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. smokingwheels

    Calculate Thermal Indicated Thermal Efficiency Of An Otto Engine

    Homework Statement What is the indicated thermal efficiency of an engine? Fuel used in total 42.61 cc/min @ 1730 rpm. Fuel used to get to 1730 rpm = 29.16 cc/min no load. Fuel left = 13.45 cc/min to do approx 4.335 kw at 1730 rpm approx 40.95 kph Fuel heat content 34.8 kj/l...
  2. P

    Simplest Experimental Method to Determine Heat Gain from an Engine in a Room

    Homework Statement This isn't an assignment per se but rather a thought exercise proposed by a professor during class. The scenario is that you have a room where an internal combustion engine is used to run a machine. You have no information about the machines power output or efficiency...
  3. A

    Problem related to 4-stroke Honda GX 35 engine

    this engine is basically the part of supermileage vehicle which is being made by a team of DELHI COLLEGE OF ENGINEERING to participate in Shell Eco Marathon, Malaysia. Due to some reason, we are getting a higher value of pressure in compression stroke which is continously leading to the failure...
  4. R

    Used Car Engine Oil: What Mechanics Do & How to Filter

    I was wondering what do mechanics do with used car engine oils( lubricants)? Like are they recyclable ..... I know how water and Oil can be separated , but how does one filter dust and other particles from oils.... thanks in advance
  5. smokingwheels

    Is this a good rule of thumb for engine exhaust temperature

    I have done a basic test on my car at idle and have found that the exhaust pipe temperature just hits 100 deg C eg boiling point of water 1050mm away from the exhaust port. Is this a good guide to exhaust gas temperature? Can you compare other engines using this method? I also can hang...
  6. K

    Why Does IC Engine Torque Change with RPM and Gearbox Mechanics?

    Hi guys! This is a question related to IC engine characteristics(performance curves, torque-speed curve). Why is the Starting torque of IC engines small? Also why does it decrease after a maximum? Secondly, In one of the lectures, our professor asked us that in a gearbox form where does the...
  7. smokingwheels

    Heat engine efficiency calculation

    Homework Statement I have an spark ignited engine and after modifying it I have improved the efficiency. What is its efficiency at idle? Fuel consumption at 650 rpm = 9.8 cc/min measured Fuel consumption at 750 rpm for normal engine = 25-30 cc/min estimated for about 5 HP Normal engine...
  8. smokingwheels

    Does the Carnot heat engine law apply to an internal combustion engine?

    The law says that the maximum thermal efficiency of a heat engine can be 88%. If I have and internal combustion engine using 9.8 cc/min instead of 25 to 30 cc/min and the other accepted figure is a 2L 4 cylinder engine for idle is it uses approx 5 HP of fuel just just to idle. So I am doing...
  9. A

    Heat Engine and Entropy Change

    Homework Statement An inventor claims to have invented an engine which operates between constant-temperature reservoirs at 400K and 300K. Data on the engine, per cycle of operation: Qh = 200J Qc -175J W = 40J Th = 400K Tc = 300K Of the first and second laws of thermodynamics, which (if...
  10. R

    Can Explosions in the Cylinder Lead to Contamination?

    Dear Experts, The car moves basically because of the energy from the explosion that happens in the cylinder which pushes the piston whose reciprocal motion turns the wheels. Does the explosion caused by the ignition of gas and air mixture lead to the exhaust gas dirtying the inside of the...
  11. T

    Carnot Heat Engine, thermodynamics

    A carnot engine has an efficiency of 59% and performs 2.5x104 J of work in each cycle. a) how much heat does the engine extract from its heat source in each cycle? b) suppose the engine exhausts heat at room temp (20oC) what is the temperature of the heat source? I know that the...
  12. M

    How Much Work Can Methanol Fuel Generate in Different Energy Systems?

