Determining the Efficiency of a Fuel

In summary, the author is trying to determine which fuel is the most efficient to power a car or truck. They are looking at the energy per unit mass and emissions.
  • #1
madoxx
7
0
Hi,

I'm trying to calculate the efficiency of fuels such as gasoline, diesel, methanol, and ethanol.

I have collected several properties such as energy content per gallon (btu) and densities for each fuel.

I'm a bit confused as to how i can calulate these fuels' efficiencies. Traditionally, i was taught Efficiency=actual/theoretical * 100%

How can i approach this problem??
 

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  • #2
Fuels, alone, don't have efficiencies. If you burn something, 100% of the energy of the reaction is available to you to do something with* - it's what you do with it that has an efficiency. So what are you really looking for here - efficiency of thermodynamic cycles? Cost efficiency? Energy per unit mass?

*Caveat - depending on how you burn it (how much oxygen and other gases, pressure, etc.), you may get more or less than the optimal energy from the reaction.
 
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  • #3
Sorry i was not clear... I am comparing fuels to power cars/trucks. I want to determine which fuel is the most efficient at powering these vehicles. I guess i am looking for:

-which fuel will provide the most energy per kilogram
-produce the least harmful emissions
 
  • #4
Again, like Russ already stated, fuels do not have an associated efficiency by themselves. The efficiency measure comes from the engine/machine that is using the fuel.

Emissions are also heavily dependant upon the process that is using the fuel. For example, two cars can have the same fuel, but because one of the cars has a higher combustion temperature, it will, most likely, put put more NOx.

Fuels will have parameters that you are interested in. For example, the energy per unit mass is stated in the fuel's lower heating value. It will be in units of BTU/lbm or MJ/kg. A quick look here: http://www.chevron.com/products/prodserv/fuels/bulletin/motorgas/img/500/fig_1-6.gif shows that there is an apparent correlation in fleet activities between a fuel's heating value and fuel efficiency. The rest of the article is here: http://www.chevron.com/products/prodserv/fuels/bulletin/motorgas/1_driving-performance/pg4.asp

You might also want to take a look here: http://www.f6rider.com/Valk2/every_thing_you_ever_wanted_to_k.htm [Broken]
 
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What is the definition of fuel efficiency?

Fuel efficiency is a measure of how well a fuel source is utilized to produce energy. It is typically calculated by dividing the amount of energy output by the amount of fuel input.

Why is determining fuel efficiency important?

Determining fuel efficiency is important for several reasons. It allows us to compare the effectiveness of different fuel sources and technologies, helps us make informed decisions about energy usage and conservation, and can even impact the cost and availability of fuels.

What factors affect the efficiency of a fuel?

The efficiency of a fuel can be influenced by a variety of factors, including the type and quality of the fuel, the technology used to convert the fuel into energy, and external factors such as weather and altitude.

How is fuel efficiency measured?

Fuel efficiency is typically measured in units of energy per unit of fuel, such as miles per gallon (mpg) for vehicles or British thermal units (BTUs) for household heating systems. It can also be expressed as a percentage, with 100% representing perfect efficiency.

What are some methods for improving fuel efficiency?

There are several ways to improve fuel efficiency, including using more efficient technologies and processes, reducing energy waste, and incorporating renewable energy sources. Regular maintenance and proper use of fuel can also help improve efficiency.

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