Design and Stress Analysis of Extraterrestrial ... - The Black Vault

Gas pressure exceeds electrolyte pressure by 0.2-0.5 at.
The high working medium pressures are a disadvantage of this fuel
element. Heating is accomplished by the thermal reaction which
occurs in the element. An advantage of the element is its high
current density, which is 0.8 A/cm 2 . Voltage in the circuit is
U = 0.7 V.
Figure 2.71b shows a simplified diagram of a fuel element with
activated graphite electrodes. In literature it is known as the
Korden diagram.
The element is made in the form of a cylindrical sealed vessel,
in which two tube electrodes are placed. Gaseous hydrogen and
oxygen pass along the electrodes. The electrodes are of pressed
porous activated graphite. Pores provide both a separation between
the gaseous reagents and the liquid electrolyte and the diffusion
necessary in order to obtain ions, electric current, and water.
This fuel element operates at 50-70'C and atmospheric gas
pressure. The output characteristics of the element are current
density i = 1 A/cm2 at U = 0.7 V.
The design of a carbon-oxygen element differs little
from the
elements examined. We know of such an elemcnt where soda N 2 CO 3
serves as the electrolyte. It operates at high temperatures (1000-
11000C). The operating time element is several hours. Melted
soda is agressive. It even corrodes platinum. The element is
also dangerously explcsive and is inferior to an oxygen-hydrogen
element in current density.
Hydrogen-oxygen element wqith an ion-exchange membrane
Liquid electrolyte in a fuel element (Fig. 2.72) creates a
4 number of specific difficulties with its location. The need to
provide a hermetic seal and packing, as well as the possibility
of the electrolyte mixing wAth the working medium, complicates
construction, makes it heavy and reduces reliability. This is
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