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The present study investigates the impact of integrating selective exhaust gas recirculation (SEGR) with a combined cycle gas turbine system (CCGT) and post-combustion capture (PCC) in a model power plant. The impacts of ambient temperature, turbine inlet temperature (TIT), and pressure ratio (PR) on the overall thermal and exergetic efficiencies at component and system levels are evaluated. Results show that the combustion chamber and absorber are the two components with the largest exergy destructions in CCGT and PCC units, with a fraction of 44.8% and 52.9%, respectively. After integrating with SEGR, CO2 concentration in flue gas rises from 3.61 to 6.08%, whereas PCC exergetic efficiency increases by 6%. A design of experiments statistical model was applied through a full factorial design to optimise the responses of minimising total exergy destruction while maximising both the thermal and exergetic efficiencies. The optimised input set for TIT of 1300 °C, PR of 15, and SEGR recycle ratio of 25% leads to the best outcome of 415.08 MW, 56.53%, and 51.04% for total exergy destruction, thermal efficiency, and exergetic efficiency, respectively. The predictor equations produced have high degrees of correlation and predictive capabilities and could be used to form empirical equations to replace thermodynamic calculations entirely. [ABSTRACT FROM AUTHOR]

The current research focuses on the efficiency of energy recovery from non-hazardous organic wastes. It entails the generation of low-chloride refuse-derived fuel (RDF) from municipal solid waste (MSW) through moderate pyrolysis of combustible components. The moderate pyrolysis settings and composition ratio of biogenic/non-biogenic content from MSW combination (food waste, plastic waste, and paper waste) had a significant impact on the thermochemical characteristics and fuel behavior of RDF. Furthermore, pyrolysis with optimal MSW composition was studied to reduce toxic elements (chlorides, sulphides, and nitrides) and enhance the energy value in RDF by utilizing potassium-rich (waste orange peels (OP); banana peels (BP); and maize cob (MC)) and calcium-rich species (waste animal bone meal (ABM); egg shells (ES); and mussel shells (MS)) as natural additives. The results showed that increasing the pyrolysis temperature maximized the carbon concentration with reduced oxygen moieties (low O/C ratio), indicating a high energy value as the oxygenates were eliminated during moderate pyrolysis. The RDF treated at 400 °C (SF4-400) with MSW composition of 55% non-biogenic carbon and 45% biogenic carbon resulted in HHV of 29.22 MJ kg−1, the lowest ash concentration (0.96%), and a densified microstructural surface. The addition of natural maize cob additive into MSW (SF4-400-MC) yielded the maximum HHV (33.07 MJ kg−1) with considerable reductions in chlorides (71.43%), sulphides (87.50%), and insignificant nitrides content, all of which meet ASTM RDF quality criteria Grade I. [ABSTRACT FROM AUTHOR]

Edible oil-based feedstocks based biodiesel is still leading the industry around the world. Canola oil (Brassica napus L.) contributes significantly to that race. Process optimisation and the development of reaction kinetic models of edible oil feedstocks are still required since the knowledge of kinetics is needed for designing industrial facilities and evaluating the performance of catalysts during transesterification or other related processes in a biorefinery. This research focuses on the transesterification process for biodiesel production because of its higher output efficiency, reactivity with feedstock, techno-economic feasibility in terms of FFA content, and environmental sustainability. The response surface method with the Box–Behnken model was used to optimise the process. Multivariate analysis of variance (ANOVA) was also performed to investigate the effectiveness of the regression model. The optimal process conditions were found to be 5.89 M methanol, 0.5% (w/w) KOH, 60 °C and 120 min. The predicted yield was 99.5% for a 95% confidence interval (99.1, 99.9). The experimental yield was 99.6% for these conditions. Two different kinetic models were also developed in this study. The activation energy was 16.9% higher for the pseudo-first-order irreversible reaction than for the pseudo-homogenous irreversible reaction. Such a comprehensive analysis will assist stakeholders in evaluating the technology for industrial development in biodiesel fuel commercialisation. [ABSTRACT FROM AUTHOR]

This correction notice provides updated information on the fuel composition of biodiesel produced from Australian Brassica napus L. oil. The corrected data shows that the biodiesel is primarily composed of methyl oleate, followed by methyl linoleate and methyl linolenate. The composition of canola biodiesel includes 12.89% saturated FAME component, 42.61% monounsaturated FAME, and 44.5% polyunsaturated FAME. A comparison with diesel fuel reveals that canola oil biodiesel has a higher cetane number but a lower LHV. The correction was made by M. A. Hazrat, M. G. Rasul, M. M. K. Khan, N. Ashwath, I. M. R. Fattah, Hwai Chyuan Ong, and T. M. I. Mahlia. [Extracted from the article]

