Papers by Keyword: EGR

Abstract: Petrol engines are known for their simplicity, low cost and maintenance. However nowadays use of two stroke petrol engines are fading away from the market. An attempt has been made here to revive the use of these old engines by using Exhaust Gas Recirculation (EGR) to improve performances.Short circuiting of fresh charge is an important contributing factor for reduction in performance in two stroke engines. Our project is aimed to reduce short circuiting of fresh charge by admitting cooled exhaust gas to pass through reed valves fitted at the upper end of the transfer passage, in a crank case scavenged two stroke engine. Reed valves were provided at the upper end of the transfer passage using a flange arrangement. Exhaust gas temperature at around 400⁰ was cooled using a heat exchanger to avoid pre-ignition inside the engine cylinder. The performance of the engine is tested using eddy current dynamometer. The study indicates an appreciable decrease in specific fuel consumption and in HC/CO emissions in a crank case scavenged two stroke engine.

Abstract: 316L stainless steel is a well known advanced material for its good corrosion resistance in many aggressive situations. As the quality of different manufacturer of the stainless steel may vary in some degree, this paper studied the corrosion resistances of three 316L stainless steels which supplied by three manufacturers. The results show that the difference of the corrosion rates of the three 316L stainless steels in 5% H₂SO₄ or 3.5%NaCl solutions is one time in quantity. The reasons for the difference can be explained by compositional and metallographic factors.

Abstract: This paper presents anexperimental study on reduction of NO_x emission of a turbochargedengine fuelled with DME by means of EGR. Effects of EGR rate on engineefficiency and emission behavior was evaluated. The results show that the EGRcould be used as an effective way to reduce NO_x emission. NO_x isreduced almost linearly with increase of EGR rate. At low load condition, theNO_x emission is reduced by 80% with 40% EGR rate without any economypenalty. At high load condition, the same substantial reduction of NO_x couldbe achieved with only 20% EGR rate. While the HC and CO emissions are increasedwith increase of EGR rate. However, it is worth noting that EGR had a negativeeffect on fuel consumption at high load. Low EGR ratio should be taken at highengine load condition.

Abstract: A calculation model of turbocharged diesel engine was developed based on one-dimension simulation software GT-power,which can provide a steady boundary condition for the flow field analysis of EGR system.The three-dimension simulation software Fluent was applied in establishing the flow field model of the air-intake system under different air inlet position to analize the distribution of the exhaust gas,and then obtained the impact of the EGRs air-inlet position to uniformity of EGR system, thereby we could acquire the parameters which achieves the best maching between the EGR system and the diesel engine, it also provided a reference for engine performance optimization.

Abstract: A new combustion concept, which is viewed increasingly as a probable solution to these issues is Controlled Auto-Ignition (CAI) Combustion. In such an engine, a homogeneous mixture of air, fuel and residual gases is compressed until auto-ignition occurs. Due to its significantly low temperature combustion, NOx will be dramatically reduced while the mixture will be under ultra-lean fuel-air condition, thus able to achieve high efficiency and low emission. In the case of two-stroke engine, problem of poor combustion efficiency and excessive white smoke emission can be addressed by the incorporation some features that will ultimately convert a typical two-stroke engine into an efficient CAI engine demonstrating the best of both features. Due to its inherent high internal residual gas rate in partial load operation, the two-stroke engine has been the first application to benefit from the unconventional CAI combustion process. This paper will concisely discuss the utilization of hot burned gas for induction thus imposing a CAI combustion feature onto two-stroke cycle engine. Among the features incorporated are the increasing in the level of Exhaust gas Recirculation and cycle-by-cycle uniformity of the air-fuel ratio (AFR) supplied to cylinder, which will be crucial in creating a suitable temperature within the engine’s combustion chamber.

Abstract: Effects of EGR on the performance of bio-diesel engine were studied on a single-cylinder bench. The results showed that EGR can reduce NOx emission and NOx reduction increased with EGR rate. When EGR increases too much, due to the deterioration of combustion, CO and HC emission increased distinctly. When the EGR rate is lower than 25%, CO, HC and PM emissions increasing is tolerable, which means that 25% EGR rate can be used to improve NOx emission of bio-diesel engine.

Abstract: The effects of EGR operating mode on particulate morphology were investigated for a 5.79-liter diesel engine which was equipped with a turbocharged and inter-cooled air induction system, a common-rail direct fuel injection system, and an EGR system. Morphological characteristics, such as primary particle size, number concentration and aggregate particle size were investigated by a transmission electron microscope (TEM) analysis and a electrical low pressure impactor (ELPI) under engine operating conditions of 0.41 in fuel/air ratio at different exhaust gas recirculation (EGR) rate from 0～35%. The experimental results indicated that primary particle were in the range of 17.05nm～18.34nm, which increased with increased EGR rate. As EGR rate increased, aggregate particle size were measured in a narrow range from 120nm to 170nm.

Abstract: Turbocharger is an effective technique to achieve higher thermal efficiency reduced emissions. And hybrid turbocharger is proven to be a promising technique to eliminate the well-known 'turbo-lag' effect of the turbocharger. In this paper, a global optimization of hybrid turbocharger technique with variable geometry turbine and exhaust gas recirculation was carried out. The diesel engine was modeled by GT-SUITE software, which is a 1D simulation environment. Moreover, a dynamic programming based optimizer, which was developed in Simulink, was integrated with the diesel engine model. Simulations results show that the optimized parameters can improve the engine fuel economy significantly under Chinese typical urban driving cycle.

Abstract: In order to study the effect of hot EGR on combustion characteristic of hydrogen internal combustion engine (HICE), experimental study was taken on a 4 cylinder, 2.0L HICE. The speed was 3000rpm, and the throttle was fully open, the load was adjusted through quality regulation. When the hydrogen flow ratio was 2.79kg /h, the ignition advanced angle was optimized as maximum brake torque (MBT) timing, then the EGR valve was opened, and EGR valve was adjusted to control the flow of exhaust gas that back into the intake manifold. The test results show that: as the EGR ratio changing from 0(the EGR valve is fully closed) to 43.8%(the EGR valve is fully opened), the in-cylinder pressure is decreasing with the EGR ratio increasing; the coefficient of variation in indicated mean effective pressure (imepCOV) is not changing significantly at high load conditions, changing range is less than 1%; CA50 is postponed from 11.8oCAto15.2 oCA with EGR ratio increasing.

Abstract: To carry out electronic control EGR strategy in diesel engine the calculation model using GT-POWER is built. The thesis uses simulation software GT-POWER to establish the calculation model of 4JB1 intake system of turbocharged diesel engine with EGR system and the results agree well. According to the simulation results, it can predict the main performance indicators of the diesel engine when it works at the maximum torque condition, which includes A/F, IMEP, Maximum Pressure, and Intake Pressure and so on. Then after controlling the volume of gas by modifying the EGR valve, it can find out the regulation how EGR effects the engine's emissions, torque, power and the inlet temperature of turbo. Referring to the simulation results, it includes from four aspects：EGR can significantly improve the quality of emission gas; NOx and PM have a trade-off relationship; applying higher EGR rate in heavy load can lead to the low torque and power less; the inlet temperature of turbo increases with the augment of EGR rate. In the experiment, the inlet oxygen concentration method is used to determine the EGR rate, and to realize it, the oxygen concentration detection module is also successful designed. Then a close-loop control strategy is proposed based on the EGR rate. It proves it is feasible to guide the ECU programmer development by the simulation results of engine control strategy. It is also can be referred by other engine control systems development.