Session: 03-06 Liquid fuels

Paper Number: 83029

83029 - A Study on Fundamental Combustion Properties of Trimethyl Orthoformate: Experiments and Modeling 

The use of alternative fuels, especially those obtained from renewable resources, is an attractive option to counteract the carbon footprint and emissions of soot and particulate matter in the transportation sector. In this context, oxygenated oxymethylene ethers (OME_n: CH₃O(CH₂O)_nCH₃, with n=1-5) have emerged as one of the most promising alternative fuel candidates and blending components for crude-based diesel,   because of  their potential to significantly reduce soot particle emissions. In addition, they can be renewably obtained, i.e. via the Power-to-Liquid (PtL) technology. Very recently, researchers have considered trimethyl orthoformate (TMOF) – the simplest orthoester – as a potential biofuel. TMOF is a branched isomer of oxymethylene ether-2 and thus, has the potential to significantly reduce the formation of soot particles due to its high oxygen content and the absence of direct carbon-carbon bonds. However, a comprehensive understanding of its fundamental combustion properties, e.g., auto-ignition and flame speeds, is a prerequisite for evaluating its engine application potential and the development of safe and more advanced engines and burners.

In the present study, the two-fundamental combustion, e.g., ignition delay times and laminar burning velocities of trimethyl orthoformate are studied through a combined experimental and modeling approach. The ignition delay times of stoichiometric mixtures of TMOF/synthetic air diluted 1:5 in N₂ were measured behind the reflected shock wave employing a shock tube at pressures of 1, 4, and 16 bar, and for temperatures ranging between 1000 to 1700 K. The laminar burning velocities of TMOF/air have been determined by using a Bunsen burner and by applying the cone angle method at ambient and at elevated pressures of 3 and 6 bar, and for equivalence ratios ranging between 0.6 to1.8. In addition, the results obtained for TMOF are compared to those of OME₂ obtained earlier at similar conditions. The experimental data sets obtained was used for validation of an in-house reaction model.

The findings of the present work will contribute to a better understanding of combustion of these ethers, and thus, to the design and optimization of burners and engines as well.

Presenting Author: John Mburu Ngugi German Aerospace Center (DLR), Stuttgart

Presenting Author Biography: John mbũrũ Ngũgĩ graduated with an MSc. degree in Mechanical Engineering (advanced thermofluids) from Jomo Kenyatta University of Agriculture and Technology (JKUAT) at Nairobi, in 2015. He obtained his BSc. Degree in Mechanical Engineering from the same university in 2011. He joined the Department of Mechanical Engineering of Dedan Kimathi University of Technology (DeKUT) in 2011 as a Tutorial fellow. He is a graduate member of the Engineers Board of Kenya (EBK).<br/>Currently, he is a Doctoral candidate at the Institute of Combustion Technology of German Aerospace Center in stuttgart (DLR) under the sponsorship of DAAD and the Government of Kenya. His research interests are in the areas of combustion science.

Authors:

John Mburu Ngugi German Aerospace Center (DLR), Stuttgart
Sandra Richter German Aerospace Center (DLR)
Marina Braun-Unkhoff German Aerospace Center (DLR)
Clemens Naumann German Aerospace Center (DLR)
Uwe Riedel German Aerospace Center (DLR)