Page 509 - Advanced thermodynamics for engineers

502 CHAPTER 21 FUEL CELLS

Anode electrode

Matrix/electrode
assembly

Cathode
Internal electrode
manifold
Cathode
current collector
Separator
Lower cell plate
assemblies

FIGURE 21.3
Molten carbonate fuel cell electrodes designed by the Institute of Gas Research and used by M–C power
corporation.
Ò
Figure is from the Website: www.mcpower.com/technology. IMHEX Technology: Internally Manifolded Heat Exchanger.

licensed to Ansaldo CLC for distribution in Europe. The operating temperature for the PAFC is
180–200 C: in combined-heat-and-power mode, it can heat city water from 13 Cto 60 C, or with

the high-grade heat exchanger, 120 C for 220 kW of thermal power.

21.1.4 MOLTEN CARBONATE FUEL CELL
The electrolyte of the Molten Carbonate Fuel Cell (MCFC) see Fig. 21.3, is composed of alkali metal
carbonates such as lithium carbonate (Li 2 CO 3 ), potassium carbonate (K 2 CO 3 ), sodium carbonate
(Na 2 CO 3 ), or a mixture of carbonates, for example, 62% Li 2 CO 3 and 38% K 2 CO 3 . The electrolyte is
coated over a porous ceramic matrix made of particles of lithium aluminate (LiAlO 2 ) or strontium
titanate (SrTiO 3 ), and the matrix, which can measure 180-mm to 500-mm thick, improves the durability
to thermal cycling (Iacovangelo & Browall, (1985)). Depending on the melting point of the carbonate
composition, the temperatures can reach 500–700 C. At these high temperatures, internal reforming

of natural gas fuel is possible.
The anode electrode is made of strontium titanate and lithium aluminate ceramic particles, which
can be plated with nickel, copper and alloys of these for internal reforming of the fuel. The cathode
side uses lithium-containing nickel oxide (NiO).

21.1.5 SOLID OXIDE FUEL CELL
The electrolyte for the Solid Oxide Fuel Cell (SOFC) is zirconia stabilised by yttria (also referred to as
yttria-stabilised zirconia, ZrO 2 (Y 2 O 3 ), and abbreviated YSZ). The yttrium-oxide dopant stabilises the