What is Engines: Definition and 301 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. B

    Actual vs MTE Efficiencies of Heat Engines

    The problem asks: A heat engine takes in 1000J of energy at 1000K and exhausts 600J at 500K. What are the actual and maximum theoretical efffiencies of this heat engine? I know the MTE is 1-Tc/Th = 1-500/1000 = .50 = 50% I'm not sure if I calculate the actual the same way with the Joules...
  2. A

    How Can I Search for Specific Characters in .html and .txt Files Offline?

    So I want to look for specific characters within my .html and .txt files offline. But even when I google offline search engine, I can't find a suitable search engine. Windows Vista Search doesn't seem to have a search engine that works for strings within particular files (it just seems to work...
  3. P

    Are Diesel Engines Really Stronger Than Gasoline Engines?

    Hi everyone, We have an argument about gasoline combustion engine and diesel engine. Some say, the diesel engine is stronger than gasoline one. My idea is if the two engines are the same dimension, they must have the same power. Am I right or wrong. Thanks
  4. B

    Refrigerator Light (power and Carnot engines)

    The inside of an ideal refrigerator is at a temperature , while the heating coils on the back of the refrigerator are at a temperature . Owing to a malfunctioning switch, the light bulb within the refrigerator remains on when the the door is closed. The power of the light bulb is ; assume that...
  5. T

    Carnot Engines in air conditioning

    Homework Statement Under many conditions, the rate at which heat enters as air conditioned building on a hot summer day is proportional to the difference in the temperature between the inside and outside, Th-Tc. (If the heat enters entirley by conduction,this statement will certainly be...
  6. B

    Help torque and heat engines

    we are learning about heat engines and the 2nd law of thermodynamics...and i don't know how to relate torque to these concepts... the question is... a multicylinder gasoline engine in an airplane, operating at 2500rev/min, takes in energy at 7.89E3 J and exhausts 4.58E3 J for each revolution...
  7. D

    Optimizing Diesel Engines for Vegetable Oil Fuels

    First let me say hello and give an introduction. I have limited academic experiecnce in Physics receiving a C-grade GCSE at 16. I then spent over a decade owning a maintaining a number of motorbikes, cars, and light and medium commercial vehicles and some light plant machinery. Mainly for...
  8. A

    Large online mulitplayer games and game engines

    Dear All, I'm still only on my second book of learning C++ although I've had plenty of programming experience writing snippets for games before. The first book was about 350 pages and introduced to me to everything up to and including OOP and inheritance. Now I'm reading one targetted at...
  9. O

    Application feilds of electrical engines

    hi. i am looking for a satisfying source about the topic written in the title. it is my semester project. if you can help me i woud be appreciated. thanks already now.
  10. E

    How do you calculate the net efficiency of a series of heat engines?

    Homework Statement Suppose that two heat engines are connected in a series, such that the heat exhaust of the first engine is used as the heat input of the second (attached diagram below). The efficiencies of the engines are e1 and e2, respectively. Show that the net efficiency of the...
  11. I

    Moller SkyCar: Wankel Rotary Engines and Lift

    i was reading on the moller skycar which has multiple wankel rotary engines powering ducted fans for lift, i was wondering if anyone had any information on how many pound of lift one of these engines on a regular ducted fan would have
  12. 5

    OT: Looking for good book on performance engines (ICE), trying to learn

    Well I have always been interested in engines and how to make them more efficient and make more power. Particularly the popular modifying of Ford and GM engines (302ci, 351ci, 350ci, etc.). I am looking for a book that could help me understand how a cam actually works, and what to tweak...
  13. Cyrus

    Search Engine Quality Decreasing - Is Anyone Else Seeing It?

    Is it just me, or is it really hard to get good results when you google something lately? It used to be that I would find what I wanted fast, now I search something and I get nothing but garbage. Anyone else notice this change lately?
  14. U

    Can Ocean Thermal Gradients Efficiently Power Heat Engines?

    It has been proposed to use the thermal gradient of the ocean to drive a heat engine. Suppose that at a certain location the water temperature is 22oC at the ocean surface and 4oC at the ocean floor. a) What is the maximum posssible efficiency of an engine operating between these two...
  15. K

    Hydrogen-Oxygen Rocket Engines

    Hi ! I remember an experiment in school where two volumes of Hydrogen and one of Oxygen were mixed in a test tube set upside down on (at the time !) a platter full of mercury. A spark in two electrodes on top of the tube would trigger an IMPLOSION and the mercury would jump upward to fill the...
  16. wolram

    Have ceramics come of age for use in ic engines?

