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. zilex191

    How Much Water Can a 1KW Carnot Engine Freeze in 5 Minutes?

    Homework Statement: In a well-insulated refrigeration unit, a Carnot engine using an ideal gas is driven by a 1KW electric motor (80% efficient) to freeze water. Assuming that the temperature of the thermal sink is 20 °C, calculate the mass of water frozen in 5 minutes. Take the latent heat of...
  2. sponteous

    Freezing Engine and Specific Heats

    I was reading The Refrigerator and the Universe, a nice book about the history of thermodynamics, and they talked about an engine that works on the principle that water expands when it freezes. As I understand their description, it is not a reversible engine, but perhaps it could be made so...
  3. S

    Automotive How to plot a power and torque graph for an engine?

    Hello all, I have designed an intake manifold for boxer-6 naturally aspirated petrol engine with 1:1 bore to stroke ratio and has a bore dia of 117.89mm and a volume of 7.8l as part of my master's project. The engine was to produce 450 bhp @ 6500 rpm and I did set a rev limit @7500 rpm. The...
  4. JD_PM

    Heat engine undergoing an elliptical cycle

    An ideal diatomic gas undergoes an elliptic cyclic process characterized by the following points in a ##PV## diagram: $$(3/2P_1, V1)$$ $$(2P_1, (V1+V2)/2)$$ $$(3/2P_1, V2)$$ $$(P_1, (V1+V2)/2)$$This system is used as a heat engine (converting the added heat into mechanical work). Evaluate the...
  5. Benjamin_harsh

    What would happen if the flywheel is not used in an IC Engine?

    What would happen if flywheel is not installed to IC Engine? Does it have serious consequences?
  6. L

    Steam Engine Questions: Confederate Torpedo Boats and Operation in the 1860s

    Were steam pressure gauges used in 1860? Was a vessel reversed by reversing the engine or within the gearing? For a small steam powered launch, how long from a dead stop would it take to get a boiler up to operating steam? This is for my study of Confederate torpedo boats. Thank you for your...
  7. Ackbach

    Wolfram releases the free Wolfram Engine for Developers

    Wolfram made what I would call a gigantic move: they released the Wolfram Engine for Developers - for zero cost! The idea of the Engine is primarily that you can call and run Wolfram Langauge commands from lots of different sources. I am not the kind of person to automate Mathematica, although...
  8. amare

    Airflow to Engine: What Happens if Air In Manifold < Cylinder?

    What-will-happen-if-the-air-entering-to-the-intake-manifold-is-smaller-than-the-air-entering-the-cylinder-from-the-manifold? the following expression is the rate of change of the manifold pressure interms of the mass flowing to the manifold and the mass of air flowing to the cylinder from the...
  9. R

    Need a better physics engine for my AI robotics

    Summary: video-> https://www.youtube.com/watch?v=6HnMPvNpEP0 ai good - physics poor. Ive stumbled apon an easy way to get a robot going with a gpu. I just treat it like a linear search and cap it off at the size of the gpu, and I get to brute force a good 3 steps in front. Only problem is...
  10. Ismael Jarada

    How to measure the torque of a compressed air engine?

    Summary: The main idea of my graduation project is to convert the motorcycle engine to work on compressed air that come from a 180 L tank (10 bar compressed air inside the tank ) I have some problems to how calculate the required torque to move the cart . The main idea of my graduation project...
  11. Scargo

    Auto/Motor Where to best increase car engine oil pressure if intervention is needed?

    Subaru flat fours (a boxer engine design) are notorious for losing oil pressure under high lateral G's. The usual solution is using a dry sump. Dry sumps are expensive and complicated. They are, based on currently available remedies, unnecessary until you exceed 1.5 G's. I am at that threshold...
  12. K

    Compressed Air Engine Calculations

    Hi, I posted a question a while ago which I have managed to do some more calculations for. I need a bit of help to see if they are correct. I am trying to obtain power and torque values at different rotational speeds of a single cylinder compressed air engine. The inlet pressure into the engine...
  13. A

    What do you think of this FTL/time travel engine?

