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

5. SIMULATION AND RESULTS
Figure 5.21: The influence of the Closest Approach Temperature for the liquid-liquid HEXes on
the COP (STD value is 5 ◦ C). The electrical efficiency is not shown since it remains virtually
constant.
Condensers (Heat exchangers)
The two condensers have liquid water inside the tubes, whereas the
refrigerant on the outside is in the 2phase region (changing from higher
gas quality to lower gas quality (saturated water)). So these heat
exchangers must be more efficient than water-gas heat exchangers but
less effective than water-water heat exchangers. Hence their standard
∆T min is 10 ◦ C. They are also investigated from 0 to 16 ◦ C: As can be seen
from figure 5.22, both condensers are far less sensitive to ∆T min than the
water-water heat exchangers, and actually the system does not benefit
from having a more efficient Condenser.
Condenser 1 is a little more sensitive to ∆T min and as this increases,
the slope of the curve becomes more negative. But when it is compared to
the black line for the absorber in figure 5.21 an interesting fact is revealed.
It turns out that the absorber curve is considerably steeper than the
Condenser1 curve (figure 5.22). This shows than the temperature level
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