What is Fuel: Definition and 579 Discussions

A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but has since also been applied to other sources of heat energy such as nuclear energy (via nuclear fission and nuclear fusion).
The heat energy released by reactions of fuels is converted into mechanical energy via a heat engine. Other times the heat itself is valued for warmth, cooking, or industrial processes, as well as the illumination that comes with combustion. Fuels are also used in the cells of organisms in a process known as cellular respiration, where organic molecules are oxidized to release usable energy. Hydrocarbons and related oxygen-containing molecules are by far the most common source of fuel used by humans, but other substances, including radioactive metals, are also utilized.
Fuels are contrasted with other substances or devices storing potential energy, such as those that directly release electrical energy (such as batteries and capacitors) or mechanical energy (such as flywheels, springs, compressed air, or water in a reservoir).

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  1. K

    Roughly, how many kg of fuel do we need to get x lbs into space?

    Is there a ballpark or rough formula to get x lbs into space how much kg of fuel is needed to do so? I know that the more fuel you have the more fuel you also need just to carry the extra fuel!
  2. G

    What's the mean of the fertile free fuel

    Hi, everyone what is fertile free fuel ?
  3. S

    Fuel that doesnt need compression?

    Excuse the language. English is not my first language and in physics terms I might be lacking. I was just brainstorming. Is there a fuel that could be used with efficiancy in a compression free engine?
  4. K

    Need to Find OCV for H2O2 Fuel Cell

    Homework Statement Calculate the open cell voltage for an H2/O2 fuel cell operating at P=1atm and T = 100°C Homework Equations Nernst Eq: Eo+(RT/nF)*ln[(aH2)*(aO2^1/2)/(aH2O)] The Attempt at a Solution E=1.17V+((8.314J/mol-K)*(373K))/((2e-)*(96486C/e-))*ln[(PH2*PO2^1/2)/PH2O]...
  5. S

    Find the calorific value of fuel, given emission data

    I have data from exhaust gas analyzer, and I have to find the calorific value or the heating value of that particular fuel using that data. Can anyone show me how to do that please. Or if there is any other way to find the calorific value of fuel. The data is in the attached pic
  6. E

    Solid Fuel Internal Combustion Engine

    Has anyone ever built an internal combustion engine which runs on solid fuel? A system would have to use waste heat or a mechanical friction device or whatever to heat the fuel and produce vapor which would be burnt in the cylinder (similar to the way coal gas was produced). Of course the vapor...
  7. P

    Help in fuel cell main references

    Hi As I am preparing for a presentation about modern http://scopewe.com/tag/fuel-cell-2/ I need some reference books or articles about fuel cells and the technology of these cells. I appreciate any information about these cells: 1.Solid oxide fuel cell (SOFC) 2.Alkaline fuel cell (AFC)...
  8. M

    Heating Torch Using a Fuel That Does Not Contain Carbon

    I am looking for a fuel for a torch to heat an experiment to 500-1200C. We do not want to introduce exterior sources of Carbon. H2 cannot be used as a fuel because excess H2 will also throw off the results. My professor suggested SiH4, but I cannot find any information on silane as a torch fuel...
  9. S

    2 Questions - Heating room air, and fuel combustion efficiency

    2 Questions -- Heating room air, and fuel combustion efficiency Homework Statement 2 questions. In advance, i needed to translate it so i am sorry if it is states incorrect. I really did my best to do it right. 1. The density of air at 1 atm and 10.0 ° C is equal to 1.24 kg / m3. (cubic...
  10. C

    Length of time to burn fuel in a fusion reactor

    If I have a fusion reactor running at some designated power output (let's say, for instance, 5x10^8 Watts), how can I find how long it takes to burn a fuel source provided I know the composition of the fuel. For this example, let me just say I have half deuterium and half tritium? I'm not...
  11. K

    Any articles on ICF fuel pellet?