    So, I have this idea for the FTL engine for artistic purposes and I wanted to ask if anybody could point out it's flaws. I would greatly appreciate if you were willing to discuss them further. It is just a rough summary, so if you want me to disclose more details, ask away. The idea is as...
  14. K

    Compressed Air Engine Calculations

    Hi,I am designing a compressed air engine for a project. A little stuck with calculations. I need to work out how long the engine will run at its top speed using a air pressure which is supplied from a compressed air tank.Compressed air pushed down a piston which is connected to a camshaft. As...
  15. T

    Efficiency of a Heat Engine: How to Calculate Heat Transfer in a Monotonic Gas

    Homework Statement I am having an issue trying to decipher this question, as I am not sure if it a lack of knowledge on my half or there is an assumption I have to make. Homework Equations ##\epsilon=\frac{W_{total}}{Q_{in}}## The Attempt at a Solution My issue is calculating the heat...
  16. X

    Engine design -- Fusion powered rockets

    I found this interesting engine design on the internet. It is one of the most powerful and largest machines human have ever designed. It is a fusion powered propulsion device, it uses “heavy fusion technology” which can use any elements lighter than Fe-56 as power source. Is this design feasible?
  17. Isolde Wilde

    Are angular & vertical velocity the same if the objects are connected

    think of a engine. it has a flywheel and a rod connected to it. a string had been totally wrapped around the rod and a mass is hanged from the very end of the rod. the system is in equilibrium. but as the engine starts to rotate, the rod with rotate as well and cause the hanged object to go...
  18. Isolde Wilde

    DIY Stirling engine project

    hello, I had made an DIY alpha type Stirling engine for my physics project and now I have to write an report about the relationship between the heat given to the engine and the motion of the wheel. I had searched a lot about Stirling engines and I learned about work, energy, efficiency...
  19. S

    Automotive Idling or turning the engine off?

    Hi all, I am aware that idling is fuel inefficient and a waste of fuel, but I guess that it is not always convenient to turn the engine off, since the turning on requires more energy than idling. So, I think that for long periods, turning the engine off is more fuel efficient than idling, but...
  20. Akita

    Automotive What happesn if you disconnect the driveshaft and rev the engine in Drive?

    [Moderator note: This thread was moved from a HW forum. Hence the template. But it doesn't sound like homework.] 1. Homework Statement What will happen if i disconnect driveshaft from transmission and rev engine in drive? Homework Equations Rear end speed sensor could be play some role in...
  21. Delta Force

    Using Fuel as a Combustion Engine Coolant?

    Some jet and rocket engines use their own fuel as coolant. Hydrocarbons have even been used to cool electronics and nuclear reactors. Would it be viable for a combustion engine to use its own fuel as coolant instead of water or another liquid?
  22. P

    Can a Jet Engine Remove drag from the Hyperloop tunnel?

    [Moderator: link removed] Can a jet engine the size of the tunnel mean that you can have an effectively have drag-free vehicle? Any lorry tethered to the jet engine would be basically be drag free? Is this correct? Thanks
  23. Delta Force

    Engine Type/Configuration and Aircraft Performance

    Some jet engines have turboprop variants, and turboprops are rated in horsepower/watts just like piston engines. It's also possible for propeller engines to be mounted in puller and pusher configurations. While it's not possible to directly compare different engine types, what would happen if...
  24. F

    Does a good heat engine make a bad refrigerator?

