Abstract:
This paper presents results of a numerical analysis of entropy generation in a parabolic trough receiver at
different concentration ratios, inlet temperatures and flow rates. Using temperature dependent thermal
properties of the heat transfer fluid, the entropy generation due to heat transfer across a finite temperature
difference and entropy generation due to fluid friction in the receiver has been determined. Results show a
reduction in the entropy generation rate as the inlet temperature increases and an increase in the entropy
generation rate as the concentration ratio increases. Results further showthat, there is an optimal flow rate
at which the entropy generated is a minimum, for every combination of concentration ratio and inlet
temperature. The optimal flowrates at which the entropy generated is minimum are presented for different
flow rate and concentration ratio, and the results are the same irrespective of the inlet temperature
considered. For the range of inlet temperatures, flow rates and concentration ratios considered, the Bejan
number, which measures the contribution of entropy generation due to heat transfer irreversibility to the
total entropy generation rate is about 1 at low flowrates and is between 0 and 0.24 at the highest flow rate.