    A graduate student I know swears that there is some form of carbon and that it is very expensive to make the fuel pellets, especially to make them smooth for the ablation process. I have read they are extremely cheap but I may be thinking of just the DT fuel and not the pellet. Either way...
  12. J

    Relationship between the number of fuel elements and criticality

    I usually do not ask for this kind of stuff, but this time I really have no way to verify if this is correct(and it has to be). So here it goes: On a subcritical nuclear reactor with 100 fuel elements we read the signal of 10e-9 A. When we add 10 more fuel elements, signal jumps to 10e-8 A. How...
  13. C

    MHB How Can Rocket Fuel Expulsion Maximize a Car's Kinetic Energy?

    Really struggling with this one. In class we used velocity not speed for starters and had $m$ and $m+\delta t$. I can't figure out how to relate it to this question at all. If someone could point me in the right direction that would be great. A car is propelled by a rocket engine along a smooth...
  14. S

    Decay power and spent fuel pond

    Hello to all, i need more details about followings problems: Why nuclear spent fuel ponds must be cooling down and which is maximum allowable temperature in cooling agent? How we can evaluate decay power using theoretical formula?
  15. K

    Rocket Burning fuel causing change in mass

    I made up a scenario: Let's say I have a rocket at rest in space. The rocket initially weighs 100 kg, 50 kg of which is fuel. If the fuel burns at a constant rate of 1 kg/s and produces a thrust of 100 N out the back of the rocket, what will the rocket's velocity be after it runs out of fuel...
  16. R

    Rocket thrust, mass, speed given initial m and fuel consumption rate?

    A rocket, which is in deep space and initially at rest relative to an inertial reference frame, has a mass of 59.5E5 kg, of which 7.39E5 kg is fuel. The rocket engine is then fired for 300 s, during which fuel is consumed at the rate of 480 kg/s. The speed of the exhaust products relative to the...
  17. M

    How to Calculate Mass or Volume of Fuel from Energy Generated

    I have a value for energy output from the engine, like e.g. 10 kJ. I now need to calculate the mass/volume of fuel (diesel is used as fuel) to generate the above energy output from the engine if the engine is running at a speed of 1200 rpm and the specific fuel consumption (if needed at all) is...
  18. K

    Chernobyl How did this worker approach this fuel mass at Chernobyl?

    I accidentally happened upon this photo while researching some things about the 1986 Chernobyl nuclear disaster and I freaked out! How did this worker get so close to this mass of melted nuclear fuel in the basement of Chernobyl without receiving several lethal doses of radiation? This mass of...
  19. D

    Thorium Fuel Cycle Reaction Initiation

    In an liquid fluoride thorium reactor, how is the reaction started? My assumption would be a piece of fissile material would be somehow inserted into the fuel to introduce neutrons to the solution, but I have not found any information to show if this is how the reaction is started. If this is...
  20. K

    Fukushima Have they located the melted fuel at Fukushima?

    Have the TEPCO workers found the precise location of the melted fuel at the affected Fukushima NPP nuclear reactors? If not, have they at least hypothesized where it might be? Cameras have been inserted into the reactor pressure vessel, but the footage hasn't revealed very much in terms of the...
  21. U

    What is the most fuel efficient Turbojet engine by pass ratio of A380?

    With four Rolls-Royce Turbojet engines attached on A380, I wonder, if the optimization of fuel efficiency as its prime design factor/variable? If so, may I know, what it is air by pass ratio?
  22. Z

    Fuel usage to accelerate to 20 mph

    In an effort to approach the EPA on the subject of eliminating unnecessary stop signs in an effort to reduce fuel consumption nationally, I am trying to determine approximately how much fuel is required to accelerate from a dead stop to 20 mph. With all the variables (vehicle weight...
  23. O

    Rocket Problem: Determining the amount of fuel burned

    The set up: A 20,000kg rocket has a motor that generates a thrust of 3x10^5 N. The problem: a)What is it's initial Acceleration? b)At an altitude of 5,000m the rockets acceleration has increased to 6 m/s^2, what mass of fuel has it burned? Relevant equations: F = ma The...
  24. V

    How much rocket fuel is burned in the first mile/kilometer?

