• Energy Research

Abstract The purpose of this work is to investigate the effect of butanol–biodiesel blends on the emissions and performance characteristics of a four-stroke, naturally aspirated, water-cooled, indirect injection diesel engine (IDI). Testing was performed comparing butanol blended with biodiesel, standard diesel (D100) and neat biodiesel (B100) at four engine loads. The biodiesel–butanol blends were 5%, 10%, and 20% butanol in volume basis (B95Bu5, B90Bu10, B80Bu20). Compared to biodiesel, butanol blended fuels showed lower exhaust gas temperatures and nitrogen oxides (NOx) emissions while exhibiting higher carbon monoxide (CO) and unburned hydrocarbons (HC) emissions. Butanol blended fuels produced lower CO and higher NOx emissions than diesel fuel for low concentrations of butanol (5% and 10%), but there was no significant change in terms of HC emissions. The biodiesel blend containing the highest concentration of butanol (20%) caused higher CO and HC emissions and lower NOx emission than diesel. Brake specific fuel consumption increased with biodiesel and biodiesel blended fuels as compared to diesel.

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.

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.

Abstract In this work, ethanol was mixed with biodiesel–diesel blends and the effect of ethanol concentration on diesel emissions was investigated. Both low and high concentrations of ethanol were studied. Ethanol concentrations were varied at 3%, 5%, 15% and 25% in biodiesel–diesel–ethanol (BDE), while biodiesel and diesel concentrations were maintained equal (BDE3, BDE5, BDE15 and BDE25). Emission characteristics for biodiesel–diesel–ethanol blends were compared to baseline curves of diesel as a function of engine load.