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

3. COMPONENT DESCRIPTION
T [° C ]
T ss , i
T c ,o
T start
ΔT min ,ws , o
T ws ,o
T c ,i
˙Q[kW ]
Figure 3.2: ABSO: The temperature of the hot fluid into the absorber is not known fore sure, so
the heat exchanger part is made as co-flow to make sure that no approach temperature difference
is smaller that the one given by ∆T min .
So by modeling the heat transfer in the absorber as a co-flow heat exchanger
(figure 3.2) there should be no doubt that the smallest approach
temperature difference (∆T min ) occurs between the solution outlet and
the cooling circuit outlet: Due to lack of knowledge about the temperature
distribution the effectiveness of the heat transfer is not determined
(it is not known which flow has the smaller heat capacity flow, since the
temperature distribution of the solution is not known), so for this component,
only ∆T min is calculated.
The amount of heat to be removed by the cooling circuit is calculated
by the energy balance, which includes a loss to the surroundings ( ˙Q loss ),
which should be zero (adiabatic component) or positive (heat loss to the
surroundings).
Ḣ ss,i + Ḣ r,i + Ḣ c,i = Ḣ ws,o + Ḣ c,o + ˙Q loss (3.4)
A mass balance of H 2 O as well as LiBr is needed, but since the absorber
is connected in a closed loop, they are not given explicitly (in one of
the components in a closed loop, the mass balance must be omitted to
avoid over specification). So the following two mass balances are given
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