Carnot Definition and 277 Threads

Homework Statement Cooling of a food from 293K (20 ⁰C), freezing it at 272K (-1⁰C), and further cooling to 253K (-20 ⁰C); using cooling water rising in temperature from 293K (20 ⁰C) to 303K (30 ⁰C) to accept heat. The specific heat of the unfrozen food is taken as 3.2 kJ/kg K, that of the...

Homework Statement The temperature inside the room ##T_I= 25 C ## and the temperature outside the house is ##T_O = 32C##. The temperature difference causes energy to flow into the room (by conduction through the walls and window glass) at the rate 3,000 J/s. To return this energy to the...

I saw a problem for which I don't really understand the idea of the solution. This is what it says: The vaporization latent heat for water (at 100 deg C) under normal pressure (101325 pa) is 2,3*10^6. What is the saturated vapor pressure for water at 105 deg C? And the solution says that we have...

Homework Statement A Carnot engine extracts 745 J from a 592-K reservoir during each cycle and rejects 485J to a cool reservoir. It operates 16 cycles per second. Find work, efficient, temp of cool reservoir. Homework Equations W = Qh - Qc n=Wout/QhThe Attempt at a Solution I'm sure I can do...

Hi there, I just sign up today. I'm curious to know about the energy added/released in a Carnot Refrigeration Cycle. Let's say the problem is like this: A Carnot Refrigerator used refrigerant-134a as the working fluid. During the heat addition process, a percentage of mass of the refrigerant...

The refrigeration cycle is often likened to a reverse Carnot cycle. I pretty much understand the Carnot cycle, but in relating it to a household refrigerator, I am lost. Where is the adiabatic compression done on the machine (inside vs. outside) , and where is the adiabatic expansion? How is...

Homework Statement An ideal Carnot process operates between a heating bath with the temperature of 20 C and a mole of hydrogen is in a container with constant volume. During the process, the work is done to remove heat from the hydrogen gas and emit heat to the heat bath. Calculate the work...

Homework Statement I don't need help solving I just need some clarification. Since the carnot cycle is adiabatic, the first law would reduce to work= mass*(change in internal energy). On my test I was asked to calculate the work of the isentropic expansion of a carnot engine with air...

I'm struggling to understand the Carnot efficiency. I can follow proofs that prove efficiency= 1- (Th/Tc), and I understand the nature of the processes that make up a carnot cycle - however I still can't make sense of it in my head. I've looked online and most people try and explain it...

I am learning the Carnot Cycle but I still get confused about this cycle. There are four steps in this cycle. 1)Isothermal expansion 2)Adiabatic expansion 3)Isothermal compression 4)Adiabatic compression After step one, we got the heat from heat reservoir through expansion but I don't...

The efficiency of a Carnot Engine is described by the relationship: Tc/Th = Qc/Qh, so that e(Carnot) = 1 - Tc/Th For heat engines, can their efficiency also be related to temperature as well? Or is the description of their efficiency just: e(heat engine) = W / Qh = 1 - Qc/Qh I am inclined to...

Homework Statement A reversible heat engine produces work from the temperature difference that exists between a mass of m = 9 kg of an ideal gas (cv = 716 J/kgK, R = 287 J/kgK) in a rigid container and a heat reservoir at THR = 285 K. The only heat transfer interaction experienced by the...

This P-V diagram summarizes the Carnot cycle. Given a working fluid whose state ##(P,V,T)## is ##(P_1,V_1,T_1)## (at point 1) where ##PV=nRT##, the working fluid undergoes a cycle of four stages and again retrieve its original state of ##(P_1,V_1,T_1)##, that is it gets back again to point 1...

My textbook gives the definition of a reversible transformation as a transformation that can be inverted by effectuating only infinitesimal changes in the surroundings. I admit that I have no idea of what infinitesimal means in a rigourous mathematical language, therefore the definition is quite...

1.what is the work done in an adiabatic compression process in a carnot cyclewhen we consider work done in efficiency why do we take heat exchange into account i.e.,qs-qrThe Attempt at a Solution

My textbook explains the Carnot cycle as follows: 1. Heat is added to the boiler, where the steam inside expands isothermally at high temperature (T(High))w(both valves closed). 2. The intake valve is opened (exhaust valve closed) and the steam expands adiabatically. The expanding steam...

are engines in our cars follow the carnot cycle or they work differently

1 - T1/T2 gives efficiency of a carnot engine working between two temperature sources T1 &T2 and we know that, that efficiency is unbeatable but can there be another engine possible serving the same purpose as that of carnot engine working in an entirely different manner and MORE EFFICIENT than...

Homework Statement A Carnot cycle, shown in Fig. 20-7, has the following conditions: Va = 7.5 L, Vb = 15 L, TH = 470°C, and TL = 260°C. The gas used in the cycle is 0.50 mil of a diatomic gas, y = 1.4. Calculate (a) the pressures at a and b; (b) the volumes at c and d. (The rest of the...

