Direct Utilization of Methane in Microtubular-SOFC

Microtubular-SOFC (μSOFC) offer many advantages over planar SOFC systems.  They offer greater resistance to thermal shock, allow rapid startup and shut down.  They have high volumetric power density and the seals can be placed out of the high temperature zone.  Liquefied natural gas (LNG) is receiving increased interest as a fuel for trucks. This is an ideal fuel for SOFC. In this paper we examine the use of LNG in μSOFC in a truck APU application and the issues associated with LNG fuel. The work mainly focuses on solving issues with temperature distribution along and across the cell. 

The key problem in the proposed system is the temperature distribution (TD).  Despite the good resistance to thermal shock, the long-term operation with unequal TD can cause cell damage.  The TD was measured along the cell (internally and externally) under different operating conditions.  H₂, CH₄ and simulated LNG (individual gases mixed in the correct ratio of LNG) were used as fuels.  CH₄ and simulated LNG were converted into syngas using semi-internal catalytic partial oxidation catalyst (CPOX) located at the entrance of the cell.  Different mixtures of fuel and air and several different catalysts were tested for the CPOX of hydrocarbons.  The figure shows a typical result during OCV using H₂ as a fuel at 700^oC furnace temperature.  It shows there was a difference of 200^oC between the internal and external part of the tube at the fuel inlet, indicating research needs to be conducted into minimising this to ensure the durability of any SOFC APU system.  

Figure 1. Temperature distribution inside the μSOFC single cell.

The results are part of the SAFARI project funded under Europe’s Fuel Cell and Hydrogen Joint Undertaking (FCH JU), Grant Agreement No.325323. The Consortium gratefully acknowledges the support of the FCH JU.