Combustion in a Steady State Combustor — Lesson 3

This lesson covers the principles of combustion in a steady state combustor. It explains how air and fuel at different temperatures enter the combustor with steady mass flow rates, undergo a chemical reaction, and then leave the combustor as products at a different temperature. The lesson also discusses the application of the steady flow energy equation to the combustor, the concept of molar basis, and the impact of heat removal on product temperature. It further delves into the calculation of heat (q dot) and the concept of exothermic reactions. The lesson concludes with examples illustrating the calculation of higher and lower calorific values of fuels and the determination of required mass flow rate of air.

Video Highlights

00:53 - Application of the steady flow energy equation to the combustor
06:06 - Calculation of the heat supplied in a combustor
10:55 - Discussion on the concept of calorific value of a fuel
18:49 - Example problem involving the combustion of liquid n-dodecane
22:30 - Calculation of the required mass flow rate of air and the corresponding equivalence ratio

Key Takeaways

- In a combustor, air and fuel enter at different temperatures, undergo a chemical reaction, and exit as products at a different temperature.
- The steady flow energy equation applied to the combustor helps in calculating the heat generated during the combustion process.
- The calorific value of fuel varies depending on whether the water in the product stream is in vapor or liquid form. The calorific value is higher when water condenses and leaves in liquid form.
- The enthalpy of the reactants is greater than the enthalpy of the products in combustion reactions, indicating that heat is released in the process.