Cycle Definition and 617 Threads

Homework Statement The figure below shows a plot of temperature T versus entropy S for the closed cycle of a particular heat engine (not necessarily an ideal gas) which consists of 3 processes and which operates between two heater reservoirs, a hot reservoir with temperature T1 and a cold...

what is the graph of carnot cycle in P-V plane using black body radiation? given the internal energy U=aVT^4 where a is the stefan's constant and P=(1/3)aT^4. thank you

While Universe now continue to expand due to the last BB, there is growing vacuum in the midst of it which with time will reach such tremendous value that the expansion will be stopped and the reverse process will start ?

Watching this lecture from nptel about NP completeness: http://www.youtube.com/watch?v=76n4BjlL1cs&feature=player_embedded -We have an algorithm, HC , which given a graph tells us whether or not it has a hamiltonian cycle. -We want to use it in order to create an algorithm that determines...

Homework Statement The problem is as following: Homework Equations \Delta E = \Delta Q-\Delta W The Attempt at a Solution Now I know that if work is done by the system then work sign is negative and that if volume remains unchanged then no work is done. Am I right to say that Internal...

Is it true that for a Carnot cycle, the entropy change for the whole system (engine plus the two reservoirs) would add up to zero? I am reasoning that it would, by the Clausius theorem that for a reversible cycle (which a Carnot cycle is), the entropy change is zero. Otherwise it would not be...

I feel like I'm doing this correctly but my professor gave us an answer that is different from what I'm getting. Composition of (12345)(12345) Reading right to left I get (13524) but the answer he gives is (135)(24) The odd thing is I'm getting the rest of these correct so I don't feel...

Hello guys. first question. you must have done cycle ride. It's our common experience that when air pressure inside tires reduced it becomes harder to ride. But as usual my question is why it is so why we need to apply more force(more likely torque ).?? As it is written in highlighted letters...

1. Statement of the Problem One mole of a monatomic ideal gas is taken through the reversible cycle shown. Process bc is an adiabatic expansion, with P_b = 10.0 atm and V_b = 1.00E-3 m^3. Find a) the energy added to the gas as heat, b) the energy leaving the gas as heat, c) the net work done by...

Homework Statement Dear members, In proton proton cycle, Two protons fuse together to form a duetron with positron and nuetrino. Then duetron combine with another proton to form 2He3, which then combines with another 2He3 to give 2He4 The final reaction is 41H1+2e---> 2He4 Homework...

I am using this battery for a boat bilge pump. It's all working as expected, but what I am trying to determine is if my battery is suitable for the charger I have and if so, I need assistance decoding the CHARGING TIME chart (picture below) in my charger manual to determine how long I should...

Hi From http://en.wikipedia.org/wiki/Carnot_cycle "Reversible isothermal expansion of the gas at the "hot" temperature, TH (isothermal heat addition). During this step the expanding gas makes the piston work on the surroundings. The gas expansion is propelled by absorption of quantity Q1 of...

I would like to use a timer to turn on and off a 220 Volt appliance. With a "mechanical" plug-in timer you have 20 minute granularity. But I would like to have a 1 minute resolution. For example - 1 minute off and 1 minute on. I bought a cheap 10 euro digital timer. I was mislead by the...

Why is it so that along with reversible isothermic processes , reversible adiabatic processes must be taken up to complete carnot's cycle?

Hi I found these two definitions of duty cycle: [SIZE="3"]1: The duty cycle of a machine refers to how long it can keep operating before it needs a rest, or what percentage of the time it's designed to be in use. For instance, a machine gun might only be able to fire continuously for 100...

Hello, I am a complete novice and would like to build a simple closed loop rankine cycle that generate electricy, even if it only enough to power a light bulb. I want to learn more about thermal energy conversion in a hands on way, but I am having trouble finding any simple, easy to follow...

A friend and I are working on this idea which is fairly common, but I'm having trouble starting out. The idea is that of a compressed air engine. Where we take a normal, small capacity engine and modify it such that only compressed air, stored in tanks is sufficient to move the piston. Now...

