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. Z

    Automotive Loss of gaseous volume because of fuel combustion

    Hi, 1st and general case: 2 H2 and 1 O2 take up 1 liter of volume at, for example, 20°C, before combustion. After combustion and cooling down to 20°C, how much volume do the exhaust gases take up? Since the stoichiometric relationsship is 2 mols of H2 for every mole of O2, so those three moles...
  2. Y

    Understanding Fuel Hose Markings: What Does "NOH-F" Mean?

    Ok the fuel hoses on my car, I see "NOH-F" written on them, along with some numbers. Just googling fuel hose, it seems "NOH-F" is on most fuel hoses. But what does it mean? I tried to search Google for an answer, but nothing. I hope somebody ok here can tell me the meaning, if it's some sort of...
  3. J

    Fuel Cell Reaction Question - is this right?

    The quantity (dE_dP)_T can be derived using the Gibbs-Helmholtz equation which states that dE = TdS - PdV + μdN where E is the internal energy of the system, S is the entropy, V is the volume, N is the number of particles and μ is the chemical potential. Differentiating this equation with...
  4. E

    Reversible operation of fuel cell

    Can someone explain me what does the underlined part of the following passage mean? "The reversible operation of a fuel cell implies that the external circuit exactly balances its emf, with the result that its current output is negligible. In actual operation under reasonable load, internal...
  5. Islam Nabil

    MCNP lattice of the fuel assembly input file?

    There is an input file for a simple 16 x 16 lattice fuel assembly. I have a message blocking the run of the code; "bad trouble in subroutine newcel of mcrun source particle no 1 random number 6647299061401 zero lattice element hit." What is wrong?
  6. P

    B Calculating Fuel Efficiency of Rocket Going Near c

    How would you calculate the fuel efficiency of a rocket (around 10 tonnes) going near the speed of light?
  7. L

    Are spent nuclear fuel rods radioactive?

    Are spent fuel rods radioactive and are the spent fuel rods cooling pools discharging radioactive water (tritium) into the environment?
  8. hilbert2

    Reactive metal wires in a fuel oxidizer mixture

    Suppose there's some slow burning pyrotechnic mixture like KNO##_3## with powdered charcoal, and several really thin threads/wires of magnesium metal (or zirconium or magnesium/aluminum alloy) are made go through a pile of that mixture. Now I would guess that because a mixture of finely powdered...
  9. J

    I Does Pulse and Glide only work with manual transmissions and a kill switch?

    When car drive uphill, gravity/weight has drag component, that is reason why you must add more throttle compare to ligther car at same constant speed uphill. So logicaly car increase fuel consumption. But if you drive downhill, gravity/weight has thrust component, so your top speed("terminal...
  10. gggnano

    What's wrong with this math: A lot of thrust and almost no fuel?

    So according to this if you need a force that can lift a human and even an extremely ultra-light craft (1500 N) and have a velocity of 200 m/s you can eject extremely small amount of fuel through the nozzle: 0.0007 or less kg per second for as long as you're using 15 MPa pressure which is doable...
  11. J

    I Car drag coefficent vs fuel consumption link

    Car has drag coeffecient of 0.35 and drink 5L/100km, if car Cd is reduced to 0.20 and everthying else stay the same(frontal area,power,weight etc),how much will car drink? Is it possible to calcualte this or we need something more? I am interested if exist direct link/formula between Cd and...
  12. G

    Model Fuel Assembly w/ Gamma Source: Solving a Sampling Problem

    Hi everyone, I'm making a fuel assembly model and I would like to have a cylindrical gamma source on each fuel rod to measure the decay heat of a fuel assembly but I'm struggling to define the source since it is in a repeated structure. This is the geometry of my model: Level 2 : cells 1, 2 3...
  13. Ozen

    Bi-propellant Liquid Fuel Engine Pressures Before Thrust Chamber

    Been reading Rocket Propulsion Elements 9th Edition and got approval from my university to design a bi-propellant liquid fuel rocket engine for my senior design project, and I've been understanding everything so far but I haven't quite found an answer to how the pressure works throughout the...
  14. A

