• Energy Research

Abstract In this study, the fresh water green microalga Scenedesmus dimorphus and the marine golden Isochrysis aff. galbana were compared at the laboratory scale for their potential in biodiesel production. For this purpose, the microalgal strains were grown over five days under the Bristol and Erdschreiber's media conditions. The cultures were supplied with 1.5% carbon dioxide (CO2) and 16:8 light to dark cycle at fixed temperature. The research performed contained the following stages: 1) Growth monitoring (analysis of growth rate), 2) Microalgae harvesting (lab-scale lipid extraction), 3) Biodiesel production and 4) Determination of biodiesel quantity and quality. The results show that the total lipids (% dry weight biomass) from Scenedesmus dimorphus and Isochrysis aff. galbana cultures were found to be 15.87 and 42.65%, respectively. The obtained yields of the transesterification reactions were 87.4% (Scenedesmus dimorphus) and 94.6% (Isochrysis aff galbana). The methyl esters of Isochrysis aff. galbana contained higher percentage of saturated fatty acids than Scenedesmus dimorphus and its fatty acid composition improved the basic fuel properties. The overall finding of the study suggested that Isochrysis aff. galbana can be considered as more viable source for biodiesel production, in part due to the relative ease in producing a high oil yield.

The study focuses on the preparation of an inexpensive, ecocompatible, and effective catalyst from the Bharatmoni (Musa AAA) plant for biodiesel synthesis using Jatropha curcas oil. The burnt ashes obtained from the Bharatmoni fruit peel, stem, and rhizome were calcined at 550°C for 2 h and characterized by analytical techniques. Utilization of CBS‐550 catalyst achieved a higher yield of biodiesel (96.97%) within 12 min compared to CBP‐550 (96.89% in 16 min) and CBR‐550 (96.53% in 18 min) catalysts under optimum reaction parameters of 5 wt% of catalyst and 9 : 1 MTOMR at 65°C. This study described that catalyst having a higher concentration of potassium in its oxide and carbonate form has higher catalytic activity. The surface morphology of the prepared catalysts revealed mesoporous in nature. The kinetic and thermodynamic studies of the reactions catalyzed by the present catalysts follow the pseudo‐first‐order kinetic model exhibiting a nonspontaneous and endothermic process. The reaction catalyzed by the CBS‐550 catalyst revealed the lowest Ea of 44.36 kJ mol-1 and is known to be the superior catalyst among the derived catalysts of this study.

Abstract The use of alcohols in diesel engines is an alternative way of reducing dependence on diesel fuel. Specifically, higher alcohols such as n-butanol (nB) and 1-pentanol (Pn), which consist of high carbons and can be produced from mainly non-edible sources, can directly be mixed with diesel fuel which in return provides significant promise from economic and environmental stand points. For this reason, the examination of the use of such high-carbon alcohols in diesel engines has become significantly important in recent years. In this work, six different binary (D-nB and D-Pn) fuel mixtures were obtained by mixing the diesel fuel with n-butanol and 1-pentanol at low and high mixing ratios (5%, 25% and 35% alcohol by volume) and basic fuel properties were examined. The test fuels were tested at four different loads (0, 3, 6 and 9 kW) at a constant engine speed (1800 rpm) in a direct injection diesel engine with diesel as the reference fuel. Fuel properties of the binary fuels were in compliance with the European Norm (EN590) and all of the fuels exhibit a steady phase without any indication of phase separation. Compared to diesel fuel’s engine characteristics, brake specific fuel consumption (BSFC) increased by 14.02% in binary blends, resulting in a 7.36% reduction in brake thermal efficiency (BTE). However, exhaust gas temperature (EGT) increased by an average of 47.55%. The addition of 1-pentanol to diesel had a significant impact on the decrease of oxides of nitrogen (NOx) emissions as an average decrease of 14.27% was observed. On the other hand, the higher latent heat of evaporation (LHE) of n-butanol and 1-pentanol had multiple disadvantageous outcomes such as a cooling effect in-cylinder, lower combustion efficiency and slightly higher carbon monoxide (CO) and hydrocarbon (HC) emissions as compared to diesel. The results indicated that the binary blends with 35% alcohol content happened to be a promising alternative for lower NOx emissions at the expense of increasing CO and HC emissions. Overall, it is concluded that n-butanol and 1-pentanol blends can be safely used in diesel engines without any engine modification or any additive.

