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 NO_x) 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 NO_x emissions will be minimum, the optimization determined that the fuel mixture 79.09% D-8.33% WOB-12.58% P concentration (DWOBP_opt) 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 (NO_x) 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.

Higher carbon alcohols such as n-propanol, n-butanol, and n-pentanol that can be produced from biomass can be used as alternative fuels in diesel engines. These alcohols can mix with both diesel fuel and biodiesel without any phase separation. Currently, unregulated emissions such as toxicity and total polycyclic aromatic hydrocarbon (PAH) from the use of these alcohols are not monitored. Investigating the effects of increasing the alternative fuel concentration for use in a diesel engine on PAH emissions will contribute to the protection of the environment and extend the engine’s operating life. In this study, the effects of adding 35% (by volume) n-propanol, n-butanol and n-pentanol to diesel and biodiesel on unregulated emissions in a diesel engine were compared. In the total PAH emission of biodiesel, the mixture containing n-pentanol stood out compared to other mixtures with a decrease of 39.17%. In higher alcohol-diesel mixtures, the highest reduction was observed in the n-butanol mixture as 80.98%. With respect to toxic emissions, very close values were obtained in biodiesel blends up to 94.15%, although n-butanol showed a maximum reduction of 84.33% in diesel blends. All these reductions also prevented the formation of high-cycle PAHs. The results obtained showed that the use of high carbon alcohols in a high mixing ratio contributed to the improvement of the fuel properties of biodiesel and to an increase in the alternative fuel mixing ratio with the reduction of PAH emissions from diesel fuel.

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 (NO_x) 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 NO_x 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 isothermal oxidation in air of high purity aluminum sheet was studied as a function of temperature using Thermogravimetric Analysis simultaneously with Differential Scanning Calorimetry (TGA/DSC). The rates and extents of oxidation were found to be non-linear functions of the temperature, in agreement with the literature. Between 650 °C and 750 °C very little oxidation took place; at 850 °C oxidation occurred after an induction period, while at 950 °C oxidation occurred without an induction period. At oxidation temperatures between 1050 °C and 1150 °C rapid passivation of the surface of the aluminum occurred, while at 1250 °C and above, an initial rapid mass increase was observed, followed by a more gradual increase in mass. The initial rapid increase in mass was accompanied by a significant exotherm, which was quantified by DSC. At temperatures of 1050 °C and above the specimen coalesced into a spheroidal particle, whereas at lower temperatures the original morphology was retained due to the cohesive strength of the native oxide layer. Cross-sections of oxidized specimens were characterized by scanning electron microscopy (SEM); the observed alumina skin thicknesses correlated qualitatively with the observed mass increases. Interrogation of the surface of an oxidized spheroidal particle by SEM showed a fractured alumina shell around a partially hollow core of aluminum which appeared to have grain boundaries.

The primary factor in the formation of polycyclic aromatic hydrocarbons (PAHs) in diesel engines, which pose environmental and health risks, is the chemical composition of the diesel fuel. Higher-carbon alcohols have emerged as promising oxygenated blending components for compression ignition engines due to their potential to improve combustion and reduce harmful emissions. However, limited data exist regarding their impact on PAH formation and toxicity characteristics. This study investigates the effects of 15% (v/v) n-propanol, n-butanol, and n-pentanol blends with petroleum diesel (D) and waste cooking oil biodiesel (B) on total PAH emissions, PAH dispersion, and toxicity in a diesel engine under steady-state conditions. Total PAH concentrations and individual species distributions were quantified, and toxicity was evaluated using toxicity equivalency factor (TEF) methodology. Results indicate that the addition of higher alcohols significantly reduces total PAH emissions compared to the respective base fuels. A marked decrease in high-molecular-weight (4–6 ring) PAH compounds was observed, suggesting suppression of heavy PAH formation pathways. Toxicity-weighted PAH emissions also decreased with alcohol blending. Furthermore, total PAH concentrations for all tested blends remained below the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL = 0.2 mg/m³) under the examined operating conditions. These findings demonstrate that 15% higher alcohol blends are effective in mitigating PAH emissions without adverse environmental health implications.