    Inconsistent flow rate measurements of an engine diesel fuel

    I am measuring the volumetric flow rate of a diesel fuel using "Turbines" flow meter, both in the supply and return fuel lines of an industrial diesel engine (https://www.cat.com/en_US/products/new/power-systems/industrial/industrial-diesel-engines/18398034.html – coupled with a generator for...
  15. M

    Researching Turboprops: Fuel Comparison of Hydrogen, Methanol, & Jet A1

    Hello I'm trying to get some good reference material so I can do a literature review on Turboprops and a comparison of PSFC of Hydrogen/Methanol/Jet A1 fuels for turboprops. If anyone knows any good source material for this please let me know as I have struggled to find anything. Regards, Michael
  16. Leo Liu

    How does D-T fusion reaction utilize its waste to create more fuel?

    In Britannica's article on nuclear fusion, I came across the following description of the recycle of triton and neutrons: What puzzle me are why the tritons are produced from the D-T fusion reaction, given that the products are alpha particle, neutron, and energy; and how the neutrons can be...
  17. A

    Beryllium n:2n reactor fuel

    This has probably been asked before but why don't commercial LWR use beryllium in the core or more likely around the fuel or mixed within the fuel as an additive? Beryllium gives off 2 neutrons if hit by a neutron that has on average more than 1.9 MeV and also produces neutrons when bombarded...
  18. R

    Can reducing Boric acid concentrations extend the life of fuel assemblies?

    Hi, do you think that reducing Boric acid concentrations at the begin of the cycle would extend the like of the fuel assembly?
  19. S

    Typical PWR fuel assembly dimensions

    What are the typical dimensions of the coolant channels and the upper and lower core support plates?
  20. S

    What is the best fast reactor fuel and why?

    I'm studying fast reactors. I can't seem to find a clear answer to my question. I know fast reactors are fueled by either plutonium 239 converting uranium 238, or uranium 233 converting thorium 232, or fueled by highly enriched uranium. Which is the better and why?
  21. BWV

    Methanol - H fuel cells for marine transport

    This privately held company developed a technology to extract H from methanol stored onboard marine craft, then the H can be used in a fuel cell for power. I assume the reason for a H fuel cell vs a direct methanol fuel cell (DMFC) in a marine vessel is that direct methanol cannot deliver large...
  22. S

    When do fission products get cooler than fuel?

    Main nuclear fuel is U-235. Actinium series to stable Pb-207 includes 7 alpha and 4 beta decays. Total energy yield 46,4 MeV. In the main branch, the 4 beta decays carry around 3 MeV energy. Meaning the alpha decays are about 43 MeV... and they have high biologic effectiveness, around 20...
  23. A

    Chernobyl loses power, spent fuel storage question #Ukraine

    So the news are in that for whatever reason the electricity to the plant has been shut down. Now given the reactor have been long stopped there is no danger I would assume to the plant as such but the question is about the spent fuel assemblies that are still on site...
  24. A

    Size Limitation of fuel Bundle in a nuclear reactor

    What is the limitation of length of a fuel bundle in a nuclear reactor. Can we increase the length of bundle consequently reducing the number of bundles in a fuel channel?
  25. A

    Model UO2(5%)+Th+U233 Fuel in MCNPX for SCWR

    Hey there, I'm working on an MCNPX modelling for SCWR using different clads and fuels, the first fuel was UO2(5%) and I have calculated the number density correctly since there was only one vector U. But now I don't know how top deal with the Th+U233 due to the existence of Thorium. Can anyone...
  26. nuclearsneke

    Uranium density in fuel meat/kernel

    Howdy partners! I am currently doing some project on Klt40s neutronic simulation (you might have heard of Akademik Lomonosov, the floating npp). But I have encountered a problem with fuel density. The only info that i got that "uranium density IN FUEL MEAT/KERNEL" is 4.5 g/cm3. The Fuel is...
  27. mesa

    Looking for specs on Failed Fuel Detectors on NPPs in US

    Hello, trying to get some specs on the FFDs typically found on a US reactor. I was told they run NaI scintillation crystals and measure just Bq's (which seems a little odd) with a follow-up with the Hot Lab once a week (at least for the reactors close to my home). Seems a bit simple to me and...
  28. C

    I 64% n.th + COP4 = more heat out of fuel than its calorific value?

