What is Engine: Definition and 999 Discussions

An engine or motor is a machine designed to convert one form of energy into mechanical energy. Heat engines convert heat into work via various thermodynamic processes. The internal combustion engine is perhaps the most common example of a heat engine, in which heat from the combustion of a fuel causes rapid pressurisation of the gaseous combustion products in the combustion chamber, causing them to expand and drive a piston, which turns a crankshaft. Electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air, and clockwork motors in wind-up toys use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces and ultimately motion.

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  1. J

    Calculating the waste heat of Carnot engine

    The answer is 6470 J. So since I have the two temperatures I could calculate the efficiency. First I convert to kelvin then get an efficiency of 0.35481. Now I can use e=W/Qin to get Qin. I get a value of 10033.54J. Now I can use e=(Qin-Qout)/Qout to get Qout, the waste heat. I get 7405.9 J...
  2. J

    Efficiency of heat engine question

    So efficiency is W/Qin. W= 0 for isochoric processes and for the isobaric, P(change in V). So W=Pi(Vi-Vf)+Pf(Vi-Vf) Qin is negative Qs.This would happen at step 2 and 3. For the isobaric, Q=ncv(change in T) and for isochoric, Q=ncp(change in T). Now if I put everything in the equation I get...
  3. Bix

    Why Does Calculating Train Engine Power Result in Different Values?

    How did you find PF?: Online [Thread moved from the New Member Intro forum, so no Schoolwork Template is shown] Hi. I'm new and am trying to solve a simple question 'Find the max power of a train engine traveling level at 50 metres per second if total resistance to motion is 30 KiloNewtons...
  4. Astronuc

    Catastrophic engine failure on Flight UA328

    https://www.flightglobal.com/safety/united-777-suffers-engine-failure-over-denver/142519.article https://www.flightglobal.com/safety/united-777s-failed-pw4000-appears-uncontained-forward-cowling-missing/142520.article...
  5. A

    Active burn control by using microwaves to control the detonation of the engine

    I was thinking the other day, would it be possible to have microwaves heat the air fuel mixture to activation point and have the microwaves bounce back off the gas to be picked up by a computer that generates a 3d image. this 3d image could be used to heat the gas up in a uniform way so as to...
  6. TiGuru22

    Maxwell3D Error -- Unable to locate COM Engine on 'Local Machine'

    I am attempting to solve a rather simple induction problem in Maxwell3D that I have solved before. But this time when I run it I am getting this error and can not seem to find a solution in ANSYS? I am running ANSYS Suite 2020 R1 Thank you in advance if anyone has a possible.
  7. I

    Turboprop engine propeller efficiency data

    Hello, I'm looking for data on turboprop aircraft engine propeller efficiencies. I'm hoping for a table of available modern engines with a propeller efficiencies for comparison. I've tried Googling but not much luck. I can't even seem to find propeller efficiencies on the individual engine...
  8. XSummer32

    Efficiency of a heat engine given a P-V diagram of its process

    I post the working in the attached file
  9. mavidias

    Heat Engine Problem - Get Help Now

    Please help answering
  10. Addez123

    What is the Probability of Engine Failure for a Plane with Four Engines?

    Given we only have one number I assume we are to use Poisson distribution. Probability for a plane with two engines to fail require both engines to fail: $$P_2 = P_o(2) =p^2/{2!} * e^{-p}$$ Probability of a four engine plane to fail requires 3 or 4 engines to fail: $$P_4 = P_o(3) + P_o(4) =...
  11. R

    Is it possible to put multiple accelerator grids in an ion engine?

