Effect of aromatic doping on the thermal and emissions characteristics of hydrogen-rich fuels in a semi-industrial scale furnace

Abstract

This work experimentally investigates the effects of aromatic doping on the combustion and pollutant emissions characteristics of an H2-rich mixture (H2/CH4/CO) in a laboratory furnace featuring an industrial-grade burner. Benzene was added to a reference H2-rich fuel mixture (up to 5%v/v) under varying stoichiometric conditions. Comprehensive temperature, exhaust emissions, and OH* and CH* chemiluminescence data were collected. This research aims to bridge the gap between laboratory-scale studies and industrial-scale applications to understand the role of aromatic compounds in NOx formation during hydrogen-rich combustion. The results highlight intriguing interactions among NO, flame temperature, and soot formation occurring in the presence of benzene. Benzene doping leads to two main competing effects: an increase of prompt NO due to enhanced CHi radical production coming from the aromatic ring oxidation; and a decrease of thermal NO when soot formation enhances flames’ emissivity, leading to increased heat transfer from the flame to its surroundings. The relative importance of the two effects governs the final NO emissions.