Search

Among the feasible options for valorizing lignocellulosic biomass into value‐added products, biochar is considered to be extremely appealing and it could be applied easily in several established thermochemical processes. Biochar possesses a large surface area due to its porous nature, which permits easy use in various applications, including catalytic biofuel production. This work summarizes research on biochar generation processes, its critical physicochemical properties, and factors that influence them. Important studies adopting biochar catalysts for liquid biofuel production are critically reviewed, and the reaction mechanisms and biofuel yield are analyzed. Finally, challenges in the use of biochar‐based catalysts for biofuel production are presented, together with possible solutions. In general, this current work aims to provide the critical characteristics of biochar as a potential catalyst to biofuel synthesis toward sustainable bioenergy production. [ABSTRACT FROM AUTHOR]

The present paper briefly elaborates upon the combination of waste palm and waste sunflower oil methyl ester as post-mixed biodiesel blends being injected into a four-stroke compression ignition engine, which is also fueled with inducted bamboo leaf generated producer gas (BLP.gas) that includes gaseous components of CO (carbon monoxide), H 2 (hydrogen), CH 4 (methane), and C x H y (hydrocarbons). The objective of the present research is to evaluate the overall performance, emission, and combustion behavior of a Kirloskar TAF1 modified dual-fuel diesel engine fueled with induced bamboo leaf-derived gaseous fuel at a fixed mass flow rate of 21.69 kg/h and injected mixed biodiesel-diesel blends. Initially, diesel fuel and post-mixed methyl ester were examined in dual-fuel mode with a fixed gas flow rate for different loads. It can be seen from the analysis that brake thermal efficiency got reduced by 4.66% and brake-specific fuel consumption increased by 5.26% for PMOME20 (20% post-mixed oil methyl ester + 80% diesel fuel) + BLP. gas with respect to diesel fuel at extreme loading conditions. Moreover, smoke opacity, carbon monoxide, and unburnt hydrocarbons were reduced by 11.22%, 20.44%, and 10.36%, respectively. On the other hand, oxides of nitrogen were reduced by 19.17% at maximum load for PMOME20 + BLP. gas in dual-fuel operation in contrast to that of petroleum diesel. In light of this, the current research concluded that the use of biodiesel and BLP. gas for dual-operative engines may be regarded as an appropriate option for reducing pollutant environment and petroleum fuel scarcity. • Influence of mixed biodiesel blends with induced bamboo leaf gaseous fuel were investigated. • NOx and smoke opacity showed trade-off curve of 19.11% and 11.22% lower emission for PMOME20+BLP.gas than diesel. • CO 2 emission for PMOME20+BLP.gas was 38.77% higher than diesel at peak load. • PMOME20+BLP.gas at peak load increased In-CP by 6.15% in contrast to diesel. • HRR and ID for PMOME20+BLP.gas decreased by 72.29% and 9.06% in contrast to diesel. [ABSTRACT FROM AUTHOR]

