What is Efficiency: Definition and 945 Discussions

Efficiency is the (often measurable) ability to avoid wasting materials, energy, efforts, money, and time in doing something or in producing a desired result. In a more general sense, it is the ability to do things well, successfully, and without waste. "Efficiency is thus not a goal in itself. It is not something we want for its own sake, but rather because it helps us attain more of the things we value". In more mathematical or scientific terms, signifies the level of performance that uses the least amount of inputs to achieve the highest amount of output. It often specifically comprises the capability of a specific application of effort to produce a specific outcome with a minimum amount or quantity of waste, expense, or unnecessary effort. Efficiency refers to very different inputs and outputs in different fields and industries.

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  1. R

    Internal combustion engine -- improving the efficiency

    can anyone suggest me the sites where i can find the methods to improve the efficiency of IC engines?
  2. davidbenari

    Understanding Thermodynamic Efficiency: Debunking Myths

    The thermodynamic efficiency ##\eta## is calculated by ##\eta= \frac{W_{out}}{Q_{in}}## Using the first law of thermodynamics we usually say that ##W_{out}## is ##Q_c+Q_h##, where ##Q_c## is the heat dissipated into a cold reservoir, and ##Q_h## is the heat absorbed by the system because of a...
  3. T

    How to find Best Efficiency Point for pumps in series?

    Homework Statement I read here http://www.engineeringtoolbox.com/pump-system-curves-d_635.html that this is where the system curve and the pump performance curve intersect. But if the situation involves pumps in series, what will the system curve be a plot of? Is it flow rate and the total...
  4. A

    Three phase induction motor efficiency

    Hi, Is there a difference in efficiency between a three phase motor and a single phase motor, in terms of power in against power out. If so, could you please explain why one is more efficient than the other. The reason I ask is because I'm researching the development of the induction motor for...
  5. K

    Efficiency of a combustion motor

    Homework Statement The efficiency of a heat machine is ##E=\frac{Q_2-Q_1}{Q_2}## where Q2 is the heat inserted because of the explosion and Q1 is the heat that leaves through the exhaust. It says in the book that E can be derived from the volumes ratio V1/V2: $$E=1-\frac{1}{\left(V_1/V_2...
  6. maistral

    Ponchon Savarit for distillation + overall efficiency?

    I'm having trouble trying to figure this out. I am aware how to employ overall efficiencies on McCabe-Thiele - IIRC it goes like: "draw a pseudoequilibrium curve in between the equilibrium line, and the rectifying/stripping lines - 100% efficiency means that it coincides with the equlibrium...
  7. L

    +1 order efficiency in a blazed transmission grating

    Homework Statement I have a blazed transmission-grating with a known blaze-angle θB and refractive index n. Is there a way (as with a blazed reflection-grating) to calculate at what incident angle maximum efficiency will be achieved for the m'th order diffraction given a wavelength? Edit: Of...
  8. anubodh

    Effect on throwing a ball up in a car on it's efficiency

    I just wanted to know when we throw something like a ball up inside a moving car, the weight of that ball till it is air is 0 on the car.Does it mean that the car has become lighter and will take less energy to run.I know the effect is every small but please tell the answer.
  9. J

    Is Multiple batteries for efficiency the answer?

    Hello, concerning power supplies. I am at the stage where all the components are ready except for the batteries. The thing is, not all the components have the same voltage. My first thought was using a high voltage battery connected to a custom made Power Distribution Board which splits and...
  10. Paulene Gueco

    Efficiency of a Solar Powered Car

    As I am currently residing in Doha, Qatar, I've decided to base my mini-thesis on Solar energy. And although I haven't got it finalized yet, I'm thinking of investigating the efficiency of solar powered cars. I could build a toy car and input solar-powered batteries as opposed to another toy...
  11. Mingsliced

    Simple Gear Train Efficiency and Torque Help

    Homework Statement I'm on the very last section of a question for the design of a simple gear train. I've managed to design the gear train with all criteria fulfilled and I am confident that it is correct. I just need clarification that my calculations thus far are correct and also a fresh...
  12. A

    Some basic questions about the second law efficiency (gas turbine cycle)

    hi , will change first law efficiency proportional to second law efficiency? for example in gas turbine cycle, how change? other equation: hi , will change first law efficiency proportional to second law efficiency? for example in gas turbine cycle, how change? other equation: How is the...
  13. N

    How to calculate solar cell efficiency with data in dark?

