Search

In the paper, the effect of water injection and different air/fuel ratio (AFR) on the gasoline engine performance and emissions was investigated theoretically. A four cylinder SI engine model was built using GT-Power professional software. The gasoline fuel was injected directly to the cylinder and the water was injected into the intake manifold with different mass flow rate. The calculated engine outputs were: cylinder pressure and temperature, brake torque, brake power, mean effective pressure, thermal efficiency, carbon monoxide, hydrocarbon, and nitrogen oxide emissions. The results of simulations shows that the increased water mass flow rate resulted in improved engine performance and decreased emissions compared to neat gasoline fuel. However, we found that the excessive increase of the water amount inside the cylinder resulted in deteriorated engine performance and, consequently, poorly combustion efficiency.

The internal combustion engine is considered as one of the main sources for air pollution due to hydrocarbon fuel combustion. The increased of the land transport usage require improvement the engine efficiency and combustion process technology to reduce engine emissions. A turbocharged engine and the gaseous fuel replacement are a green tools proposed by researchers to enhance fuel saving and emissions reduction. In this paper both methods have been investigated. The methane fuel is a preferred gaseous fuel due to it is lower carbon to hydrogen ratio resulting in less HC and CO emissions. In this paper a turbocharged compression ignition engine with methane/diesel dual fuel is simulated using professional GT-power code to investigate the effect of methane percentage in mixture on the engine performance and emissions. A turbocharged 6 cylinders compression ignition engine has been built and investigated. During the simulation the methane/diesel ratios were varied from pure diesel with zero percent methane to 90% methane concentration by mass with 10% increment every run. The results show that the engine brake power and specific fuel consumption increased while thermal efficiency decreased for lower CH4 concentration. For higher CH4 percentage the brake power and thermal efficiency increased while specific fuel consumption decreased. Moreover, NO emission has 35% reduction compared to neat diesel fuel when 50% of methane added to the mixture. Conversely, the CO and HC concentration increased when the methane ratio is less than 50% compared to neat diesel combustion. In general, the engine efficiency improved when methane added to diesel fuel in CI engine with turbocharger boost resulting in less emissions and cleaner environment.

Several automobile manufacturers are interested in investigating of dual fuel internal combustion engines, due to high efficiencand low emissions. Many alternative fuels have been used in dual fuel mode for IC engine, such as methane, hydrogen, and natural gas. In the present study, a reactivity controlled compression ignition (RCCI) engine using gasoline/diesel (G/D) dual fuel has been investigated. The effectof mixing gasoline with diesel fuel on combustion characteristic, engine performance and emissions has been studied. The gasoline was injected in the engine intake port, to produce a homogeneous mixture with air. The diesel fuel was injected directly to the combustion chamber during compression stroke to initiate the combustion process. A direct injection compression ignition engine has been built and simulated using ANSYS Forte professional code. The gasoline amount in the simulation varied from (50%-80%) by volume. The diesel fuel was injected to the cylinder in two stages. The model has been validated and calibrated for neat diesel fuel using available data from the literature. The results show that the heat release rate and the cylinder pressure increased when the amount of added gasoline is between 50%-60% volume of the total injected fuels, compared to the neat diesel fuel. Further addition of gasoline will have a contrary effect. In addition, the combustion duration is extended drastically when the gasoline ratio is higher than 60% which results in an incomplete combustion. The NO emission decreased drastically as the gasoline ratio increased. Moreover, addition of gasoline to the mixture increased the engine power, thermal efficienc and combustion efficienc compared to neat diesel fuel.

The spark ignition engine is the most widely used in land transport sector. Hence, studies to predict and improve its behavior continue to be essential. The behavior of the intake and exhaust systems is important because these systems govern the air flow into the engine's cylinders. Inducting the maximum air flow at full load at any given speed and retaining that mass within the engine's cylinders is a primary design goal. The higher the air flow, the larger the amount of fuel that can be burned and the greater the power produced. The important parameter is the volumetric efficiency along with equal air flows to each engine cylinder. The valves and ports, which together provide the major restriction to intake and exhaust flows, largely decouple the manifolds from the cylinders. In this work it was intended to find out the effect of variable valve lift and throat diameter on the performance of the SI engine, namely volumetric efficiency, power, brake specific fuel consumption, and pollutants. Hence, it contributes toward having greener cars in the future. A specially designed computer program (Lotus) was used to predict the gas flows, combustion and overall performance. The results of this investigation show that increasing the valve lift is relatively more effective than throat diameter in boosting volumetric efficiency and power and reducing specific fuel consumption, nitrogen oxide and carbon monoxide emissions. A 10% increase in valve lift resulted in an improvement of 1.8% in η v , 3.3% in power and a decrease of 1.5% in BSFC and (0.3–0.8)% in engine emissions. However, a 10% increase in valve throat diameter causes 50% less effects than the valve lift.

Internal combustion engines are a main power source for vehicles. Improving the engine power is important which involved optimizing combustion timing and quantity of fuel. Variable valve timing (VVT) can be used in this respect to increase peak torque and power. In this work Artificial Neural Network (ANN) is used to model the effect of the VVT on the power and genetic algorithm (GA) as an optimization technique to find the optimal power setting. The same proposed technique can be used to improve fuel economy or a balanced combination of both fuel and power. Based on the findings of this work, it was noticed that the VVT setting is more important at high speed. It was also noticed that optimal power can be obtained by changing the VVT settings as a function of speed. Also to reduce computational time in obtaining the optimal VVT setting, an ANN was successfully used to model the optimal setting as a function of speed.