    Homework Statement An internal combustion engine operated with methanol (CH3OH) as the fuel has a thermodynamic efficiency of 20%. a) How much work is derived from burning one mole of ethanol in the engine? b) What is the max work that could be derived by reacting the methanol with pure...
  13. R

    Performance Envelope of a Turbojet Engine

    In this project I'm tasked to do several things: (1) Find the area at each station in the turbojet and calculate the thrust, \dot{m}_{fuel} by calculating all relevant parameters at each station. On-Design Values M_0=0.8 \pi_c=15.472 M_2=0.5 \dot{m}_{corr,2}=35...
  14. P

    Academic Physics Engine: Free Simulation Software

    Hello! First I would like to greet everyone on this forum. I'm a electrical engineering student in Portugal and I found this forum very helpful so I decided to join. I'm now having a subject about vibrations and I was wondering if anyone knows about some freeware software that can run...
  15. M

    What is a Farnboro Engine Indicator and How is it Used?

    what is a farnboro engine indicator and what is it used for?
  16. C

    Engine Efficiency: 1.4 kg Gasoline/hr = 3.5 kW Power

    Homework Statement An engine burns 1.4 kg of gasoline per hour and yields 3.5 kW of power. Homework Equations Calculate the efficiency of the engine when the heating value of gasoline is 43 MJ/kg. The Attempt at a Solution Plz i just need the rule for engine efficiency.
  17. S

    Designing an engine and drive system for a well winch

    [b]1. Farmers take about 5 mins to lift a 4 gallon bucket of water from a well. They desire to achieve at least a ten minute time increase in the speed at which they can retrieve water from the well. Design a 2 stroke gas engine and transmission system for the winch. The winch itself is assumed...
  18. K

    Carnot Heat Engine to Carnot Heat Pump

    We have a carnot engine with Th = 800 degrees Celsius, and Tc = 50 degrees Celsius. This produces a work which is drives a carnot heat pump which has heat reservoirs at Th' = 50 degrees celsius and Tc' = 0 degress Celsius. What is the ratio of heat absorbed by the Heat Engine to the heat...
  19. K

    Final Temperature of Carnot Heat Engine with Same U and N,C

    Two bodies have the same Internal Energy. (U = N C T) Both N and C are the same for each of these bodies. The initial Temperatures of these bodies are T1i and T2i Using these bodies to produce work from a Carnot Heat Engine, they are brought to a final temperature Tf. What is this final...
  20. M

    Calculating Acceleration of Stellar Engines: A Comparison to Wikipedia Example

    Has anyone here looked at the physics of stellar engines? See http://en.wikipedia.org/wiki/Stellar_engine for an overview. In particular, I have done a simple calculation for the acceleration due to light pressure of a "Shkadov thruster", which is a reflective shell on one side of a star that...
  21. A

    Has Anyone Designed a Four-Spool Engine?

    Actually, we have three spool, two spool engine and single spool engines, how about the four spool engine? did anyone came across the design of four spool engine? I think adding an extra spool leads to increase in engine weight and becomes more complex in its mechanism.
  22. J

    Efficiency of a heat engine in a reversible cycle

    Homework Statement A heat engine operates in a reversible cycle with the following steps: (i) An ideal gas characterized by γ = 1.4 expands adiabatically, so that it cools from an initial temperature of 330°C to 30°C. (ii) It is compressed isothermally until it reaches its initial volume...
  23. F

    Air compressor calculations for engine super charger

    I am an engineer but have a rather dumb question regarding superchargers for engines and probably compressors in general. Most specifications are give as XXcfm at XX psi. I am trying to understand if this truly means we are moving that amount of air at the rated psi or if that means that...
  24. M

    IC Engine converted to hybrid air engine

    I was thinking the other day about a possible hybrid conversion vehicle that could store braking energy as compressed air. The setup is like this: The engine valves are all electric solenoid controlled. When the motor is running on gasoline it run like any other 4-stroke IC engine. There is...
  25. T

    Solving Entropy of Carnot Engine for Homework

    Homework Statement You want to boil a pot of water at 20C by heating it to 100C. I suggest a way of heating the pot in a reversible manner: simply inserting a Carnot engine between the reservoir (at 100C) and the pot. The Carnot engine operates between two temperatures, absorbing heat dQ_1...
  26. T

    What is the thermal efficiency of an ideal gas cycle?

