30-08-2014, 03:28 PM
RECENT TRENDS IN AUTOMOBILE ENGINEERING
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ABSTRACT:
Depleting fossil fuel reserves and increasing vehicular emission have forced the attention of various petroleum industries to find and alternate fuel that will power the vehicle in future based on the present day internal design as the deposits of crude oil is expected to last for another 50 years at the minimum utilization level .the proposed fuel should suitably replace the existing fuel and at the same time it should be renewable Hydrogen is one such fuel that has been proposed for the purpose which was suitable for spark ignition engines .hydrogen combines the properties of higher calorific value ,higher velocity of flame propagation ,non toxicity as well as lowest possible emission levels that do not affect the balance of the water of the hydrosphere.
More over the by product of combustion are devoid of carbon dioxide, carbon monoxide which is the major advantage of vehicles powered by fuel cell vehicles.
Fuel cell vehicles represent one of the emerging technologies of the innovation age. An efficient, combustion less, virtually pollution free, free power source capable of being sited down town urban areas or in remote regions, that runs almost silently, and has few moving parts but these vehicles are more reality than dreams. Fuel cells are one of the cleanest and most efficient technologies for generating electricity. In the quest of environment friendly energy generation researchers have come up with comparatively much safer fuels. It is truly a green technology. Fuel cell is the practical, feasible and marketable solution to the energy crisis. The technology is extremely intersecting to people in all walks of life because it offers a mean of making power more efficiently and without pollution.
World automakers seem to believe that low emissions, high efficiency fuel cell will eventually deliver the power and the performance that users expect. Despite difficult technical and market challenges to over come, the latest crop of fuel cell powered concept car appears to exhibit many basic feature required for the success of this concept.
Fuel cell or ZEV’S as they are called are vehicles to look up for as future vehicles. The topic on fuel cell vehicles deals with all the issues and signs related to fuel cell vehicles and their future that is sometimes questioned. However the answers to these questions have been successfully dealt with in the following sub-topics:
INTRODUCTION:-
Another type of Zero-Emission Vehicle is the fuel cell powered vehicle. When the fuel cells are fueled with pure hydrogen, they are considered to be zero emission vehicles. Fuel cells have been used on spacecraft for many years to power electric equipment. These are fueled with liquid hydrogen from the spacecraft's rocket fuel tanks.
What Is a Fuel Cell?
A fuel cell produces electricity directly from the reaction between hydrogen (derived from a hydrogen-containing fuel or produced from the electrolysis of water) and oxygen from the air. Like an internal combustion engine in a conventional car, it turns fuel into power by causing it to release energy. In an internal combustion engine, the fuel burns in tiny explosions that push the pistons up and down. When the fuel burns, it is being oxidized. In a fuel cell, the fuel is also oxidized, but the resulting energy takes the form of electricity .
Hydrogen & fuel cell vehicles:
Hydrogen is the most abundant element in the universe, but it currently is not be a practical transportation fuel by itself because of storage problems. Hydrogen is normally a gas at room temperature, and storage as a gas requires large containers. Storing it as a liquid requires super-cold temperatures. And because hydrogen is the simplest element, it can even "leak" through the strongest container walls.
Use of battery unit:-
Small test batteries made under the technology department are stored in one unit to form a single module model of ten batteries.This unit is then used to power the vehicle through the power train and motor as well as the controller which are installed accordingly and this method proves useful in special cases where the fuel cell stack is not work properly due to technical difficulties.
Fuel cell design issues:
At the same time many other variables must be juggled, including temperature throughout the cell (which changes and can sometimes destroy a cell through thermal loading), reactant and product levels at various cells. Materials must be chosen to do various tasks which none fill completely. In vehicle usage, many problems are amplified. For instance, cars must be required to start in any weather conditions a person can reasonably expect to encounter: about 80% of the world's car park is legally subject to the requirement of being able to start from sub-zero temperatures. Fuel cells have no difficulty operating in the hottest locations, but the coldest do present a problem.
Benefits:
Using pure hydrogen to power fuel cell vehicles offers the distinct advantage of zero emissions, but only on the vehicle, not at the hydrogen production source. However, emissions created at a single point of production are often easier to control than those produced by a moving vehicle. A fuel cell vehicle that runs on pure hydrogen produces only water vapor—using any other fuel will produce some carbon dioxide and other emissions, but far less than what is produced by a conventional vehicle.
Fuel cell vehicles are expected to achieve overall energy conversion throughput efficiencies around twice that of today's typical gasoline internal combustion engines. The fuel cell system is being targeted by DOE to achieve 60% efficiency by 2010. Fuel cell vehicles can run on any hydrogen-rich liquid or gas, as long as it is suitably processed. Gasoline is one possibility, but in addition to pure hydrogen, alternative fuels such as ethanol, methanol, natural gas, and propane can also be used.