    Hi all, the efficiency ##\eta## of a generic heat engine working between two temperatures is bound from above by the efficiency ##\eta_{\rm C}## of a Carnot machine working between the same temperatures. That is, if the temperatures are the same, a (ideal) Carnot machine is better than any...
  25. YC_128

    Thermal efficiency of the engine in a PV diagram

    A heat engine takes 2.0 moles of an ideal gas through the reversible cycle abca, on the pV diagram shown in the figure. The path bc is an isothermal process. The temperature at c is 820 K, and the volumes at a and c are 0.010 m3 and 0.16 m3, respectively. The molar heat capacity at constant...
  26. G

    What is the name of this Heat Engine?

    We all know how a thermostat works 2 different type of metal are attach together, when temperature changes 1 metal strap expands more than the other strap causing the straight metal strap to bend. 45 years ago when I was in college the professor brought a desk top heat engine to class. He...
  27. raclemai

    I need to maximize my RPMs in a single cylinder flywheel

    I am working on a flywheel single-cylinder engine powered by a 40 psi air compressor. My task is to achieve as many RPMs as I can. I have already bored two exhaust ports in the frame as shown in the pictures attached. I've done some 600grit sanding on points of contact, am using lubricant prior...
  28. trungnguyen89

    Is this Engine Operational?

    Does this engine work?
  29. D

    Harnessing Energy in an Engine: Unlocking the Secrets of Thermodynamics

    Homework Statement You're in Paris, working on your first novel and short on cash. The owner of the cabaret downstairs has offered to take care of your rent if you'll help her design a climate control system for the place. It gets too hot and damp in the summer, and too cold and dry in the...
  30. SeeSharp

    Automotive Design and Simulation of a four stroke Otto engine

    Hello, I am looking for resources that show you how to design an simulate and engine from scratch. I want to design a complete engine using CAD. Afterwards I would like to analyze the engine using FEA and CFD (Heat transfer, fluid flow etc.) simulations. This is all for learning purposes. I...
  31. vysqn

    Acceleration of a car and jet plane problem

    As we know, POWER is what accelerate a car, FORCE itself doesn't accelerate a car, if FORCE cousing movement it change into work, and work over time = POWER. The FORCE from jet engine pushes a plane forward. But as we know (or I'am wrong) FORCE don't push enything, only POWER couses...
  32. vysqn

    Is engine torque a static force?

    Maybe stupid question but it confuses me:) For Example engine produces 100Nm of torque at 3000RPM. So that's mean that this 100Nm at 3000RPM in this particular moment is static force? Because torque doesn't move anything. If it start to spin, it doing work and work over time is POWER. (~43Hp at...
  33. S

    Work done by Octane Combustion Engine

    Homework Statement There is an insulated internal combustion engine fueled by one mole of octane. It operates at a constant pressure of 5.0 bar. The initial temperature is 200°C. Calculate the heat exchanged with the surroundings, the Δh for the gas, the final temperature, the work performed...
  34. José Ricardo

    About the efficiency of engines

    if we had an entire car made of Starlite (a material that was created resistant to 18032 °F). Would the efficiency of the combustion engine be close to that of the electric and that of the electric would be almost 100% efficient? https://en.wikipedia.org/wiki/Starlite
  35. H

    New Google scientific data search engine

    I tried a search for this first and had negative results so I thought it might be helpful. Google has launched a new https://www.techsupportalert.com/content/google-launches-new-dataset-search-engine.htm feature that enables laypersons to retrieve highly specific results from millions of...
  36. L

    Partial Thermo analysis of a Crower engine

    Hi everyone. Some years ago I read about the Crower six cycle engine. Always wanted to understand it better. And now is the time to follow up on that desire. I’m trying to calculate what happens during the water injection. The goal is to determine the conditions (pressure, temperature)...
  37. Arjun Singh

    KiloNewton/Pound foot of thrust into Horsepower units

    Hi, I am currently studying aviation engine outputs and to make my study linear in comparative analysis with standard Automotive engines I need some expert help. Can anyone help me drive precise equations to convert: 1. Engine thrust in Kilo Newton into Horse Power and Watts 2. Engine thrust in...
  38. V

