EXPERIMENTAL AND NUMERICAL INVESTIGATION OF THE EFFECTS OF NITROUS OXIDE (NTEXTSUSCRIPT{2}O) AND NITROGEN DIOXIDE (NOTEXTSUSCRIPT{2}) ON IGNITION DELAY TIMES IN LEAN HYDROGEN COMBUSTION

• Main Author: Aswin Luthfia Zufar, Fakhrianda
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86897
• Institution: Institut Teknologi Bandung

Greenhouse gas emissions have contributed to climate change, global warming, and rising sea levels. Numerous actions to reduce carbon emissions and promote the utilization of non-carbon fuels have been encouraged by all parties, such as using hydrogen and ammonia in industries or the transportation domain. However, burning hydrogen and ammonia or even blending those fuels creates harmful emissions, commonly called nitrogen oxides (NOx), consisting of NO2, N2O, and NO. Applying pre- and post-treatment methods for NOx emission in industrial operations or transportation sectors is governing significant attention, such as Exhaust Gas Recirculation (EGR) or Selective Catalytic Reduction (SCR). Nowadays, hydrogen can potentially be a primary fuel in internal combustion engines (H2-ICE), with NOx emission as the harmful exhaust emission. Therefore, integrating EGR systems into the engine is one of the possible options to control NOx emissions. In ICE, ignition delay time is the key parameter that represents the reactivity of the mixture. In kinetic studies, ignition delay times are commonly used as the parameter to evaluate the elementary reactions. Thus, in this work, ignition delay times (IDTs) of hydrogen and nitrogen oxides were measured in the presence of N2O and NO2 levels over 1020 – 1200 K and pressures between 20 and 40 bar using KAUST’s high-pressure shock tube. Measured datasets were compared with chemical kinetic simulations using several mechanisms. Sensitivity analyses were used to identify the most significant reactions and illustrate the observed trends among various datasets. Generally, ignition delay times were reduced when NO2 and N2O concentrations were added to the mixture. Brute force ignition delay time sensitivity analyses showed that several reactions were activated due to the presence of NO2 and N2O as promoting and inhibiting reactions. The effect of N2O activated the reaction of N2O+M ? N2+O+(M), which created an O atom to enhance the reaction of O+H2 ? OH+H. Meanwhile, the effect of NO2 enhances the reaction of NO2+H ? NO+OH will provide OH radicals and NO that decompose into NO2 and OH through the reaction of NO+HO2 ? NO2+OH. Therefore, the impact of NO2 and N2O on ignition delay times was clearly investigated numerically and experimentally in this work.