Conventional fossil fuels are being substituted with alternative green fuels because of their greenhouse gas emissions and pollution problems, which pose a severe threat to the environment. Several studies have reported the usage of biodiesel and gaseous fuels in both single and dual-fuel modes. Gaseous fuels such as producer gas, biogas, syngas, and hydrogen produced from renewable biomass could potentially be used along with biodiesel in dual-fuel engines. Still, these are the least investigated in terms of their use as potential energy carriers. This review article encapsulates the viability as well as the impact of various gaseous fuels, including producer gas, biogas, compressed natural gas, liquefied petroleum gas, syngas, and hydrogen, in dual-fuel mode diesel engines with the aim of evaluating the performance, emission, and combustion behavior at various induction as well as operational parameters. Considering emission behaviors of diesel engines fueled with producer gas, biogas, compressed natural gas, and hydrogen, it is found that hydrocarbon and carbon monoxide emissions increase in the range 17.5–31.4% and 11.73–23.6%, respectively. On the contrary, oxide of nitrogen and smoke opacity tend to reduce from 14.3 to 18.2% and 21.4%36.5–63.7%, respectively. Moreover, there is a slight deterioration in performance characteristics for diesel engines fueled with producer gas, biogas, compressed natural gas, and hydrogen in the range of 2.1–8.84% for brake thermal efficiency, and 3.1–7.3% for brake-specific energy consumption. In addition, the combustion characteristics of gaseous fuels is also discussed in detail. Moreover, a SWOT analysis has been carried out with an emphasis on possibilities for usage of gaseous fuels in dual-fuel diesel engines. Finally, the limitations and perspectives of using gaseous fuels are also critically presented. • Key applications of gaseous fuels to dual-fuel engines were critically presented. • Performance and emission of engines running on gaseous fuels were scrutinized. • Engines powered by gaseous fuels could increase global energy consumption. • NOx and greenhouse gas emissions could be remarkably reduced by using gaseous fuels. • SWOT analysis for gaseous fuels was discussed in detail. [ABSTRACT FROM AUTHOR]

Due to recent emission-associated regulations imposed on marine fuel, ship owners have been forced to seek alternate fuels, in order to meet the new limits. The aim of achieving low-carbon shipping by the year 2050, has meant that alternative marine fuels, as well as various technological and operational initiatives, need to be taken into account. This article evaluates and examines recent clean fuels and novel clean technologies for vessels. The alternative fuels are classified as low-carbon fuels, carbon-free fuels, and carbon neutral fuels, based on their properties. Fuel properties, the status of technological development, and existing challenges are also summarised in this paper. Furthermore, researchers have also investigated energy-saving devices and discovered that zero-carbon and virtually zero-carbon clean fuels, together with clean production, might play an important part in shipping, despite the commercial impracticability of existing costs and infrastructure. More interestingly, the transition to marine fuel is known to be a lengthy process; thus, early consensus-building, as well as action-adoption, in the maritime community is critical for meeting the expectations and aims of sustainable marine transportation. [ABSTRACT FROM AUTHOR]

The paper presents a 3D model of the processes taking place in the cylinder of a large 4-stroke marine engine. The model is based on CFD calculations performed on the moving mesh. The modelling range includes the full duty cycle (720° crankshaft position) and the complete geometry of the cylinder with inlet and exhaust ducts. The input data, boundary conditions and validation data were obtained by direct measurements on the real object. Fuel injection characteristics were obtained by Mie scattering measurements in a fixed-volume chamber. The modelling results have been validated in terms of the pressure characteristics of the engine's cylinder within the entire range of its loads. The mean error did not exceed 1.42% for the maximum combustion pressure and 1.13% for the MIP (Mean Indicated Pressure). The model was also positively validated in terms of the O2 and NOx content of the exhaust gas. The mean error in this case was 1.2% for NOx fractions in the exhaust gas and 0.4% for O2 fractions. The complete model data has been made available in the research data repository on an open access basis. [ABSTRACT FROM AUTHOR]

