Dynamic test model for the transient thermal performance of parabolic trough solar collectors

•Dynamic model offers convenient thermal tests of parabolic trough solar collectors.•The model is suitable for the on-site long collector’s row in realistic conditions.•The outlet temperature, output energy and thermal efficiency are predicted.•Very small differences show that this model is reliable for even unsteady conditions. An on-site test model was developed to evaluate the thermal performance of parabolic trough solar collectors under dynamic conditions based on energy balance equations and a thermodynamics analysis. The primary benefit of this approach compared with steady-state test models is that this model includes the effect of the incident angle on the overall collector performance of a long row of collectors, so the model can be applied on-site to parabolic trough collectors in actual conditions that track the sun only along one axis. This added flexibility in the test requirements means that all tests can be conducted as transient tests, which considerably reduces the testing time spent in waiting for the ideal conditions. Furthermore, the dynamic model predictions for the outlet temperature, output energy and thermal efficiency are in good agreement with measured results on both clear and cloudy days, which shows that this model can provide quick, reliable on-site testing.