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. F

    Why are startup sources typically not used in BWRs?

    Why doesn't the ceramic pellets react with each other in the fuel tube when it is being fabricated?
  2. RaulTheUCSCSlug

    Benefits of Carburetor over Fuel Injection?

    What are the benefits of carburetors over fuel injection methods in engines? I have started working on motorcycles and have noticed that even modern motorcycles are carb'ed rather than fuel inject. Is it because of the cost of adding a computer? Or is there something else to it? I know that...
  3. A

    How does a car's loads affect it's fuel consumption?

    Hi, so I was wondering about how the car's LED, MP3/IPOD, AC systems consumes up electrical power and then to fuel? Let's say that the loads are running for 5-7 hours. Thanks for the replies/ideas!
  4. H

    Copper Sulfate Pentahydrarte will dissolve in diesel fuel?

    Hello all, In interested making a wood preservative using diesel fuel, paraffin plus an algaeicide. I am wondering if Copper Sulfate Pentahydrarte will dissolve in diesel fuel? If not are there other copper chemicals that may? thanks in advance, HarryA
  5. j3dwards

    Rocket expelling fuel velocity relative to earth

    Homework Statement A rocket moving in space, far from all other objects, has a speed of 3.0 × 103 ms−1 relative to the Earth. Its engines are turned on, and fuel is ejected in a direction opposite to the rocket’s motion at a speed of 5.0 × 103 ms−1 relative to the rocket. What is the speed of...
  6. Prashan Shan

    What will be the rate of fuel consumption of a rocket near 'c'

    when an object moves relative to something it experiences time at a slower rate right? now let's assume that an rocket moves 99.99% the speed of light, then what will be the rate of fuel consumption? will it remain the same or it will increase/decrease?
  7. Hunter Bliss

    Calculus of Variations: Minimizing Fuel Consumption w/ v(t)

    Homework Statement (I'm learning all of this in German, so I apologize if something is translated incorrectly.) So last week we started calculus of variations, and I'm rather confused about how to approach the following problem: The fuel consumption of a vehicle per unit of time is expressed...
  8. R

    Speed/Distance/Time + Fuel Consumption

    Homework Statement Distance = Speed / Time Speed = Distance / Time Distance = Speed * Time Also breaking up "chunks of time" in an hour 2 of 30 mins 3 of 20 mins 4 of 15 mins 5 of 12 mins 10 of 6 mins 12 of 5 mins 15 of 4 mins 20 of 3 mins 30 of 2 mins Homework Equations 1) An example of an...
  9. M

    How aircraft reduce fuel splashes inside a wing

    Some passenger aircraft have fuel in their wings. How they manage to reduce fuel splashes inside wing when aircraft tilt left or right for turning. The immediate guess in my mind is multiple baffles to reduce fuel excessive movement. Am I right? Can someone explain or give some link where I can...
  10. rumborak

    Could you send an object into space completely without fuel?

    Was pondering this today. Obviously you wouldn't be able to accelerate a 1-ton satellite to escape velocity, but what about small objects? 11km/s (well, even more, to overcome friction on the way) is very daunting, but if it could be managed you could easily send large amounts into space. And...
  11. 0

    Application of Series/Parallel connection of DMFC? (Direct Methanol Fuel Cell)

    Hello, Just as the title asks, what sort of applications would series and parallel connections of Direct Methanol Fuel Cell suit the best? Based from my understanding of Fuel Cells and experimental results, one cell is not enough to power anything, hence they are used in stacks, in addition...
  12. H

    Lightning vs Hydrogen Fuel for Space Travel

    In space Hydrogen fuel is burned and propels the spaceship forward in the direction it's facing. Newton's third law of motion states that for every reaction there is an equal and opposite reaction. A lightning bolt makes around Five Billion Joules of energy. I can't find specific numbers for...
  13. marcophys

    Miscible - acetone in petrol/oil & water?