The rising human population is causing the utilization of enormous amounts of fossil fuels to fulfill energy needs. Various renewable sources are used as fossil fuels however those resources are not powerful in supplanting customary non-renewable energy sources like gasoline in vehicles. The depletion of conventional fossil fuel utilized in a vehicle contributes to an increased portion of air contamination and is a danger to human well-being. Also, to maintain the supply demand, many active types of research have been carried out in mixing a higher percentage of ethanol over gasoline and further moving towards flex-fuel vehicles. But there arises a problem of knocking and higher CO, and HC emissions from the engine. To overcome the above problem, ethanol could be mixed in a higher percentage over gasoline with the help of hydrogen assistance and can completely avoid the problem of knocking and reducing CO and HC emissions. In this research, the combustion, emission, and performance characteristics of a variable-speed gasoline engine fuelled with ethanol-blended gasoline along with hydrogen assistance are taken for investigation at variable speeds like 1800, 1600, 1400, and 1200 rpm. Hydrogen is added to blended fuel (E30) which has better combustion, emission, and performance than other blended fuels. Hydrogen addition is done at 2, 3, and 4 ms respectively. The outcomes showed that the E30 + H 2 at 3 ms has better combustion, emission, and performance, still, the emission of NOx is higher in comparison with all the other blends due to complete combustion. Thus, a two-stage analysis has been done, one is making a comparison among various blends of ethanol, and the second one is the comparison among the various energy shares of hydrogen. • Hydrogen injection timing variation at 2, 3, and 4 ms over the E30 fuel blend. • Hydrogen injecting strategy enhancing the usage of flex fuels in SI engine. • Split hydrogen and E30 fuel over port injection at the inlet manifold. • BTE was highest with E30 + H 2 at 3 ms and also the emissions were optimum. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW)-to-energy systems have gained significant attention in recent years for their potential to produce renewable energy from waste. These systems involve the conversion of MSW into electricity, heat or fuel. One of the most promising applications of MSW-to-energy systems is the production of hydrogen, which is considered a clean and sustainable fuel. Machine learning algorithms have the potential to revolutionize the way MSW-to-energy systems are managed. The integration of machine learning into MSW-to-energy systems has the potential to significantly improve the sustainability and profitability of this industry. In this study, a novel integrated MSW-to-energy system is modeled to produce hydrogen, power, and oxygen and with capacities of heating water and air. Hydrogen production, power production, oxygen storage, hot water, hot air, and system emission are predicted using machine learning algorithms based on regression models with high validity and R2 values more than 99.8% having errors smaller than 1%. The reduced regression models are developed by eliminating the insignificant variables from the full algorithms using the analysis of variance. The findings reveal high accuracy for the reduced regression models while their errors slightly decrease to 2%. This suggests that the machine learning algorithms can also be used as an effective tool to further improve MSW-to-energy systems. [Display omitted] • A novel municipal solid waste-to-energy system is modeled. • Hydrogen and oxygen are produced as well as electrical power, hot water and air. • Machine learning algorithms are developed using regression models. • Reduced regression models are developed using analysis of variance. • Machine learning algorithms show a high accuracy with errors less than 1%. [ABSTRACT FROM AUTHOR]

The majority of research in the carbon-based nanomaterials (CNMs) field has concentrated on the classification and synthesis of CNMs, with relatively few studies focusing on CNMs' roles in photocatalytic hydrogen production. CNMs have proven their potential as an effective addition to the appeal of photocatalytic hydrogen evolution because of their superior chemical and physical properties. This paper explores the recent advancements in photocatalytic hydrogen (H 2) production utilizing CNMs. As evidenced in the literature, carbon quantum dot (CQD)-sensitized titanium dioxide (TiO 2) can demonstrate to have a photocatalytic hydrogen generation activity of 472 mol g−1 h−1 and 1458 mol g−1 h−1 without and with loading metal co-catalyst (Pt). The optimum catalyst, 0.4 CQD/CdS, contributes to the highest H 2 production rate of 309 mmol g−1 h−1 (apparent quantum yield of 32.6%), which is 1.5 times greater than that of bare CdS. This would significantly accelerate the hydrogen production process. There are still challenges to reaching maximum photocatalytic hydrogen production, including low hydrogen storage. The overall price of hydrogen produced via photocatalysis is also higher because of the energy needed to store the hydrogen. Even though the problem is not directly related to the usage of CNMs, this restriction generates uncertainty and limits commercial investment. Given the rising demand for energy and the trend toward green power, it is recommended that extensive industrial uses of photocatalytic hydrogen produced by employing CNMs be investigated for better and more sustainable energy frameworks. • Recent advances in photocatalytic H 2 production are investigated utilizing CNMs. • The optimum catalyst, 0.4 CQD/CdS can produce the highest H 2 at 309 mmol g−1 h−1. • CQD-sensitized TiO 2 can generate 1458 mol g−1 h−1 photocatalytic hydrogen with Pt. • Photocatalytic H 2 production using CNMs should be investigated for industrial use. [ABSTRACT FROM AUTHOR]

