Optical, 2D thermal modeling and exergy analysis applied for performance prediction of a solar PTC

In the present work, a detailed optical and thermodynamic analysis of the solar Parabolic Trough Collector (PTC) is presented. At first, an optical and 2D thermal modeling of a PTC is developed. This thermal modeling is coupled to an exergy analysis to construct a single model for the PTC's overall performances prediction. The results are compared to the experimental measurements carried out at Sandia National Laboratories. Then, a parametric study was first performed by using a commercial PTC (Eurotrough ET-150) and a Schott PTR-70 receiver in order to study the effect of some operating and environmental parameters on the PTC's optical, thermal and exergy efficiencies. The exergy losses and the exergy destruction rates through these parameters are also evaluated. In all cases, the results are in accordance and showed a good agreement with experimental data. The results show that the PTC's performances are very sensitive to the beam solar radiation and the incidence angle as well as to the PTC's aperture width, the heat transfer fluid inlet temperature and the mass flow rate. The main deviations in the performances are caused by heat losses from the heat transfer fluid to the surroundings (exergy losses), and/or by the fact of thermal differential through flow direction (exergy destruction) that is the main of the dissipation in the system process. In addition, the simulation of the performance of four Eurotrough ET-150 mounted in series (one loop) under the running conditions of site of Hassi R'Mel (located at the heart of Algerian Sahara) on two typical days is predicted. On summer solstice, the daily maximum energy efficiency and exergy efficiency are 67.91% and 36.08%, respectively. They, however, decrease to 31% and 22.1%, respectively on winter solstice. The overall performance prediction guarantees the real-time evaluation of the PTC with more accuracy.