Utilization

An Essay Not on Renewable Energy

In the quest for greener sources of energy in consumer vehicles, all eyes seem to be turned toward finding a new means of extracting energy as well as from an entirely new source. It is a jump the country will eventually need to make, but it is not one readily taken by the economy or the general population. Using alternative energy is only part of the answer. No matter how drastic the change is, it takes time and effort to make an effect. Hybrids and electric vehicles are on the market right now, but the portion of the country that owns these vehicles still needs to increase substantially. Small changes over time are will grow throughout the United States at a quicker pace and move the country towards using environmentally friendly vehicles. While people wait to purchase hybrids and electric vehicles, people will more readily purchase cars using energy that already exists. This would allow the portions of the country not ready to make the change to alternative energy vehicles to participate in going green.  The key is not in finding new sources of energy but in using the energy that is already there.

At this time, the internal combustion engine is the most commonly used engine in vehicles today. In order to use more of the energy being produced, it is necessary to find where energy is not being utilized. In a modern internal combustion engine, chemical potential energy is released through combustion to push the top-dead-center pistons back down the cylinders for a power stroke strong enough to send the pistons past bottom-dead-center and back up the cylinder to push the burnt gasses out of the combustion chamber. As the piston moves up and down within the cylinder, it is connected to the crank shaft by the connecting rod so, as the piston moves, the crank shaft turns creating the mechanical energy used to power the vehicle  (Four Stroke). This is where the train of thought stops. What is not considered is the hot exhaust gasses leaving the engine and escaping out of the tailpipe.

In the exhaust system, there are many types of energy present that are not being used. The energy, mainly heat, leaves the engine without any work being extracted from it. With this system, no matter how much energy is put into the engine, the amount of energy produced and used will always be significantly less. In an ideal engine, the amount of energy used would be equal to how much energy is put out. The laws of physics make this ideal an impossibility, but through learning to maximize our use of the energy already present we can get closer to the elusive ideal.

The air leaving the engine, as it moves through the exhaust system, is at an extreme temperature. It moves due to the pressure created behind it from the movement of the piston forcing the burnt gasses out of the combustion chamber using the force created at the moment of combustion during the power stroke. This pressure pushes the gasses with enough force to make it out of the engine through the muffler and the catalytic converter out the tailpipe and to the outside. The energy making this happen can be used to make more power for the car; the difficulty is capturing it and transforming it into useable mechanical energy.

Since the first engine, heat has been the source of energy to make our machinery run. In the past, the steam engine used the energy from heat to excite water molecules enough to transform into steam (Steam Engines). The difference in pressure created by the cooler water and the hotter steam forces it to rise and push the piston until the pressure of the steam is released. The process then starts over creating the mechanical energy to move the machine. It is not truly the heat’s energy being used to run the engine, but instead it is the force of pressure that is used. If it were the heat’s energy being used, the additional piping and coolant used to bring the vapor back into a gaseous state would not be necessary. Once the system reaches the temperature equal to the temperature of the steam, the heat’s energy is no longer being used and the work is left to the pressure difference between the cooler water and the warm steam of the system to make it run. If the energy stored within the molecules as heat was used in the machine, the temperature of the molecules would begin to drop in proportion to the work it is doing. Even though the steam engine is obsolete, this same idea can still be applied to modern internal combustion engines. Hot gases and pressure are still being used to run our machinery and the energy found in the heat of the gasses still escapes.

While the development of vehicles that use alternative energy is important, how the energy from current technology is used also needs to be examined. How will the energy of our future cars be maximized if we cannot utilize what energy is created with current techniques? Like energy, ideas and knowledge can change form and can always be reapplied.

The recently released EcoBoost engine uses the principle of reapplied energy. It captures energy already produced from the combustion process and uses that energy to increase the cars performance when needed. The mixture of hot gasses leaving the engine moves with such speed that it can be captured by using a turbine added into the exhaust system of the vehicle. The addition, though simple, makes a big difference. A six-cylinder vehicle can now reach the same power as the typical eight-cylinder engine. This is achieved because the engine utilizes energy already being produced instead of needing to release more energy to gain the additional power, which allows it to use less fuel than the eight-cylinder engine.

Although not realized, the principle for the EcoBoost engine has been around for 90 years. The EcoBoost engine’s development came down to the matter of considering the idea and applying old technology in a new fashion. Since the 1920’s, turbochargers have been used in locomotives and diesel ships then later were applied to automobiles. These vehicles used a single large turbocharger on the exhaust system of the engine. By capturing the energy in the hot exhaust, the car can exert more power without burning more fuel.  The turbochargers worked well, but there was still room for improvement even though the theory behind it was spot on. The next step was learning how to maximize the effect while making minimal alterations to the engine itself. The largest alteration made was using two small turbochargers instead of one large turbocharger. The EcoBoost engine was developed with this modification and uses it to capture the escaping energy. As the exhaust leaves the engine, it passes through a turbine inside the turbocharger causing it to spin (How Turbo Chargers Work). This spin is used to generate the energy used to run a compressor. The compressor forces more air into the combustion chamber allowing the engine to exert more power.