Gaseous-liquid fuel combinations of biogas as primary fuel and diesel as pilot fuel were employed to power a compression ignition (CI) engine in this study. The effects of variable input factors such as engine load, compression ratio, and pilot fuel injection advance on the dual-fuel engine's combustion, thermal, and emission performance were investigated. The data acquired during this lab-based testing was used to develop a prognostic model using a Bayesian optimization strategy for hyperparameter optimization and a contemporary ensemble Gaussian process regression (GPR) technique. During model testing, the error analysis revealed that the developed model could predict the experimental data rather correctly, with R2 values ranging from 0.9995 to 0.9999 and MSE values ranging from 0.00018 to 0.1334. The mean absolute error was discovered to be between 0.0091 and 0.3065. Consequently, the developed GPR model can effectively simulate the on-board performance, emission, and combustion characteristics of a diesel-biogas dual-fuel setting. As a consequence, the current work established the GPR model in the existing CI engine meta-modeling framework as a consistent, trustworthy, and robust system analytical approach for diesel-biogas dual fuel mode of operation. • Waste-derived biogas was used to power the diesel engine in dual-fuel mode. • Gaussian process regression was employed to develop a prognostic model. • Bayesian approach was used for hyper parameter optimization for best results. • Used model could predict emission and performance of the engine with 99.9% accuracy. • A precise metamodel framework to simulate the input–output paradigm was developed. [ABSTRACT FROM AUTHOR]

Summary: Thermal energy storage (TES) plays a significant role in storing heat energy during the availability of a source. The phase change material (PCM) storage density is high, but its meager thermal conductivity leads to ineffective heat transfer. This mathematical modeling work simulates two different heat transfer tube (HTT) arrangements in a horizontal cylindrical container to melt the PCM using the enthalpy‐porosity method. Case‐1 with a single HTT at the centroidal axis and Case‐2 with multiple tubes spread radially. Cases‐1 and 2 are observed with melting and solidification duration of 39.8 and 184 minutes, and 69.83 and 292.5 minutes respectively. Case‐1 has a shorter melting and solidification time because of the optimal HTT location. Case‐2 is observed with a high heat storage density of 224.95 MJ/m3, compared to Case‐1 with 224.571 MJ/m3. Nusselt number is higher for Case‐2 (385.86) during charging and higher for Case‐1 (208) during discharging. Nusselt number initially varies for both cases due to effective heat convection at the start; however, Case‐1 has a shorter melting duration with its energy density lower than the Case‐2. Based on the obtained results, it could be suggested that Case‐1 could be applicable when simultaneous heat transfer requires less energy storage and a faster melting rate, while Case‐2 could be used in places that demand a higher storage density. [ABSTRACT FROM AUTHOR]

The current study intends to assess the impact of incorporating an oxygenated fuel additive (hydrogen peroxide (H2O2)) into a biodiesel/diesel fuel mix on diesel engine combustion efficiency and instability. The combustion, performance, and emission properties were evaluated using advanced test equipment to offer a full study. The combustion instabilities in terms of cyclic fluctuations were investigated to discover any unusual behavior when H2O2 was added to biodiesel/diesel fuel mixtures. Statistical and continuous wavelet transformations were used to investigate the cyclic fluctuations in peak cylinder pressure and indicated mean effective pressure (IMEP). Diesel, B20 (20%/80% of biodiesel/diesel fuel), B20H5 (20%/5%/75% of biodiesel/H2O2/diesel fuel), and B20H10 (20%/10%/70% of biodiesel/H2O2/diesel fuel) were tested in the study. Experiment results indicated that B20H10 produced the best results. In comparison to B20, B20H10 improved BTE by 6.56% and HRR by 8.5%, while decreasing BSFC by 7.98%, CO and HC emissions by 26.5%, and 6.67%, respectively. Furthermore, the peak pressure and IMEP cyclic changes were also well within permissible ranges. However, it was shown that adding H2O2 to B20 increased NOx emissions. The cyclic variations in the cylinder peak pressure and indicated mean effective pressure were analyzed using statistical methods and continuous wavelet transformation. No abnormality was detected in cyclic variation, thus ruling out any unsafe behavior in introducing test fuel additive to biodiesel blends. In principle, introducing H2O2 into a biodiesel/diesel fuel mix helped improve the engine performance and emissions while having no negative effects on engine life. [ABSTRACT FROM AUTHOR]