    Have ceramics come of age for use in ic engines? from what i can make out they do not improve performance by much, but do make the engine more reliable, coating the piston crown and cylinder head seem to be the favorite use, or components that require little or no lubrication..
  17. wolram

    Gaining Speed & Power with Velocity Stack for IC Engines

    Why would a velocity stack improve an ic engines performance?
  18. A

    Do All Engines Have the Same Efficiency as Carnot Engines?

    My book states: "To prove that no real heat engine operating between two reservoirs is more efficient than a carnot engine between the same reservoirs, imagine a more efficient engine to drive a less efficient carnot refrigerator. For the combination of the engine and refrigerator you get a...
  19. A

    Two-Stroke Engine Tuning: Maximizing Performance

    hey all, I just completed putting a small 2 stroke on my old bicycle, yes majorly geared down, I am actually rather pleased with it. I used an internally geared 3 speed hub on the rear wheel so i could shift back down to 1st gear after being in 3rd and coasting to a stop (you don't have to have...
  20. M

    Kitty's Guide to Heat Engines, Refrigerators, & Air Conditioners

    Could someone explain to me how heat engines and refrigerators and air conditioners work. I'm very confused about the process and if they are isothermic, isovolumetric, or adiabatic. ~Kitty
  21. B

    Seeking Answers on Jet Engines

    i found this on another messageboard and couldn't find an answer. any help? Question about jet engines... From: Bisected8 | Posted: 2/6/2006 9:26:42 AM | Message Detail | #001 Is the fuel used to move the fans by way of an internal combustion engine (thus compressing the air and forcing it...
  22. B

    Most Advanced Internal Combustion Engines

    Hey guys ,can u just let me know about the most advanced or developed IC engine.Plz help.
  23. I

    Calculating Piston Speed in Single Cylinder Engines

    how do you calculate piston speed with a single cylinder engine no transmission what I am trying to do is determine the influence of rod length in that problem
  24. R

    2 cycle engines (& dyno)

    I have a couple of questions about 2 cycle engines: 1) Can someone further explain “time-area” to me in regard to the 2 cycle engine porting? I do grasp the basic concept of time-area values and I do have a formula to calculate the time-area values for a 2 cycle engine however there is still...
  25. A

    High speed jets used in rocket engines

    Ok, so I feel really stupid asking this question, but I guess you've got to start somewhere to reach somewhere, so here goes nothing: I have this report to write and the title of the report has got me a bit confused. The professor's asked me to "write and present a technical report abut high...
  26. S

    Why V-engines Are Better Than In Line Engines?

    Hi Guys Could Some One Tell Why V-engines Are Better Than In Line Engines
  27. Pengwuino

    How do hydrogen combustion engines work?

    I was reading an article and they were talken about this new hydrogen hummer that will be powered by hydrogen. But it was a hydrogen combustion engine instead of a hydrogen electric vehicle. How does the combustion engine work? I thought hydrogen doesn't have that really quick explosive...
  28. S

    How do you design a flame holder for a jet engine?

    I don't quite understand how it is supposed to work. How do you determine what the flame holder is supposed to look like ,where to put the holes, and how big the holes should be? What are the physics and equations for it?
  29. D

    Vegetable Oil conversion for diesel engines

    Does anyone know if there have been any posts on the vegetable oil to diesel conversions. I am very interested in the topic, but couldn't find anything yet. I guess if there is nothing yet posted, this could be the new post. I'll try and get some of the info that I have and post it.
  30. N

    Diesel Cycle - Heat Engines - Thermo.

    Hello, If anybody could answer this question for me that would be great. I have been wondering about it all morning. In the Diesel cycle for heat engines, on the second stage of operation, the Volume increases while pressure stays the same. I understand how this can be accomplished by raising...
  31. N

    Diesel Cycle - Heat Engines - Thermo.

    Hello, If anybody could answer this question for me that would be great. I have been wondering about it all morning. In the Diesel cycle for heat engines, on the second stage of operation, the Volume increases while pressure stays the same. I understand how this can be accomplished by raising...
  32. D

    How is DNA Nanotechnology Revolutionizing Drug Delivery Systems?