    Hi mates, I have to find solar cell efficiency by datas that given. These datas comes from an experiment in light and in dark. I found efficiency in light by square method with IV curve. But i don't know how to find in dark. The square method doesn't work cos data crossing the origin, no area to...
  14. ChrisVer

    Inverse Efficiency Matrix (error)

    Hi, let's say in some experiment with ##Z^0## (eg LEP) you are able to determine the "misidentification" of your particles. Then you can find the efficiency matrix ##M_{eff}## which is given (for ##Z^0## decays to leptons or hadrons): \begin{pmatrix} N_e \\ N_\mu \\ N_\tau \\ N_{had}...
  15. A

    Interpreting efficiency of heat pump

    Hi everyone, I have a report to write for tomorrow and I am struggling with part of my conclusions. Essentially we have gained results from a heat pump as follows COP = 2.56 Carnot COP = 18.9 Energy Discrepancy = 0.015 Would anybody be able to help me interpret these results, ie are they...
  16. I

    Fortran Program in FORTRAN which calculate the detection efficiency

    Hi everyone, I want to write a program in FORTRAN which calculate the detection efficiency for a punctual source and a disc source at a distance from the detector .The disc detector is assumed to be perfect: ie photon absorbing everything that falls on it. So here I am working in 3D and I use...
  17. C

    Thermodynamics - Regenerator Efficiency

    Homework Statement Hey I just have a question about regenerator efficiency. I have a problem where the efficiency of the regenerator in a Regenerative Brayton cycle is 0.75, the regenerator takes air in from a compressor which I called h2=636.109 kJ/kg, air then leaves the regenerator and is...
  18. S

    Heat engine efficiency could approach 100%?

    According to Carnot theorem, the higher temperature of a hot side and the lower temperature of a cold side the higher is the efficiency of a heat engine. Does it mean that in theory it could get anywhere close to 100%? If we take in account that 100% efficiency means it is a perpetuum mobile...
  19. B

    Calculating Efficiency of Electric Vehicle

    Homework Statement For the following calculations, assume a typical electric car will need to apply a constant forc of 165 N to maintain a typical highway speed of 100 km/hr (27.7778 m/s). A: What power (watts) is needed to maintain this speed? B: What energy (Joules) is needed to travel 100...
  20. G

    Turbocharger (Physics of Fuel Efficiency)

    I have a general understanding of how superchargers and turbochargers work; however, there is something that I have always had a hard time conceptualizing as a physics problem. Super/Turbo chargers add horsepower. This makes sense as they essentially cram more fuel into the combustion chamber...
  21. Amr Ali 33

    Boiler efficiency using ASTM PC6 standards

    can anyone provide a sample calculation for this particular standard the input output/method or the indirect way, I'm familiar with british standards i.e. boiler efficiency = output /fuel energy input ...but the ASTM standard give a more detailed calculation
  22. T

    Improving Machine Efficiency through Gear Ratio

    Does altering Gear Ratio improve efficiency (loss of energy as heat while converting EE to ME) of a machine? I also read online that having higher gear contact ratio improves the efficiency, but I really don't understand how.
  23. lpetrich

    Making gold by nuclear reactions -- what efficiency?

    This was one of the alchemists' big quests, and it is evident that it is impossible with the methods that they had available. But how feasible is it to do that with nuclear reactions? Especially nuclear reactions that start with relatively common materials, like hydrogen or carbon or silicon or...
  24. E

    Insolation, efficiency, and area

    Homework Statement What size FPC is needed to supply a family's domestic hot water needs in March in Denver, CO? Assume 80 gallons per day are needed (1gal=8.3 lb.) for the water and that the collector-heat exchanger system has an average efficiency of 40%. The collector tilt angle is equal to...
  25. D

    Energy efficiency, Transformer?