Integrating nanotechnology into phase change materials (PCMs) has emerged as a novel approach to improving PCM thermal properties and performance in various thermal energy storage applications. Nanofluids, nanoparticle suspensions in a base fluid, have been identified as a promising method of increasing the thermal conductivity of PCMs and thus reducing thermal energy charging and discharging duration. This review paper investigates recent advances in incorporating nanotechnology into PCMs, focusing on their applications in the solar energy sector. Thermal conductivity, specific heat, viscosity, density, and convective heat transfer coefficient of nanofluids are discussed, as are the thermal properties of nano-enhanced PCMs (NEPCMs), including thermal conductivity, latent heat, specific heat, viscosity, supercooling, and phase-change temperature. The paper also gives an in-depth look at the uses of nanofluids and NEPCMs in solar collectors, photovoltaic/thermal (PV/T) systems, coolants, and desalination, emphasizing their potential to improve system efficiency. The review also considers the potential environmental and human health concerns connected with using nanofluids and NEPCMs, emphasizing the importance of rigorous evaluation and risk assessment in developing and applying these materials. Overall, the review provides valuable insights into the potential benefits and challenges of incorporating nanotechnology into PCMs and emphasizes the importance of ongoing research and development in this field to further advance the use of thermal energy storage technologies in various applications, including solar energy systems. [Display omitted] • Nanofluids and nanomaterials are considered as innovative heat transfer medium. • Phase change materials (PCMs) for harvesting thermal energy are scrutinized. • Recent developments and properties of nanofluids and nano-enhanced PCM. • Potential applications of nanofluids and nano-enhanced PCM are fully presented. • Environmental impacts and human health risks are comprehensively discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biodiesel with a higher degree of unsaturation exhibits poor engine characteristics. • Increasing the degree of unsaturation of biodiesels limits H 2 induction tolerance. • Hydrogen enrichment enhances the performance of slow-burning oils. • Lower biodiesel unsaturation degree and higher H 2 induction reduce carbon emissions. • CO emissions decrease and NOx emissions increase with increasing H 2 induction rate. In this study, a comparison of the behavioural characteristics of CI engine operated under single-fuel mode with biodiesel and dual-fuel mode enriched with hydrogen was conducted. The influence of unsaturation degree on the engine behaviour has been assessed and compared between Grapeseed biodiesel (GSBD) and Wheat Germ biodiesel (WGBD) with Coconut biodiesel (CBD) since CBD has a very low level of unsaturation compared to the other two fuels in the single-fuel mode. In addition, this work also investigates the impact of unsaturation on the H 2 induction, performance, combustion and emission characteristics of a CI engine in dual-fuel operation. The obtained results showed that with the increasing degree of unsaturation, H 2 induction decreases, with CBD tolerating Hydrogen Energy Share (HES) of 13.8 % without knocking, followed by 13.5 % and 12.5 % for GSBD and WGBD, respectively. Comparing the industrial biomass residues alone in dual fuel mode for maximum HES, GSBD-H 2 exhibited superior characteristics with 34 % brake thermal efficiency, 0.22 g/kWh of hydrocarbon, 2.3 g/kWh of carbon monoxide and 35.4 % of smoke opacity as against 32.5 %, 0.31 g/kWh, 3.5 g/kWh and 40.3 % for WGBD, respectively. However, the nitric oxide emissions were slightly higher for GSBD compared to WGBD in both single-fuel and dual-fuel modes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biodiesel with a higher degree of unsaturation