Abstract
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•A Bond Graph model and a simulation of a parabolic-trough collector are proposed.•A good agreement is observed between the simulated results and experimental tests.•Exergy dynamic performance assessment of the PTC is presented.•The PBG model proposed is recommended for a PTC solar field control.
The present paper deals with the modeling of a solar parabolic trough collector (PTC).The system is described by a lumped parameter model; its dynamic modeling is performed using the bond graph methodology which allows having a graphical structure of the modeled phenomena where the multi-domain coupling relationships are explicitly represented. The thermal domain of the pseudo bond graph (PBG) supports all heat transfer modes established between the environment, the glass cover, the absorber tube and the fluid. The mass accumulation in the control volume is not taken into account since its dynamic effect remains largely negligible as demonstrated in this contribution. The state equation of the system is developed from the laws of the junctions, the resistance elements and capacitance elements. Numerical simulation is carried out via the Matlab software environment and the predicted results are compared with the experimental tests of the Sandia National Laboratory. For on-sun tests, the average relative errors obtained are about 0.17% for the heat transfer fluid (HTF) output temperature and about 0.96% for the energy efficiency. In the case of off-sun tests, the average relative error calculated for the predicted HTF output temperature is estimated at 0.08% and the heat losses absolute error is equal to 4.9 (W/m2). According to the previous comparisons, there is reason to affirm that the proposed model can accurately predict the thermal behavior of the collector. Finally, this work includes a case study that consists of PTC exergy performance assessment under climate conditions of three different North Africa sites.