Carnot cycle Definition and 109 Threads

Homework Statement A heat engine containing an ideal gas has a reversible cycle which consists of 2 constant volume segments with V = 1ℓ and V = 3ℓ and two constant pressure segments with P = 1 atm and P = 2 atm (see figure below). The temperature at point “c” is Tc = 273 K. A) Is the path...

Homework Statement 2. The attempt at a solution Is it only possible when 600J of heat is exhausted and 400J of heat is converted into work? Is the 600J heat will enter the cold reservoir and available to do work again? q1/T hot + q3 / T cold = 0 q3 = 600 when T = 300K

Greetings, Here is my thought process on the carnot cycle, regarding heat pumps and engines. I'd much appreciate it if you can clear up any misconceptions and answer my question at the very end. So my book states that there is no change in internal energy in a heat engine, but neither confirm...

Homework Statement The temperature in a refrigerator evaporator coil is -6oC and that in the condenser coil is 22oC. Assuming that the machine operates on the reversed Carnot cycle, calculate the COPref , the refrigerant effect per kW of input work, and the heat rejected to the condenser...

Homework Statement Let the radiant energy in a cylinder be carried through a Carnot cycle. The cycle consists of an isothermal expansion at temperature T, an infinitesimal adiabatic expansion where the temperature drops to T-dT, ad returning to the original state via an isothermal compression...

Homework Statement See attachment Im struggling with b and c. I did an attempt, but really don't know if it is correct. Homework Equations The Attempt at a Solution See attachment

Homework Statement An ideal gas is taken through a Carnot cycle. The isothermal expansion occurs at 250°C, and the isothermal compression takes place at 50.0°C. The gas takes in 1 200 J of energy from the hot reservoir during the isothermal expansion. Find (a) the energy expelled to the cold...

What happens in a reversed carnot cycle? I mean in refrigerators.The gas is adiabatically compressed so that it's temperature rises.Then it is isothermally compressed so that the heat is rejected to the sink.But then why it is said everywhere that the working substance absorbs heat from sink...

Homework Statement An approximate equation of state for a gas is P(v-b) = RT with b constant. The specific internal energy of the gas is u = c_vT + const . a) show that the specific heat at constant pressure of this gas is c_v +R and b) show that the equation of a reversible adabiatic...

Homework Statement Basically I have the following problem. Given the equation of state \sigma = \frac{b}{T}\frac{L - L_0}{L_0} where b and L_0 are positive constants, calculate the work done over a Carnot cycle by a wire with this equation of state.Homework EquationsI already have the work...

The question is: Consider a thermal battery - a device for storing mechanical energy. Use two large containers as heat reservoirs where one contains ice and water in equilibrium and the other contains steam and water in equilibrium. Both are held at pressure=1atm. Energy is stored by using a...

I'm having some difficulty understanding how to find the work and heat transferred in a carnot cycle. Problem: One mole of ideal gas (cV=1.5 R) perform a Carnot cycle between the temperature 400 K and 300 K. On the upper isothermal transformation, the initial volume is 1 liter and the final...

Hello, In the Volume vs. pressure graph I understand the area under the curve is work. However, I have a hard time reconciling this graph with a pressure vs. temperature or a temperature vs. volume graph. What does the area inside the box represent? Work? Like which parts on the P vs. V graph...

Hi, For my Bachelor's thesis I've been working on a finite time Carnot cycle. I've finished my numerical analysis using the differential equations governing the time evolution. My next step should be a simulation. First I should stick to a 1 dimensional system. This system consists of a...

Hallo, I read about thr Carnot-Cycle and got a problem. A->B: isothermal B->C: adiabatic C->D: isothermal D->A: adiabatic I want to understand how to calculate the work done in the isothermal processes. I have read: W_{AB}= T_{H}Nk\ln{(\frac{V_{A}}{V_{\text{B}}})}\\...

Homework Statement Consider the gas do the themodynamics process. If the process graph is one line with constant gradient, Homework Equations What process was happened? How to calculate its amount of heat which absorbed or liberated? The Attempt at a Solution I really need your...

I'm trying to resolve some of my conceptual sticking points with the Carnot cycle. For one thing, I'm reading Reiss's Methods of Thermodynamics, and he offers a proof that the Carnot cycle obtains maximum efficiency when conducted reversibly. How can the cycle be conducted reversibly? During...

Homework Statement A Carnot engine operates between 230°C and 120°C, absorbing 6.30*10^4 J per cycle at the higher temperature. What is the efficiency of the engine? Homework Equations eff = 1 - (Tcold/Thot) The Attempt at a Solution Using this equation, I get 47.83 percent...

In Carnot cycle we assume that heat addition takes place at constant temperature(temperature of system and source being same) and same is the case for Heat rejection. But as we know that for heat flow (ie heat addition and heat rejection), temperature difference has to be there between system...

Homework Statement Assuming that the auxiliary system in the Carnot cycle is a monoatomic ideal gas whose fundamental equation is S=\frac{NS_0}{N_0} +NR \ln \left [ \left ( \frac{U}{U_0} \right ) ^{3/2} \left ( \frac{V}{V_0} \right ) \left ( \frac{N}{N_0} \right ) ^{-5/2} \right ]. 1)Find...

I have some trouble understanding the carnot cycle and why you have to make it so complicated, i.e. this process involves 2 isothermal and 2 adiabatic processes. If you want an engine with maximum efficiency why can't you just have a system whose temperature is just a tiny inch above your hot...