    Homework Statement A power plant produces energy at a voltage of Vi = 12693 V. Before being sent along long distance power lines this electricity is sent through a transformer with 166 turns in the primary coil and 6917 turns in the secondary coil. The voltage of the electricity sent through...
  26. R

    Calculating Efficiency and Thermal Source Rate in a Steam-Electric Power Plant

    Homework Statement A steam-electric power plant delivers 900 MW of electric power. The surplus heat is exhausted into a river with a flow of 5.51×105 kg/s, causing a change in temperature of 1.35 oC. What is the efficiency of the power plant? What is the rate of the thermal source? Homework...
  27. Amr Ali 33

    Maximizing Boiler Efficiency: The Indirect Method

    Homework Statement i have a project regarding to boiler efficiency and how can it varies with excess air and flue gas temperature ( using the indirect method ) i will estimate the boiler efficiency at a different conditions , it's not that i can't do the calculations but doing the same thing...
  28. G

    Greetings from a 70 year old generalist

    Many folk like to use the phrase "talking truth to power", but those of us who do have colorful work histories. My life has been in technical fields, both in the Air Force and industry. Now retired, I earned a Master of Science in Energy and the Environment, was a Senior Engineer for a large...
  29. E

    Organic Rankine Cycle efficiency issue

    hi all. just to give you a background story - i am graduate student at U of Calgary in the ECE department. My colleague, from the Mechanical department did not show up yet, because of which I have to work alone on my project, including the mechanical part at which i am no expert but have some...
  30. M

    Noise efficiency of fan designs

    In particular I am wondering about compressor blades, but it's an interesting question to pose for household type fans as well. We can imagine "waterwheel" type schemes, and also the more traditional schemes where the axis of rotation is parallel to the flow. Which produces more noise per...
  31. David Carroll

    How do you calculate recursive efficiency?

    Greetings ladies and gentlemen. I am right now working on a recursive formula whose nature I'll define later. Unfortunately, I have no formal education in math. What I want is some references to where I can find how to calculate the efficiency of a recursive formula and how to prove its...
  32. Z

    Efficiency of non-linear optical device

    It is said that a non-linear optical device may convert light into its higher order components. So what is the highest efficiency of the conversion? Can a non-linear device convert all input light into its higher order frequency? Thanks.
  33. S

    Silicon: The Key to Solar Panel Efficiency & Why Carbon Isn't Used

    How does the crystalline structure of silicon make it useful in solar panels? Why is carbon not used?
  34. robotpie3000

    Improving the Efficiency of Light Bulbs: Possible Solutions?

    I just finished an experiment on blackbody radiation, and one of the post lab questions asked me on the possible ways in which a light bulb can be made more efficient such that the majority of the light it produces falls in the visible spectrum. After some quick research I think one of the...
  35. K

    Burning fuel and a motor's efficiency

    Homework Statement A motor burns 20 liter per hour. the fuel's combustion heat is 6.6E6[cal/liter] (i don't know if it's kcal or cal, but i assume it's cal). the motor produces 40 [Hp], what's the efficiency. Homework Equations 1[Hp]=746[W]. 1[W]=[Joule/sec] 1[cal]=4.186[Joule] The Attempt at...
  36. ajayguhan

    How Does the Efficiency Formula Change for Reversible Heat Engines?

    efficiency n=1 -(q1/q2) for a normal heat engine But how efficiency n=1 -(t1/t2) ? for reversible heat engine
  37. Amr Ali 33

    Hey i need some help in calculating the thermal efficiency of steam turbine

    guys i just wanted to know the formula by which i can calculate the thermal efficiency of a pass out steam turbine( a steam turbine with an extraction for process ) I've attached a simple diagram explaining my problem can anyone please help !
  38. N

    Mechanical efficiency of a compressor #polytropic compression

    Hy please help me .i am strugling to calculate the mechanical efficiency of a compressor as i am not given power output and power output
  39. D

    Efficiency of a Jet-Powered Rotor Engine

    If we make an engine/rotating machine with the use of jets placed around the circumference of a wheel, then how to find its efficiency? This could be something like an Aeolipile (Refer Wikipedia for the same) but without steam.Instead we can use petrol for combustion.Would that make a good engine?
  40. evinda

    MHB Checking the Efficiency of Function(int n) - Let's Count Key++ Executions!