Why fuel cells for vehicles?
The advantages of fuel cells for transport are both environmental and economic. The only emissions from a fuel cell vehicle come from the generation of hydrogen. These emissions are hardly measurable, making fuel cell vehicles virtually equivalent to zero-emission vehicles. Fuel cell cars will have similar range and performance to cars with internal combustion engines, but the superior energy efficiency of fuel cell engines will bring a significant reduction in carbon dioxide, a greenhouse gas, for every mile travelled. If fuelled directly by hydrogen, there will be no carbon dioxide emissions at all.
Portable fuel cells:
Fuel cells can compete with batteries and generators for portable use, from a few kilowatts to power a mobile home down to a few watts to power a laptop computer. Prototypes have been publicly shown of this type of technology and fuel cell powered mobile phones and laptops are being exhibited at the World Expo 2005 in Japan.
NEW BICYCLE POWERED BY FUEL CELL:
Manhattan Scientifics Inc. has developed a fuel-cell-powered mountain bike that uses hydrogen and air as fuel and emits only water vapor as a waste product. According to its developers, the "Hydrocycle" has a top range of 40 to 60 miles (70-100 km) along a flat surface and can achieve a top speed of 18 mph (30 km/h). Because a fuel cell stack powers its electric motor, the Hydro cycle is extremely quiet and does not need to be recharged like existing electric bicycles; it only needs to be refueled. This would come as a welcome advancement for electric-bike riders frustrated with waiting hours to recharge their battery-powered bicycles
Efficiency of Fuel Cells:
Pollution reduction is one of the primary goals of the fuel cell. By comparing a fuel-cell-powered car to a gasoline-engine-powered car and a battery-powered car, you can see how fuel cells might improve the efficiency of cars today.
Since all three types of cars have many of the same components (tires, transmissions, etc.), we'll ignore that part of the car and compare efficiencies up to the point where mechanical power is generated. Let's start with the fuel-cell car. (All of these efficiencies are approximations, but they should be close enough to make a rough comparison.)
Fuel-Cell-Powered Electric Car:
If the fuel cell is powered with pure hydrogen, it has the potential to be up to 80-percent efficient. That is, it converts 80 percent of the energy content of the hydrogen into electrical energy. But, as we learned in the previous section, hydrogen is difficult to store in a car. When we add a reformer to convert methanol to hydrogen, the overall efficiency drops to about 30 to 40 percent.
We still need to convert the electrical energy into mechanical work. This is accomplished by the electric motor and inverter. A reasonable number for the efficiency of the motor/inverter is about 80 percent. So we have 30- to 40-percent efficiency at converting methanol to electricity, and 80-percent efficiency converting electricity to mechanical power. That gives an overall efficiency of about 24 to 32 percent
Battery-Powered Electric Car :
This type of car has a fairly high efficiency. The battery is about 90-percent efficient (most batteries generate some heat, or require heating), and the electric motor/inverter is about 80-percent efficient. This gives an overall efficiency of about 72 percent.
But that is not the whole story. The electricity used to power the car had to be generated somewhere. If it was generated at a power plant that used a combustion process (rather than nuclear, hydroelectric, solar or wind), then only about 40 percent of the fuel required by the power plant was converted into electricity. The process of charging the car requires the conversion of alternating current (AC) power to direct current (DC) power. This process has an efficiency of about 90 percent.
So, if we look at the whole cycle, the efficiency of an electric car is 72 percent for the car, 40 percent for the power plant and 90 percent for charging the car. That gives an overall efficiency of 26 percent. The overall efficiency varies considerably depending on what sort of power plant is used. If the electricity for the car is generated by a hydroelectric plant for instance, then it is basically free (we didn't burn any fuel to generate it), and the efficiency of the electric car is about 65 percent.
Surprised?
Maybe you are surprised by how close these three technologies are. This exercise points out the importance of considering the whole system, not just the car. We could even go a step further and ask what the efficiency of producing gasoline, methanol or coal is.
Efficiency is not the only consideration, however. People will not drive a car just because it is the most efficient if it makes them change their behavior. They are concerned about many other issues as well. They want to know:
Is the car quick and easy to refuel?
Can it travel a good distance before refueling?
Is it as fast as the other cars on the road?
How much pollution does it produce?
Fuel cell cars are a long way off:
Hybrid cars already exist as commercial products and are available to cut pollution now. On the other hand, fuel-cell cars are expected on the same schedule as NASA's manned trip to Mars—and have about the same level of likelihood.
CONCLUSION: -
We have succesfully studied the various technicialities and the experimental procedures carried out by the various automobile companies and their respective research and development departments in depth which do provide a ray of hope .the practical implementation being’s dependancy on oil reserves and their rising costs and their by stabilise the economy for the common man and hence make the environment polution free which is the ultimate goal