Higher alcohols can be included as a third component in biodiesel-diesel mixtures to improve fuel properties and reduce emissions. Determining the optimum concentrations of these fuels according to the purpose of engine use is important both environmentally and economically. In this study, eight different concentrations of diesel (D), waste oil derived biodiesel (WOB), and 1-pentanol (P) ternary mixtures were determined by the design of experimental method (DOE). In order to determine the engine performance and exhaust emission parameters of these fuels, they were tested on a diesel engine with a constant load of 6 kW and a constant engine speed of 1800 rpm. Using the test results obtained, a full quadratic mathematical model with a 95% confidence level was created using the Response Surface Method (RSM) to predict five different output parameters (BSFC, BTE, CO, HC, and NOx) according to the fuel mixture ratios. The R2 accuracy values of the outputs were found at the reliability level. According to the criteria that BTE will be maximum and BSFC, CO, HC, and NOx emissions will be minimum, the optimization determined that the fuel mixture 79.09% D-8.33% WOB-12.58% P concentration (DWOBPopt) will produce the desired result. A low prediction error was obtained with the confirmation test. As a result, it is concluded that the optimized fuel can be an alternative to the commonly accepted B7 blend and can be used safely in diesel engines.

There are a number of emissions produced by internal combustion engines that are regulated to limit atmospheric pollution. However, it is equally important for both environmental and human health to also monitor and control polycyclic aromatic hydrocarbons (PAHs). Using high-carbon alcohols with straight-chain structures, such as n-propanol (Pro), n-butanol (Bu) and n-pentanol (Pen), together with diesel fuel (D), can be a way to reduce these harmful pollutants. In this study, nine different test fuels were created by mixing each higher alcohol with diesel fuel at 5%, 20% and 30% mixing ratios. In order to compare the effects of these test fuels on regulated pollutants and PAH compounds, fuel blends were evaluated in a diesel engine at partial loads and at a constant speed. Regulated emissions were measured using a standard 5-gas analyzer, and PAHs were detected and quantified using rigorous analytical chemistry methods, such as gas chromatography–mass spectrometry (GC–MS). While higher carbon monoxide (CO) and hydrocarbon (HC) pollutants were emitted by the binary blends due to their high oxygen content and latent heat of evaporation (LHE), a decrease in nitrogen oxides (NOx) emissions between 4.98% and 20.08% was observed depending on the alcohol concentration. With the exception of the 20% n-pentanol mixture, PAH concentrations in the exhaust gas were significantly reduced in other binary blends. The 35% n-butanol mixture stood out in reducing total PAHs by 80.98%. In toxicity reduction, the 20% n-propanol mixture was the most effective with a decrease of 91.23% in toxicity. Overall, higher alcohols have been shown to be effective additives not only in reducing overall PAH emissions and toxicity, but also in reducing high-ring and heavier PAHs, which are more carcinogenic and cause a greater risk to engine lifedue to wet stacking under cold starting or low-load conditions.

