Preparatory Tests for 1kW Diesel-Powered SOFC Systems

High operating temperature of SOFCs can make internal reforming effective as well as inhibit CO poison over the Ni-based anode. Therefore, SOFCs give us a wide range of fuel choice. In this study, diesel known as a very tough fuel for fuel cell applications was chosen as the SOFC fuel. Our final goal is to develop the 1kW_e diesel-powered SOFC systems for residential power generation purpose. Before the system construction, we have drawn a few engineering and scientific problems from the bench tests of reformer and stack. Most of all, coke formation in the reformer and stack was very serious. Coking in the diesel reformer was greatly associated with fuel delivery process in our micro-reactor tests, which was more serious in scaled-up reformer. With several fundamental tests, the prototype construction of 1kW_e SOFC system is in progress. Essentially, all heat-related components (e.g. stack, reformer, heat exchanges, after-burner) were installed inside one chamber, so called ‘hot box’. The design was mainly focused on thermal sustenance. In a 6-cell stack test using sulfur-free synthetic diesel, the system initially showed the power of ∼110W_e at average 0.8V of the cells. But, there was severe coke formation after a few hours operation.