    Something that has been on my mind a while. If a CCGT generates electrical power at 64% efficiency, and a COP4 heat pump, powered by that generator, generates 4 times the thermal power to electrical power, wouldn't that mean we can get 256% heat out of the fuel's calorific value? Maybe that is...
  29. A

    Coolant Mass Flow Rate Through Subchannel in Nuclear Fuel Assembly

    I am trying to find the mass flow rate of coolant through a channel within a hexagonal nuclear fuel assembly. I am given the specific heat of the fluid, the coolant inlet and outlet temperatures, the total power produced by a single fuel pin, the diameter of the fuel pin, the length of the fuel...
  30. T

    What waste products are formed from sugar rocket fuel?

    Hello, forums! So I recently have been getting into chemistry stuff. my latest endeavor is the "sugar rocket fuel" thing where you mix potassium nitrate (stump remover) and sugar (granulated) together to make something that when lit on fire, burns very quickly while releasing tons of hot...
  31. S

    Can Spent Nuclear Fuel Be Used as an Alternate Heat Source?

    Hi, I have some questions about nuclear fuel, I hope I could get some direction here. Firstly, based on research I've done it appears that spent fuel rods come out of the reactor around 5000 F, is this true? Secondly, if the previous statement is true how does the water in the fuel pool not get...
  32. A

    Heat Transfer Through Cylindrical Nuclear Fuel Pin

    Let's say we have a cylindrical fuel pin with fissile material in the middle, followed by a gas gap and cladding material. It is being cooled by water on the outside. The temperature drop through the fissile material should be parabolic due to heat generation, and the temperature drops through...
  33. MattGeo

    I Reference Frame, Difference in Kinetic Energy, Fuel Consumed

    Say 2 cars are traveling side by side at 10 m/s in some flat, wide open space. Relative to each other they are stationary. Relative to someone on the ground they are both moving at 10 m/s. Now say you're in 1 of the cars and you see the other car accelerate, changing his velocity by 10 m/s in...
  34. Astronuc

    Mining waste for cheaper hydrogen fuel production

  35. hartmais

    A Can Raoult's Law Determine Boiling Points of Fuel Oil?

    Fuel oil like heavy fuel oil consists of multiple different Carbon and Hydrogen molecule strains. This means that there are a multiple of different boiling points with in the same oil. Cavitation in pumps and valves happen when due to the acceleration of the fluid the pressure drop causing the...
  36. R

    B Launching into space without fuel -- Please bare with me....

    So carbon nanotubes are incredible. Is a macrtube a possibility? If we stretched one out for centuries, and landed it on another planet, would it transfer gravity?
  37. fatpanda1

    I Rocket Fuel Ejection: Intuitive & Math Explained

    Can you give both intuitive and mathematical explanation please.
  38. Astronuc

    Hexagonal fuel arrays (VVER and fast reactor fuel)

    I'm working on an interesting task at the moment related to a core and fuel design for a fast reactor system. Given that the system is a fast reactor, we select a sensible lattice, i.e., a triangular or hexagonal lattice. Neutronically, one can solve for the necessary mass of enriched (less...
  39. A

    Rocket problem -- separated fuel tank in free fall

    I know that this should be a very simple problem, but I don't understand how to solve it without knowing the height at which the tank is separated from the rocket. I will be very grateful for any hint.
  40. K

    I What happens to a small star after burning all of its fuel?