    Hello! (Wave) I have the following function: Function(int n){ int key,j,k; for (j=2; j<=5n^3; j+=5){ for (k=j; k<=3n^(2/3); k+=3){ key++; } } } I want to find how many times the command key++ is executed. That's what I thought (Thinking) : The outer for...
  41. E

    Highest possible efficiency of an engine

    Homework Statement The highest theoretical efficiency of an engine is e=(TH-TC)/TH where TH is the highest and TC is the lowest temperature during the circuit process. In a test car with a stirling engine the highest temperature during the circuit process is 700 °C and the lowest temperature...
  42. F

    Mechanical efficiency with regards to torque and rotational speed

    In what way does mechanical efficiency in gears affect output torque and angular velocity? Mechanical efficiency affects power which is the product of torque and angular velocity. Let's say we have a gearbox with a mechanical efficiency of 0.95, hence the output power is 95% of the input power...
  43. adjacent

    Increasing the efficiency of a python code.

    Here is a python function to check whether a given list or string contains duplicate values: def has_duplicates(x): t = [] for i in x: if i not in t: t.append(i) if t != list(x): return True else: return False But I am sure this approach will be slow for...
  44. D

    Efficiency, Stirling heat engine

    Homework Statement We have a Stirling heat engine. I'm calculating the efficiency \eta. Homework Equations Q_{12} = \frac{m R T_2}{M} \ln(\frac{V_2}{V_1}) > 0 Q_{23} = m c_v (T_1 - T_2) < 0 Q_{34} = \frac{m R T_1}{M} \ln(\frac{V_1}{V_2}) < 0 Q_{41} = m c_v (T_2 - T_1) > 0 \kappa =...
  45. L

    Energy Efficiency Assignment Help - 9th Grade

    hi everyone so i am working on an assignment to overall find the efficiency of a small electric motor. i need help with the following things: 1. Factors that can affect efficiency of a small motor (i need to talk about mass as the factor) 2. Why it is important to understand efficiency...
  46. B

    What is a valid assumption for modeling electrical systems as heat sources?

    Hi all, I've been looking for an answer to this for a while now but I can't explain to Google what I want to know. Hope I have better luck here. I'm an aerospace engineer working on a satellite project. In particular I'm currently working on the thermal analysis and I need to model up each of...
  47. N

    Rocket engine vs jet engine efficiency

    Which are more efficient, Rocket Engines or Jet engines, and why? It would make sense that rocket engines are more efficient because they aren't effected by air pressure but I have been told by some people that actually Jet engines are more efficient so I am confused. If you know of any link...
  48. R

    Fuels and Engine efficiency Mechanical Engineering

    Homework Statement Car (A) C180K WITH A 1.8 litre supercharged spark ignition, Maximum power output 104kw, based upon standard fuel efficiency test a vehicle with this engine would consume 6.1 liters over 100k journey Car (B) C220 CDI with a 2.0 litre turbocharged diesel engine. Maximum...
  49. J

    Thermal Efficiency of a Heat Engine based on pV-diagram

    Homework Statement Here's a link to the pV-diagram I am using - http://session.masteringphysics.com/problemAsset/1396784/2/p16.7.jpg 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...
  50. K

    What is the Efficiency of the system?

    Question: An hand crank is used to life a bucket of water from a well. The bucket and water have a combined mass of 12.0 kg and must be raised 8.5 m. The force used to lift this load is 40.0 N and must be applied over a total circular distance of 15.0 m. What is the efficiency of the system...
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