Sangho Yoon

The Tests of 1 kWe Diesel Reformer and Solid Oxide Fuel Cell System

The high temperatures required to operate solid oxide fuel cells (SOFCs) allow for internal reforming of hydrocarbon fuels over a Ni-based anode. With their capability of being fuel flexible, SOFCs have operated under a wide range of fuels including diesel as examined in this study. But in order to reduce high possibilities of deposit formation in diesel internal reforming, additional external reforming technology was used for our system. The final goal of this research is to develop 1 kWe diesel-powered SOFC systems for residential power generation. Before constructing a complete 1 kWe SOFC system, a series of durability experiments were conducted on individual components of the system including the fuel reformer and stack. After testing the full-scale 1 kWe diesel reformer, deposit formation was visible within the catalyst and on the surface of the reactor head, which seriously degraded the performance. With several individual components tested, the construction of one-box type 1 kWe SOFC system is in progress. In a preliminary six-cell stack test using sulfur-free synthetic diesel, the system initially showed an output power of ∼110 kWe at a 0.8 V average cell potential. However, there was a significant drop off in output power after a few hours of operation, which was likely caused by severe deposit formation on the SOFC stack. Light hydrocarbons such as ethylene and/or “less reformed” heavier hydrocarbons caused by gas reactions under the incomplete fuel mixing upstream of the catalyst were likely responsible for the deposit formation.

Effect of the Molar H 2 O/ and the Molar O 2/C Ratio on Long-Term Performance of Diesel Autothermal Reformer for Solid Oxide Fuel Cell

Solid oxide fuel cell(SOFC) has high fuel flexibility due to its high operating temperatures. Hydrocarbonaceous fuels such as diesel has several advantages such as high energy density and established infrastructure for fuel cell applications. However diesel reforming has technical problems like coke formation in a reactor, which results in catastrophic failure of whole system. Performance degradation of diesel autothermal reforming (ATR) leads to increase of undesirable hydrocarbons at reformed gases and subsequently degrades SOFC performance. In this study, we investigate the degradation of SOFC performance(OCV, open circuit voltage) under hydrocarbon(n-Butane) feeds and characteristics of diesel performing under various ratios of reactants( molar ratios) for improvement of SOFC performance. Especially we achieved relatively high performance of diesel ATR under

kW-class Diesel Autothermal Reformer with Microchannel Catalyst for Solid Oxide Fuel Cell System

H_2O/C

Performance Analysis of CH

Abstract Solid oxide fuel cell(SOFC) has a higher fuel flexibility than low temperature fuel cells, such as polymer electrolyte fuel cell(PEMFC) and phosphoric acid fuel cell(PAFC). SOFCs also use CO and CH 4 as a fuel, because SOFCs are hot enough to allow the CH 4 steam reformation(SR) reaction and water-gas shift(WGS) reaction occur within the SOFC stack itself. Diesel is a good candidate for SOFC system fuel because diesel reformate gas include a higher degree of CO and CH 4 concentration than other hydrocarbon(methane, butane, etc.) reformate gas. Selection of catalyst for autothermalr reforming of diesel was performed in this paper, and characteristics of reforming performance between packed-bed and microchannel catalyst are compared for SOFC system. The mesh-typed microchannel catalyst also investigated for diesel ATR operation for 1kW-class SOFC system. 1kW-class diesel microchannel ATR was continuously operated about 30 hours and its reforming efficiency was achieved nearly 55%.

Effects of ethylene on carbon formation in diesel autothermal reforming

The performance of a solid oxide fuel cell (SOFC) stack system driven by simulated reformate was investigated in this study. CH4 was used as a surrogate fuel for low hydrocarbon components in reformate gas. One of the motivations for this study is to articulate the effects of low hydrocarbons in reformate gas, such as CH4 , on SOFCs. The effects of low hydrocarbons on SOFC have been widely investigated in SOFC button cells, but it does not provide the practical information to develop an SOFC system. Hence, we investigated the performance changes in SOFC stack operation with simulated reformate gas. Open-circuit voltage of the SOFC and discharge condition decreased as the fraction of CH4 in anode inlet gas was increased. The limit current density also decreased. As Eguchi et al. reported, CH4 does not directly participate in the electrode reaction (14). Hence, concentration overvoltage occurred in SOFC operation with CH4 . The effect of CH4 on SOFC long-term performance will be investigated in future studies.Copyright