    I read this little article today, regarding self-building drug delivery systems. It reads a lot like how our immune system works. Then again, my degree in molecular biology is something for my next lifetime. This is from Scientific American...
  33. Reshma

    Heat Engines: An Undergraduate Guide to Books

    Could anyone suggest a book on heat engines at undergraduate level?
  34. Clausius2

    Uncovering the True Nature of NOx Production in Heat Engines

    As a future engineer, my proffessors teach us to be concerned about pollutant emissions. I always hear about NOx production inside heat engines and turbomachinery. But little is explained about the true nature of this problem. Usually, we are told that NOx is produced at high temperatures...
  35. Y

    Can Jet Engines Run on Hydrogen and Oxygen?

    thinking of a project and was wondering can a jet engine be modified to run on just hydrogen and oxygen as the fuel, or is it too explosive? if not can a pulse jet?
  36. S

    Exploring Heat Engines: Carnot Engines & Beyond

    In class, we're being introduced to thermodynamics, and one of the topics is heat engines. Steam engines were also mentioned. Carot engines also entered the pic. They are described as ideal systems. Exactly why are Carnot engines not "real" engines, or are not possible? I'm sorry if...
  37. U

    Space Shuttle Main Engines

    NERVA2 RE: Watters and Enigma In light of the latest shutdown thread - Nerva - "what the hell" Firstly neither of you have ever posted any replies on that thread. Secondly, i doubt it that you Enigma, are an aerospace engineer. I have been looking at your posts and am amazed at what...
  38. U

    Revolutionizing Rocket Engines: The Power of Direct Fusion and Fission Reactions

    [Note: hi everyone, this is my first post, my name is U235 or more conversly Dion. I am 16] Why is it everytime i look over schematics for the next nuclear rocket engine the design's are completley blindsided to nuclear physics and the harnessing of direct fusion and fission reactions...
  39. E

    Fighter aircrafts have the jet engines buried inside the fuselage

    Unlike commercial airplane, many fighter aircrafts have the jet engines buried inside the fuselage instead of in pods hung beneath the wings. Do you know why?
  40. A

    Optimizing Heat Engines: Finding the Temperature of the Hot Reservoir

    A 20% efficient real engine is used to speed up a train from rest to 5 m/s. It is known that an ideal (Carnot) engine using the same cold and hot reservoirs would accelerate the same train from rest to a speed of 6.5 m/s using the same amount of fuel. The engines use air at 300 K as a cold...
  41. C

    Jet Engines: Momentum, Pressure and Thrust

    I am just about to start my Aero. Eng. degree in a few days time and am currently ploughing my way through all the reccommended reading. A lot of it either gives textual explanations (rather than mathematical proofs or both) or gives a brief description, glossing over anything that may be...
  42. X

    How does the shape of a scramjet engine affect its thrust?

    I'm trying to fully understand scramjet engines but I can't seem to find a good source of information. I know the gist of what a scramjet engine is; I want to really understand the physics behind how it works and how the air flows thru the structure. If anyone help me and or knows a site or book...
  43. Clausius2

    Shuttle Main Engines: What's Happening?

    I am going to inaugurate the "What is happening here?" post series. I am interested on knowing what is happening physically in some aspects of flow around aircrafts. And surely, due to the high level of the co-forum-ers people :thumbs_up , you could provide me an answer, if you want of course...
  44. G

    Designing an Annular Aerospike Engine: Collaborating with Other Groups

    I am a part of a student organization that will be atempting to design, machine, and test fire an Annulare Aerospike engine. We are now in the info gathering phase and finding it difficult to locate informative and helpful information on the design part. If anyone has any ideas, please either...
  45. D

    Is Ford's Duratec 20E Engine Enough to Compete in the Green Car Race?

    FordVehicles.com There have been lengthy delays on Ford's first hybrid car (The Escape). There was news about Ford offering a Focus Hybrid to the public, but with an engine like that, is it neccesary? Honda and Toyota have a strong hold on Hybrid technology as far as compact sedans go...
  46. K

    Air resistance and jet engines

    When a jet aircraft is flying at high speed doesn't the air impacting on the front of the engines compress the air before it gets into the compressor. And how fast does the combusted fuel leave an engine compared to the speed of airflow at the intake?
  47. FZ+

    Can the noise level of jet engines be reduced?

    A number of deceptively simple, but hopefully interesting questions. 1. Why are jet engines so noisy? 2. Is there a way to make them quieter, or otherwise register less on the human ear?
  48. Clausius2

    Exploring Rocket Engines Exhaust Modes

    When I was viewing some photos about rocket engines (spatial ones), I wondered me in what mode is operating the nozzle in the normal working.I am going to try to explain it better (do not show me a strange face yet). I studied the different exhaust modes of a convergent-divergent nozzle...
  49. U

    Can You Explain How Heat Engines Work?

    Can someone explain to me how Heat engines work?
  50. M

    Greatest Thrust of All Rocket Engines Constructed

    Hello, I'm interested in knowing which is the rocket engine of all that have been constructed to date that has major thrust The first in my list is the RD-170, that was used in the Energia launch vehicle, and is still used in the Zenith rocket. The RD-170 rocket engine has a nominal thrust of...
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