    Hello! As far as I understand, after a star reaches iron in its core, if it is not massive enough it turns into a white or brown dwarf. What happens when all the energy of the dwarf is gone? Are we left with a huge sphere made almost entirely of iron?
  41. P

    Finding the reqiured fuel mass for a nuclear reaction

    Hi I need to find the amount of fuel needed for a nuclear reaction to produce 800MW daily . The reaction is n + 𝟗𝟒𝑷𝒖 𝟐𝟑𝟗 → 𝟓𝟐𝑻𝒆 𝟏𝟑𝟒 + 𝟒𝟐𝑴𝒐 𝟏𝟎𝟑 + 𝟑 𝒏 Can you please give me a hint on how to do this? Thank you very much for your help
  42. N

    Is this solution correct? (amount of fuel needed for orbital maneuvers)

    The kinetic energy of a ##m_s##= 1.5 kg satellite in an orbit of ##h## = 200 km = 200##\times 10^3## m is \begin{eqnarray*} K.E. &=& G \frac{m_s . m_e}{2(R_e+h)}\\ &=& (6.67 \times 10^{-11} \ \mathrm{N.m^2.kg^{-2}}) \times \frac{(1.5\ \mathrm{kg})\times (5.972\times 10^{24}\...
  43. M

    Conversion to fuel economy in equivalent MPG using kcal/h and mi/h

    So I'm guessing we need our end unit to be in MPG? a) walking ( 220 kcal/ 1 hr )⋅ ( 1hr / 3 mile ) = 73 .3 kcal/mi⋅⋅ (73 .3 kcal/ 1 mile) ⋅ (4,186 J/1 kcal) = 3,06833.8 J/mi (1.30 x 10^8 J/ 1 gal)(1 mile / 3,06833.8 J) = 423.68 MPG b) bicycling Not sure as it says,"...when riding at 10.0...
  44. N

    More fuel efficient drivers = better drivers?

    All other things like make and condition of the car, manual/automatic/hybrid, traffic, etc. being equal. Just got my driving license and since I started paying for my own gas bills now I am starting to read about fuel efficient driving :smile: It occurred to me that many fuel efficient driving...
  45. mfb

    Boeing Debris found in fuel tanks of 70% of inspected 737 Max jets

    Yes, that 737 Max. News. It's unclear if these airplanes were supposed to be delivered to customers already if the 737 Max wouldn't be grounded for other reasons, but foreign objects in more than half of the inspected planes is certainly nothing customers want to see. There are 350 more aircraft...
  46. M

    A Validation of MCU Code for HTTR with TRISO Fuel

    I am working on validation of Monte Carlo Universal code (MCU) for High Temperature engineering Test Reactor (HTTR). The fuel is TRISO particle which consist of UO2 kernel then layer of bouros carbide, a layer of inner PyC, a layer of SiC then outer layer of PYC. According to publications SiC...
  47. PainterGuy

    B Time dilation, relativistic mass and fuel consumption

    Hi, Could you please help me with the queries below? Question 1: A GPS satellite is moving faster than the earth, for every day on Earth the clock on the satellite shows one day minus 7 microseconds due to time dilation due to special relativity. However, since the Earth's gravitational pull...
  48. P

    Fission products released from failed fuel rods in a PWR

    There are a lot of fission products accumulated in the fuel pellet and gap in the fuel cladding during PWR operation. Howeve, some iodine and noble gas will release to the primary loops in case of fuel failure. The fission product release rate can be described as the escape rate coefficent which...
  49. E

    Breeder fuel efficiency question

    I've looked reasonably to see if I could find this answer, I'm not a nuke engineer so perhaps my search terms are not correct. I've seen the fuel cycle charts (eg:https://en.wikipedia.org/wiki/Thorium_fuel_cycle, but not clear how to work from this to a percentage mass consumed) I'm interested...
  50. DEvens

    Is there an alternate fuel that de-emphasizes carbon?

    Is there a potential fuel, for some kind of engine, not necessarily similar to existing car or diesel engines, that does not have carbon in it? That is, that you might manufacture from water and air without having to concentrate the carbon dioxide somehow. And that's liquid at ordinary...