Investigations on the Tribological Characteristics of TiO2-Doped Nanofluid Fuel (Biodiesel/Diesel Blend) at Different Contact Parameters

The fuels (diesel/biodiesel blends) for diesel engines must possess a minimum of lubricating characteristics to prolong the life of some of the engine vital parts lubricated by the fuel itself. Hence, the tribological characteristic of the modified nanofluid fuel blends needs to be investigated for its suitability and sustainability. In the present study, an experimental analysis on the tribological aspect of fuel blends comprising 40% Acacia concinna biodiesel and 60% diesel (by volume) mixed with titanium dioxide (TiO2) nanoparticles in a concentration of 50–200 mg/l was conducted. The prepared fuel blends in varying volume concentrations were tested on a four-ball tribotester. The effects of varying operating parameters such as load and temperature as well as oxidation of biodiesel fuel blend on friction and wear behavior were evaluated with the help of three-dimensional (3D) surface plots (response surface methodology approach). Further, wear patch diameter, wear debris, wear volume, and flash temperature parameter were analyzed using optical micrographs and ferrographs. The obtained results revealed that despite having an influence of all parameters, the effect of TiO2 nanoparticles is more significant in improving the antiwear/friction characteristics of modified nanofluid fuel blends. It was observed that a TiO2 concentration of 150 mg/l in fuel blend was found to be the most suitable to reduce the friction, wear, and wear volume compared with those of diesel and biodiesel blend.

Study on the influence of alumina nanomethanol fluid on the performance, combustion and emission of DMDF diesel engine

With the increasingly strict domestic emission regulations, how to reduce diesel emission without affecting its output power has become a hot and important research topic. Due to their unique physical and chemical properties, the combined use of methanol and Al2O3 nanoparticles plays a unique role in promoting combustion and reducing emissions. In this study, Al2O3 methanol nanofluid fuel was injected into the inlet and diesel fuel was injected into the cylinder to explore the influence of Al2O3 nanoparticles on the performance, combustion and emissions of diesel methanol dual fuel (DMDF) entered. The experienced results showed that with the addition of Al2O3 nanoparticles in methanol, the peak pressure and heat release rate in the cylinder of the diesel engine were improved, the combustion delay period and the combustion duration were shortened, the fuel consumption rate was reduced by up to 10.8%, and the braking thermal efficiency was increased by 12.11% at most. With the addition of Al2O3 nanoparticles, NOx, CO, HC and soot ratio emissions of the engine were reduced, among which the NOx reduction ratio was small, and the maximum reduction ratio of the last three was 28.82%, 83.33% and 29.27% respectively.

Secondary Breakup Characteristics and Mechanism of Single Electrified Al/N-Decane Nanofluid Fuel Droplet in Electrostatic Field

The combustion characteristics of nanofluid fuels have been widely investigated, but rare studies on the atomization were reported. Atomization is an imperative and crucial step to improve the combustion performance of nanofluid fuels, and the secondary breakup of droplets is an important segment for atomization to produce uniform fine droplets and distribute nanoparticles in each droplet. This paper firstly presents the secondary breakup characteristics of single electrified Al/n-decane nanofluid fuel droplets and revealed the mechanism of the secondary breakup. The results demonstrated that fine droplets could be produced in the electrostatic field and Al nanoparticles were distributed in each droplet. Before the breakup, the single electrified droplets experienced surface charge transportation, deformation, and Taylor cone formation. A gradient of the electric field deformed the droplet to produce the Taylor cone. As the Taylor cones were stabilized, the fluid was extruded from the tips of stable Taylor cones to produce jet filament parallel to the electric field direction and correspondingly broke up into fine sub droplets. At the nanoparticle concentration range of 1.0~10 mg/mL, the minimum average diameter of breakup sub droplets could achieve ~55.4 μm at 6.0 mg/mL. The Al nanoparticle concentration had a significant effect on the breakup performance by influencing the physical properties and charging. The order of the Charge-to-Mass ratio magnitude was 10−7~10−5 C/kg. Furthermore, the secondary breakup mechanism of single electrified nanofluid fuel droplets in the uniform electrostatic field was revealed by analyzing the droplet surface charge, deformation, Taylor cone formation, and nanoparticle concentration effect.