Abdülvahap Çakmak

Stationary diesel engines remain important for agricultural, industrial, and power‐generation applications, yet limited emission‐control technologies can lead to elevated pollutant emissions and environmental burdens. For large existing fleets, engine replacement or extensive hardware upgrades may be impractical. This study investigates hybrid biofuel formulations as a fuel‐based strategy to reduce the environmental impact of existing stationary diesel engines. Two formulations were developed using waste cooking oil biodiesel, ethanol, n‐butanol, 2‐ethylhexyl nitrate (EHN), and multi‐walled carbon nanotubes (MWCNTs). FF‐1 consisted of 68 vol% diesel, 17 vol% waste cooking oil biodiesel, 10 vol% ethanol, and 5 vol% n‐butanol, while FF‐2 incorporated 3000 ppm EHN and 100 ppm MWCNTs into FF‐1. The formulations were experimentally evaluated under five load conditions, considering energy performance, combustion behavior, emissions, environmental impact rate, environmental damage cost, exergy efficiency, and sustainability index. Compared with diesel fuel, FF‐1 and FF‐2 reduced average NO _X emissions by 38.5% and 21.1%, respectively, and CO emissions by 47.9% and 50.1%. Although brake‐specific fuel consumption increased by 4.3–6.1%, FF‐2 achieved 4.9% higher brake thermal efficiency than B20. FF‐1 and FF‐2 reduced the environmental impact rate by 36.16% and 24.89%, respectively, and the environmental damage cost by 21.46% and 16.42%. FF‐2 achieved a peak exergy efficiency (37.5%) and sustainability index (1.60). Overall, hybrid biofuels with functional additives can reduce pollutant emissions and environmental impacts of stationary diesel engines while promoting cleaner use of waste‐derived and renewable energy resources. However, some fuel‐property non‐conformities under EN590 and high fuel costs appear to be major constraints on their practical use.

Crystalline nanocellulose (CNC), derived from various biomass sources, is gaining attention as a sustainable nanomaterial for energy applications due to its high surface area-to-volume ratio, lightweight nature, biodegradability, and associated environmental benefits. This experimental research investigated the potential of CNC as an alternative to traditional metallic nanofuel additives, presenting preliminary results that have not been previously reported. Commercially available CNC was blended into standard diesel fuel at concentrations of 100 ppm, 250 ppm, and 500 ppm, and engine performance and emission tests were conducted. CNC demonstrated potential as a nanofuel additive in diesel, offering benefits like improved combustion, enhanced engine performance, and reduced NOx emissions and exhaust smoke opacity. However, higher concentrations were less effective in lowering nitrogen oxides (NOx) levels, and carbon dioxide (CO2) emissions increased due to more complete combustion. The highest engine performance was achieved with a CNC concentration of 500 ppm, resulting in an average reduction in brake-specific fuel consumption (BSFC) by 3.95% and an increase in brake thermal efficiency (BTE) by 2.73% compared to diesel fuel. The fuel cost analysis indicated that CNC is economically viable at a 100-ppm concentration; however, higher concentrations resulted in a substantial increase in fuel costs, despite reducing fuel consumption. The initial results are promising and suggest CNC could be a suitable alternative to traditional metallic nanofuel additives.

Bu çalışmada, çeşitli bitki ekstraktlarının (Achillea millefolium L., Helichrysum arenarium L. Moench ve Rosa Canina L.) biyodizelin oksidatif kararlılığı üzerindeki doğal antioksidan etkinlikleri araştırılmıştır. Bitki ekstraktları Soxhlet yöntemi ile elde edilmiş ve biyodizel-dizel karışımları üzerindeki antioksidan aktiviteleri Yüksek Performanslı Sıvı Kromatografisi (HPLC) ve Fourier Dönüşümlü Kızılötesi Spektroskopisi (FT-IR) teknikleri ile değerlendirilmiştir. Achillea millefolium L.'nin FT-IR spektrumu, ekstrakt içerisinde ferulik asit, kafeik asit ve kumarik asit varlığını gösterirken, 2959 cm-1 ve 2923 cm-1'de tespit edilen C-H gerilme titreşimleri, ekstrakt içerisinde kateşin, taksifolin ve naringenin varlığını göstermiştir. Helichrysum arenarium L. Moench ve Rosa Canina L. IR Spectra'da kaempherol, naringenin, chrysin ve butein varlığı göstermiştir. 3000 ppm konsantrasyonlu bitki özleri, %20 biyodizel ve %80 dizelden oluşan biyodizel-dizel karışımlarına doğal antioksidanlar olarak eklendi. Karışım örnekleri D100, B20D80, B20D80A, B20D80H ve B20D80R olarak isimlendirilmiştir. Kristalleşme sıcaklıkları (Tcr), Diferansiyel Taramalı Kalorimetre (DSC) ile belirlenmiştir ve sonuçlar D100, B20D80, B20D80A, B20D803000H, B20D80R için kristalleşme başlangıç ​​sıcaklıklarının sırasıyla -7,71 °C, -8,07 °C, -8,16 °C, -8,34 °C ve -8,61 °C olduğunu gösterdi. Antioksidan içeren numunelerin Tcr değerleri, antioksidan içermeyen biyodizel numunesine (B20D80) kıyasla azalmıştır. Ayrıca, numunelerin termofiziksel özellikleri belirlenmiştir ve sonuçlar, temel yakıt özelliklerinin baz yakıt numunesine bitki özlerinin eklenmesiyle hafif etkilendiğini gösterdmiştir.

Ethanol, with its high octane rating and emissions advantages, is a viable and renewable alternative to gasoline for Spark-Ignition (SI) engines. However, when mixed with gasoline, ethanol forms an azeotropic mixture that increases the fuel's vapor pressure, potentially causing a clogged fuel line, engine stalling, and unstable operation. This study aimed to address the high vapor pressure challenge by adding C3, C4, and C5 iso-alcohols, namely, isopropanol (IP), isobutanol (IB), and isoamyl alcohol (IA), to reduce the vapor pressure of ethanol-gasoline blends. Fuel properties, including Reid vapor pressure (RVP), density, and distillation temperatures, were measured after each iso-alcohol was individually added to ethanol-gasoline blends (E10, E20, and E30) at a 5% volumetric ratio. According to the findings, E10 and E20 behaved as an azeotropic mixture, yielding increased vapor pressure. The highest RVP of 63.2 kPa was measured for E10. However, adding IP, IB, and IA alcohols to E10 reduced the RVP to 61.8 kPa, 61.3 kPa, and 61.1 kPa, respectively. Including iso-alcohols also increased the density of ethanol-gasoline blends, with the highest density of 763.6 kg/m³ was measured for E30+IA5. Furthermore, adding iso-alcohols improved the distillation profiles, octane rating, and heating value of the ethanol-gasoline blends. More importantly, it was found that the measured fuel properties met the requirements of the European Standards for Gasoline (EN 228) except for some gasoline samples' distilled values for E70 and E100. Based on the findings, C3-C5 iso-alcohols effectively reduce the high vapor pressure associated with ethanol-gasoline azeotropic mixtures, allowing a higher volume of renewable ethanol blending.