Chemical Awareness June 2014 | страница 15

What is a Combustion Engine?

The internal combustion engine is an integral part of our life that very few people know about it. A combustion engine is an engine that relies on a combustion reaction to create energy. A combustion reaction is when some type of fuel containing carbon and hydrogen is burned in the presence of oxygen. The products of a

combustion reaction are always

water and carbon dioxide. Often, a fuel source is burned in a chamber. “When fuel is burned, it gives off energy in the form of heat, which creates the expansion of gas.” (Internal combustion engine). This explosion of energy is useless unless channeled in a small area. For example, when the gunpowder in a gun is lit, the explosion is channeled through the barrel of the gun, which forces out the bullet. Without this channeling, the gunpowder would simply explode and the energy would be wasted (Internal combustion engine).

In a combustion engine, the

energy must be channeled. In cars, the energy is carried from the cylinder to the pistons.

Pistons are structures in the engine that help create kinetic energy. The energy from the

cylinder forces the pistons to

move up and down in a process called reciprocating motion (Internal combustion engine). In a car, the pistons are attached to a crankshaft. The reciprocating motion of the pistons turns the crankshaft and, in turn, the wheels.

History of Combustion Engine and Impact on Society

The idea of an internal combustion engine first came from a French physicist named Nicolas Carnot. He published the idea in 1824 in a book about thermodynamics. At the time, the idea was impractical because there was a lack of available fuel (Jean-Joseph-Étienne Lenoir). Later, Jean-Joseph-Étienne Lenoir created the first practical internal combustion engine in 1859. In 1863, he went on to create an improved version that could power carriages (Jean-Joseph-Étienne Lenoir). Over time, improvements were made to the internal combustion engine for increased efficiency.

The invention of the internal combustion came amidst a big change in the world known as the Industrial Revolution. It was a period of time from the middle of the 19th century to the early 20th century when technologies of all aspects of life were improving. Innovation occurred in fields such as medicine, transportation, manufacturing, farming, etc.

(The Internal Combustion Engine). The internal combustion engine played a big role in transportation and industrial plants. In fact, it is conceivable to think the Industrial Revolution could not have happened without the internal combustion engine. Without the Industrial Revolution, some of the technologies that society enjoys may have never been invented.

Although the internal

Environmental Problems

Although the internal combustion engine has greatly helped society, it has also created many unseen environmental issues. All these environmental issues, which will be discussed below, stem from the internal combustion engine’s consumption of fuel.

Emissions

One of the greatest problems with the internal combustion engine is the emission. An emission is a product of the combustion reaction that takes place in the engine. For any combustion reaction, some type of fuel is burned in the presence of oxygen. This always creates two products, water and carbon dioxide.

Carbon dioxide is a= known greenhouse gas. When released into the atmosphere in large quantities, it can trap heat from the sun and prevent it from leaving the Earth, which is a possible contribution to global warming (The Internal Combustion Engine). Carbon dioxide from fuel combustion makes up 82% of the carbon dioxide in the atmosphere (Greenhouse Gases, Climate Change, and Energy).

It is also believed that global warming causes many other environmental problems including higher ocean levels, melting of polar ice caps, increased rain, increased drought, and more extreme temperatures. The combustion engine has been blamed for many of the environmental issues we face. In fact, in Figure 1, we can see the increase of carbon dioxide in the atmosphere. Unsurprisingly, this rise correlates with the surge of the combustion engine’s emissions.

Figure 1: This graph shows a rise in the concentration of carbon dioxide in the atmosphere and a rise in emissions from combustion engines (Greenhouse Gases, Climate Change, and Energy).

*Note: Anthropogenic means an affect or object that comes from human activity.

The rise in global temperatures,also known as global warming, correlates with an increase use of the internal combustion engine and an increase in emissions. Since 1880, there has a steady increase in the average temperature of the world (A Warming World).

Although it has yet to be proven, many scientists believe that the increased use of combustion engines’ emissions is the reason behind for global warming and the main issue associated with it, climate change.

Obtaining Fuel

An essential component of the combustion engine is fuel. The crucial role the combustion engine plays in our lives today has driven our need for fuel, which are commonly known as fossil fuels. Examples of fossil fuels are oil, coal, and natural gas. Obtaining these fossil fuels involves many different complex procedures. For example, companies must go through a process called oil drilling in order to get oil. In Layman’s terms, oil drilling is simply drilling a metal bit into hard rock to take out oil from the ground (Oil well drilling). Whether drilling on land or offshore, the process is very similar.

One of the biggest concerns with offshore drilling is the adverse environmental effect. If something goes wrong on an offshore drilling site, billions of gallons of oil can pour into the ocean. If an accident happens near the shores, seabirds often get covered in oil. This thick crude oil makes it hard for them to fluff their wings, which they must do in order to stay warm. Even if an explosion is far offshore, the oil will always come to the surface of the water. Birds who skim the water surface for fish will lose a source of food and, in their attempt to get fish, ingest large amounts of oil. Oil spills can also cause plants and animals that live on the shore to suffocate (Oil spills). When these animals die, scavengers who feed off of their bodies are also indirectly ingest the oil. Ingesting oil kills some animals right away, but usually results in kidney, liver, and brain damage (Effects of Oil on Wildlife and Habitat).

Oil spills can often affect animals in the future. It is very difficult to remove millions of barrels of oil out of water. Even years later, there are still hints of oil in these environments. “Oil has the potential to persist in the environment long after a spill event and has been detected in sediment 30 years after a spill.” (Effects of Oil on Wildlife and Habitat).

Air Pollution

Air pollution is the presence of harmful airborne chemicals in the atmosphere. The Gale Encyclopedia of Science states, “Air pollution is a serious health issue. According to the World Health Organization, nearly five million people die annually from causes directly due to air pollution. Examples include aggravation of asthma, emphysema, bronchitis, lung disease, and heart disease” (Air Pollution).

One of the leading causes of air pollution is emission from burning fossil fuels. As we know, fossil fuels are essential in combustion engines.

Question for Mrs.Radebe: The biggest thing that contributes to air pollution are plants that burn coal. The only time any reading talks about emissions from engines is involving smog, but when I only found a mention of smog relating to car exhausts in one reading. What do I do?

New Technology

Since the invention of the combustion engine, there have been more innovations that have increased efficiency. In recent years, this push has been even greater due to environmental concerns. One idea is a technique called exhaust gas recirculation. This involves taking the exhaust gas from an engine and recirculating it back into the engine. Studies from Jilin University, in China, show that this technique decreases the amount of carbon dioxide emissions. The study states, “ emissions decreased with the EGR (exhaust gas recirculation) level increment" (Studies from Jilin). It is also used in an older technology called the BICR self-recuperative burner (Self-recuperative burner).

Alternate Fuel Sources

Over the years, many fuels have been discussed to possibly replace fossil fuels. The top examples are ethanol (C2H6O), biodiesel (animals-fat or vegetable oil based), propane(C3H8), natural gas (methane mixed with other hydrocarbons), and hydrogen gas (H2). While all of these provide a “clean” fuel source, none are practical: there are very few cars that can run on these alternate fuel sources, there are very few stations that provide these fuels for cars, there are hefty expenses in making fuel, and they are inefficient in offering less power and miles per gallon (Alternative Fuel Vehicles).

Conclusion

Internal combustion engines have played a crucial role in the industrialized world since the mid 1800’s. However, the negative effects the engines create on the environment cannot be ignored. The harmful emissions of the internal combustion engines and the consequences of seeking fuel have powerful ramifications for the world down the road.

Internal Combustion

By: David Ceasar

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