost of production for this scenario is estimated at $270.8 billion. However, each scenario presents its own set of technological, economic, and policy-related challenges, necessitating strategic solutions for a successful transition to sustainable energy systems.

Numerical study on infrared radiation intensity and suppression methods of nozzle considering multi-component effects

Improving the accuracy of infrared intensity calculation in exhaust system and expanding infrared suppression methods are of great significance for enhancing aircraft stealth performanc. In this paper, the infrared radiation (IR) intensity (3–5 µm) of nozzle considering the influence of turbine and afterburner are numerically studied. Initially, the flow field characteristics are computed using commercial software, followed by ray tracing simulations using the reverse Monte Carlo method (RMCM) and transmission calculations using the multi-scale multi-group wideband k distribution model (MSMGWB). The wall emissivity is determined experimentally. This paper quantitatively analyzes the difference between infrared intensity obtained through traditional computational methods and that of the actual model, revealing the impact of low-emissivity coating and turbine cooling on the infrared intensity of the integrated model. It emphasizes the suppression effects and physical mechanisms of the heat shield flanging structure on the infrared characteristics of the integrated model. The results indicate significant differences between infrared intensity derived from traditional computational methods and that from actual models. The influence of the afterburner and turbine infrared characteristics must be considered in infrared numerical studies. When the computation model is a standalone nozzle, the infrared intensity can increase by up to 541.78 % and decrease by a maximum of 14.02 % compared to the integrated model compose of the turbine, afterburner, and nozzle. For the model composed of nozzle and afterburner, the infrared intensity can decrease by up to 10.5 % under non-swirl flow condition, without any increase observed. Compared with turbine wall, changing the emissivity of afterburner wall has more significant effect on infrared suppression of integrated calculation model. Reducing the emissivity of all afterburner walls from 0.7 to 0.1 significantly reduces the infrared characteristics in the range of 0° to 12.5°, while increasing it in the range of 12.5° to 45°. Applying a low-emissivity coating only to the high-temperature walls of the afterburner can inhibit the increase in emitted radiation on the wall, thereby eliminating the increase in infrared intensity mentioned above and reducing the infrared intensity by up to 39.14 %. Compared to low-emissivity coating technology for turbine, implementing cooling measures on turbine blades can effectively reduce the infrared intensity of the integrated model, achieving a maximum reduction of 19.7 % when the blade temperature is lowered by 240 K. Adding flanging structure to the heat shield in the convergent section alters the flow field structure near the nozzle walls, lowering wall temperature and thereby suppressing the infrared characteristics of the integrated model between 10° and 80°. This results in a maximum reduction in infrared intensity of 14.75 % with negligible impact on thrust coefficients. This is the angle range where afterburner low emissivity coatings and turbine cooling cannot achieve infrared suppression. This is of great significance for infrared stealth in large angle range. Combined with the above effective infrared suppression measures, the infrared intensity can be reduced by up to 49.42 %.

How do meteorological conditions impact the effectiveness of various traffic measures on NOx concentrations in a real hot-spot?

Recently, air quality has become a major concern for policy makers around the world, which has led to the implementation of mitigation measures. In particular, in urban areas most measures affect the road transport sector, as this is one of the main contributors to air pollution in those areas. Recent studies have pointed out the need to determine the importance of external factors such as the meteorological conditions on the net effect on air quality of mitigation strategies. Due to the strong spatial variability of urban air pollution, high spatial resolution modelling is necessary. In this work, the impacts on emissions and nitrogen oxides (NOx) concentrations of several mitigation strategies on a real air pollution hot spot in southern Madrid (Spain) are simulated at microscale under different meteorological conditions. The results show that the meteorological conditions affect local NOx concentrations, and its net changes can be comparable to those due to emission reductions. In particular, meteorological conditions in 2019 induced higher NOx concentrations than in 2016, despite the local emissions were reduced by 50 % from 2016 to 2019. On the other hand, the impact of the implementation of a Low Emissions Zone (LEZ) on NOx concentrations is small and consistent with values found in other LEZs around Europe. However, this impact varies up to 70 % depending on the meteorological conditions. The impacts of a mitigation strategy are largely influenced by the meteorological conditions, and therefore the achievement of the target reduction of concentrations pursued by these measures will depend on the meteorological conditions.

