Influence of Fuel System Variations on Performance and Emission Characteristics of Combined Air-Wall Guided Mode Modified GDI engine with Alcoholic Fuels and Exhaust Gas Recirculation

GDI engines commercially existed with spray guided mode where the fuel injector placed almost vertically and sprayed fuel is occupied throughout the volume of combustion chamber. With the advanced emission norms, NOx and Soot emissions control is the major task along with lower fuel consumption. To achieve the advanced emission norms, further modifications are required before or during combustion. Combined air-wall guided mode combustion chamber modification is the advanced stage required for further improvement in mixing and superior combustion. Air-wall combined mode involved piston crown shape modification so that the modified shape should impart turbulence effects and divert the fuel/mixture flow towards the spark plug tip to initiate the combustion process. In this study, the combined air-wall guided mode gasoline direct injection engine was tested with gasoline blends using Ethanol, Methanol and N-Butanol at 20, 35 and 50% proportions under specific fixed conditions: 1500 rpm speed, 10% EGR and FIP of 150 bars with three split injections at 320˚, 220˚ and 100˚ before TDC. Tests were conducted over these gasoline blend proportions for engine performance and emission characteristics and achieved beneficial results with E20 gasoline blend over the entire applied torque values.

Water-air ejector with conical-cylindrical mixing chamber

In the paper, the hydrodynamics of the liquid-gas mixture in the mixing chamber of the ejectors at different spatial positions was analyzed and the comparative study of such ejectors was carried out. It was found that a more ordered mode of movement of the mixture in the mixing chamber is created as a result of the coincidence of the velocity vector of liquid drops and the direction of gravity in the vertical position of the ejectors. This leads to increasing the volume entrainment ratio almost twice. The analysis of the liquid-gas mixture flow in the mixing chamber, evaluation calculations and research allowed to develop and to patent a jet apparatus with a conical-cylindrical (combined) mixing chamber. It was also found that for such ejectors, the volume entrainment ratio is 15–55% higher than for a jet apparatus with a cylindrical mixing chamber due to the reduction of the resistance of the passive flow into the mixing chamber and prevention of the formation of reverse-circulating flows. A study has been conducted on liquid-gas ejectors in the range of the main geometric parameter m (ratio of the mixing chamber area to the nozzle area) 9.4–126.5, which allowed to establish its rational values at which the maximum volume entrainment ratio is achieved (m = 25–40).

Understanding the relationship between composition and rheology in alkali-activated binders

Based on the knowledge that exists today, it is generally accepted that there are basic parameters and characteristics to obtain effective mixtures for their use in 3D printing. Rheological behavior and setting time (initial and final) are those characteristics that determine workability, as well as the speed and nature of hardening of the molded pastes and, as a result, the final framework and the integrity of the resulted structure. Among the promising options for 3D printing, the literature often contains information on alkali-activated binders. In this work, an alkali-activated binding system based on electrometallurgical slag, as well as citrogypsum, a waste of the industrial production of citric acid, was studied. Some rheological characteristics of experimental binders were considered: the nature of the mixture flow under the action of torsional loads and their initial and final setting times. It was found that the joined use of both components in the experimental system “slag - water”: an alkaline activator and citrogypsum, promotes the transition of the character of the system from thixotropic to mixed: dilatant-thixotropic (for the Na2SiO3 activator) and dilatant (for the NaOH activator). It was found that the addition of alkaline activators and citrogypsum to the binding system separately in both cases helps to reduce the initial and final setting times from 18 and 22 hours to 1 hour and 1.5 hours. Also, experimental results have shown that the jointed action of both components: an alkaline activator and cytogypsum, has a synergistic effect on the setting time.

Improved model of powder blend compacting in a roll compactor

A new mathematical model of mineral fertilizer compacting using a roll compactor is developed. This model is based on the transition to the values of stress tensor components averaged over the cross-sectional area of the powder mixture flow. To define these stresses, equations of equilibrium of the elementary layer determined in the mixture by two planes perpendicular to the flow direction are composed. To obtain relatively simple analytical relations in the calculations, the hypothesis of a power-law dependence of hydrostatic pressure on mixture density, accepted in the framework of the Johansen model, was used. In order to take into account changes in the mechanical characteristics of the mixture (angle of internal friction, coefficient of external friction, transverse strain coefficient) while compacting, we approximated the known experimental dependencies of the corresponding characteristics on the density. The inter-particle cohesion parameter was taken to be proportional to the hydrostatic pressure. The model allows calculating the gap between the rolls surfaces for a given initial bulk density and the required flake density. With the known gap value, the distribution of the axial average stresses in the powder mixture, the normal and shear stresses on the rolls’ surfaces are determined. The results of the calculations of the rolls surface gap and the normal roll pressure diagram are compared with the experimental data given in the literature for the urea compacting process.