Thermal Effect Essay
The change in specific heat capacity results from charge dilution and represents the thermal effect. The added-mass effect is represented by the change in mass Δm. To achieve higher NOx emissions reductions, gases of higher specific heat capacity are ideal.
The Chemical effect can affect and alter the combustion temperature …show more content…
The formation of NO during equation 1 is much slower than by equation 2. NO formation is strongly dependent on temperature therefore it is called a ‘kinetically controlled reaction’. In other words, the chemical reaction kinetics at the temperatures in the combustion chamber are slow compared to the physical time-scale of the flow field and equilibrium cannot be achieved.
Prompt NO formation
The formation of NO is related to the formation of CH-radicals. Prompt NO formation by Fennimore is expressed by the equation
In this equation the forward reaction coefficient, Kg,r, is obtained by the equation
Prompt NO formation amount is smaller when compared to Thermal NO formation due to lower activation temperature and it is associated with local fuel concentration. Moreover, Prompt NO formation requires low energy for the reaction, since the formation of NO begins before