    This refers to the addition of acetone in petrol and diesel, and the potential action on any water within the fuel. For interest: https://www.physicsforums.com/threads/adding-acetone-to-the-gasoline.366946/ The above provides an interesting live understanding of the benefits to be gained...
  14. K

    Fuel evaporation in a tank - Pressure calculation

    Hello everybody, I have the following problem: I have a fuel tank, with a liquid phase (the fuel) and gas phase at To and P0, where T is temperature and P pressure. I assume that the gas phase at the instant t=t0 is air. (Is this assumption correct?) The temperature of the liquid phase...
  15. M

    Fuel Cells; PEMFC; Cause of Proton Movement

    Lately I've started learning about fuel cells, particularly proton exchange membrane fuel cells (PEMFC), and a fairly basic question that has been bugging me is: Since the cathode is positive, it is clear why the electrons flow through the load and to the cathode, but why do the...
  16. C

    Efficient, carbon neutral fuel for cars

    Assuming that a carbon neutral fuel for cars has to be used, what would be most practical and efficient? (Assumption: there is electricity from hydropower/nuclear or possibility to grow plants for biofuels) 1) Hydrogen from water hydrolysis? (If I get it right, production is simple but the...
  17. J

    How does a fuel gas system operate

    Any of you know how a fuel gas system operates
  18. Jon Richfield

    Disposition of Spent Fuel - Separation option

    But nikkkom, that makes no sense. 1: Vitrification is not cheap; I doubt that even superficially it is significantly cheaper than reprocessing; you know perfectly well that one does not simply dunk spent fuel rods in molten glass and bobsyouruncle. You first have to get the relevant materials...
  19. M

    Fuel cell open circuit voltage and pressure of reactants

    Hello, I have some questions regarding the nernst equation at open circuit voltage. We know E(OCV) = E0+ ln (PH2*PO2^0.5 / PH2O) I have some trouble with this: If I have dry gas (both for O2 and H2), and my circuit is open at 25°C and 1 atm I have no water in the circuit so what become the...
  20. marcus

    I Dawn dead in Ceres orbit, ran out of fuel Oct 2018

    Published on Jan 19, 2015 The Dawn spacecraft observed Ceres for an hour on Jan. 13, 2015, from a distance of 238,000 miles (383,000 kilometres). A little more than half of its surface was observed at a resolution of 27 pixels. This video shows bright and dark features. This video was created...
  21. D

    Fossil Fuels vs. Natural Gas: Carbon Emissions Explained

    Hi there, Could someone explain to me why fossil fuels, such as coal and oil, produce fewer particulate matter emissions than natural gas? Also, how would you expect the combustion temperature of these fuels to affect particulate emissions? Would a higher temperature lead to a more complete...
  22. N

    VVER Fuel Assemblies: Advanced Hexagonal Arrangement

    I was surprised to learn recently that VVER fuel assemblies are in some respects more advanced than typical Western PWR fuel: namely, fuel rods are arranged in a hexagonal pattern in the fuel bundle: https://www.google.cz/search?q=vver fuel&tbm=isch This is the most dense and uniform packing...
  23. B

    Atom or weight fraction in MOX fuel

    Hi. I have a problem with some calculations. I have to find atom or weight fraction in MOX fuel. MOX fuel is a mixture of UO2 and PuO2. It can be mixed with a various enrichment of PuO2. The fraction of isotopes of uranium and plutonium are as here: U234 234,041...
  24. G

    Turbocharger (Physics of Fuel Efficiency)

    I have a general understanding of how superchargers and turbochargers work; however, there is something that I have always had a hard time conceptualizing as a physics problem. Super/Turbo chargers add horsepower. This makes sense as they essentially cram more fuel into the combustion chamber...
  25. J

    Why aren't drones and aircraft using hydrogen-oxygen fuel cells?

