Analysis of Aircraft Emissions Based on Flight Trajectory : ATR 72-500 trajectory and emission study

Abstract: Emissions related to aviation have during the last decades become an important topic of discussion. Besides carbon dioxide ($CO_2$) which is the major pollutant from air travel, other gas emissions such as hydrocarbons ($HC$), nitrogen oxides ($NO_x$), carbon monoxide ($CO$) and sulfur oxides ($SO_x$) also need to be investigated. The work within this field has traditionally been challenged by the fact that aircraft emission calculations often required engine proprietary data which usually is difficult to obtain. However, in recent years other methods have been developed and this report investigates one such method, namely The Boeing Fuel Flow Method 2. The analysis is carried out on an ATR 72-500 turboprop aircraft flying at $13000$ feet from Visby to Bromma, Sweden. The method uses continuous data of fuel flow and altitude together with estimated emission index data at sea level for the specific engine to estimate the amount of emissions emitted during the flight. From this it was possible to determine the levels of $HC$,$NO_x$,$CO$, $CO_2$ and $SO_x$ emitted during the different stages of flight. There was a clear trend that $HC$ and $CO$ emissions were the highest at low fuel flow levels, i.e. at low power, while $NO_x$ increased with increasing fuel flow. Emission levels of $CO_2$ and $SO_x$ were found to be proportional to fuel flow. In addition, two alternative trajectories at $10000$ and $24000$ feet were studied. When comparing the $10000$ feet route with the original $13000$ feet route the the level of $NO_x$, $CO_2$ and $SO_x$ were unaffected while $HC$ and $CO$ decreased as the period of high fuel flow were shortened. In the $24000$ feet route the levels of $HC$, $CO$ and $SO_x$ were unaffected while the level of $CO_2$ and $NO_x$ decreased. This decrease can be explained by the lowered fuel flow rate as air resistance is significantly lower at $24000$ feet compared to $13000$ feet.