Question: How Do You Increase Carnot Efficiency?

Why Stirling engines are not used?

Stirling engines are not good for applications that need to change their power output levels quickly, like cars for example.

Stirling engines like to change their power output levels slowly.

Plus, they tend to be heavier (and more expensive) than gasoline or diesel engines of a similar power output..

What is the maximum Carnot efficiency?

A Carnot engine operating between two given temperatures has the greatest possible efficiency of any heat engine operating between these two temperatures. … No real heat engine can do as well as the Carnot efficiency—an actual efficiency of about 0.7 of this maximum is usually the best that can be accomplished.

Is Carnot engine 100 efficient?

In order to achieve 100% efficiency (η=1), Q2 must be equal to 0 which means that all the heat form the source is converted to work. The temperature of sink means a negative temperature on the absolute scale at which the temperature is greater than unity.

Is Carnot a cycle?

The Carnot cycle is a theoretical ideal thermodynamic cycle proposed by French physicist Sadi Carnot in 1824 and expanded upon by others in the 1830s and 1840s. … It is not an actual thermodynamic cycle but is a theoretical construct. Every single thermodynamic system exists in a particular state.

What is Carnot efficiency?

Carnot efficiency is the maximum efficiency that a heat engine may have operating between the two temperatures (Figure 2-7). Figure 2-7. Carnot process efficiency. The Carnot efficiency has little practical value. It is a maximum theoretical efficiency of a hypothetical engine.

Why is the Carnot engine the most efficient?

The Carnot cycle can be thought of as the most efficient heat engine cycle allowed by physical laws. … This means that the Carnot cycle is an idealization, since no real engine processes are reversible and all real physical processes involve some increase in entropy.

How can the efficiency of an engine be increased?

Most petrol (gasoline, Otto cycle) and diesel (Diesel cycle) engines have an expansion ratio equal to the compression ratio. Some engines, which use the Atkinson cycle or the Miller cycle achieve increased efficiency by having an expansion ratio larger than the compression ratio.

Why 100 efficiency is impossible?

It is impossible for heat engines to achieve 100% thermal efficiency () according to the Second law of thermodynamics. This is impossible because some waste heat is always produced produced in a heat engine, shown in Figure 1 by the term.

What ways can you suggest for us to increase the efficiency of the heat engines?

Run the engine fuel-lean, that is, use excess air. It is well known that fuel-lean running improves the efficiency. … Higher compression ratio. … We need new cycles put into practical use. … Run the engine at optimum conditions, meaning low friction (modest engine speed) and low pumping work (air throttle more open).

Do Carnot engines exist?

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. … The Carnot engine has too low an efficiency. The Carnot cycle contains only reversible processes.

Which is the most efficient cycle?

Classical thermodynamics indicates that the most efficient thermodynamic cycle operating between two heat reservoirs is the Carnot engine [1] , and a basic theorem expresses that any reversible cycle working between two constant temperature levels should have the same efficiency as a Carnot cycle [2].

Is Carnot engine reversible?

The Carnot cycle is essentially a reversible cycle that itself consists of four reversible processes. A reversible process is a process that is carried out infinitely slow, so that the entire process can be through of as consisting of a series of equilibrium states.

Is there any way to increase the efficiency of a Carnot heat engine other than by increasing th or decreasing TL?

Is there anyway to increase the efficiency of a carnot heat engine other than increasing Th or decreasing Tl? energy cannot be created or destroyed.

Which Stirling engine is the most powerful?

One of the most efficient Stirling engines ever made was the MOD II automotive engine, produced in the 1980′s. It reached a peak thermal efficiency of 38.5%. Compare this to a modern spark-ignition (gasoline) engine, which has a peak efficiency of 20-25%.

Why Carnot cycle is not possible?

Carnot cycles are not encountered in reality since achieving isothermal heat transfer is very difficult (needs very large heat exchangers and long time). Also process 3-4 requires a pump or compressor that can handle two phase mixture (liquid and vapor) which is impractical.