    Is it possible to put multiple accelerator grid in ion engine instead of one? So we will get higher exhaust velocity and benefit for us right? or is there any disadvantages?
  12. R

    Unreasonable values for engine torque in vehicle simulation

    I'm trying to simulate the physics of a Toyota Camry during acceleration with a time granularity of 100ms. My simulated conditions are as follows: m = 1590 kg v = 17 m/s a = 1.5 m/s2 η (transmission efficiency) = 0.85 rwheel = 0.35 m Fdrag = 100 N Ffriction = 260 N Faccel = 1590 kg × 1.5 m/s2 =...
  13. S

    Piston Engine versus Jet Engine Power

    Hello All The power output of piston engines fitted to aircraft were (and still are?) specified in terms of their HP rating, whereas jet engines are typically rated in terms of their trust. For example, a Mosquito two engined fighter/bomber was equipped with two Merlins, each producing...
  14. D

    Automotive Diesel engine parts for post-treatment of diesel engine gas exhaust

    Hi folks, Any idea about what is it? I am required to find parts like these items which are made of stainless steel 304 and used on the post-treatment of diesel engine gas.
  15. J

    Automotive What parameters make a long lasting engine?

    What is most important parameter when we must build long last internal combustion engine and why? specific output : HP/Displacement ? HP per each cylinder? Torque per cylinder? Displacement per cylinder? HP / piston area ? RPM / displacement of one cylinder? Numbers of cylinder? Low RPM as...
  16. B

    Hydrogen Fusion Engine: Steel Sphere & Sulfuric Acid

    Have a thick steel hollow sphere with a inside radius of 20 cm. Then fill it up with sulfuric acid and add water. Then remove the oxygen ions. then give the sphere a negative charge and all the hydrogen ions move to the surface of the inside sphere. then charge sphere positive and the hydrogen...
  17. phyzguy

    Efficiency of a heat engine in space

    I have a question about building efficient heat engines in outer space. In theory you could have a hot reservoir heated by the sun that was several hundred degrees C, and a cold reservoir that was very cold - maybe 50K - 100K or even colder. Thus, theoretically at least, a heat engine could be...
  18. W

    Motion equation problem -- Car accelerating with a constant power engine

    So I tried to solve this in two methods, but I keep getting different results, and I don't know why.
  19. Twigg

    Kelvin-Planck 2nd Law of Thermo & a Syringe Steam Engine

    So I found this steam engine on the youtubes: Consider the system not including the candles, only including the can that makes up the boiler shell and the piston, flywheel, etc. The boiler can acts as a hot reservoir; however, the Kelvin-Planck statement of the 2nd law says you can't have an...
  20. L

    DIY Simple analog engine dynamometer -- How to do it?

    Hi, I have to measure the HP of a small engine at the crankshaft. The only usable things are. A dinamometer A brake disk An rpm meter The brake caliper is floating so when we apply de load it pull the dinamometer. The rpm meter show the revolution during the load apply. It can works? How I...
  21. L

    Turbocharging carbureted petrol 2 stroke engines

    Hi everyone, online I ve seen some images about 2 stroke carbureted turbo (motorcycle derivation engine). Now.. In the past in this forum some members spoke about turbocharging 2 stroke but not in sufficient detail. The intake and the exhaust are open at the same time and there are no valves...
  22. iVenky

    Automotive Engine mechanisms during coasting (in drive mode) and engine braking

    I am trying to understand what happens in the engine (especially gasoline vehicles) during coasting (in drive mode) and engine braking. It looks like both mechanisms shut off the fuel injectors. Then how is the former (coasting in drive mode) able to use the momentum while the latter (engine...
  23. P

    Heat engine that uses a rubber band (Thermodynamics)

    Nota that the path a to b is isothermal since J is proportional to L, then we can find the value of T_a and T_b using the equation of state and the figure. We have, \begin{equation} J_0=\alpha L_0T_b \end{equation} or \begin{equation} T_b=T_a=\frac{J_0}{\alpha L_0}=T_0 \end{equation} Also, by...
  24. Tom Booth

    Should ice take longer to melt when used to run a heat engine?

