Abstract

Trimethyl orthoformate (TMOF) has recently been examined as a viable biofuel. TMOF is a branched isomer of oxymethylene ether-2 (OME2) that can reduce the formation of soot particles. A detailed understanding of its combustion properties is essential for its safe and efficient utilization. In this work, two fundamental combustion properties of TMOF were studied: (i) Auto-ignition of TMOF/synthetic air (φ = 1.0; diluted 1:5 with N2) using the shock tube method at 1, 4, and 16 bar, and (ii) Laminar burning velocities of TMOF/air using the cone angle method at 1, 3, and 6 bar. Furthermore, ignition delay times (IDTs) of a blend of 70% (liq. vol.) TMOF and 30% gasoline surrogate (PRF90) were studied at φ = 1.0, dilution of 1:5 with N2, and at 4 bar. The experimental data sets have been compared with predictions of the DLR Concise mechanism. The results demonstrate that the IDTs of TMOF and OME2 are nearly identical for all pressures studied in the moderate-to high-temperature region. The results obtained for the blend indicate that IDTs of the TMOF/PRF90 blend are shorter than those of PRF90 at 4 bar. In the lean-to stoichiometric region, the results obtained for laminar burning velocities of TMOF and OME2 are similar. However, for φ = 1.0, laminar burning velocities for TMOF are noticeably lower, indicating a decreased reactivity. The closeness of measured data and model predictions is observed for most conditions within the experimental uncertainty range.

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