    Homework Statement A possible ideal gas cycle operates as follows: (i) From an initial state (p_1,V_1), the gas is cooled at constant pressure to (p_1,V_2); (ii) the gas is heated at constant volume to (p_2,V_2); (iii) the gas expands adiabatically back to (p_1,V_1). Assuming...
  27. R

    How cfm 56 -3 turbofan engine start ?

    I know all procees of cfm 56 -3 . how its work and everything but i am not understanding starting system of cfm56 - 3. cfm 56 -3 has two shaft n1 and n2 . N1 is coneected with low pressure compressor , lp turbine and connected with fan . N2 shaft is coneected with hp turbine and hp...
  28. U

    How to determine wankel engine pressure p1,p2,p3

    i want to calculate the torque vs crank angle for wankel engine...however i get stuck on entering the pressure value which is p1,p2,p3...how can i determine the pressure value?
  29. S

    Ideal Gas Carnot engine refrigeration

    Homework Statement What is the relationship between the heat absorbed and rejected by the reservoirs and their temperature. If a heat pump is used to transfer heat what is the rate at which heat is added to the hot reservoir in terms of the temperatures of the reservoir and the work done by...
  30. A

    Energy to heat water in a stem engine

    Homework Statement Using the conversion rate of 4.19 joules per calorie, how much energy is necessary to heat 2.50 liters (2500 grams) of water in a steam engine from 100 Celsius Degrees to 250 Celsius Degrees? Homework Equations ? The Attempt at a Solution IM LOST
  31. N

    Thermodynamics - Carnot Engine

    Homework Statement (a.) For an Ideal Gas Carnot engine, what is the relationship between heat absorbed and rejected by the reservoirs and their temperature? If a heat pump is used to transfer this heat, what is the rate at which heat is added to the hot reservoir in terms of the temperatures of...
  32. H

    The efficiency of a vehicle engine

    Homework Statement A vehicle engine has a power output of 6.2 KW and uses fuel which releases 45 MJ per kilogram when burned. At a speed of 30ms ^-1 on a level road, the fuel usage of the vehicle is 18km per kilogram. Calculate: the useful energy supplied by the engine in this time...
  33. S

    Researching Oil Coolers & Filters for F1 Car Engine

    i have a groub project which am facing lots of problems with it as am a girl and my knowladge in cars and engins very poor we are trying to improve a sump system in a formula one car engine (yamaha r6 bsl 600cc) the group has already decided not to use an oil cooler in the system and mu...
  34. W

    Work done by a non-reversible heat engine

    Hello. I have a question about a theoretical heat engine I recently encountered in my coursework: The setup is two chambers, one with more moles of a gas than the other, separated by a heat-conducting barrier. The right chamber has a small piston attached to it and is at a lower temperature...
  35. M

    Thermodynamics: Carnot Engine, WHY IS Qhot NEGATIVE?

    Homework Statement 1. A heat engine operating between 200°C and 80.0°C achieves 20.0% of the maximum possible efficiency. What energy input will enable the engine to perform 10.0 kJ of work? Homework Equations e =1- Tc/Th W=e*Qh The Attempt at a Solution I got the answer but I...
  36. J

    Engine Cycles: Otto, Diesel and Carnot

    Problem / Question 1)Study the engine cycles for the Otto cycle, Diesel cycle, the Carnot cycle and the standard air cycle. Explain the principles of how they work why they are different and the benefits and disadvantages of each of the systems. I have wrote about the otto cycle...
  37. R

    Four-stroke 'Crower' Otto/steam engine

    I imagine most of you know of the 6-stroke Crower engine. By adding a 2 more cycles when steam is injected, it is attempting to recover mechanical work from waste heat from cylinder walls and crown. One of supposed advantages of it is it doesn't need block cooling due to the steam cycle taking...
  38. K

    A question about the relationship between MPG and engine TORQUE

    Is it true that a car has it's best fuel consumption in max torque RPM? For example, if a car produces it's max torque in 4500 RPM, does it use the least amount of fuel by driving constantly in 4500 RPM?
  39. T

    Maximum Work from Carnot Engine

    Homework Statement A 200 litre container of boiling water and a 200 litre container of ice cold water are used as heat source and sink for a Carnot engine. Calculate the maximum amount of useful work that can be obtained from the system and the final temperature of the two containers of...
  40. K

    Which Temperature Adjustment Improves Carnot Engine Efficiency More?

