Efficiency Definition and 948 Threads

Homework Statement Transformer efficiency loss Homework Equations Larger transformers are more efficient than smaller The Attempt at a Solution I understand the basics of energy loss through heat etc but i don't understand why it would be different for the sizes of transformers. Is it to do...

So, I'm doing this coursework right now, and I know that this equation is what's needed to get to the efficiency but I have only a little idea why. I'm given this formula...

hi friends, I've used the following equation in Thermodynamics: an engineering approach(Cengel) for calculating exergy efficiency of compressor. In fact, for an adiabatic compressor with negligible kinetic and potential energies, the second-law(exergy) efficiency becomes...

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

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...

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...

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...

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...

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...

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...

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.

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...

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...

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...

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...

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...

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}...

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...

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...

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...

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...

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...

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...

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

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.

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...

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...

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...

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...

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...

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...

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...

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...

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...

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.

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

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...

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...

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

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 !

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

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?

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...

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...

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...

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...

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 =...

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...

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...

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...