This study examined hybrid nanofluids of graphene nanoplatelets (GNP) and graphene oxide (GO) in terms of their stability and performance as a working fluid in a flat plate solar thermal collector. Instead of functionalisation, this experiment utilises the synergetic effect of GO, which stabilises GNP nanofluids by acting like an amphiphilic surfactant. Experimental results found that stability is significantly improved with a sufficiently high concentration of GO. Stability improved as the proportion of GO was increased. In particular, the sample with an equal 50:50 ratio of GNP and GO showed good stability in sedimentation measurements, retaining over 90% of its concentration over one month. Stability was also measured under working pipe flow conditions in a solar collector test rig. This type of data has not previously been reported in the literature. Measurement of the change in concentration showed that in addition to sedimentation, concentration loss can occur via an alternative mechanism: deposition of the nanoparticles inside the pipes. The pristine GNP sample lost over 80% of its concentration over one day of running in the test rig, despite showing moderate stability over one month under still conditions. This shows that measurement of stability in still conditions does not fully describe the stability of nanofluids intended to be working fluids in heat transfer. The sample with a 50:50 ratio of GNP and GO retained around 66% of its concentration over five days of running in the test rig, and the concentration seemed to stabilise, reaching equilibrium, implying no further decreases. Viscosity measurements showed a small increase. Despite the moderately encouraging stability results, however, solar collector testing showed no discernible change in heat transfer performance when using nanofluids compared to water, making these nanofluids unsuitable for this particular flat plate solar collector design. [ABSTRACT FROM AUTHOR]

Sustainable fuel production techniques and feedstocks are essential to meet the future energy demand. In this context, the present study is aimed at sustainably producing low-density biodiesel from Chlorella pyrenoidosa microalgae by heterotrophic means and processed using enzymatic transesterification. To assess the potential of the low-density biodiesel, the fatty acid methyl profile is analyzed and homogenized with diesel fuel at 10, 20, 30, and 40% (v/v/) and tested in a light commercial compression ignition engine at maximum throttle pedal position condition. Furthermore, to identify the optimal mixture proportion and predict the engine outputs, statistical tools like multivariate principal component analysis–desirability approach are employed. From the study, it was inferred that the biomass concentrations of the cultures from 100, 200, and 300L stir tank bioreactor reached up to 5.15, 4.24, and 4.36 g/L on scaling-up. The maximum biodiesel conversion rate of 98% was achieved at an optimal reaction time of 12 h and temperature of 37 °C during enzymatic transesterification. During engine testing, the lowest fuel consumption of 0.41 kg/kWh was attained at full load condition while operating on 40% biodiesel composition. At 20% biodiesel composition, hydrocarbon, nitrogen oxides, and smoke emissions reduce by 44.26, 23.55, and 11.69% as compared to diesel fuel at full load condition. Maximum in-cylinder pressure and heat release rate were achieved by CP30D70 at full load condition as compared to diesel fuel. The optimal biodiesel proportion was identified as 20 and 30% based on the cluster similarly index of 89.67% and desirability value. [ABSTRACT FROM AUTHOR]

Non-edible Ceiba oil has the potential to be a sustainable biofuel resource in tropical countries that can replace a portion of today's fossil fuels. Catalytic deoxygenation of the Ceiba oil (high O/C ratio) was conducted to produce hydrocarbon biofuel (high H/C ratio) over NiO-CaO5/SiO2-Al2O3 catalyst with aims of high diesel selectivity and catalyst reusability. In the present study, response surface methodology (RSM) technique with Box-Behnken experimental designs (BBD) was used to evaluate and optimize liquid hydrocarbon yield by considering the following deoxygenation parameters: catalyst loading (1–9 wt. %), reaction temperature (300–380 °C) and reaction time (30–180 min). According to the RSM results, the maximum yield for liquid hydrocarbon n-(C8–C20) was found to be 77% at 340 °C within 105 min and 5 wt. % catalyst loading. In addition, the deoxygenation model showed that the catalyst loading-reaction time interaction has a major impact on the deoxygenation activity. Based on the product analysis, oxygenated species from Ceiba oil were successfully removed in the form of CO2/CO via decarboxylation/decarbonylation (deCOx) pathways. The NiO-CaO5/SiO2-Al2O3 catalyst rendered stable reusability for five consecutive runs with liquid hydrocarbon yield within the range of 66–75% with n-(C15 + C17) selectivity of 64–72%. Despite this, coke deposition was observed after several times of catalyst usage, which is due to the high deoxygenation temperature (> 300 °C) that resulted in unfavourable polymerization side reaction. [ABSTRACT FROM AUTHOR]