    Take a typical single-stage rocket that reaches low Earth orbit (that's around 2000 km). How much fuel is burnt just to get the thing a foot off the ground? Or a kilometer or a mile? 10%?
  25. G

    About nuclear fuel cycle simulation software

    Hello ,everybody I plan to develop a nuclear fuel cycle simulation software . Is there any body interesting it. I think this is a very complex project. :)
  26. B

    The fuel level inside a tank.

    . I do not know how to solve this problem. I need some help. How would we find out A, the angle between the horizontal and the fuel level line inside the tank of a car?. The car speed does not change, let´s say 60 km/hr, but we are driving in a roundabout. So, the fuel inside the tank...
  27. B

    Determining efficiency of fuel cells

    Hi I need to compare solid working with \frac{1}{2}O_{2}+H_{2}O+2e^{-} \rightarrow 2OH^{-} and H_{2}+2OH^{-} \rightarrow 2H_{2}O+2e^{-} and liquid fuel cells working with H_{2}\rightarrow 2H^{+}+2e^{-} and \frac{1}{2}O_{2}+2H^{+}+2e^{-} \rightarrow H_{2}O My...
  28. S

    Split of fuel oil consumption to heatup multiple type liquid

    I have three different liquids l1, l2 and l3 stored for 10 days. The liquid are required to be kept in temp x1, x2 and x3. As input i have following: 1) daily temp of all three liquids 2) daily qty i need to keep temp of all three liquid constant - to do that heating is done. Due to...
  29. 4

    Natural Gas to generate hydrogen, fuel cell?

    Hi all, one last question for today - Given steam reforming of natural gas to generate hydrogen, what is the major difficulty with it with respect to most fuel cells? Thank you,
  30. 4

    Fuel Cell, Etn, Er and polarizations

    Can anyone help me explain the elements of the fuel cell polarization curve. Please be sure to include Etn, Er, and the various polarizations. I am interested by the use of thermodynamics as well... Thank you-
  31. C

    Fuel consumption increases during winter?

    I guess that if the answer is "yes" then the difference will be neglectable, but anyway... I was wondering if during winter, fuel is less efficient than summer. During summer, there is some extra energy content in the fuel, due to increased temperature. This extra energy is added to the energy...
  32. E

    Modelling fuel economy and more economical options

    Consider a situation in which two motorists, Arwa and Bao, share the same driving route but own different sized vehicles. Arwa fills up her vehicle’s tank at a station along her normal route for US$ p(1) per litre. On the other hand, Bao drives an extra d kilometres out of his normal route to...
  33. S

    Hydrogen and oxygen used as fuel in internal combution engine

    why cannot hydrogen and oxygen not used in internal combution engine as fuel? it would be pollution free.
  34. N

    Time dependent surface temperature of a nuclear fuel rod

    I was wondering if anyone has any actual data on the surface temperature of a fuel rod as a function of time. I am really curious as I am trying out a model I found which uses the fractional calculus. Or if anyone could point in the right direction to find said data that would be great as well.
  35. S

    How to use a fuel regulator and where to place it?

    I have to design and construct an fuel system in one of my projects. In this project, I am designing fuel system which uses liquid fuel. The fuel is meant to be burnt in a gas turbine engine - thus the fuel will be injected in atomized form inside the combustion chamber. ___________ There is...
  36. C

    Meaning of fuel gas ring main?

    Aparently the fuel gas is used for the heater in the production of benzene from toluene. But once this, it goes to the fuel gas ring main which I have no clue of what it is! Help :)
  37. B

    Understanding the Role of Fuel Rods in a BWR - Explained Simply

    I need just one thing I need help to understand? The Core in a BWR just a BWR has Fuel Rods that Heat water to make Steam. But one thing when the watter Heats up is the Steam in the same place as the Fuel Rods? What I meen is this. Every photo I look at shows Fuel Rods in the Watter...
  38. R

    Is a fuel cell technically an energy storage device?