    If a heat engine converts heat into "work", will ice used to run a Stirling heat engine last longer than ice allowed to melt by itself? To try and answer this, I obtained a Stirling engine and ran this experiment: With the engine running: And not running: Without the engine running the...
  25. M

    B Is a Black Hole Engine Viable?

    https://phys.org/news/2020-06-year-old-theory-alien-civilization-exploit.html Do we think this makes it possible using a Black Hole? Seems highly likely that it could be used as a power source one day if we are around long enough to sufficiently advance enough to make this possible.
  26. Nexus99

    Understanding Work Calculation in an Engine: External vs. Internal Forces

    I'm really struggling with this problem. I can't understand which are the forces that i need to calculate work. Probabily when the sand falls the force of which i need to calculate work is weight force, but which is the force that carries the sand at the top of the roller?
  27. S

    Engine working between multiple temperature baths worse than Carnot

    Let the new engine, NE, extract heat from a certain subset of these baths, and let heat obtained from the ##i^{\rm th}## bath be denoted by ##Q_i##, and let the heat rejected to the ##j^{\rm th}## be denoted by ##Q_j##. Let the engine perform an amount of work ##W##. Now right beside this...
  28. L

    Calculating heat recovery from engine exhaust gases

    Hello, I am doing a study for my final years Uni project, which includes waste heat recovery from gas fuelled engine exhaust. I am using a data sheet for a Jenbacher J620 engine-. In the data sheet it is stated that; exhaust gas mass flow (wet) = 17325 kg hr ( not sure about the wet part?)...
  29. A

    Shear Force on Bolts mounting gearbox to engine

    Hello, I have designed a gearbox that bolts on to a fixed engine and fixed pump. It is completely supported by them. The total mass of the gearbox and the components attaching it to the engine and pump is 7.7kg. Its centre of mass is 0.167m along the x-axis and 0.09m along the z-axis from the...
  30. B

    Ammonia Rankine cycle heat engine calculation

    A Rankine Cycle heat engine uses ammonia as a working fluid, turbine entry temperature is 25 Bar at 60 degrees Celsius. The turbine outlet pressure is 4 Bar, the question is: what is the outlet temperature? and if the output power is 6 Gigawatt (6x10^9 watt) what would the mass flow rate of the...
  31. M

    Thermodynamics Problem: Heat Engine Between Two Blocks

    Hi, I am quite confused about how to approach this problem. I have seen variations of this problem where there is a heat engine between two blocks, but in this case the surroundings are massless, so I don't believe that approach will work here. Method: I have first started with the case that...
  32. Pouyan

    What is the change in entropy of the water in a reversible heat engine?

    My attempt: I though : ΔQ_w= 1*4200 * (-100) J=-420000J Q_ice=334000*m_ice = ΔQ_w But it was totaly wrong! The solution showed : Because the heat engine is reversible the efficiency η = 1- (T_cold / T) T_cold is always 273 K while the hot temperature changes from 373 K to 273 K during this...
  33. R

    What is the electrical power output of a turbofan engine?

    Hello All, Happy New Year! A typical modern turbofan engine system creates lift as well as propulsion for the aircraft. Somewhere inside the system, the fast rotating device also works as a generator (alternator) to produce the electricity powering electrical/electronics equipments. What is the...
  34. M

    Are these internal combusion (IC) engine claims physically possible?

    For the most part, I ignore seeming cranks on other platforms, but the persistence - and insistence - of one who keeps claiming what looks to be physically impossible attributes of his ICE engine finally triggered my "Okay, I'll ask some experts." His written posts are along the lines of this...
  35. Parzeevahl

    Obtaining work from two bodies by a heat engine

    Here's my attempt for the first part: For the first body, the work obtained is ##W_1 = C_P (T_1 - T_f)## while for the second body, it is ##W_2 = C_P(T_2 - T_f).## So the net work obtained is the sum of these two: ##W = W_1 + W_2 = C_P (T_1 + T_2 - 2 T_f)## and that proves the first part...
  36. E

    Engine explodes out of tractor pull semi truck

    A diesel engine explodes and literally shoots out of a tractor pulling truck. Apparently this type of thing is fairly common in the sport of tractor pulling, but it's much more common for the engine to simply explode.
  37. gregorspv