    I've heard they were much more efficient then li-ion batteries and anything else really.. and drones today are all about flight time, wouldn't hydrogen fuel cells result in a great flight time advantage? why are they not in use?
  26. C

    Fuel Cell Collector: Optimizing Flow & Pressure

    Hi, I haven't posted anything on here in a long time, but thought somebody here could help me out. I am building a fuel system for an endurance sports car. I have a sealed 0.6 gallon collector in the fuel cell with three 75gph pumps, capable of 95psi feeding it, through 3/8" hose. It then...
  27. K

    Burning fuel and a motor's efficiency

    Homework Statement A motor burns 20 liter per hour. the fuel's combustion heat is 6.6E6[cal/liter] (i don't know if it's kcal or cal, but i assume it's cal). the motor produces 40 [Hp], what's the efficiency. Homework Equations 1[Hp]=746[W]. 1[W]=[Joule/sec] 1[cal]=4.186[Joule] The Attempt at...
  28. M

    What Affects Generator Load and Fuel Consumption?

    What I know is there 2 friction; Air resistance and Weight of rotor? Is load of generator consider as friction? I noticed that when generator's load is half, fuel consumption is reduced (but RPM and frequency is still same). I tried to think how that, although weight of rotor is constant. does...
  29. A

    Vaporization pressure in a fuel can

    A normal behavior of a plastic jerry can used for gasoline is that it expands by the pressure caused by vaporization of the gas. Which option below will be the best alternative to reduce the pressure caused by vaporization in a jerry can during storage? : - Fill up the can as much as possible...
  30. S

    How to calculate boiler Fuel Requirement for how much water?

    I am doing my research thesis. I want to operate a steam turbine through biogas. I need to know how do I calculate the boiler water requirements i.e how much biogas heat will be required to heat an exact amount of water? Is there a specific way to calculate it? thanks
  31. P

    Maximum temperature of fuel air cycle

    When Stiochiometrically correct mixture(equivalence ratio=1) is burned in air fuel cycle some of the air is still left after point 3 in P-V diagram...Theoretically the whole fuel and air should combust till point 3..Then why is some air left out there.And thus the max temp is when mixture is 6%...
  32. C

    Questions Regarding Homemade Liquid Fuel Engine

    For the last six or so months I've recaptured my childhood love of rockets (I'm now in college), and have spent a great deal of time both reacquainting myself with the basic information and also learning more about the engineering and technical side of them (now that I've learned things like...
  33. V

    RELAP fuel rod-coolant response modeling

    Hi, I am a beginner with the use of relap. So this might be a bit silly. I am studying the heat transfer between a fuel rod and a single channel of coolant. One of the inputs for the heat structure is the direct moderator heating multiplier. What is that and how do I find its value? Thanks...
  34. P

    Fuel Query: Converting Liquid Oxygen & Ethanol into Mechanical Energy

    I write as one with a background in molecular biology and nothing in engineering. Looking to advance an idea of using a former rocket fuel for a terrestrial purpose. A mixture of liquid oxygen and ethanol was used in past decades.. What engine elements would be required to convert this fuel...
  35. I

    Making Methane a More Useful Fuel: Catalyst Possibilities?

    This might be a stupid question so forgive me if it is. I am looking for a way to make methane more useful as a fule and it seems to me that to do that I would have to make it into a longer hydro-carbon chane. Is there a catalyst that could be used to do this? Thanks in advance.
  36. T

    Intense light igniting a mixture of fuel and air

    Homework Statement We are working on a project for a class. I was given a part of the project where focused light is used to burn off carbohydrates. I want to know names of the following values so I can look them up and their relationships. Energy required to start combustion at atmospheric...
  37. P

    Fuel Cells -catalyst converter

    Homework Statement Do fuel cell vehicles have a catalytic converter? Where is it located? The attempt at a solution[/b] I am guessing that the the question qould be referring to precious metal catalyst located at anode region which breaks the fuel into protons and electrons?
  38. T

    Reactor fuel and waste: fission/fusion problem

    Homework Statement In this problem, we're going get a rough estimate the amount of uranium fuel it would take if the US received all its electrical power from nuclear power plants. The size of a power plant in normally given as the about of electrical power it can produce when running a...
  39. C

    Height of Rocket After Fuel Burn

    Homework Statement Consider a rocket making a vertical ascent in a uniform gravitational field, g. Show that the height of the rocket when the fuel is exhausted is given by x = ut_b - \frac{1}{2}g{t_b}^2-\frac{um_R}{α}ln{\frac{m_R+m_F}{m_R}} where "u" is the exhaust velocity of the fuel...
  40. 256bits

    Can the US Navy really make jet fuel from seawater?