    I've heard fuel cells being called energy storage devices. However, unlike batteries, they only convert energy. They don't store anything unless you consider the brief moment of converting chemical energy to electrical energy storage time? Are there fuel cell types that store let's say hydrogen...
  39. P

    Automotive Fuel Injector Angle Within Fuel Injector Port

    I'm trying to find information regarding the angle of the fuel injector with respect to the air intake. Basically, I want to know how important it is, and how changing that angle would affect the performance of a vehicle. I'm working on a Formula SAE race car, and my team and I are looking to...
  40. A

    Equation of non-symmetric cone for fuel consumption maps

    Dear Brains I am working on fuel consumption maps to be included in vehicle simulation software to calculate the fuel consumption. To be able to create the map you need 3 things : RPM, Engine Power, and consumption (kgr/h) or efficiency of the engine (Depending on the consumption). You take...
  41. smokingwheels

    Is reducing an engines fuel consumption by 85% impossible?

    I expect to be shot down in flames but I don't mine one bit. I have just done a bit of a drive in my 28 year old Nissan Bluebird Wagon about 10% city 90% HWY...NO Fancy EFI systems or direct injection here just a plain old carburetor running slightly rich at idle. I just did a rough...
  42. T

    Fuel combustion under compression alone VS combustion under heat

    I'm just trying to figure out a theory. Forget what you know about a reciprocating piston engine, and just dream with me for a second. Say a piston could just turn around and come back down the cylinder at ANYTIME in the stroke, would the fuel always burn most efficiently? It's hard to...
  43. L

    Why would fuel cells be good for the economy?

    Congratulations, you've created a fuel cell car! Now you need electricity or fossil fuels to create hydrogen to fuel the car. So burn some coal to get electricity. How exactly does this help the environment again? What am I missing here?
  44. R

    Fuel per unit distance decreasing?

    I was reading a link i found here on physicsforums called "The relativistic rocket". There was lots of calculations of the required fuel for certain distances and such. However, I understand that time→0 when our velocity v→c. And that will mean we travel a larger distance for a shorter...
  45. L

    Fuel velocity vs exhaust velocity difference?

    hi all, i've been confused about what the difference is between fuel velocity and exhaust velocity. apparently, fuel velocity is equal to rocket velocity minus exhaust velocity. attached are screenshots of the textbook reading that confused me. if anyone can explain this section to me, i...
  46. T

    News Great Green Fleet and $26/gal fuel

    “Great Green Fleet” and $26/gal fuel http://www.foxnews.com/politics/2012/07/02/gop-in-congress-critical-navy-great-green-fleet/#ixzz1zX8phjVc?test=latestnews I'm surprised the navy pays as much as $3.60/gal for the fuel it normally uses. I would have thought it much lower. Don't they get a...
  47. R

    Help in Understanding Hydrogen Fuel Cells?

    I'm doing a presentation on Hydrogen Fuel Cells for my class, but I'm having a hard time understanding how exactly it is that they work. I'm only able to find information on fuel cells and they tend to not be descriptive on the hydrogen part. If someone could please link some articles that...
  48. S

    Efficient Rocket Fuel Ejection Using Angular Momentum

    I've been thinking. Would it be any more efficient to use the angular momentum of a spinning rocket engine nozzle to eject the rocket fuel? Just an idea. Post any questions below
  49. M

    Is the Carnot efficiency valid for fuel cells?

    So, I've read in books and on Wikipedia (see for instance http://en.wikipedia.org/wiki/Carnot%27s_theorem_%28thermodynamics%29#Applicability_to_fuel_cells_and_batteries) that the Carnot efficiency cannot be applied to a fuel cell because it is not a heat engine that produces work, operating...
  50. A

    Fuel Cell with unpressurised Hydrogen and Oxygen

    Let's say I have a balloon full of Hydrogen that is STP, and outside this balloon I have normal air (containing oxygen) which is also STP. Is there a way to produce energy by turning these 2 items into a fuel cell, if so how practical is it (in a DIY setting) and is there anything that would...
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