integration of solid oxide fuel cells and ... - Ea Energianalyse

C H A P T E R
8
CONCLUSION
System configuration
It turned out that a double stage configuration for the ABS unit could
give a cooling power of around 59kW of cooling per 100kW fuel input
in contrast to the only 26kW of cooling that was obtained with the single
stage.
An additional air preheating (GGHEX4) turned out to give 14kW of
extra cooling for the double stage with the optimized parameters, so this
must be considered a very worthwhile addition.
The model showed that it was almost essential to use a wet cooling
tower. If a dry cooling tower was used, the ABS unit could only
run at ambient temperatures below 20 ◦ C for a desorber temperature of
150 ◦ C. If the desorber temperature was increased to 190 ◦ C, the ambient
temperature could be up to 30 ◦ C, but this would increase corrosion of
the desorber significantly. Since air conditioning is not so necessary
when the ambient temperature is much below 30 ◦ C, the conclusion of
the absorber/condenser-cooling was that the tower had to be wet or at
least semi-wet, whereby the amount of water used for evaporation could
be controlled to fit the need.
Critical components for good performance
The investigations showed that the most critical heat exchangers with
respect to the system COP were: the internal water-LiBr heat exchangers
(SHEX1+2), the evaporator (EVAP) and the air pre heater (GGHEX4).
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