To Study the Effects of Microemulsion Based Hybrid Biofuel on Emission Characteristics of CI Engine: A Short Review

AbstractMicroemulsion based fuels (MBF) have gained significant attention in recent years due to their potential to enhance combustion efficiency, reduce emissions, and improve overall engine performance. This research paper enlightens the effects of physiochemical properties on the emission characteristics of CI engine. The microemulsions are formulated using surfactants, co‐surfactants, water or alcohols, and fuel components. The effects of density, viscosity, calorific value, cold flow properties, and cetane number along with the stability and the multi‐component characteristics of (MBF) has been taken into consideration to examine its effects on Emission characteristics such as nitrogen oxides (NOx), sulfur oxides (SOx), carbon monoxide (CO), particulate matter (PM), and unburned hydrocarbons (UHC). Microemulsion‐based fuels lower emissions of NOx and PM, recognized to the more complete combustion. The review highlights various studies that have investigated the benefits of microemulsion fuels, including reduced emissions of different pollutants and thus reduce the adverse effect on environment.In conclusion, microemulsion‐based fuels show likely physiochemical properties, as well as favorable emission characteristics, with reduced NOx, SOx, CO, PM, and UHC emissions. This study highlights the potential of microemulsion‐based fuels as environment friendly alternatives, flagging the way for further research.

Combustion behavior of solid waste fuels in the vertical tube reactor under different oxy-fuel environments

Oxy-fuel combustion technology has been recognized as one of the promising ways for cost-effective CO2 capture. The co-combustion characteristics of flax straw biomass/bituminous coal mixture (FS/BC) and flax straw biomass/sewage sludge mixture (FS/SS) under air, oxy-fuel (21%/79% O2/CO2) and oxygen-enriched oxy-fuel (30%/70% and 40%/60% O2/CO2) conditions were investigated in the vertical tube reactor. In particular, the study focused on the burning characteristics, the effect of blending ratio, and flue gas emissions. The findings indicated that flax straw biomass exhibited superior ignition performance compared to its blends with sewage sludge and bituminous coal. A higher O2 concentration from 21% to 40 led to a reduction in ignition delay time by 4s at 850 ℃ and by up to 10s at 950 ℃. Moreover, char combustion time was reduced by 50% for FS/SS blends due to the lower fixed carbon content compared to FS/BC blends. Additionally, increasing the O2 concentration resulted in lower emissions of CO by ∽40% and N2O by ∽45% for both blends. However, this also led to a slight increase in SO2 and NO emissions by ∽15% and ∽26%, respectively. The optimal conditions for the tested samples in oxy-fuel environment were found to be 30% O2/70 CO2, which enhanced combustion performance while lowering flue gas emissions.

Emission Characteristics of Aerosols Generated during the Micro-Nano Bubble Aeration Process in Wastewater.

Micro-nano bubble (MNB) aeration is an emerging technology that considerably enhances the aeration efficiency of wastewater. This study evaluates, for the first time, aerosolization at the water-air interface during MNB aeration. Our results show that the concentration of culturable mixed microorganisms (i.e., bacteria, fungi, and intestinal bacteria) in the in situ MNB generation (MNBs-G) phase is 2170 CFU/m3, 1.38 and 1.58-fold higher than those in medium-bubble aeration (MBA; 1568 CFU/m3) and small-bubble aeration (SBA; 1376 CFU/m3) aerosols, respectively. Conversely, the concentration of culturable mixed microorganisms in the MNB persistent dissolved oxygen (MNBs-O) phase is only 914 CFU/m3. Microbiological analysis shows a lower abundance of bacterial pathogens in MNBs-G (34.12%) and MNBs-O (34.02%) phases than in MBA (39.63%) and SBA (38.87%) aerosols. Acinetobacter is prevalent in MNBs-G (14.76%) and MNBs-O (8.22%) aerosols, whereas Bacillus and Arcobacter are prevalent in MBA (23.96%) and SBA (6.92%) aerosols, respectively. The total concentrations of chemicals [i.e., total organic carbon, water-soluble ions, and metal(loid)s] in aerosols formed via MNB aeration (205.98-373.74 μg/m3) are lower than those in MBA and SBA (398.69-594.92 μg/m3). Compared to MBA and SBA, the MNBs-G phase exhibits higher emissions of 12 elements in aerosols (i.e., NO3-, NO2-, Ca2+, Na+, K+, Mg2+, Zn, Cd, Fe, Mn, As, and Cr), whereas the MNBs-O phase generally shows lower emissions. These findings highlight the potential of optimized MNB aeration technology in considerably mitigating aerosol emissions and thereby advancing environmental sustainability in wastewater treatment.

Lower NO emission conditions of NH3–H2 mixtures under the oxygen-enriched premixed combustion mode

