Thermal Effect Lab

Thermal effect results from the change in the heat capacity of the gases in the combustion chamber. It is worth mentioning that EGR contains water and CO2 which have higher specific heat capacity than air. The change in absorbing heat is proportional to the added mass, to the heat capacity at constant pressure and to the difference in temperature between the EGR and the combustion temperature.
ΔQ=Δm*Cp*(Tcom-Tegr)
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.
Chemical effect
The Chemical effect can affect and alter the combustion temperature due to chemical reactions …show more content…
K1 is the forward reaction coefficient of the first equation and K2 is for the second one.
K1=F1*7.6*〖10〗^10*exp⁡(-(38000*A1)/Tb)
K2=F2*4.1*〖10〗^10
Where F1 is the N2 Oxidation rate multiplier, F2 is the N Oxidation rate multiplier, F3 is the OH Oxidation rate multiplier, A1 is the N2 Oxidation Activation temperature multiplier, A2 is the N Oxidation Activation temperature multiplier and TB is the burned sub-zone temperature in Kelvin.
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