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. R

    Finding work, heat, and entropy in a heat engine

    Homework Statement An engine operates with n = 1.94 moles of a monatomic ideal gas as its working substance, starting at volume VA = 21.4 L and pressure PA = 2.77 atm. The cycle consists of: - A to B: an isobaric expansion until its volume is VB = 50.1 L - B to C: an isochoric (constant...
  2. L

    Thermodynamics and heat engine

    Homework Statement A certain engine can propel a 1600 kg car from rest to a speed of 22 m/s in 9.7 s with an efficiency of 23%. what is the rate of heat flow into the engine at the high temperature? what is the rate of heat flow out of the engine at the low temperature? 2. Homework...
  3. A

    Higher efficiency - 2 stroke or 4 stroke diesel engine?

    Hi evry1! Just wanted to know that which has got higher efficiency - 2 stroke diesel engine or 4 stroke diesel engine. I believe that direct injection of fuel in diesel engines prevents the loss of unburnt fuel in exhust of 2S engine. And simpler mechanism and lesser no. of moving parts in 2S...
  4. G

    What is the efficiency of this reversible engine?

    Homework Statement A reversible engine contains 0.5 mol of an ideal monatomic gas and operates using a cycle, similar to that shown in Fig. 19.21 on page 324 of the textbook, consisting of constant volume and constant pressure segments. (You will need to draw your own diagram using the data...
  5. M

    What Is the Heat Capacity in an Isothermal Process?

    Homework Statement The question is presented as picture. Homework Equations What is the expression of this 'heat capacity C'? The x-process is isothermal then C=nCΔT=0? Please give me some ideas. The Attempt at a Solution set V1=V2, V3=V4, T1=T4, T2=T3, p1+p0=p2, p3-p0=p4...
  6. C

    What is the most efficient small-scale low-temperature heat engine?

    I’ve recently become fascinated by high power density energy conversion devices… I was looking at the 100W incandescent light bulb lamp on my desk as 90% of its energy was being wasted as heat and started thinking… I know it is only a rather small amount of energy, but what would be the most...
  7. D

    AZING CLIMBER! What is the efficiency of this mountain climber as a heat engine?

    Homework Statement A 52-kg mountain climber, starting from rest, climbs a vertical distance of 730 m. At the top, she is again at rest. In the process, her body generates 4.1 × 10^10 J of energy via metabolic processes. In fact, her body acts like a heat engine, the efficiency of which is...
  8. P

    Carnot Engine refrigerator temp

    Homework Statement A Carnot engine is operated as a refrigerator, taking in 18 J of heat every second and expelling 20 J into a 23oC room. What is the temperature inside the refrigerator? a. 15.4oC b. 3.33oC c. -6.62 oC d. -15.4 oC Homework Equations e=1-T(cold)/T(hot) U=Q-W...
  9. M

    How can I prevent overheating in a Pulse Detonation Engine (PDE)?

    Hi, I'm new here and I'm really hoping that someone could answer my question. i am trying to design a PDE but the problem about this is that the temperature caused by detonation (3461 K) is so high that it is really difficult to find a suitable material for the detonation chamber and thermal...
  10. J

    Three-stage boost for 4-cyl engine?

    I have a 2004 Chevy Cavalier with the 2.2L Ecotec. I already have a supercharger and charge air cooler on it. What I'm contemplating is adding ram air and an "e-turbo". Since the boost is multiplied in each stage of boost, any increase into the throttle body would be multiplied considerably...
  11. T

    Stirling Engine Help for High School Engineering Project

    I'm designing a stirling engine for a high school engineering project. I need to know more information about them though before I start machining out the parts. I looked at Wikipedia and a few other sites, but I need something a little more in depth. I'm looking for a good stirling engine book...
  12. T

    Stirling engine survey for high school engineering class

    I am making a CNC machined stirling engine for high school my engineering class. Before I can get started I need people to fill out this survey to help me decide which design to go with. Thanks! Stirling Info http://en.wikipedia.org/wiki/Stirling_engine...
  13. M

    How Does a Turbojet Engine Work for a Mechanical Engineering Student?

    I'm brand new to this forum, although I've been browsing the threads for a while now. I'm currently majoring in mechanical engineering at the University of South Florida. I'm in my third semester, and I have been assigned this problem and I am struggling very much with it. (I haven't taken...
  14. U

    Rocketdyne H-1 Rocket Engine, plans/blueprints

    Hello, I am searching for plans or copies of the blueprints for the Rocketdyne H-1 engine used in the Saturn I/IB rocket, any help would be appreciated.
  15. B

    Car engine block/head metal temp limits?

    Good Morning, I am working on a project that is designing a water pump for a car engine without any mechanical parts (works on waste heat building pressure to circulate the water). I know that most of the car engine heads are aluminum and that blocks are part cast steel and part aluminum. In...
  16. S

    Valve spring in engine, why the closer coil must be down?

