Lecture # 6 Automobiles and the environment
Environmental impacts • Air pollution Automobiles are responsible for a tremendous amount of air pollution. - The main source of CO and hydrocarbons was Incomplete combustion of fuel. - Nitrogen oxides were formed during combustion
Example 1: Calculate the percentage reduction in CO, HC, and NOx Exhaust emissions from a new passenger car in 1997 Relative to an uncontrolled car in 1967. Grams per mile
Despite these impressive reductions in new car emissions, the air Quality impacts of automotive emissions continue to be of concern, because of: 1- Increasing vehicle population
It is noticed that the total number of vehicles on the road Continues to grow, more vehicles caused more emissions 2- increasing travel per vehicle 3- Departures from federal standards 2. Greenhouse Gas emissions Example 2: Annual CO2 emissions from cars. Estimate the total annual Emissions of CO2 from gasoline-burning vehicles in the united states in 1995. the density of gasoline is 739 g/L. the total gasoline Consumption by motor vehicles was 455*109 liters/yr. we had 352 g CO2 Per 114 g of fuel burned.
Example 3: Automobile solid waste, estimate the total quantities of (a) recycled materials (b) solid wastes from US passenger car retirements in 1995. Based on 1995 data, assume that 95% of retired vehicles undergo recycling and that 75% of each car’s total weight is recovered. Use the average weight of 1985 vehicles to estimate the per-vehicle Weight of cars retired in 1995 (in millions)
4. Other environmental impacts • Lead emissions • CFC emissions • waste motor oil • waste tires
Energy efficiency -the engine including all auxiliary system and standby losses. -the drive-train includes transmission, gear and drive wheels
Example 4: Calculate the power needed to maintain a speed of 25 m/s on a level highway for a midsize car weighing 15000 N. The vehicle has a cross-sectional area of 2 m2 and a drag coefficient of 0.5. The coefficient of rolling friction is 0.02, and the density of air is 1.2 kg/m3
- Power for acceleration Example 5: The car in previous example accelerates from rest to 25 m/s in 10 seconds Calculate the average power required in the absence of air Resistance and road friction.
ENGINEERING CLEANER CARS 1- Designing For Energy Efficiency 2- understanding pollutant formation
Engine design is continually changing, mostly driven by the demand for better fuel economy and lower emissions. Small design changes such as improved valve stem seals prevent lubrication from entering the combustion chamber and exiting the exhaust. Moving the top piston ring higher on the piston helps reduce the crevices that unburned fuel can "hide" in and reduces hydrocarbon emissions. Improved cylinder bore geometry stability allows the piston rings to seal better and prevents oil from entering the combustion chamber. New fuel injectors give more consistent fuel spray patterns allowing for more complete combustion of the fuel.
Bioethanol: - Bioethanol comes from plants and is a renewable resource. - Local emissions are up to 70% lower than standard petrol or diesel cars Biodiesel: - Biodiesel is a renewable fuel that is produced from the oil of crops - It gives a 60% reduction in C0² Hydrogen: - Hydrogen fuel is produced from either the breakdown of a hydrocarbon source or by the electrolysis of water.
5- Alternative Vehicles - Battery Power Electric Vehicles Rechargeable batteries used in electric vehicles include lead-acid, NiCd, nickel metal hydride, lithium ion, Li-ion polymer Electric vehicle in Malta
Clever car has three wheels, holds half as many passengers (two) than most cars do and manages to emit less then half the CO2 emissions than even the most efficient cars currently for sale. The vehicle was designed at the Technical University of Berlin