2C.6 When doing a cycle analysis, do we have to consider combustion products and the effect on specific heat ratio (y is not 1.4)? The specific heat ratio does depend on combustion products but the effect is not large because the fuel air ratio is small. For example, for conditions of fuel air ratio ).034, the specific heat ratio at room temperature is about 1.38. A larger variation encountered in practice is with temperature; for a temperature of 1750k the specific heat ratio of pure air 2C.7 Does adiabatic flame temperature"assume 100% combustion? Yes. This is the maximum temperature that could be produced. Incomplete combustion will lower the temperature, as will heat transfer out of the combustion region 2C.8 What part of the computation for adiabatic flame temperature involves iteration? If the specific heat is not a simple analytic function of temperature (i.e, suppose it is known only in tabular form), we cannot get a closed form solution for the adiabatic flame temperature. We can, however, readily solve the enthalpy balance (SFEE)numericall (this is where the iteration comes in) to find at what temperature the products have to come out to have the same enthalpy (including the enthalpy of formation)as the reactants. We did not do this calculation yet, but we will do it to show what the iteration Remember that the assumption of constant specific heat is just that, an assum While this is an excellent assumption for many practical problems, if the precision of the answer needed is very high, or if the range of temperatures is large(see Figure 5.11 in SB&vw), then we cannot assume constant specific heat2C.6 When doing a cycle analysis, do we have to consider combustion products and their effect on specific heat ratio (γ is not 1.4)? The specific heat ratio does depend on combustion products but the effect is not large because the fuel air ratio is small. For example, for conditions of fuel air ratio ).034, the specific heat ratio at room temperature is about 1.38. A larger variation encountered in practice is with temperature; for a temperature of 1750K the specific heat ratio of pure air is 1.3. 2C.7 Does "adiabatic flame temperature" assume 100% combustion? Yes. This is the maximum temperature that could be produced. Incomplete combustion will lower the temperature, as will heat transfer out of the combustion region. 2C.8 What part of the computation for adiabatic flame temperature involves iteration? If the specific heat is not a simple analytic function of temperature (i.e., suppose it is known only in tabular form), we cannot get a closed form solution for the adiabatic flame temperature. We can, however, readily solve the enthalpy balance (SFEE) numerically (this is where the iteration comes in) to find at what temperature the products have to come out to have the same enthalpy (including the enthalpy of formation) as the reactants. We did not do this calculation yet, but we will do it to show what the iteration is all about. Remember that the assumption of constant specific heat is just that, an assumption. While this is an excellent assumption for many practical problems, if the precision of the answer needed is very high, or if the range of temperatures is large (see Figure 5.11 in SB&VW), then we cannot assume constant specific heat