Homework Statement explain, briefly, what a hysteresis cycle is [2 marks] The Attempt at a Solution I don't think the answer is to draw a graph because that is the next question. The subject is electricity and magnetism but the above question does not refer specifically to electricity...

This is a simple question I have because I am looking at a particular engine cycle, and I can't seem to think of its name...thus it is very difficult to search for discussions of something you don't know the name of. I'll describe the cycle, if anyone knows the name of the cycle please let me...

Here is a second thought experiment I designed to test if I understand certain concepts concerning electrostatics correctly. Help will be appreciated. There must be an error somewhere in the explanation below; I am giving the explanation as if “factual” only to explain how I understand it at...

I am casually working through Introduction to Electrodynamics, 3rd ed. by David J. Griffiths and created some theoretical situations to test my understanding of the subject matter. I am having difficulty with some, and will appreciate input. Consider the following theoretical cycle (see the...

I am a lay person trying to solve a bet. I contend that pedalling a bike uphill can easier than pedalling on a level plane at a 1:1 gear ratio, if: [a] The bike is put in a higher gear ratio such as 10:1 [b] The rider accepts travel at a reduced speed and therefore a longer duration ride, if...

Homework Statement Show that the net work done by the otto engine per cycle is Cv(Tc - Tb)(1 - Ta/Tb) PV diagram: [PLAIN]http://www.antonine-education.co.uk/physics_a2/options/module_7/topic_4/Otto_indic.gif Homework Equations Work done by a kmole of gas expanding irreversibly and...

Hi there, I joined specifically to ask for help in exploring the possibility of harvesting the waste heat from a cars engine and recycling this energy to improve the engines efficiency. I'm assuming most people know about thermo dynamics, internal combustion and volumetric efficiency I:-p...

Homework Statement This is part of a bigger problem, I simplify to just: P=k sin^2 \omega t How do I integrate over one cycle? The Attempt at a Solution \left\langle P \right\rangle = \int_0^T k\; sin^2 (\omega t) d t \;\hbox { where }\; T= \frac c f = \frac {2\pi}{ \omega}...

In a Rankine cycle such as a steam power plant, why does the liquid (water) have be condensed before being reheated first? Isn't the Q just extracted during the condensation stage, wasted into a nearby reservoir, and then re-added in the boiler? Could this water not be fed straight to the...

Hi, :smile: So I am learning about how refrigerators work. First I have to show the Carnot cycle and explain why it does not work in reverse - from my understanding, it does not. And then show how it actually works in real life, with the phase transitions, which I am guessing don't exist for...

All reversible cyclic processes (engines) have the same efficiency: 1-T2/T1. And Carnot demostrated this efficiency with the Carnot Cycle and went on to use this to demonstrate that this was the upper limit for efficiency. My question is, why is it that there is such importance placed on...

If a question asks for the "quantity of work input to the pump" is it acceptable to present the answer as positive. I think so because the direction of energy transfer has been defined in the question itself hence there is no need for a sign on the answer. All that's asked for is the...

Help with Organic Rankine Cycle Project please! Moderator's note: this thread is from May 2011 Hi there everyone, I'm posting here in the hope that someone will be willing to help an engineering layman do some calculations, I'm a plumber not an engineer. Thanks to anyone who decides to help...

I need to find out how a certain pulse width modulation duty cycle is used in SMPS power supplies (specifically a boost converter). Also, how does the oscillation contribute to a voltage transformation? (step up) Any pointers to some articles are welcome

Hello, Lately I encountered thermodynamics. And all that world is very new to me, gas expansion etc etc. I recently learned about Carnot's cycle. IT has 2 isotherms and 2 adiabatic processes. Now, I understand what those processes in separation mean. Adiabatic processes don't...

Homework Statement All i want to know is how do i find the temperature of my heat and cold reservoir, given that they have a 90 degree celsius/kelvin differential and a 28% efficency. Homework Equations Efficency= Work out/ Work in = 1- Q out/Q in The Attempt at a Solution I been...