With the increasing awareness of green energy, electric vehicles have become the future trend, with lithium-ion batteries (LIBs) regarded as the most suitable energy storage carrier. Therefore, more and more research topics are focused on LIBs, and all parties are working hard to improve the performance of LIBs. Yet, the safety concerns caused by the failure of LIBs cannot be ignored. LIBs themselves are energetic materials, and the causes of accidents often go through multistage irreversible reactions. Several studies have also pointed out that the electrolyte has a significant correlation with the response characteristics because, in the process of LIBs thermal runaway, the electrolyte participating in the oxidation of the entire battery leads to a considerable amount of heat and even runaway reaction as well. Accordingly, it is necessary to obtain a safer electrolyte by modification. In this study, a significant flame retardant (FR) additive, tris (2,2,2-trifluoroethyl) phosphite (TTFP), is used to suppress lithium-ion battery fires or even explosions and maintain typical battery performance. The performance of the electrolyte was tested by differential scanning calorimetry and thermogravimetric analyzer, and the electrolysis was examined on liquid flash point (FP), self-extinguishing time (SET), and conductivity. During the heating process, adding TTFP to the electrolyte effectively delayed the exothermic peak, reduced the amount of heat, improved the FP, and curtailed the SET. The hazard degree of the electrolyte under high-temperature environment was much lower than before adding the additives, and the additives were finally obtained. It can conclusively prove the safety of lithium batteries without lessening the practical performance of the batteries. [ABSTRACT FROM AUTHOR]

Biodiesel is an alternative to fossil fuels for diesel engines, yet actual biofuel properties need to be tuned to comply with fuel standards. In particular, fuel stability is required for efficiency and commercial use. Fuel stability varies with the nature and proportion of chemical functional groups of biodiesel. Optimum oxidation stability is required because degradation by oxidation gives products that compromise fuel properties and impair fuel quality and engine performance. For instance, oxidation induces the formation of short-chain corrosive acids and deposits. Here, we review techniques to improve the oxidation stability of biodiesel. For instance, stability is improved by additives such as antioxidants. Factors influencing oxidation stability include composition of fatty acids, acid content, peroxide content, iodine content, viscosity, insoluble impurities, external conditions, and storage material. Antioxidants reduce lipid peroxidation at the beginning of the chain reaction and increase the onset temperatures. [ABSTRACT FROM AUTHOR]

In the current study, anaerobic digestion method efficiency on biogas production and chemical oxygen demand (COD) degradation was assessed through a sequence of laboratory-scale batch experimentations to compute the role of chosen process parameters, viz., solid concentration (5–15%), pH (5–9), temperature (30–60 °C), and co-digestion (0–40% of poultry manure). Biogas production and COD degradation were significantly dependent on the selected process parameters with independent conditions to accomplish active performance of the process. Central composite design (CCD)-based response surface methodology (RSM) was adopted for evaluation and optimizing of the combined performance of system considering two responses. Among various combinations, it was observed that solid concentration of 7.38%, pH value as 7, temperature at 48.43 °C, and co-digestion as 29% produce biogas of 6344 ml and COD degradation as 38%. Confirmation experiment performed shows a deviation of 4.93% maximum between the predicted and experimental results. [ABSTRACT FROM AUTHOR]

Microalgae cultivation and biomass to biochar conversion is a potential approach for global carbon sequestration in microalgal biorefinery. Excessive atmospheric carbon dioxide (CO2) is utilized in microalgal biomass cultivation for biochar production. In the current study, microalgal biomass productivity was determined using different CO2 concentrations for biochar production, and the physicochemical properties of microalgal biochar were characterized to determine its potential applications for carbon sequestration and biorefinery. The indigenous microalga Chlorella vulgaris FSP-E was cultivated in photobioreactors under controlled environment with different CO2 gas concentrations as the sole carbon source. Microalgal biomass pyrolysis was performed thereafter in a fixed-bed reactor to produce biochar and other coproducts. C. vulgaris FSP-E showed a maximum biomass productivity of 0.87 g L−1 day−1. A biochar yield of 26.9% was obtained from pyrolysis under an optimum temperature of 500 °C at a heating rate of 10 °C min−1. C. vulgaris FSP-E biochar showed an alkaline pH value of 8.1 with H/C and O/C atomic ratios beneficial for carbon sequestration and soil application. The potential use of microalgal biochar as an alternative coal was also demonstrated by the increased heating value of 23.42 MJ kg−1. C. vulgaris FSP-E biochar exhibited a surface morphology, thereby suggesting its applicability as a bio-adsorbent. The cultivation of microalgae C. vulgaris FSP-E and the production of its respective biochar is a potential approach as clean technology for carbon sequestration and microalgal biorefinery toward a sustainable environment. [ABSTRACT FROM AUTHOR]

Biodiesels have gained much popularity because they are cleaner alternative fuels and they can be used directly in diesel engines without modifications. In this paper, a brief review of the key studies pertaining to the engine performance and exhaust emission characteristics of diesel engines fueled with biodiesel blends, exhaust aftertreatment systems, and low-temperature combustion technology is presented. In general, most biodiesel blends result in a significant decrease in carbon monoxide and total unburned hydrocarbon emissions. There is also a decrease in carbon monoxide, nitrogen oxide, and total unburned hydrocarbon emissions while the engine performance increases for diesel engines fueled with biodiesels blended with nano-additives. The development of automotive technologies, such as exhaust gas recirculation systems and low-temperature combustion technology, also improves the thermal efficiency of diesel engines and reduces nitrogen oxide and particulate matter emissions. [ABSTRACT FROM AUTHOR]