    In engine, there is valve and the valve spring. If you have ever look at the valve spring before, then you will notice that one end has its coil closer together than the other end. So a valve spring is a kind of progressive spring. In almost all engine repair manual I read, the instruction is...
  17. C

    Heat engine and Heat pump in combination

    Question is attached I have spent a great deal of time on this problem and I am hoping someone can help me out. My attempt at problem. first for the heat engine QL/Qw1 = TL/Twaste so efficiency = 1- Tl/Twaste efficiency = 0.93808 and I know that efficiency = Wout/ Qw1 This is as...
  18. S

    Calculating Car Engine Torque to Plotting the Torque Curve

    I have a car engine specs and I wanted to estimate the torque at each speed and plot the torque curve. I have calculated the road load or the running resistance force for all gears at different RPM's and found the speed (m/s) for each RPM. How to estimate the torque of the engine in order...
  19. S

    Exploring Cyclic Symmetry: A Jet Engine Primer

    Hi, Please can anyone explian what is cyclic symmetry? I'm new to this term and have encountered this in jet engine example Vishal
  20. A

    Thermodynamics: Efficiency for Stirling engine

    Homework Statement I'm trying to find an expression for the efficiency of a stirling engine operating with an ideal diatomic gas, and cycling through a volume V and a multiple of its compression ratio, r, Vr. Homework Equations processes: 1-2 isothermal expansion 2-3 isochoric...
  21. A

    Water pump design of an engine?

    Hey all, So I'm trying to figure out a design for an engine that will fit in a rectangle space, longer horizontally than vertically, so I thought of a water pump. A water pump is a blade that channels one stream of water into another channel. Picture: So then I thought why can't I do the...
  22. C

    Can supercharging of an engine ever lead to reduced power?

    Hi, I have decided to increase inlet T and P of a typical diesel engine (operatiing on dual air standard cycle). THeoretically if all other parameters r same, I have observed that t2 (temp at the end of compression) and p2 increases, but t3 (temp at the end of constant volume heating) and...
  23. A

    Calculating Engine Power Output for 4000kg Car

    Homework Statement In order for a car of 4000kg to travel at 10m/s with a frictional force of 400N, find the power output of the engine. Homework Equations P=Fv The Attempt at a Solution I found 40000*10+400*10=400400W, is this right?
  24. T

    Homemade Dynomometer for 1HP Engine

    Hi guys. I'm building a dynomometer for a 1hp engine. I plan to use something like an alternator or a dc generator to do the braking. I will mount the alternator or generator so it is free to rotate around the shaft and measure the force at a distance to get the torque. The idea is to vary the...
  25. J

    What is the point of having different engine cycles?

    For example, what is the difference between Otto cycle, Carnot cycle, Diesel cycle other than that they have different compression/power strokes and ignition/exhaustion strokes?
  26. T

    Carnot Heat Engine: Solve for Heat Expelled to Cold Res.

    Homework Statement Consider a Carnot engine that operates between a hot reservoir at 63°C and a cold reservoir at -14°C. In running 25 minutes, this engine absorbs 590 J of heat from the hot reservoir. How much heat does it expel to the cold reservoir? Homework Equations Q_H/Q_C =...
  27. rhody

    ResearchGate.net, better semantic search engine ?

    Here is their http://en.wikipedia.org/wiki/ResearchGate" , note the section I highlighted below: It appears this http://www.researchgate.net/" is young (2010) has roots in Berlin, Germany and Cambridge, Massachusetts. Is anyone here using it ? If so is the search engine everything they claim...
  28. Z

    Any physical engine free and open source?

    Hi, I'm trying to simulate the ship traveling in ice. Basically, I would like to assume that the rigid body dynamics is sufficient to do the job since the main point here is the interactions between rigid ice fragments and the rigid ship. The fluid interactions with ice fragments should be...
  29. C

    Compressor section of gas turbine engine duct shaoes

    why convergent rather than divergent? is this to maintain the constant air velocity. Can someone explain this better to me. Would be helpfull
  30. M

    Why do you need to start this Stirling engine by hand?

    Homework Statement Why do you need to start this Stirling engine by hand? Homework Equations N/A The Attempt at a Solution there is not sufficient power at first to overcome the inertia, so external work in the form of pushing it by hand is needed. however once started the momentum of the...
  31. 8

    Steam Engine work application problem

    Homework Statement In a steam engine the pressure and volume of steam satisfy the equation PV1.4=k, where k is a constant. Calculate the work done by the engine (in ft/lbs) during a cycle when the steam starts at a pressure of 100 lb/in2 and a volume of 400in3 and expands to a volume of...
  32. A

    How exactly does a gas turbine engine produce thrust?

