Fuel HotSpot

Few data are publicly available on fuel processor efficiency. However, a typical value of 77.3% was determined over the New European Drive Cycle (NEDC) for a fuel cell drive system supplied by methanol [8]. Johnson-Matthey reports even 89% for its HotSpot module combined with a gas purification system [9],... 

Whereas uniform distribution of water within the membrane is desired, the permeability of the material to reactants (i.e., hydrogen or methanol and oxygen) has to be low to prevent direct chemical reaction between fuel and oxidant, which may lead to hotspots and, eventually, pinhole formation. Methanol permeability is a major challenge in the direct methanol fuel cell (DMFC), largely because methanol transport is strongly correlated with water transport, leading to significant penalties in fuel efficiency and poor cathode performance [189]. 

A prominent example of a fixed-bed reactor applied for auto-thermal reforming is the HotSpot fuel processor developed by Johnson Matthey. Platinum and chromium catalyst were introduced as fixed bed. The reformer could be started from ambient temperature when methanol was used as feedstock [49, 50]. The reactor was preheated initially by methanol combustion and then operated under autothermal conditions. 

The famous HotSpot fuel processor developed by Johnson Matthey was actually a fixed-bed reactor. Platinum and chromium catalyst were applied for the reactor, which was able to start from ambient conditions when methanol was used as the feedstock [5,472]. Through the initial methanol combustion, the reactor was preheated and then able to produce hydrogen containing reformate under autothermal conditions. 

Johnson Matthqr developed the HotSpot fuel processor, a modular autother-mal reformer. The basic idea of the HotSpot was that hydrogen back-diffusion to the reaction front, where it would be consumed by the oxygen feed, was prevented by the spot wise feed injection into the centre of the reactor. The heat of the exothermic reaction was also distributed from the centre of the reactor to its periphery, where it was required to supply the endothermic reactions with energy... 

Figure 9.4 8 unit HotSpot fuel processor producing 6 h hydrogen [577]. 

Figure 9.5 P2 HotSpot fuel processor (top) linked to a Demonox carbon monoxide clean-up unit (bottom) the manifolds were placed in the centre [575].

Reinkingh et al. from Johnson Matthqr reported on a 5-kWd HotSpot natural gas fuel processor [576]. The multi-step unit produced reformate containing 43 vol.% hydrogen, 1 vol.% methane and less than 10 ppm carbon monoxide. The reformer itself produced between only 1 and 2 vol.% carbon monoxide. The natural gas conversion exceeded 90%. 

Gray, P.G. and Fetch, M.I. (2000) Advances with HotSpot fuel processing. Efficient hydrogen production for use with solid polymer fuel cells. Platinum Met. Rev, 44 (3), 108-111. 

Most of the development by Nuvera has been for stationary systems however, Johnson Matthey has demonstrated its HotSpot reactor on reformulated gasoline (Ellis et al., 2001). They built a 10-kW fuel processor that met their technical targets, but they also addressed issues relating to mass manufacture their work has identified areas that will require further work to enable gasoline reforming to become a commercial reality. These included the following ... 

ABSTRACT This paper aims to analyze the Critical Heat Flux (CHF) experimental design for a small-scaled pressurized nuclear reactor. The CHF or Departure from Nucleate Boihng (DNB) is one of the most important thermal-hydraulic safety criteria for pressurized reactors since its occurrence can lead to fuel damage. A 3 x 3 test section is simulated through COBRAIUc/MIT-l code for thirty operational conditions. The results are presented through response surfaces and used to evaluate the DNBR (DNBR ratio) at the hotspot. The lowest DNBR value was 1.587 for the maximum pressure, mass flux and inlet temperature. 

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