Monday, January 28, 2008

How do Car Engines Work? (How does gasoline make our cars ‘go places’)?

(Although the topic for my blog is nuclear energy, I am going to focus this post on car engines/combustion engines and improving their miles per gallon/efficiencies. I will compare combustion to nuclear energy processes in later posts.)

To start off, cars are powered by internal combustion engines. As the name suggests, these engines are powered by the combustion of gasoline. (During combustion, gasoline is ignited, releasing large amounts of energy to power a car). There are four steps to a car’s combustion cycle (commonly known as the Otto cycle). In the first step, air and gasoline enter the engine to be used in the combustion reaction; chemically speaking, combustion reactions require a hydrocarbon and oxygen to produce carbon dioxide, water, and energy. For this reaction, the oxygen comes from the air, and the gasoline serves as our hydrocarbon. In the second step, the engine compresses to increase the energy which will be produced in the explosion (HowStuffWorks, 2). During the third step, a spark ignites the gasoline, causing a reaction (the combustion reaction). The energy from this reaction forces down the engine’s turbine. The turbine then transforms this energy into rotational motion to be used by our cars. In the fourth step, the byproducts of the combustion reaction, mostly carbon dioxide and carbon monoxide, are released as exhaust. And then the cycle repeats.

While reading about car engines, I also came across an interesting article discussing ethanol’s usefulness in improving the combustion reaction. When ethanol is added to gasoline, the ethanol “enhances” the gasoline, increasing the distance that the gasoline will last your car (Journey to Forever, 3). The ethanol also decreases carbon monoxide products in the combustion reaction. Overall, the ethanol increases the efficiency of your car’s engine by a few percent, yet this reaction is still very inefficient. A lot energy is lost to heat, exhaust, and friction, making the reaction only 20% efficient (Wikipedia, 3).

It appears that combustion and gasoline are not a very efficient method of producing energy. In later research, I will compare combustion’s 20% with statistics concerning nuclear and other types of energy.

Without knowledge of chemistry, it would be difficult to describe the combustion reaction that takes place in a car’s engine. As mentioned earlier, this particular reaction requires oxygen, a hydrocarbon, and something to ignite the hydrocarbon so that it can take place. An understanding of chemistry is useful in recognizing the products of the reaction. Also, chemistry can help explain that in incomplete reactions, carbon monoxide is formed instead of carbon dioxide. Furthermore, if one understands the bonding of carbon monoxide, it is easy to see why this molecule can be dangerous.

Works Cited

Ethanol Fuel. Journey to Forever. 28 January 2008.

____http://journeytoforever.org/ethanol.html.

How Car Engines Work. HowStuffWorks. 28 January 2008.

____http://auto.howstuffworks.com/engine1.htm.

Internal Combustion Engine. 28 January 2008. Wikipedia. 28 January

____2008. http://en.wikipedia.org/wiki/Internal_combustion_engine.

*Ms. V, I had difficulty formatting the indentations and '<>' s in my citations.


5 comments:

Zach said...

great article on internal combustion engine. I didn't know that the four step cycle was called the otto cycle. Maybe you could put a graphic link on your blog....that would be interesting to see.

McLovin said...

I was also very interested by the otto cycle. It might be cool to focus on this topic instead of nuclear energy. Like you said, there is alot of chemistry invovled; it would be cool to see a picture like zach said because i didn't understand how the power from the combustion causes the rotators to move in the energy. A picture of an engine with chemistry analysis would be sweet.

James said...

I think I'll hop on the bandwagon and agree that the Otto cycle is cool and that you should include a picture of it. I thought it was really interesting that ethanol increases the efficiency of the process, and that the process itself is quite inefficient. I look forward to reading about nuclear energy processes (actually, no sarcasm).

Julia said...

Ooh, I agree with Zach as well- I always see engines visually, so a picture (perhaps an animation?) would be great. You answered your question well, but I'd like to see you go more in depth- I started getting interested when you started talking about ethanol and efficiency. I look forward to your future posts about nuclear power and other forms of energy!

gealina said...

Hey Rick, Interesting post. It's sad that the reaction is only 20% efficient... how efficient is using a car that runs on hydrogen?