    The efficiency of a heat engine

    The first picture was provided along the problem statement. The second has my annotations. I initially began by calculating the ratio of efficiencies, since the work done is obviously the same and cancels out, but after failing and having seen the form of the solution I saw that that cannot...
  38. J

    Stirling engine LTD (Low Temperature Differential) plate size / energy

    i need a simple calculation of a stirling ltd surface area calculation per watt produced and would a very rough surface and very large surface area hinder heat flow if the distance to re generator is extreme /would folding the surface area of a flat plat ltr help increase the power of engine...
  39. F

    Temperatures of the hot source and cold sink in a heat engine

    Hi, I was just wondering about the efficiency of a cycle that is not Carnot cycle. In that case one should use \eta = 1-\left|\frac{Q_{\rm out}}{Q_{\rm in}}\right|, where Q_{\rm in} and Q_{\rm out} are the amounts of heat absorbed and released during the cycle. For instance, I guess that in...
  40. Stephen Bulking

    Thermodynamics problem involving engine efficiency

    Q2: An engine has power of 26.5 kW, needs 9 kg coal during an hour for energy. The heat capacity of coal is 7800 cal/g. Define the engine’s efficiency. Qh= mcΔT = 9000x7800xΔT ( stuck) P=26.5kW(is this the power output of the engine in an hour?) If only I could find ΔT, thenI would be able to...
  41. A

    Power delivered/Internal work done by a car's engine

    Attached is an example from my Tipler physics book of a determining the power delivered from a cars engine. I get the derivation(math), but am having some issues with the understanding/concept. Mainly, isn't Power=Work done/time. If so, they define the system as Car-earth. There is no external...
  42. M

    Engine wont start unless I heat up the engine first

    I took my car to the shop and they had it for 3 straight weeks even changed the spark plugs but they never could figure out what was wrong with it. Now that it's getting cooler weather it's taking bout 2 hours of having the hair dryer blowing on the back of the engine for it yo start up, does...
  43. BWV

    NASA hypothetical engine w/ relativistic ions

    Does this violate conservation of momentum or some other law? It claims to take advantage relativistic mass increases to achieve propulsion https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20190029657.pdf
  44. Mbenj

    How do I calculate the torque of an Internal Combustion Engine?

    Hello all, This is my first post on here so sorry if its not the greatest. I am starting to make a car based video game for the ios in which you are able to customise cars and race them. One feature i wanted to include in this game was the ability to create unique engines. I don't want it...
  45. T

    Automotive What Are the Benefits and Challenges of Using a Turbine Engine in Cars?

    For me, and what I understand the main problem with turbine engines in cars is MPG because they required to run constantly at same rpm. Why no some kind of hybrid combo? With the way transmission have changed in last 5 year's how difficult would it be to transfer energy? As far as I understand...
  46. V

    Transient vibration of an engine

    How is the transient vibration of a piston engine usually simulated? I know that in order to define the vibration loading you need the mass properties and dimensions of the moving components plus the cylinder pressure curve. And of course you need to know the firing order, V-angle (if...
  47. N

    Understanding the Risks of Overfilled Engine Oil and How to Test for Damage

    It is said that if you overfill the engine oil. It can damage the engine. Why is that and is there a way to test if there is already damage?
  48. Jregan

    Rocket Engine Failure: Calculating Velocity at 1055m/s | 21.1*50 = 1055

    21.1*50=1055 1055m/s is the velocity when the engine fails. I don’t know what the time should be in the second equation.
  49. VTOL147

    VTOL Jet Engine Aircraft and VTOL Jet Engine

    I am thinking about VTOL jet engine aircrafts like the following example (an ambulance). To be able to buid that kind of aircraft VTOL jet engines are needed. At the moment there are no VTOL jet engines available, but I have my own proposal: I have questions to jet engine experts. Is my...
  50. D

    Venturi pipe in engine exhaust flow

    I would appreciate opinions on this...on which setup would create the best vacuum in an exhaust gas stream? The #1 drawing is a pipe that has a birds eye cut in it. These are sold for engine crankcase exhaust ventilation. There are some that say they work, then others that say they don't work...
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