# Question regarding Heat Transfer in Carnot Engine

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• Harikesh_33
In summary, the Carnot Engine is a theoretical engine that is different from a Sterling Engine which can be made practically. It has some drawbacks, such as the heat transfer only occurring during isothermal processes and the use of adiabatic processes to produce a proper cycle. Additionally, the amount of work produced is ##Q_H - Q_C##, not just ##Q_H##. It is also difficult, if not impossible, to physically achieve the shutting down of heat transfer during adiabatic processes.
Harikesh_33
***A Carnot Engine*** is a theoretical engine unlike a Sterling Engine which can be made practically.

Some of the drawbacks of Carnot Engine are,

1)The Heat Transfer occurs only during isothermal process(compression and expansion),this is because the working material (ie) gas or fuel used, if it's at a different temperature(technically the temperature of the working material is infinitesimally smaller)than the hot reservoir ,then some amount of heat get's used up to attain thermal equilibrium (ie) it's irreversibly lost .

Now my question is ,if ##Q_H## is the heat supplied by the #Heat# #Reservoir# ,then the heat is used to do some work of say ##dW=pdV## and if entire heat ##Q_H## gets used as Work, then how does it transfer ##Q_c## amount of heat to the cold reservoir?

And it seems so odd to say that once the Isothermal processes are over ,it expands /contracts adiabatically ,are we physically removing the sources here ? **Is the only use of Adiabatic process in ***"Imaginary Carnot Cycle"*** to produce a proper cycle**?

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Harikesh_33 said:
Now my question is ,if ##Q_H## is the heat supplied by the #Heat# #Reservoir# ,then the heat is used to do some work of say ##dW=pdV## and if entire heat ##Q_H## gets used as Work, then how does it transfer ##Q_c## amount of heat to the cold reservoir?
The amount of work is ##Q_H - Q_C##, not just ##Q_H##.

Harikesh_33 said:
are we physically removing the sources here ? **Is the only use of Adiabatic process in ***"Imaginary Carnot Cycle"*** to produce a proper cycle**?
Yes, you are shutting down the heat transfer process, Something similar to closing a valve to shut down a mass flow. Something very difficult to achieve physically, most likely impossible at high speed.

hutchphd

## 1. What is a Carnot engine?

A Carnot engine is a theoretical heat engine that operates on the Carnot cycle, which is a reversible thermodynamic cycle. It is used to model the most efficient possible heat engine and serves as a benchmark for real-world engines.

## 2. How does a Carnot engine work?

A Carnot engine works by taking in heat energy from a high-temperature reservoir, converting some of it into work, and then releasing the remaining heat energy into a low-temperature reservoir. This process is repeated in a cycle, with the engine always operating at maximum efficiency.

## 3. What is the efficiency of a Carnot engine?

The efficiency of a Carnot engine is given by the Carnot efficiency formula: efficiency = (Thigh - Tlow) / Thigh, where Thigh is the temperature of the high-temperature reservoir and Tlow is the temperature of the low-temperature reservoir. This means that the efficiency of a Carnot engine is dependent on the temperature difference between the two reservoirs.

## 4. What are the limitations of a Carnot engine?

A Carnot engine is a theoretical model and does not take into account real-world factors such as friction, heat loss, and the time it takes for the engine to complete a cycle. Additionally, it is limited by the maximum temperature difference that can be achieved between the two reservoirs.

## 5. How is a Carnot engine used in real-world applications?

While a Carnot engine itself is not used in real-world applications, the Carnot cycle is used as a basis for the design and optimization of various heat engines, such as steam turbines and gas turbines. It helps engineers to understand the theoretical limits of these engines and make them more efficient.

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