    Homework Statement Determine which gives the higher efficiency of a Carnot engine, increasing the temperature of the hot reservoir, or decreasing the temperature of the cold reservoir by the same amount. Justify your answer carefully. Homework Equations (TH-TC)/TH)The Attempt at a Solution By...
  41. V

    Stirling engine to electric motor

    Does anyone know what stirling engine could be used to power a generator which in turn powers an electric motor? I am thinking of using this concept in a vehicle. A diagram is here: It shows a metal sphere in vacuum sealed container. It would be connected to by a retractable contact...
  42. M

    Pressures in front and behind LP fan on jet engine

    My friends (all A&P Aircraft mechanics) say I'm nuts. A co-worker and I attended a Honneywell TFE731 jet engine maintenance school. During the class the instructor asked this question, "which side of the front fan on a TFE731 engine has the highest pressure?" His answer was the front. (we are...
  43. K

    How Much Power Does the Heat Engine Generate?

    Homework Statement The hot reservoir of a heat engine is steam at 100 Celsius while the cold reservoir is ice at 0Celsius In 1.4 hours of operation, 12 kg of steam condenses and 60 kg of ice melts. What is the power output of the heat engine? Homework Equations Efficiency =...
  44. J

    How Do I Customize Parameters in a Simulink Engine Model?

    Homework Statement I am modelling an engine, I have attached a picture of my model. It is the basic engine model that comes with Simulink, with my attachments included. My question is, how and where do I enter my own values? I'm pretty new to using Simulink, so I don't really know where...
  45. S

    Internal Combustion Engine Loading

    Hey people I intend to self learn IC engines. I am a a little confused by what this sentence says in my textbook. "An idling engine is one which operates at no load and with nearly closed throttle" I basically want to know what loading means in this particular context? And what else can...
  46. D

    Projectile Motion - rocket launched, engine, fail

    Homework Statement A rocket is launched at an angle of 58.0° above the horizontal with an initial speed of 98 m/s. It moves for 3.00 s along its initial line of motion with an acceleration of 28.0 m/s2. At this time its engines fail and the rocket proceeds to move as a free body. Maximum...
  47. MattRob

    Home-Made Liquid-Fuel Rocket Engine

    So I'm looking and researching to build a small liquid-fueled rocket engine. So far I think my choice for fuel is definitely unleaded gasoline because of it's high impulse when mixed with Gas-state O2 and how easy it is to obtain. Previously, I was looking at using Hydrogen Peroxide (H202) for...
  48. T

    Heating a Heat Engine - Efficiency Calculation

    Hi. Im trying to measure the efficiency of a heat engine. I therefore need to work out what the input energy is to the heat engine. I have two problems. Firstly, how should I measure the heat going into the stirling rather than the heat coming out of the heater. Is it ok to measure the...
  49. J

    Solving a Steam Engine Flywheel Angular Displacement Problem

    Homework Statement The flywheel of a steam engine begins to rotate from rest with a constant angular acceleration of 1.33 rad/s2. It accelerates for 23.5 s, then maintains a constant angular velocity. Calculate the total angle through which the wheel has turned 67.3 s after it begins...
  50. M

    Reverse Carnot Engine (Heat Pump)

    Homework Statement A house is heated by means of a carnot engine operating in reverse (Heat Pump). The outside Temperature (Tc) is 270k, and the required inside temperature (Th) is 300k. If heating the house to this temperature normally requires 10kW of electrical heating, how much power is...
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