Why do we always talk about the Carnot cycle as being the most efficient, ideal engine? Doesn't the same equation hold for any reversible heat engine operating between two thermal reservoirs? Couldn't you prove e = 1-T_{L}/T_{H} for any reversible cycle? And then you can apply the usual "no...

Homework Statement A borehole produces 120kg/s of high pressure water at 165°C. A powerplant is to be designed to extract heat from the water, reducing the temp to 147°C. The plant which will initially be assumed to be reversible, will reject heat at 17°C to a river. Take 147°C as the highest...

Homework Statement its part VI) of a big problem, where: 0.12 moles of argon (40) undergoes the cycle abca described in the graph. Process ab lies on a 540k isotherm. In the previious 5 sub problems, i figured that: Tc=270k Qbc=670J (lost) Qca=400J (added) Wab=370J Wabca=100J...

An ideal, monatomic gas is going through a 4 step Carnot cycle. Step 1 is an adiabatic expansion. Step 2 is an isothermal expansion. Step 3 is an adiabatic compression. Step 4 is an isothermal compression. The whole cycle is reversible. My question is how would the cycle change if step 1 is done...

Homework Statement An ideal engine operating on the Carnot cycle with a minimum temperature of 25°C develops 20 kW and rejects heat a rate of 12 kW. Calculate the maximum cycle temperature and the required heat supply of the cycle. Homework Equations Qhot/Thot =Qcold/Tcold...

1. Please help with the following question. Given: A Heat engine goes through a Carnot Cycle as the following states: State 2 to 3: air compresses adiabatically (pressure increasing) State 3 to 4: air expanded under isobaric process State 4 to 1: air goes under adiabatic expansion process...

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

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...

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...

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...

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...

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...

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

Nevermind for now, just redid the whole thing and saw I made a stupid little mistake in computing the first volumes that messed everything else up. A Carnot engineer operating with a perfect gas between 800C and 25C has an operating pressure range between 20kPa and 6000kPa. Determine the work...

Homework Statement Consider a Carnot Cycle that absorbs heat from the hot reservoir at Thw and expels to the cold reservoir at Tcw just below Th and above Tc respectively. a.) Derive an equation that relates the four temperatures. b.) Using the first and second law, write down an...

Homework Statement I'm trying to understand how one would plot this. Homework Equations dS = dQ/T dU = dQ-dW (W is work done by the system, Q is heat absorbed by system, U is energy) For a closed cycle, dU = 0. Carnot Cycle: 1- isothermal expansion at Th 2- adiabatic expansion to Tc...

in a carnot cycle the gas expands adiabatically from 200 degrees to 500 degrees. what is the efficecy? and what is the entropy change of the gas during the expansion? sorry - i got the efficiency to be: 38.8% however I am unsure how to work out the entropy chance? any hints?

Is it possible (at least theoretically) to construct engine which uses Carnot cycle and two reservoirs with temperatures T_1<0<T_2 (one of them has negative temperature which is possible e.g. in case of two-state paramagnet). Such cycle would have efficiency greater then 1. (of course the...

The Attempt at a Solution For a) I imagine it is easier to control the temperature of the hot reservoir because you could use a constant heat source e.g. bunsen burner. c) melting/freezing water. d) Entropy of the environment increases and the entropy of the universe always increases...

Hey. I'm supposed to calculate the work done in an adiabatic process, B-C, and I only know the values of the temperatures and the volume in the first point (point B). It is not known if it is a mono or diatomic gas, therefore i don't know the value of gamma. I've tried T*V^(gamma-1)=K and the...

i want to ask why heat transfer is considered ti be an irreversibility and why in carnot carnot cycle heat addititon is at constant temperature to make this process reversible

In the textbook, it reads: the reverse of carnot cycle is just a refrigerator or heat pump. In this sense, except for the direction of carnot cycle is reverse, could I say the way to calculate the efficiency of the carnot refrigerator is the same? That is, could be still use \eta = 1 -...

Homework Statement an ideal gas operates in a carnot cycle so that it produces a net positive work of 400 joules per cycle. the maximum temperature during the cycle is 300 deg celsius and the heat lost to a low temperature bath is 600 joules per cycle. a) what must be the temperature of the...

I have a question on Why the Carnot cycle is not used with real engines? I need to refer to real cycles in my explanation.

[SOLVED] Heat Engines and the Carnot Cycle Homework Statement The operating temperatures for a Carnot engine are Tc and Th= Tc + 55K. The efficiency of the engine is 15%. How do i find Tc?

Homework Statement Homework Equations You are designing a steam engine and you want to make it as efficient as possible in terms of the energy used to run it and the useful energy it can produce. What do you want to maximize and minimize in terms of the steam temperature and the...

I have two short questions: 1) Is the Carnot cycle completely reversible? 2) \Delta S = 0 for a reversible process, right?

Homework Statement We have stressed that the Carnot engine does not exist in real life: It is a purely theoretical device, useful for understanding the limitations of heat engines. Real engines never operate on the Carnot cycle; their efficiency is hence lower than that of the Carnot engine...

Is it possible to show that the maximum efficiency for a heat engine is given by \eta = 1 - \frac{T_c}{T_h} where T_c is the temperature of the cold sink and T_c is the temperature of the warm sink? In other words: How do I prove that a engine run by a Carnot cycle is the most efficient engine?