Direct-Flame Metal-Supported Solid Oxide Fuel Cells
Authors: Tucker Michael C , Ying Andrew 
Published: February 2020

Metal-Supported solid oxide fuel cells (mSOFCs) tolerate rapid thermal cycling [1,2]. This makes them ideally suited for applications requiring rapid start-up time, or tolerance to thermal fluctuations arising from load-following or intermittent fuel flow. In direct flame mode, SOFCs are heated by a flame impinging on the anode side of the cell, and the flame also partially oxidizes the fuel to electrochemically- active species (such as hydrogen and carbon monoxide) [3–6]. In this work we study the behavior of mSOFCs in direct-flame mode, which has not been reported previously to the best of our knowledge. The results are of fundamental interest, and also inform the feasibility of utilizing mSOFCs to produce power in situations where fuel is burned in an open flame (such as cooking, well-head or land-fill gas flaring, water heating, etc.).
Figure 1 shows an mSOFC partially heated by an impinging butane flame. The cell tolerated very high thermal gradient, estimated to be ~250°C/cm. This particular cell has survived about 100 cycles between room temperature and ~800°C, with extremely rapid startup in less than 10 seconds when the cell is exposed to flame. Figure 2 shows the polarization performance of an mSOFC operating with direct propane flame. The low open circuit voltage is consistent with previous direct-flame results using anode-supported SOFCs [[3–6]], and is due to the low concentration of active species in the flame, as most of the fuel is completely oxidized in the flame before reaching the mSOFC anode. The power output is much lower than that achieved previously for mSOFCs with pure hydrogen fuel [7], but is marginally higher than identical mSOFCs operated with gasified charcoal [8].
This paper will present a systematic study of the impact of various operational parameters on direct-flame mSOFC temperature, performance, and durability. Key parameters of interest are: air-to-fuel ratio in the flame, fuel flow velocity, burner-to-mSOFC distance, catalyst composition, and application of thermal insulation to the cell.
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Figure 1