Homework Statement I think I understand the first 3 steps of the Carnot cycle but not the 4th. Homework Equations The cycle here: http://en.wikipedia.org/wiki/Carnot_cycle#Stages The Attempt at a Solution I understand that in stage 1, the gas expands by taking in heat from the hot reservoir...

In a reversible carnot cycle the amount of heat added is always more than the amount of heat taken out. So why doesn't it explode? I'm wondering how heat is conserved mathematically as the area under the curve of a p-v diagram. u=q+w. If the heat during expansion is always more than the heat...

I have 2 questions, which are related, and was hoping someone could help me clear things up. First question, isn't the Otto cycle reversible and usable as a refrigerator? Referring to the diagram above & let me go part by part. AD: Assume the corresponding part of the working substance is...

I can't realize the proving why Carnot engine has the highest efficiency. "Let εc be the efficiency of a Carnot engine operating between two given temperatures.If an engine X, which has an efficiency εx that is greater than εc.We can couple engine X to a Carnot refrigerator , and they make a...

Homework Statement The oxygen contained in a thermally insulated container will be cooled down to its boiling point (-183 C), and then condensed. Thereby one uses a reverse Carnot process operating between the oxygen gas (instantaneous) temperature and the room temperature (17 C). What is the...

Homework Statement You have an infinite heat reservoir with temperature Th. But you’ve only got a finite cool reservoir, with initial temperature Tc0 and heat capacity C. Find an expression for the maximum work you can extract if you operate an engine between these two reservoirs. Homework...

Homework Statement a refrigerator is used to convert 1 kg of liquid water at 30 degree celsius to ice at -18 degree celsius.the refrigerator rejects heat to surroundings which are at 30 degree celsius.the specific heat values of liquid water and ice are 4.18 kj/kgk and 1.9 kj/kgk respectively...

1-Is the efficiency of heat engines working in cycles other than Carnot independent of the nature of substance used? Can we still claim that maximum efficiency in converting heat to work is attained during reversible processes for such cycles? For which engines/cycles can we do this? 2- Why is...

I am teaching myself thermodynamics (and really enjoying it!) but am slightly confused about Carnot's engine. From the equation efficiency=1-T(cold reservoir)/T(hot reservoir), I see that the most efficient engine is one where the difference in temperature between the cold and hot reservoirs is...

Is Carnot engine the only form of reversible engine? Is it possible to have a different form of reversible engine that goes through different processes? For a standard Otto cycle working with ideal gas, theoretically the two processes involving isochoric pressure change can be reversible...

So I have been thinking about the photon gas, and I have read several papers talking about how a Carnot cycle could be created for it. This is fantastic, and it is something I am quite comfortable with. All of the papers present the P-V diagram as the "golden" Carnot cycle for the photon gas...

Greetings, A Thesis regarding the historical accuracy of portrayal Sadi Carnot and Lord Kelvin's work seeks a University. It is based largely on the images below (note highlighted areas), taken from their original work. As you know, Sadi Carnot and Lord Kelvin are the fathers of the science of...

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...

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 A Carnot engine uses a hot reservoir consisting of a large amount of boiling water and a cold reservoir consisting of a large tub of ice and water. When 6437 J of heat is put into the engine and the engine produces work, how many kilograms of ice in the tub are melted due to...

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...

Why can we say that a Carnot's machine efficiency does not depend on the fluid that you are heating? Is it because Carnot's machine is very ideal, a mere thought experiment? I have another question. I know that the efficiency of a heat engine depends on the quantity of heat that enter and...

I was reading Cengel's thermodynamics and noticed that he uses a thought experiment to show that there is no machine that is more efficient than the Carnot reversible machine. He says that both a reversible machine and an irreversible machine are connected to high and low temperature deposits...

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 a)A stone at 400K with heat capacity ##c_p## is placed in a very large lake at 300K. The stone cools rapidly to 300K. Calculate the entropy change, due to this process, of the stone and lake. b)An insulated cool-box of a Carnot refrigerator at temperature T loses heat...

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 A Carnot engine operates with 1 kg of methane, which we will consider an ideal gas. The ratio of specific heat capacities \gamma is 1.35. The ratio of maximum volume to minimum volume is 4 and the cycle efficiency is 25%. Find the entropy increase during the...

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...

Homework Statement A Carnot engine operates between two finite heat reservoirs of total heat capacity CtH and CtC. a) Develop an expression relating TH to TC at any time. b) Determine an expression for the work obtained as a function of CtH ,CtC , TH and initial temperatures TH0 and TC0...

Homework Statement A Carnot engine operates between a warmer reservoir at a temperature T1 and a cooler reservoir at a temperature T2. It is found that increasing the temperature of the warmer reservoir by a factor of 2.00 while keeping the same temperature for the cooler reservoir increases...

I have undertaken a course on Semiconductors. My professor told us that a sun-solar cell system can be taken as a Carnot Engine. He assumed that the surface temperature of sun is 6000k and that of solar cell is 300k.And then he found out the efficiency by (1-T1/T2), which came out close to be...

A Carnot engine is operating between a source and a sink at temperatures T1 & T2 (T1>T2) respectively.. The heat capacities of the source and the sink are equal. Find the final temperature attained.