Figure 11. Performance
data for the cryocooler. Circles indicate the experimental data, the
dotted line shows a linear fit to the data, and the dashed line
indicates the operating temperature for the cryocooler in the MCD
system.
These results suggest that the cryocooler was providing about 12.7 W of
duty to the condenser during MCD operation, which is 3.3 W less than the
manufacturer’s specifications. Reducing the condenser duty in the model
to 12.7 W improves the fit with the experimental data, but there is
still some disagreement. Reducing the duty in the model to 10.5 W allows
the model to agree closely with the data. This additional 2.2 W
difference is likely the result of parasitic heat losses (i.e., losses
that result from imperfect insulation of the process).
One note about these results should be emphasized. The condenser duty in
the model has only minimal impact on composition when the bottoms flow
rate is small and the boil up ratio is high. Since the modeling and
experiments used to determine column efficiency was performed at small
bottoms flow rates, this finding about the actual condenser duty had no
impact on the determination of the HETP values for each column.