Automotive Science and Engineering

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Many studies have been done on hybrid vehicles in the past few years. The full hybrid vehicles need a large number of batteries creating up to 300 (V) to meet the required voltage of electric motor. The size and weight of the batteries cause some problems. This research investigates the mild hybrid vehicle. This vehicle includes a small electric motor and a high power internal combustion engine. In most cases the car’s driving force is created by an internal combustion part. A small electric motor, which can operate as engine starter, generator and traction motor, is located between the engine and an automatically shifted multi-gear transmission (gearbox). The clutch is used to disconnect the gearbox from the engine when needed such as during gear shifting and low vehicle speed. The power rating of the electric motor may be in the range of about 15% of the IC engine power rating. The electric motor can be smoothly controlled to operate at any speed and torque, thus, isolation between the electric motor and transmission is not necessary. The present study evaluates the properties of the mild hybrid vehicle, its structure and performance and proposes an energy control model for its optimum operation.

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Among human activities, motor vehicles play the most important role in air pollution. Air pollution has negative impacts on people and on the environment. In this paper the effect of oxygen-enriched air (20.8%, 21.8%, 22.8%, 23.8% and 24.8%) and different bioethanol-gasoline blends (zero, 5%, 10%, 15%, 20% and 25%) in different engine speeds (1000 rpm, 2000 rpm and 3000 rpm) on the amount of pollutants, particles, and fuel consumption were studied. To do so, a four-cylinder, four-stroke gasoline engine with Siemens fueling system was used. The results showed that when oxygen percentage in the inlet increased from 20.8% to 24.8%, the average amount of UHC, CO, fuel consumption and the number of fine and coarse particles decreased 126.75%, 11.25%, 17.02%, 77.37% and 243.25%, respectively, while the amount of CO2 and NOX increased 5.36% and 113.27%, respectively. Also the results showed that when bioethanol percentage in the mixture increased from zero to 25%, the average amount of UHC, CO2, CO and the number of fine and coarse particles decreased 104.53%, 3.45%, 34.57%, 41.42% and 96.09%, respectively, while the amount of NOX and fuel consumption increased 163.41% and 15.75%, respectively.

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Use of natural gas has been proposed as one of the solutions to reduce fossil fuel consumption such as petrol and gasoline, which emit more pollutants. In this regard, more attention has been directed toward use of natural gas due to its high calorific value and low pollution. This paper studies the effect of different fluid rotation coefficients in parallel form with a surface of a piston bowl (Swirl). And, it attempts to explore the changing effects of this indicator on power and major pollutants of sparking ignition gas engines. Three-dimensional computational fluid dynamics are employed to simulate the procedure. Open-cycle engine, the moment between air-intake-valve opens and the exhaust-valve opens, is simulated through applying combustion equations of turbulence and emissions. First, the results are validated based on experimental data. Then, an analysis of different rotation coefficients is used to compare the temperature and pressure inside the cylinder, productivity, and the amount of generated pollution. The results demonstrate that changing the shape of entrance port, which leads to concomitant change in the fluid rotation rate in the chamber, causes a slight change in the output power. But, the change has a significant impact on the production of pollutants.

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Today most countries, examine the problem of car pollution. They enacted laws to prevent environmental polluting cars. They also try to find out wither pollution standards are applied by cars manufacturers or not.  The purpose of this study is to rank domestically produced cars quality based on manufacturing technology and exhaust emissions. Variables HC, CO, O2, CO2, and λ are analyzed for 10 selected car types, and results are presented with a box chart and finally, the considered cars are ranked according to the scored values. In practice, regarding the results of pollution variable, domestically produced cars can be ranked in terms of pollution quality parameters.  According to the numeric range determined for each variable, a number is assigned to each car and finally, the average score is calculated for each car.
 

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Today, many car manufacturers can achieve emission standards through catalytic converters. The goals of this research was in tow sections. Initially, the amount of pollutants was measured to determine the role of the catalytic converters in the reduction of pollutants for 3 types of vehicles and in 50 cases, in the two stages before and after the catalytic converter. Then, to achieve the useful life of the catalytic converter, out of 750 test vehicle emissions were tested. Data analysis was done by SPSS software, which shows that catalytic converters can reduce up to 80% of exhaust emissions. This is independent of the type of vehicle. The useful life of the catalytic converters is up to 36 months, so they should be replaced at least every three years. Also, the pollutant standards of the technical examination centers are reviewed. For this purpose, the pollutants have been measured in 2200 vehicles. Due to the huge difference in technology, cars are divided into two main categories of carburetor and injector and are analyzed statistically. Eventually, for each group of these vehicles, the values of HC, CO and O₂ are obtained.