Nano-additives In Diesel, Biodiesel Fuel Blends For Automotive Traction With A Focus On Their Stability, Engine Performance And Emission Characteristics
- Introduction:Biodiesel is an unsurpassed alternative fuel source intended to extend the value to fossil fuels, and the longevity and cleanliness of diesel engines. It reduces the dependence on foreign fuels and reduces the greenhouse gas emissions due to its closed carbon cycle. The plentiful advantages of biodiesel are overcome by few drawbacks such as the increase in the nitrogen oxide emission, its incompatibility with cold weather conditions, and the regular intervals of engine parts replacement such as fuel filters, fuel tanks and fuel lines due to clogging. There is a further scope for enhancement in fuel properties and to overcome the drawbacks by addition of nanoparticles as fuel additives. Recent researches on fuel additives indicated the inclusion of nano-sized particles (metallic, non-metallic, oxygenated, organic and combination) with diesel-biodiesel fuel emulsion. The results achieved demonstrated an improvement in the thermophysical properties, enhancement in the heat transfer rate, and stabilization of the fuel mixtures. Also, there was an increase in the engine performance parameters and reduction in the exhaust emissions depending on the dosage of nanofluid additives. This work provides a bird view of the methods for preparation of nanofluids, the stability enhancement of nanofluids, characterization methods to find the chemical bonding, nanoparticle shape, and size, dispersion of nano-additives in liquid fuel, the health effects, and applications of nanoparticles in the automotive industry. The experimental results from the various researchers were not generalized to reach a general accord regarding this innovative approach of fuel adulteration. The present work summarizes the literature from most recent articles on nanoparticles as a liquid fuel additive*.The effect of dispersion of several nanoparticles on the enhancement in the performance characteristics and reduction in emission of a CI engine fuelled with diesel-biodiesel blends were discussed. The further scope suggests the development of an economically sustainable and feasible nanoparticle additive for diesel and biodiesel fuel. Nevertheless, few obstacles and challenges which have been recognized in this review must be addressed before they can be fully put into practice in the industrial applications.
- Preparation of Nano-diesel and Biodiesels and their stability aspects:The fuel (diesel and biodiesels) enrichment method by addition of nano-additives is widely accepted by numerous researchers. The nano-additives are used to achieve specific fuel properties and to improve the diesel engine performance characteristics and to attain a good engine emission control without any engine modification. Technological advancement of nano-additives and their use in biodiesel blended fuel combinations reduced engine out emissions, which proved to be a potential fuel additive. Non-edible oils such as Honge, Jatropha and Simarouba oils were selected in the present study. Nano-biodiesel blends were than prepared using nanoparticles (NPs) such as aluminium, silver and graphene along with suitable surfactants**. The stability of nanoparticle suspension especially the long-term stability under practical conditions is a crucial issue for both scientific research and practical applications. An anionic surfactant, namely sodium dodecyl sulfate (SDS) was used and Figure 1 shows the structure of the SDS surfactant and the nano-biodiesel blend formation.
It was found that an optimum graphene-to-surfactant ratio of 1:4 gives a homogenous, uniform and stable dispersion. This ratio was taken as standard for preparation of biodiesel blends of 20, 40 and 60 ppm that are named as BD2020, BD2040 and BD2060, respectively***. Figure 2 shows an ultra-sonicator set up used in nano-biodiesel blends preparation.
Experimental Test Rig:
The developed biodiesel and nano-biodiesel blends were tested in a single cylinder, high-pressure CRDi injection facilitated diesel engine as shown in Fig. 4.
Based on the results obtained from the engine tests conducted on the diesel engine, the following conclusions can be drawn:
- Stable and homogeneously dispersed nano-biodiesels can be prepared with the help of suitable surfactant.
- Fuel modification of Biodiesels can be made to improve performance and emission characteristics of a CI engine significantly.
- BTE was improved with optimized biodiesel-NPs blends while harmful emissions of CO, HC and NOx were reduced as compared to neat biodiesel operation.
- Nano-biodiesels fuel accelerated evaporation which reduced the ID and CD, while higher PP and HRR were observed.