    Hi I have been trying to figure out the force experienced by individual components of a gas turbine engine. Generally, the thrust of the engine is defined / calculated as the change in the momentum of the fluid. Usual formula is mass flow X (C_jet - C_intake) + the pressure difference in...
  33. P

    Diesel Engine Problem - Find total work

    Homework Statement The problem is in the attached document Homework Equations attached in pdf document The Attempt at a Solution 1->2 adiabatic compression T2=(V2/V1)^1-(Cp/Cv) = 987.7K w1=nCvdT = (1mol)((3/2)*8.314J/molK)(987.7K-298K) = 8601.3 J 2->3 w2=-PdV=-Pmax(V3-V2)...
  34. N

    Water Piston Engine: Learn What It Is & How It Works

    Water Piston Engine...! what do you know about water piston engine ! is there any online documents you provide me with , because I couldn't find anything online! I know it uses no cylinders and the thrust is generated by the water somehow! I wish I can find something to read about the...
  35. I

    Adiabatic process - Diesel engine

    Homework Statement A diesel engine requires no spark plug. The air in a cylinder is compressed so highly that the fuel spontaneously ignites when sprayed into cylinder. If the air is initially at 20°C and is then compressed by a factor of 15 in volume, what final temperature is attained...
  36. T

    Building a rotary piston engine

    This project is a basic 6 inch rotary piston engine. The rotary engine project is to build a external combustion chamber that will redirect the expanding heat into a rotor housing and turn a rotor with a single piston vane 340 degrees to the exhaust port. The basic piston,rod and crank...
  37. M

    Engine cylinder weight and power

    Can anyone tell me if engine cylinder weight lowers, does it make change in fuel consumption or the power of engine?
  38. S

    How do I Calculate the Force Transmitted by a Clutch?

    hi, I'm designing a clutch and need to calculate the force transmitted by the clutch. engine power is 30hp and rpm is 3000. How to calculate.
  39. A

    Use of Design point for a gas turbine engine

    In order to test the performance of a specific engine, is it necessary to find a design point? If so could anyone tell me how to find the design point for gas turbine engine and suggest any useful materials that gives good information about Design point performance. Thank you!
  40. B

    How Do I Light My Steam Engine Fuel Tablets?

    I recently bought one of those model steam engines, which came with a box of fuel tablets which I can't figure out how to light. I've put them over my cigarette lighter until they snap, crackle, and pop but they just won't catch and my engine won't go. How do you light these things? The box...
  41. A

    Rocket fires its engine, force/acceleration

    Homework Statement A small space probe of mass 235 kg is traveling at 85.0 m/s. It fires its main engine at an angle of 63.00 to its original direction of travel. The engine produces a thrust of 12,000 N and there is enough fuel on board for a 10.0 s burn. What distance will it have traveled...
  42. F

    Role of Reversibility in Carnot Cycle Efficiency

    what role dos the reversibility play in making the carnot cycle most efficient?
  43. B

    Exploring Jet Propulsion: Building a Replica Model of a Hero's Engine

    hi Im currently studying aeronautical engineering at college and needed some ideas for projects and whether they would be pliable or not My current idea: A replica of hero's engine to show the basic principles of jet propulsion but to spice the idea up a little bit, i was thinking about...
  44. D

    Design of IC engine coolant pump (centrifugal)

    Hello, I am to design a pump for the cooling circuit of a 4-stroke, 4-cylinder gasoline engine. The engine has already been designed. I am currently referring to Pump Handbook (McGraw Hill publications) and trying to get a hold of Centrifugal Pumps-Design & Application (Ross-Lobanoff). One...
  45. G

    Cogeneration (CHP) engine electrical efficiency

    Hello to you all, Does anyone know if gas engines running on a cogeneration (combined heat & power) mode can achieve electrical efficiency rates as high as 40% as it is...
  46. Vorde

    Understanding the Alfvén Engine

    Can anyone here explain to me the concept of an Alfvén engine? I heard about it sometime ago in a science fiction book and I have found little on the internet regarding it except enough for me to know it has something to do with interstellar magnetic fields (hence why I am posting here...
  47. M

    Minimum Power of the engine on a car climbing a hill

    Hi, Can someone please solve this question for me, including step by step instructions ? I can solve the ones where the mass of a car is given, but can't do this one. Homework Statement Setting off from rest the car accelerates uniformly and climbs a steep hill which has a gradient of 1...
  48. B

    What are the Zero Kelvin enthalpies of CO2, CO, and H2O?

    Hey there, I am trying to model engine combustion dynamics on MatLab using basic physical laws. My code starts bugging just at the start of the Power Stroke. The pressure value shoots off to 60 bars right at the start. I tried narrowing down the error and I think i have a problem...
  49. J

    Trying to calculate necessary spark energy for engine

    Hi, I am working on a school design team where we are building a small scale formula car. I am a member of the engine group, and am tasked with CALCULATING the minimum spark energy required to start combustion in our engine. I know there is an official term for this, (required spark energy?)...
  50. B

    Thermodynamics heat engine Question

    Homework Statement A 1500kW heat engine operates at 25% efficiency. The heat energy expelled at the low temperature is absorbed by a stream of water that enters the cooling coils at 20 degrees C. If 60L flows across the coils per second, determine the increase in temperature of the water...
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