    This could be chemistry, but I'll put it here. Research by the US Navy to make jet fuel from seawater. And it works. And all we thought they did was stare down the bad guys. http://www.nrl.navy.mil/media/news-releases/2012/fueling-the-fleet-navy-looks-to-the-seas
  41. S

    Why is there a flux depression in CANDU fuel and how is it addressed in design?

    let say there is an bundle of fuel with 4 rings. Where ring 1 is center most ring and ring 4 is outer most ring. 1st ring contains: 1 fuel element 2nd ring contains : 6 fuel elements 3rd ring contains: 12 fuel element 4th ring contains : 18 fuel elements The general distribution of...
  42. Y

    Fuel conservation near a Schwarzschild black hole

    In another thread we determined that the proper total force acting on an orbiting object in the Schwarzschild metric, is given by: ##f_{total} = \frac{Mm}{r^2\sqrt{1-2M/r}} - \frac{mv^2}{r}\left(\frac{1-3M/r}{(1 - v^2)\sqrt{1-M/r}}\right)## One interesting aspect of the equation is that when...
  43. V

    Car acceleration, fuel usage and kinetic energy

    Someone said the following and it just doesn't sit right with me. How do I effectively tell them what's wrong here? " It applies to physics the same, as can be seen with the Kinetic Energy Formula Ke = 1/2MV^2...
  44. B

    Using a Catalyst With Fuel Cells: Benefits and Challenges

    With galvanic cells, we assume that the redox reaction is kinetically inhibited so that equilibrium takes a long time to reach, so we can make a good measurement of the potential difference V. I thought fuel cells were the same originally, except that we recycle in reactants and products to make...
  45. A

    Troubleshooting a Faulty Fuel Pump: How Does It Work?

    Good Morning Please can anyone help, i would like to know if an engineer can tell me how this fuel pump works, I'm trying to establish if it is faulty or not, my actual fuel pump is shown in the pictures below, when i try to suck on the outlet or blow into it, i cannot get air through it...
  46. H

    Is Beryllium a Viable Nuclear Fuel Option?

    4Be8 + 0n1 → 3Li7 +2 0n1 Can we use above reaction for the production of neutrons? Is it possible to obtain a sustainable chain reaction when using Be as fuel?
  47. S

    Flux in Moderator vs Flux in fuel

    I was reading about different flux shapes, and it depicted the the shape of the fission neutron spectrum to be in the shape of y=e^-x*sinh(sqrt(x)), where y is the spectrum and x is the energy in MeV. note: put that equation into wolfram for easy visualization Then it depicted the slowing down...
  48. V

    Which Platform is Best for Integrating FRAPTRAN/FRAPCON Codes: Windows or Linux?

    Hi all, I am a graduate student of Nuclear Engineering studying fuel and cladding performance during different conditions in the reactor. I have access to FRAPTRAN/FRAPCON codes from frapcon.labworks.org. Being a newbie, I am quite unfamiliar as to how it all works. So is it ok if I...
  49. N

    Minimum Rate of Rocket Fuel Consumption

    Homework Statement A rocket which has an exhaust speed of 8.0 km/s is to have a vertical acceleration of 8.0 m/s2. If the initial mass of the rocket is 6.0x106 kg, at what minimum rate must the rocket consume fuel? Homework Equations F = ma F = RVREL The Attempt at a Solution F...
  50. S

    Help with engine displacement volume, fuel flow rate and crank angle

    Homework Statement An automobile has a 2.5-litre, four-cylinder, homogeneously charged, direct injected, four-stroke diesel engine. The maximum power output of this naturally aspirated engine is 200 HP at 4000 rpm. By turbocharging, the intake pressure is boosted twice as that for the naturally...
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