Efficiency Definition and 901 Threads

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...

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...

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...

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...

hi.I would like to know something about the IC engine.I just read an article.It said that 30% efficiency is gone through conduction of heat by the cylinder wall.If it is reason for one of the efficiency loss why can't we build an cylinder coated with a material that is non conduction.So only...

Homework Statement A single phase half wave rectifier produces a DC signal ##V_{DC} = (4.6 \pm 0.78) V## and AC signal ##V_{AC} = (0.22 \pm 0.036) V##. What is the error on the efficiency? Homework Equations Functional dependence, propagation of error: ##\sigma_f = \sqrt{...

Hello Guys, From the torque curves of most of the ic engines it can be seen that torque is maximum at a particular rpm range then it starts dropping. It is said that the torque is maximum when the volumetric efficiency is maximum , i just can't understand the relationship between the both...

Hi there, I have been thinking about attempting to quantify the statement that: "Gasification is more efficient thermodynamically than direct combustion of the fuel source as the gas can be combusted at higher temperatures, resulting in higher thermodynamic efficiencies as defined by...

What do I look for to determine the efficiency factor to know how many watts I can get out of a generator given a specific known HP sized engine? Example: 12.6 HP gives 9395 Watts from the standard HP to Watts conversion... however on a Markon generator, the spec sheet says that a 12.6 HP...

Homework Statement Objects A (2.0 kg), B (1.0 kg), and C (1.0 kg) are pushed up a ramp, which is 4.0 m and 1.2 m high. The applied forces are parallel to the ramp with magnitudes of 9.8 N on A, 4.9 N on B, and 3.1 N on C. Homework Equations Eff = W(output) ÷ E(Input) x 100% W = F...

I read there are transparent solar panels which are also flexible, Then I read carbon base solar panel. Then sun capture that concentrate to panels like other fresnel lens or dish like. Then there is this idea that people can print out their own flexible solar panels with photovoltaic ink...

Homework Statement A snowboarder goes down a ramp when initially at rest. The Total mechanical energy on top of the hill is 980 J and 400J at the bottom of the hill. Calculate efficiency of the ramp. Homework Equations Efficency = (Power out) over (Power in) The Attempt at a...

Discuss two measures that can improve the cooling efficiency.