It is very important to determine the polycyclic aromatic hydrocarbon (PAH) emissions caused by the use of renewable fuels in diesel engines and to know the possible damages. This study investigates the emissions (regulated and unregulated) of biodiesel/n-pentanol mixtures, which are free of aromatic content, with emphasis on PAH formation and an examination of toxicity to public health and the environment. Engine failures caused by wetstacking are also discussed. Biodiesel/n-pentanol fuel mixtures with alcohol concentrations of 5%, 20%, and 35% by volume (v/v) served as test fuels in a compression ignition engine. A five-gas analyzer was used to measure hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) emissions. Polycyclic aromatic hydrocarbons were detected and measured using gas chromatography-mass spectrometry (GC-MS). Against the baseline diesel fuel, the biodiesel/n-pentanol fuel blends and neat biodiesel reduced NOx emissions and produced significantly fewer PAHs and toxicity, confirming the significance of the aromatic content of the fuel. Biodiesel reduced total PAHs by 48.02% and the addition of 5% n-pentanol to biodiesel further decreased total PAHs by 21.26%. The total toxicity (BaPeq (benzo[a]pyrene equivalent)) as a result of biodiesel was 83.49% less than diesel. The addition of n-pentanol to biodiesel further reduced toxicity by 59.15%, 57.89%, and 48.33% for BPen5, BPen20, and BPen35 blends, respectively. In addition, n-pentanol was shown to be effective for reducing total PAH emissions, as well as heavier PAHs, which have greater carcinogenicity and pose a greater likelihood of engine damage from wetstacking when running in low-load conditions at cold temperatures.

The production of biochar from biomass and industrial wastes provides both environmental and economic sustainability. An effective way to ensure the sustainability of biochar is to produce high value-added activated carbon. The desirable characteristic of activated carbon is its high surface area for efficient adsorption of contaminants. Feedstocks can include a number of locally available materials with little or negative value, such as orchard slash and crop residue. In this context, it is necessary to determine and know the conversion effects of the feedstocks to be used in the production of activated carbon. In the study conducted for this purpose; several samples (piñon wood, pecan wood, hardwood, dried grass, Wyoming coal dust, Illinois coal dust, Missouri coal dust, and tire residue) of biomass and industrial waste products were investigated for their conversion into activated carbon. Small samples (approximately 0.02 g) of the feedstocks were pyrolyzed under inert or mildly oxidizing conditions in a thermal analyzer to determine their mass loss as a function of temperature and atmosphere. Once suitable conditions were established, larger quantities (up to 0.6 g) were pyrolyzed in a tube furnace and harvested for characterization of their surface area and porosity via gas sorption analysis. Among the samples used, piñon wood gave the best results, and pyrolysis temperatures between 600 and 650 °C gave the highest yield. Slow pyrolysis or hydrothermal carbonization have come to the fore as recommended production methods for the conversion of biochar, which can be produced from biomass and industrial wastes, into activated carbon.

Abstract1‐pentanol has been gathering attention because of its advantages over the lower alcohols, and the researchers consider that it is a promising alternative fuel for diesel engines. In this study, two types of diesel engines were fueled with various blends of 1‐pentanol (5%–35%) and diesel blends. Engine tests were performed using Onan DJC and Subaru RGD (3300H) unmodified diesel engines under different engine loads and speeds and results were reported and compared for both diesel engines. Test results of Onan and Subaru engines showed that average brake thermal efficiency (BTE) decreased, while brake specific fuel consumption (BSFC), and exhaust gas temperature (EGT) increased with increasing presence of 1‐pentanol in the binary blends. Addition of 1‐pentanol to diesel fuel significantly decreased oxides of nitrogen (NOx) emissions, while hydrocarbon (HC) and carbon monoxide (CO) emissions increased drastically with the use of 1‐pentanol as compared to diesel fuel. It is noted that the engine specifications, operating conditions and 1‐pentanol blend ratio significantly affect HC emissions. As a result, the lowest ratio of 1‐pentanol is the most promising candidate for decreasing NOx emissions, but at the expense of increasing BSFC for any type of diesel engine without any engine modification.

Abstract In this study, aluminum particle burn in a gap created between a downward facing combusting propellant surface and an upward facing inert surface was modeled with sensitivity testing on propellant surface velocity, propellant surface temperature, propellant surface radiation temperature, parcel count, particle diameter, turbulent Prandtl number and turbulent Schmidt number. Decreasing the turbulent Prandtl and turbulent Schmidt number appeared to have little effect on the maximum temperature. Increasing/decreasing the velocity of the propellant surface and propellant surface temperature showed greater sensitivity on the plume temperature. Perturbation of the propellant surface temperature had the greatest influence on the maximum gas temperature. By increasing and decreasing the surface temperature by ten percent of its original value, a temperature difference of 265.4 K and 248.7 K were observed, respectively.