    Increasing Diesel Engine Efficiency with Retractable Plates

    In case of diesel cycle thermal efficiency is low, because heat addition takes place at constant pressure.so can we introduce some retractable plate which sits below the piston during end of compression stroke,and retracts back after heat addition,thus providing constant volume heat addition and...
  39. Russell Patterson

    Insights Orbital Mechanics in Unity Game Engine for Augmented Reality - Comments

    Greg Bernhardt submitted a new PF Insights post Orbital Mechanics in Unity Game Engine for Augmented Reality Continue reading the Original PF Insights Post.
  40. J

    Simple reversed heat engine problem

    Homework Statement In a reversed heat engine, the work done on the engine is 85 kJ and the heat transfer to the engine from the low temperature region is 260 kJ. Determine: 1. the heat transfer to the high temperature region 2. the coefficient of performance as a refrigerator Homework...
  41. A

    How to save petrol in a Petrol Engine

    Like Gas Engine can we use Petrol Engine working as Gas Engine? I mean instead injecting petrol directly into engine can we inject vapours of petrol into engine using vacuum pump? Can we save petrol in this way without using stroke oil?
  42. Roy S Ramirez

    Injector pressure drop in a liquid rocket engine

    Hello everybody, I hope you are doing fine. I'm currently designing an injector for a hydrogen peroxide - ethanol engine, and the following formula is confusing me: Q = Cd * A * sqrt( 2 * dP / rho); where Cd is the discharge coefficient, A the total area, dP the pressure drop, and rho the...
  43. bob012345

    Can a Vertical Lift Engine Hover With 30 Pounds?

    I'd trying to design a vertical lift engine to lift about 30 pounds in the air about one foot off the ground with minimum power. The device has to hover. The engine should itself weight 5 pounds or less and have a footprint no larger than one square foot. By minimum power, I mean something like...
  44. V

    Automotive Calculation of the efficiency of an engine

    We know efficiency (η) = Woutput/Winput Now in any cycle, for instance, the Otto cycle, let the total work output be WO, total heat added be WH & the total work done on the gas to compress it be WC. Then, will efficiency be equal to (η) = (WO-WC)/WH ? Or will it be equal to (η) = WO/(WH+WC) ?
  45. T

    Is the human body a heat engine?

    If this is a valid enough definition of a heat engine: All heat engines transfer heat energy from higher to lower temperatures, and do work in the process. ... then is the human body a heat engine?
  46. R

    Wattage an of engine sufficient to move a car

    I am tutoring a student, and this question was given to her. I believe it is not clearly stated and wanted your opinion. I hope this is the best forum for this. 1. Homework Statement What is the minimum wattage required to accelerate a car of mass m (don't remember the value) from 0 to 28 m/s...
  47. vysqn

    Ek vs engine power in cars and space

    Help me please:) (1) An idealized engine with constant torque curve means constant acceleration. So for example if there is no air resistance and no frictions and car is on fixed gear and at 3000Rpm it produces 50Hp so at 6000Rpm will produce 100Hp. So he doubles the speed , doubles power and...
  48. E

    Engine with 432,000 miles is in surprisingly good condition

    A 4-cyilinder engine with a staggering 432,000 miles on it is actually in surprising good condition.
  49. S

    Engine sizing (torque/power) question

    Homework Statement There is a 1 kg (52x52x52mm) square block attached to a 200 mm long (d = 8 mm, weight = 0.03 kg) rod what is connected to an electric motor. The setup is vertical and needs to achieve about 90 rpm. So, the 1 kg square block will circle on the outer rim, connected to the...
  50. J

    Evidence that the ship had its engine turned on

    Homework Statement Homework Equations a = v/t p=mv(?) The Attempt at a Solution If an engine is turned on, that means that the ships are accelerating since the engine pushes back on air with a force and air pushes back to propel the ships forward, so I thought (A) would be the answer, even...
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