Fuels of the furan family, i.e. furan itself, 2-methylfuran (MF), and 2,5-dimethylfuran (DMF) are being proposed as alternatives to hydrocarbon fuels and are potentially accessible from cellulosic biomass. While some experiments and modeling results are becoming available for each of these fuels, a comprehensive experimental and modeling analysis of the three fuels under the same conditions, simulated using the same chemical reaction model, has -to the best of our knowledge -not been attempted before. The present series of three papers, detailing the results obtained in flat flames for each of the three fuels separately, reports experimental data and explores their combustion chemistry using kinetic modeling. The first part of this series focuses on the chemistry of low-pressure furan flames. Two laminar premixed low-pressure (20 and 40 mbar) flat argondiluted (50%) flames of furan were studied at two equivalence ratios (φ=1.0 and 1.7) using an analytical combination of high-resolution electron-ionization molecular-beam mass spectrometry (EI-MBMS) in Bielefeld and gas chromatography (GC) in Nancy. The time-of-flight MBMS with its high mass resolution enables the detection of both stable and reactive species, while the gas chromatograph permits the separation of isomers. Mole fractions of reactants, products, and stable and radical intermediates were measured as a function of the distance to the burner. A single kinetic model was used to predict the flame structure of the three fuels: furan (in this paper), 2-methylfuran (in Part II), and 2,5-dimethylfuran (in Part III). A refined sub-mechanism for furan combustion, based on the work of Tian et al. [Combustion and Flame 158 (2011) 756-773] was developed which was then compared to the present experimental results. Overall, the agreement is encouraging. The main reaction pathways involved in furan combustion were delineated computing the rates of formation and consumption of all species. It is seen that the predominant furan consumption pathway is initiated by H-addition on the carbon atom neighboring the O-atom with acetylene as one of the dominant products.

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Wall temperatures were measured with thermographic phosphors on the quartz walls of a model combustor in ethylene/air swirl ames at 3 bar. Three operating conditions were investigated with dierent stoichiometries and with or without additional injection of oxidation air downstream of the primary combustion zone. YAG:Eu and YAG:Dy were used to cover a total temperature range of 10001800 K. Measurements were challenging due to the high thermal background from soot and window degradation at high temperatures. The heat ux through the windows was estimated from the temperature gradient between the in-and outside of the windows. Dierences in temperature and heat ux density proles for the investigated cases can be explained very well with the previously measured dierences in ame temperatures and ame shapes. The heat loss relative to thermal load is quite similar for all investigated ames (1516 %). The results complement previous measurements in these ames to investigate soot formation and oxidation. It is expected, that the data set is a valuable input for numerical simulations of these ames. 1 Introduction Because of the increasingly stringent regulations for particle emissions, i.e. mainly soot, continuing eort is needed for the development and improvement of gas turbines for propulsion and power generation. Soot formation and oxidation in high-pressure turbulent ames are complex processes that are still not completely understood. Numerical simulation is an important tool for the development of gas turbine combustors. However, to evaluate and improve the reliability of numerical predictions, comprehensive experimental data sets are needed from technically-relevant sooting ames under elevated pressures with well-dened boundary conditions. An important parameter in this respect is the temperature of the combustor walls. Due to the lack of accurate measure

Phosphor thermometry has been developed for wall temperature measurements in gas turbines and gas turbine model combustors. An array of phosphors has been examined in detail for spatially and temporally resolved surface temperature measurements. Two examples are provided, one at high pressure (8 bar) and high temperature and one at atmospheric pressure with high time resolution. To study the feasibility of this technique for full-scale gas turbine applications, a high momentum confined jet combustor at 8 bar was used. Successful measurements up to 1700 K on a ceramic surface are shown with good accuracy. In the same combustor, temperatures on the combustor quartz walls were measured, which can be used as boundary conditions for numerical simulations. An atmospheric swirl-stabilized flame was used to study transient temperature changes on the bluff body. For this purpose, a high-speed setup (1 kHz) was used to measure the wall temperatures at an operating condition where the flame switches between being attached (M-flame) and being lifted (V-flame) (bistable). The influence of a precessing vortex core (PVC) present during M-flame periods is identified on the bluff body tip, but not at positions further inside the nozzle.

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