exhibits poor engine characteristics. • Increasing the degree of unsaturation of biodiesels limits H 2 induction tolerance. • Hydrogen enrichment enhances the performance of slow-burning oils. • Lower biodiesel unsaturation degree and higher H 2 induction reduce carbon emissions. • CO emissions decrease and NOx emissions increase with increasing H 2 induction rate. In this study, a comparison of the behavioural characteristics of CI engine operated under single-fuel mode with biodiesel and dual-fuel mode enriched with hydrogen was conducted. The influence of unsaturation degree on the engine behaviour has been assessed and compared between Grapeseed biodiesel (GSBD) and Wheat Germ biodiesel (WGBD) with Coconut biodiesel (CBD) since CBD has a very low level of unsaturation compared to the other two fuels in the single-fuel mode. In addition, this work also investigates the impact of unsaturation on the H 2 induction, performance, combustion and emission characteristics of a CI engine in dual-fuel operation. The obtained results showed that with the increasing degree of unsaturation, H 2 induction decreases, with CBD tolerating Hydrogen Energy Share (HES) of 13.8 % without knocking, followed by 13.5 % and 12.5 % for GSBD and WGBD, respectively. Comparing the industrial biomass residues alone in dual fuel mode for maximum HES, GSBD-H 2 exhibited superior characteristics with 34 % brake thermal efficiency, 0.22 g/kWh of hydrocarbon, 2.3 g/kWh of carbon monoxide and 35.4 % of smoke opacity as against 32.5 %, 0.31 g/kWh, 3.5 g/kWh and 40.3 % for WGBD, respectively. However, the nitric oxide emissions were slightly higher for GSBD compared to WGBD in both single-fuel and dual-fuel modes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Aviation fuel prepared from microalgal species Chlorella Pyrenoidosa. • Box-Behnken design used for economical use of resources during experiments. • Neuro-fuzzy approach used for robust prognostic modeling achieving R > 0.9995. • Desirability based optimization helped in gaining a 91% yield of esters. • Properties of aviation fuel prepared were comparable to Jet A-1 kerosene. The aviation sector has been one of the most significant contributors to greenhouse gas (GHG) emissions; there is an urgent need to transition from traditional fossil-based jet fuel to sustainable aviation fuel to meet net-zero targets by 2030. The use of renewable aviation fuel may be regarded as the most effective option for reducing GHG emissions in the aviation sector while allowing for long-term growth. In this study, the microalgae oil was transformed to develop hydrocarbons with the boiling point range of jet fuel. Following the transesterification of algal oil fatty acids to algal oil methyl ester, fractional distillation was carried out. The Box-Behnken technique was used to design experiments for efficient resource utilization by minimizing the number of tests during transesterification. The quantitative relationship function between input (molar ratio of methanol to oil, catalyst concentration, and temperature) and % yield of methyl ester as an output of the process was developed using analysis of variance (ANOVA). The ANFIS (adaptive neuro-fuzzy inference system) was utilized to develop a prognostic model with good prediction effectiveness. MORSM (multi-objective response surface methodology) was also used to build a prediction model using correlations. A set of statistical indicators and Theil's U2 were used to examine the prediction efficacy and model uncertainty of ANFIS and MORSM. On both statistical indices and Theil's U2, the ANFIS-based model outperformed. To get the best results, the desirability approach was used to improve operating parameters. According to the desirability approach, the best operating parameters were catalyst concentration at 2.09%, methanol to oil ratio at 9.17%, and temperature at 60.49 °C, which resulted in the greatest yield of 91%. [ABSTRACT FROM AUTHOR]