Simple physics can be used to prove that changing from one large turbine to two smaller separate ones makes the process more efficient. First, using a single but larger turbine increases the mass that the exhaust has to move. This means there is more torque required for the system. Ultimately, the turbine does not reach as high of speeds nor does it reach maximum speed as quickly. With the turbine larger, it also means that the mass is distributed further away from the center of rotation giving the turbine as a whole a higher moment of inertia. The higher the moment of inertia, the more energy it takes to alter the turbine’s rotation (Giancoli 206). Using a larger turbine also puts more strain on the system because more force is needed to rotate the turbine so more pressure builds behind the turbine as it moves. Also, the larger the turbine the larger the gap between each blade, this means that more of the air leaving the engine goes past the turbine without exerting its energy on the turbine and generate energy. The effect is similar to as if the turbine were too small for its enclosure; air would move around the turbine and the energy would not be captured.

Other than the comparison between a single turbocharger and two small turbochargers, is the difference between a six-cylinder engine with EcoBoost and a basic eight-cylinder engine. When comparing a six-cylinder EcoBoost engine to an eight-cylinder engine, the EcoBoost engine is 150 pounds lighter. The mass of a car plays a role in the fuel economy of the vehicle. Most of that mass is at the front of the vehicle under the hood. The engine block is smaller because it does not need to accommodate two more pistons and a longer crank shaft along with all the hardware needed to make the two more pistons run. The material used for the turbochargers is much lighter than what is used for engine blocks and less material over all is needed to fashion two turbines than to fashion two pistons.

The power gained from using the energy in the exhaust to turn the two turbines is enough to equal and even exceed that of an eight-cylinder engine. This is mainly due to how the EcoBoost engine can generate more torque at the lower speeds that people will typically drive at. For a standard six-cylinder engine, maximum torque is just over 200 foot pounds compared to a six-cylinder engine with EcoBoost with a maximum torque of over 225 foot pounds. It is not just the amount of torque each engine has but also the speed the engine must be at to generate this torque. An EcoBoost engine reaches maximum torque at a much lower revolution speed than the standard engine. To reach peak torque the EcoBoost engine does not even need to be at 2000 revolutions per minute (RPM) while a standard six cylinder needs to be at near 5000 RPM to reach peak torque (Ford Expounds On EcoBoost Engines). When the torque of an EcoBoost engine is graphed, the torque line is nearly horizontal. As the RPM increases past 2000, the torque of an EcoBoost engine is much more stable. An EcoBoost engine’s torque remains stable at approximately 235 foot pounds when the RPM is between 2000 and 5500 giving the car a much more predictable performance meaning better control for the driver.

Another alteration was changing the fuel injectors’ location to get the maximum effect out of the compressors. The EcoBoost engine uses fuel injectors that are located inside the combustion chambers. By changing the fuel injectors’ location, the intake manifold is freed from the aerosolized fuel and allows air to move more freely into the combustion chambers. Because the air moves easier, more air is able to be forced into the cylinder to create higher pressures and thus, more power for the engine. The intake manifold is no longer exposed to the gasoline so it stays cleaner longer. Having more air and a cleaner system keeps the engine running with better performance for a longer period of time.

Unfortunately, by moving the fuel injectors into the combustion chambers, new challenges were forged, such as the fuel not vaporizing before ignition. In order for the fuel to burn, it must be allowed to vaporize completely before ignition. Ideally, the fuel would vaporize before reaching the other side of the cylinder or touching the piston. To achieve this, modifications had to be made. This means adjusting the fuel injection angle, creating a finer gasoline mist and changing the characteristics of the piston’s surface. The fuel injectors now use smaller holes and pressurize the gasoline to force it into a finer mist. With the injected fuel released in smaller droplets, it takes less time for it to vaporize.

The surface of the pistons and the fuel injection angle were also altered in order to give the mist of gasoline maximum space to evaporate. Typically, the piston is flat on the top or is slightly curved out; this has been changed to being bowl-shaped. The concave structure lets more of the gasoline evaporate before actually touching the piston. Moving the fuel injectors into the combustion chambers does create a lot more planning and work but the benefits for the EcoBoost system outweigh the extra effort put into creating it.

There are already much greener vehicles on the market than the cars using EcoBoost engines. There are hybrids and even full electric cars that are much more efficient, but their prices prevent any significant sales in this economy. The technology for greener cars is here but there is not enough of it is being used to make its impact. This economy does not allow people to afford alternative energy vehicles; however, this does not mean that people do not want to do their part in “going green” or do not want better fuel economy. Now, with the cars built using the new EcoBoost engines, people who cannot afford a hybrid can take part. The EcoBoost cars are nearly the same price as their non-EcoBoost counterparts. One thousand people taking part in a small way has a larger impact than one hundred people taking part in a big way.

Solving the energy crisis is more than a matter of discovering new ways to get energy. Even after the country makes the switch to green energy, any techniques learned by finding ways to maximize the use of produced energy can be reapplied to vehicles of the future and eventually to the manufacturing process itself. Imagine using the energy produced by a factory’s furnace to run its own lighting. A basic law of science is that energy is never created or destroyed, it simply changes form. The EcoBoost engine is a step in the right direction as it makes more power for the engine by putting energy made by the engine back into it. If more ways were discovered to use more of the energy produced by the means we use today, the energy made could stretch much further. As the world waits for alternative energy to become more affordable to the average person, the EcoBoost engine is a good start. the Solving the energy crisis means being able to maximize how we use the energy already being produced in addition to using alternative energy sources.