Environmental Engineering Reference
In-Depth Information
Fig. 6.5 Stoichiometric ratio
values utilized in experimen-
tal tests as function of stack
power
Fig. 6.6 Stack and fuel cell
system efficiency versus
DC-DC converter inlet elec-
tric power under the experi-
mental conditions of Fig. 6.4
The voltage data of Fig. 6.4 are presented also in terms of stack efficiency curve
in Fig. 6.6 , where g stack is plotted against the electric power produced by the FCS
and measured at the DC-DC converter inlet. In the same figure, the actual and
''theoretical'' curves of FCS efficiency (g FCS ) are also reported, they refer to the
real consumptions of ancillary components or to the ''ideal'' losses expected for
that same system after optimization of all individual components (maximum FCS
efficiency in Fig. 6.6 ). The stack efficiency varies from 0.7 at 0.1 kW to 0.56 at
1.8 kW of FCS power, while actual FCS efficiency does not result higher than
50%, due to the different sources of energy loss inside the system.
In order to better understand the above values for FCS efficiency, the main
parasitic losses are shown in Fig. 6.7 , where each curve is representative of the
electric power absorbed by each auxiliary component of the FCS, and is reported
as a function of the DC-DC converter power. The major consumption is due to the
Search WWH ::




Custom Search