An experimental and modeling study of the combustion of tetrahydrofuran

Abstract

International audienceTetrahydrofuran (THF) is a well suited starting point fuel to study the combustion chemistry of saturated cyclic esters that are being considered as promising bio-fuels. To better understand the combustion chemistry of THF, laminar low-pressure premixed flame structure, atmospheric adiabatic laminar burning velocities, and high-pressure ignition delay times were investigated. The structure of laminar premixed low-pressure (6.7 kPa) argon-diluted (78%) flames of THF were studied at three equivalence ratios (0.7, 1.0 and 1.3) using on-line gas chromatography analyses. The results consist of temperature and mole fraction profiles (about 40 species) measured as a function of the height above the burner. Ethylene, propene, formaldehyde, acetaldehyde, and dihydrofurans were observed as important intermediates. Aromatic species were detected in very low amounts. The adiabatic laminar burning velocities of THF–air mixtures were measured using the heat flux burner method at atmospheric pressure (initial temperatures from 298 to 398 K, at equivalence ratios from 0.55 to 1.60). The maximum burning velocity of THF was comparable to that of ethanol and diethyl ether. The ignition delay times of THF–oxygen–argon mixtures were measured behind reflected shock waves (temperatures from 1300 to 1700 K, pressures around 8.5 atm, mixtures containing 0.25–1% of fuel for equivalence ratios of 0.5–2.0). A new detailed kinetic model for THF combustion was developed using a combination of automatic generation (EXGAS), Evans–Polanyi correlations (for H-abstraction kinetic data), and CBS-QB3 theoretical calculations (for unimolecular initiation, H-abstraction and β-scission kinetic data). An overall good agreement between simulations and the present experimental results has been found. The main THF reaction pathways under flame conditions have been identified from flow rate analyses

Recent Trends in the Production, Combustion and Modeling of Furan-Based Fuels

“…Wang et al [203] compared shock tube ignition delay times of 2-MTHF with the predictions of the model by Moshammer et al [27] (Mech I) and the model by Tran et al [158] (Mech II). The results revealed that Mech II under-predicted ignition delay times of 2-MTHF, with better agreement observed at lower temperatures.…”

“…Reaction pathway and sensitivity analyses revealed that the prediction of ignition delay times depends on the balance between the different radicals resulting from H abstraction. Further, Tran et al [158] developed a detailed kinetic model for THF combustion. The authors used an automatic model generation tool (EXGAS), Evans-Polanyi correlations and CBS-QB3 theoretical calculations.…”

“…Chemical kinetic models of tetrahydrofurans have been proposed [27,146,157,158]. The first 2-MTHF model by Moshammer et al [27] was developed based on mole fraction profiles of products, reactants and a number of intermediate species including radicals obtained experimentally for premixed low-pressure 2-MTHF flames at an equivalence ratio of 1.7.…”

Advanced Biofuels and Beyond: Chemistry Solutions for Propulsion and Production

“…Te trahydrofurans have also been investigated in some detail in shocktube [216] and flame experiments, [179,180,229] and complemented by recent theoretical work. [230,231] Theo verall analysis is still more limited than for the furans,but some indications are reported that 2-MTHF [229] and tetrahydrofuran [179] have aconsiderably lower tendency to form aromatic compounds than do the furans under similar conditions.…”

“…[167,168] Quite recently,c hemical mechanisms have also been developed for fuels from second-generation processes and beyond, including larger alcohols, [164,165] ethers, [169] and ketones, [170,171] and as ubstantial amount of work has been devoted to the furans [172][173][174][175][176][177][178] and tetrahydrofurans,w hich are in the focus of the present Review. [69,179,180] It is interesting to understand how macroscopic properties such as derived cetane numbers (compare Section 2a nd Figure 1) for advanced biofuels relate to the chemical kinetics mechanisms,s ince such understanding can substantially support strategies for fuel design. This approach was followed in the recent study by Sudholt et al on the furan family.…”