How Do Air-Fuel Ratios Affect Gas Turbine Temperatures?

[simonre7]

Going to be honest this is a ibt of homework i have been set but from the note i hae it doesn't make any sense what so ever! so any help would be greatly appreciated :-)

A gas turbine plant is fuelled by Methane,. After compresssion the air and fuel enter the combustion chamber at a temp of 600K and excess air is supplied in order to limit the temp of the combustion products to 1200K after steady flow, adiabatic combustion.

1) Illustrate the combustion process on a temp-enthalpy axes (have got this question right i believe but wouldn't hurt to double check my graph)

2) Find the volumetric air-fuel-ratio used

3) What air-fuel-ratio would be required to achieve the maximum temp of the combustion products?

As mentioned before and help what so ever would help, even just a push in the right direction.

Cheers guys!

 

[lippyka]

To answer questions 2 and 3, you will need to examine the energy balance for the combustion process. You can do this by accounting for the energy of the air and fuel entering the combustion chamber, and then comparing it to the energy of the products exiting the combustion chamber. To find the air-fuel-ratio, you need to calculate the ratio of air to fuel that would be needed to ensure that the energy of the products is equal to the energy of the air and fuel entering the combustion chamber. For question 3, you need to calculate the air-fuel-ratio that would be required to achieve the maximum temperature of the combustion products.

 

[m2003]

Thank you for reaching out for help. I am happy to assist you with your homework. Let's break down the questions one by one to understand them better.

1) Illustrating the combustion process on a temperature-enthalpy axes is essentially plotting the change in temperature and enthalpy (heat content) during the combustion process. This can be done by using a graph or a diagram, with temperature on the x-axis and enthalpy on the y-axis. You are correct in your understanding of this question.

2) The volumetric air-fuel ratio used can be calculated by dividing the volume of air by the volume of fuel. In this case, the air-fuel ratio would be 600K/1200K = 0.5.

3) To achieve the maximum temperature of the combustion products, the air-fuel ratio would need to be adjusted. This can be done by increasing the amount of fuel or decreasing the amount of air. The exact air-fuel ratio required would depend on the specific conditions of the gas turbine plant, such as the type of fuel used and the design of the combustion chamber.

I hope this helps you understand the questions better. Remember to always check your calculations and assumptions, and if you need further assistance, don't hesitate to ask for help from your teacher or classmates. Good luck with your homework!