Maximum temperature of fuel air cycle

In summary, when the stoichiometrically correct mixture (equivalence ratio=1) is burned in an air fuel cycle, some air is left after point 3 on the P-V diagram. Theoretically, the entire fuel and air mixture should combust until point 3, but in practice, this is not possible. To achieve better performance, it is easier to have an air-rich mixture, resulting in more fuel being burned and some air being left. This is due to the difficulties in achieving a complete and efficient combustion process, with issues such as the shape of the flame front and surface effects affecting the performance of the engine. Designing a solution for these inefficiencies could lead to advancements in the engine industry.
  • #1
pnkj115
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When Stiochiometrically correct mixture(equivalence ratio=1) is burned in air fuel cycle some of the air is still left after point 3 in P-V diagram...Theoretically the whole fuel and air should combust till point 3..Then why is some air left out there.And thus the max temp is when mixture is 6% richer.Wh is this so??. Please help me
 
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  • #2
pnkj115 said:
Theoretically the whole fuel and air should combust till point 3..

That is the theory. In practice the fuel air mixture does not burn completely and it would be quite a bother to make it combust to full completion in the whole RPM range. It is easier to make the mixture air rich for better performance, thus more fuel is burned and some air is still left.

The main problem is with the flame front that would prefer a spherical combustion cavity, yet that is not practical, and thus at the cylinder edges the flame does not perform too well.

There are linear spark plugs that start the flame front in a line and get a more or less cylindrical flame front, but they have issues too. The Flame front performs differently in the middle that next to the walls of the cavity, as you have surface effects, thermal cooling and reflection of thermal radiation and not to forget different air/fuel mixtures.
 
  • #3
If you can design a solution for thermodynamic inefficiencies in a combustion engine, you have a bright future in the engine business.
 

1. What is the maximum temperature of a fuel air cycle?

The maximum temperature of a fuel air cycle is the highest temperature that can be achieved within the cycle, typically at the end of the compression or combustion process. This temperature is important because it affects the efficiency and power output of the cycle.

2. How is the maximum temperature of a fuel air cycle determined?

The maximum temperature is determined by the properties of the fuel and air mixture, as well as the design and operating conditions of the cycle. It can be calculated using thermodynamic equations or determined experimentally.

3. What factors can affect the maximum temperature of a fuel air cycle?

The maximum temperature of a fuel air cycle can be influenced by several factors, including the type of fuel used, the compression ratio, the inlet air temperature, and the combustion chamber design.

4. Why is the maximum temperature of a fuel air cycle important?

The maximum temperature is important because it directly affects the efficiency of the cycle. A higher maximum temperature can result in better performance and power output, but it also increases the risk of engine damage and can lead to increased emissions.

5. Can the maximum temperature of a fuel air cycle be exceeded?

Yes, it is possible for the maximum temperature to be exceeded, especially in high-performance engines. However, this can lead to engine damage and decreased efficiency. Proper design and control of the cycle is necessary to prevent exceeding the maximum temperature.

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