Combustion Chemistry of Fuels: Quantitative Speciation Data Obtained from an Atmospheric High-temperature Flow Reactor with Coupled Molecular-beam Mass Spectrometer

Abstract

This manuscript describes a high-temperature flow reactor experiment coupled to the powerful molecular beam mass spectrometry (MBMS) technique. This flexible tool offers a detailed observation of chemical gas-phase kinetics in reacting flows under well-controlled conditions. The vast range of operating conditions available in a laminar flow reactor enables access to extraordinary combustion applications that are typically not achievable by flame experiments. These include rich conditions at high temperatures relevant for gasification processes, the peroxy chemistry governing the low temperature oxidation regime or investigations of complex technical fuels. The presented setup allows measurements of quantitative speciation data for reaction model validation of combustion, gasification and pyrolysis processes, while enabling a systematic general understanding of the reaction chemistry. Validation of kinetic reaction models is generally performed by investigating combustion processes of pure compounds. The flow reactor has been enhanced to be suitable for technical fuels (e.g. multi-component mixtures like Jet A-1) to allow for phenomenological analysis of occurring combustion intermediates like soot precursors or pollutants. The controlled and comparable boundary conditions provided by the experimental design allow for predictions of pollutant formation tendencies. Cold reactants are fed premixed into the reactor that are highly diluted (in around 99 vol% in Ar) in order to suppress self-sustaining combustion reactions. The laminar flowing reactant mixture passes through a known temperature field, while the gas composition is determined at the reactors exhaust as a function of the oven temperature. The flow reactor is operated at atmospheric pressures with temperatures up to 1,800 K. The measurements themselves are performed by decreasing the temperature monotonically at a rate of -200 K/h. With the sensitive MBMS technique, detailed speciation data is acquired and quantified for almost all chemical species in the reactive process, including radical species.

Technical application of a ternary alternative jet fuel blend – Chemical characterization and impact on jet engine particle emission

“…Subsequently, only reaction products can be detected at the reactor outlet beyond 1050 K. For lean condition (Φ = 0.8) CO2, H2O, and a corresponding excess of O2 is present as product, while for slightly-rich conditions (Φ = 1.2) CO and H2 are added as products. The major species profiles of the three investigated jet fuels are qualitatively and quantitatively very similar (same plot pattern) and are in line with previous findings for certified kerosene [16,24,25]. Thus, the ternary fuel blending with alternative kerosene does not lead to significant changes in the global reaction behavior under the examined conditions.…”

“…The oxidation of jet fuels was investigated at DLR's high-temperature flow reactor with coupled molecular-beam mass spectrometry (MBMS) to estimate the influence of the kerosene composition on the kinetic reaction process during combustion. In previous studies detailed description of the atmospheric MBMS flow reactor system [14][15][16] as well as the signal evaluation [17][18][19] is given and only a brief summary is provided in the following.…”

Assessment of combustion properties of non-hydroprocessed Fischer-Tropsch fuels for aviation

“…technical fuels like Jet A-1). Since comprehensive recent literature on the applied experimental setup is available [60][61][62][63][64] , only a brief description is given here.…”

Experimental Investigation of Soot Oxidation under Well-Controlled Conditions in a High-Temperature Flow Reactor

“…Soot oxidation is investigated under well-controlled conditions in a high-temperature flow reactor, which was also used for mass spectrometric studies of the chemical gas-phase kinetics of single compounds (Kathrotia et al, 2018;Oßwald et al, 2017) and technical fuels (Köhler et al, 2018). The new soot oxidation experiment consists of five key elements: (1) A flat-flame McKenna burner as the soot source, (2) a Dekati diluter to sample flame gases and soot particles directly from the flame, (3) the high-temperature flow reactor for soot oxidation at well-controlled conditions, (4) a particle sizer to measure the particle size distribution (PSD) before (reactor inlet) and after (reactor outlet) passing a distinct temperature profile in the reactor, and (5) a molecular-beam mass spectrometer to quantify both small molecular species originated from the sampled flame and oxidation products.…”