Compared with pure NH3 fuel, the lower NO emission conditions of NH3–H2 mixtures under the oxygen-enriched combustion mode have been identified quantitatively. Furthermore, the effects of the H2 addition on the NO productions of premixed oxygen-enriched NH3–H2 flames are studied numerically, while the major reactions responsible for the variation of total NO are identified. Results show that the H2 addition is eligible to reduce the NO emissions of the oxygen-enriched NH3 combustion if the laminar burning velocity is fixed to a larger value (>23 cm/s). The quantitative equations are obtained to determine the optimum oxygen-enriched conditions of the NH3–H2 mixture, aiming to achieve lower NO emission and similar or improved combustion stability compared to pure NH3 fuel by restricting the minimum and maximum O2 percentages for the NH3–H2 mixtures. Based on the rate of production (ROP) analysis, for the oxygen-enriched NH3–H2 combustion, R144 (HNO + H<=>H2+NO) is consistently the most significant NO production reaction, while R85 (NH + NO<=>N2O + H) and R91 (N + NO<=>O + N2) play significant roles in the NO consumption. When the laminar burning velocity (SL) is kept to a lower value, the increased total NO of the oxygen-enriched NH3 flames with the H2 addition is ascribed to more efficient suppressions on the NO consumption reactions of R85, R91 and R77 (NH2+NO<=>NNH + OH). In contrast, thanks to the extra impact of the higher O2 percentage on the H/O/OH radical pool at larger SL, the NO production reactions begin to suffer stronger suppressions of the H2 addition, resulting in the reduced total NO of NH3–H2 mixtures. Furthermore, R144 is identified as the key reaction influencing the variation trend of total NO at both lower and higher SL values.

An Experimental Study on Algae Biodiesel with Nano-additives for Engine Performance and Emission Reduction

Introducing nano-additives like aluminum oxide and cerium oxide into the B20 blend biodiesel exhibited encouraging outcomes of combustion efficiency and emission reduction. These additives likely catalyzed combustion, leading to more complete fuel burn and lower emissions. Additionally, the presence of nano-additives might have facilitated better fuel atomization and distribution within the combustion chamber, resulting in enhanced engine performance. The results indicate that adding nano-additives to biodiesel blends has significant potential for reducing environmental impact and enhancing engine longevity and efficiency. Moreover, the utilization of nano-additives represents a promising avenue for addressing the dual challenges of energy sustainability and environmental preservation. By harnessing the synergistic effects of nano-scale materials, such as aluminum oxide and cerium oxide, in biodiesel formulations, engineers and researchers can strive towards developing cleaner and more efficient propulsion systems. This holistic approach underscores the importance of cooperation across disciplines between materials science, engineering, and environmental studies to advance the frontiers of sustainable energy technologies. The study attempted to improve combustion efficiency and reduce emissions by introducing nano-additives like aluminum oxide and cerium oxide into B20 biodiesel. The outcome showed enhanced engine performance, more complete fuel burn, and significant potential for reducing environmental impact.

Evaluation of the Possible Effects of Varying the Volumetric Ratio of Lpg on the Spark Ignition Engine's Performance, Emissions, and Combustion

This study investigated the performance, emission reactions, and combustion of liquefied petroleum gas (LPG) at various volumetric ratios with gasoline. The experiments were carried out on a single cylinder spark ignition (SI) engine at different engine loads (500 to 3000 W). In general, the use of LPG has a negative effect on performance and combustion, while making a positive contribution to emissions. The brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) values closest to 100% gasoline were obtained with 25% LPG and were lower by 0.36% and 4.55%, respectively. Conversely, using LPG resulted in lower emissions of carbon dioxide (CO2), hydrocarbons (HC), and carbon monoxide (CO). The lowest emissions were obtained with the use of 100% LPG as 0.5%, 65 ppm and 9.5%, respectively. Compared to 100% gasoline, 20.63%, 27.78% and 5.19% improvements were achieved. Finally, the cylinder gas pressure value was negatively affected using LPG. Compared to 100% gasoline, the gas pressure value obtained with 75% LPG content fuel was 7.81% lower. It has been concluded that LPG is an environmentally friendly alternative fuel in terms of emissions, and considering the decrease in performance values, 25% LPG can be used successfully in SI engines instead of 100% LPG.

Influence of the flame jet on heat loss and thermal efficiency of lean burn pre-chamber natural gas engine with various geometrical combustion chambers

Due to relatively high thermal efficiency and low NOx emission, the pre-chamber type lean burn natural gas engine for cogeneration is expected to be spread rapidly in the near future. To offer a guidance for designing the pre-chamber natural gas engines, in the present study, the influence of the flame jets on combustion process and thermal efficiency of pre-chamber type lean burn natural gas engine was investigated with various pre-chamber orifice diameters and angles and piston bowl shapes by numerical simulation. The presented results showed that when the orifice diameter is smaller, it results in higher heat loss with the stronger gas flame jets impinging on piston top and cylinder liner walls, but the higher degree of constant volume heat release can be also obtained. Consequently, there is no significant difference in the thermal efficiency for these four orifice diameters. Increasing the angle of the orifice and the depth of the piston bowl can avoid the heat loss caused by the early impact of flame jets on the piston top wall. In addition, compared to the diameter of piston bowl, the depth of piston bowl, which is related to the distance from the orifice to the piston bowl, should have more effect on the combustion process and thermal efficiency. For wider orifice angle, the heat loss was also increased, particularly to cylinder head. Finally, the optimal thermal efficiency obtained by balancing heat loss and the degree of constant volume heat release is 44.73%.