Hi, An amount of ideal gas undergoes the folowing cycle process in the following graph: This process can be presented by the following PV-graph : The answer has to be the upper graph but why can't it be the lower graph ? Thank you!

According to the Milankovitch 100,000 years cycles, there is a problem. The orbit of the Earth will change to a gradually more ecliptic orbit, and it will be a bit colder when this happen. But the problem is that this is not enough to explain ice ages. How much is missing. I mean how much...

So I can follow the sequence of operations: the refrigerant enters the compression stage as a saturated vapour(a gas?) and it's compressed raising the temperature of the refrigerant, it gives off some of this heat to the surrounding ambient air, causing a decrease in temperature and an according...

Researchers at Sandia have found the Brayton cycle with supercritical CO2 to be 50% more efficient than existing steam turbine technology used with nuclear reactors: http://www.eurekalert.org/pub_releases/2011-03/dnl-scd030311.php I suppose it's safer too, since the CO2 would help to...

Hello! first time user, in desperate need of advice: My company (start up) has built a 5 hp Rankine cycle generator with a thermal efficiency of about 33%, it works fantastic in an open cycle, however 6 engineers and many pump specialists later, and i am still at a loss... My system uses...

My team has recorded information on a single cylinder Otto cycle from a lab we have done. We are supposed to compare the theoretical efficiency of the cycle to the experimental efficiency. Using a given compression ratio of 3 and the ratio of specific heats for the fuels we used we were able to...

Hi I am trying to model the Brayton cycle in a gas turbine that is used for electricity generation. My main aim is to be able to fully power the x amount of daily electricity load of a building using this machine. In order to do this, is it correct to do a backwards model and find what...

Do exist some proposed nuclear fuel cycle in which uranium or thorium whoud be first converted in some beta or alpha emitting isotope and after energy whould be harnessed with direct energy conversion methods?Possibly, it could reduce size of power plant and make steam turbine unnecessary.

How can equipments work in ac current even it is oscillating from +ve to -ve and to zero? Alternating current is alternation of positive and negative values.If we consider the sinusoidal case,the current value becomes zero,negative,positive in a cycle.In that case,how can electrical equipment...

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...

Homework Statement 1. In a set-up of Brayton cycle , I know that the turbine has to give a greater magnitude of work output than the magnitude of the work done by the compressor (because the turbine has to run the compressor)...but the turbine and compressor are at the ends of the same shaft...

http://www.accuweather.com/blogs/news/story/45263/devastating-tc-yasi-crashing-a-1.asp Landfall between Cairns and Townsville (actually between Innisfail and Cardwell), Queensland, on Feb. 2, 2011 http://www.bom.gov.au/products/IDQ65002.shtml

Homework Statement (a.) This was just a log-log plot of the otto cycle (b.) Derive an expression for the ratio of maximum to minimum temperature experienced by the cylinder head during the part of the cycle that contains only isochoric and and adiabatic transitions in terms of the compression...

Homework Statement Dear All, I have a question regarding the Carnot Cycle: (The image is taken from Wikipedia, I hope that is not a problem... In case it is I will change it.) Points one to two are an isothermal reaction. The gas, kept at constant temperature, is expanding, the...

……Independence Family Clan Tribe Sovereignty Aristocracy Rebellion…… It seems to me that humans have repeated this same cycle of organization and disorganization throughout history. Would you agree? If so, do you think this cycle has...

Homework Statement Determine Whether or not this cycle violates the first law and if it is reversible, irreversible, or not possible. 2000kW or power are produced by taking 3000 kW of heat transfer from a 750C reservior and rejecting 1000kW of heat to a 20C reservoir. Homework...

Homework Statement I don't understand the process between the points in a carnot cycle. Homework Equations Can someone please explain what is going on from point to point in terms of Q (heat), U(thermal energy), and Work? The Attempt at a Solution