The present investigation is directed towards synthesis of zinc oxide (ZnO) nanoparticles and steady blending with soybean biodiesel (SBME25) to improve the fuel properties of SBME25 and enhance the overall characteristics of a variable compression ratio diesel engine. The soybean biodiesel (SBME) was prepared using the transesterification reaction. Numerous characterization tests were carried out to ascertain the shape and size of zinc oxide nanoparticles. The synthesized asymmetric ZnO nanoparticles were dispersed in SBME25 at three dosage levels (25, 50, and 75 ppm) with sodium dodecyl benzene sulphonate (SDBS) surfactant using the ultrasonication process. The quantified physicochemical properties of all the fuels blends were in symmetry with the American society for testing and materials (ASTM) standards. Nanofuel blends demonstrated enhanced fuel properties compared with SBME25. The engine was operated at two different compression ratios (18.5 and 21.5) and a comparison was made, and best fuel blend and compression ratio (CR) were selected. Fuel blend SBME25ZnO50 and compression ratio (CR) of 21.5 illustrated an overall enhancement in engine characteristics. For SBME25ZnO50 and CR 21.5 fuel blend, brake thermal efficiency (BTE) increased by 23.2%, brake specific fuel consumption (BSFC) were reduced by 26.66%, and hydrocarbon (HC), CO, smoke, and CO2 emissions were reduced by 32.234%, 28.21% 22.55% and 21.66%, respectively; in addition, the heat release rate (HRR) and mean gas temperature (MGT) improved, and ignition delay (ID) was reduced. In contrast, the NOx emissions increased for all the nanofuel blends due to greater supply of oxygen and increase in the temperature of the combustion chamber. At a CR of 18.5, a similar trend was observed, while the values of engine characteristics were lower compared with CR of 21.5. The properties of nanofuel blend SBME25ZnO50 were in symmetry and comparable to the diesel fuel.

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The utilization of biodiesel‐diesel blends in compression ignition (CI) engines are a viable option for the current energy crises. But due to better combustion features of biodiesel‐diesel blends leading to high NOx release from engine exhaust hinders the use of such blends. Usually all of the harmful exhaust emissions like HC and CO reduces marginally, except nitrogen oxides at higher compression ratios with biodiesel blended fuel. The present paper focuses on the study of variation of compression ratio and use of NiO nanoparticles in neem biodiesel‐diesel mixture (NB25) at different braking loads. A total of four test fuels of NB25 blend were prepared having nickel oxides at different concentration levels of 25, 50, 75, and 100 ppm. The current findings reveal that the use of 75 ppm of NiO in NB25 blend reduces the amount of thermal NOx by 6.2% compared to the absence of nanoparticles. Also, the performance parameters such as brake thermal efficiency improved by 2.9% and brake specific fuel consumption reduced by 1.8%. The presence of 75 ppm of NiO in NB25 not only shows best performance and also lower harmful emission.

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The present work investigates the emission and thermal performance of DI CI variable compression ratio engine using blends of biodiesel and standard diesel as a fuel at compression ratios of 15,16,17 and 18. The biodiesel derived from non edible Calophyllum Inophyllum linn oil is used on the engine. The blends of biodiesel and diesel used were B20, B40, B60, B80 and 100% biodiesel. At 18 CR the brake thermal efficiency of the engine operated with 100% biodiesel is 8.9% less than Diesel and the brake specific fuel consumption for biodiesel found to be more than that of diesel. There is major reduction in Carbon monoxide and Hydrocarbon emissions with 100% biodiesel as a fuel compared to diesel at compression ratio of 18.

This paper presents the effect of static fuel injection timings and blends of biodiesel with conventional diesel on the performance and emission characteristics of a DI-CI VCR engine. Blends of Honne oil methyl ester (HnOME) and diesel was used as fuel. The default value of static injection timing of the engine was 23 bTDC (before top dead centre). Injection timing was retarded and advanced from default value by 4 bTDC. Experiments were conducted at three levels of timings using the blends B20, B40, B60, B80 and B100 (pure HnOME). Conventional diesel was used as a reference fuel. The decrease in brake thermal efficiency for B20, B40, B60, B80 and HnOME compared to diesel at 19 bTDC were 5.4, 15.7, 13, 10 and 2.9% respectively. Brake thermal efficiency decreased by 4.2, 15.7, 13.5, 10.15 and 2.96% for B20, B40, B60, B80 and HnOME respectively compared to diesel at 27 bTDC. Nitric oxide emissions reduced for both advanced and retarded timings, but the reduction was more for retarded timing. Smoke intensity increased for retarded timing. Blend B60 to B80 can be successfully used by retarded timing combined with higher compression ratio and fuel injection pressure. KEYWORDSHonne oil methyl ester; fuel injection timing; thermal performance; emission characteristics; brake specific energy consumption Acronyms HnOME Honne oil methyl ester CI Compression Ignition DI Direct injection VCR Variable compression ratio B80 80% HnOME and 20% mineral diesel by volume BTE Brake thermal efficiency BSFC Brake specific fuel consumption EGT Exhaust gas temperature BSEC Brake specific energy consumption HC Unburned hydrocarbon CO Carbon monoxide CO 2 Carbon dioxide NO X Oxides of nitrogen HSU Hartridge smoke unit

The present study examines the effect of SiO2 nano-additives on the performance and emission characteristics of a diesel engine fuelled with soybean biodiesel. Soybean biofuel was prepared using the transesterification process. Nano-additives characterisations were done using different tests such as FESEM, XRD, EDS, etc., to study the morphology of nano-additives. For proper blending of nano-additives with biodiesel, the ultrasonication process was used. Surfactant was used for the stabilisation of nano-additives. After making all the combinations of nano fuel blends, physicochemical properties were measured as per ASTM standards. Performance and emissions readings were taken at different load conditions. It was found that with the addition of SiO2 nano-additives, brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) was increased by 3.48-6.39% and 5.81-9.88%, respectively. Significant reduction of CO, CO2, NOx, and smoke emissions were also observed compared to baseline fule due to better combustion efficiency with the use of SiO2 nano-additive.

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