Volumetric flow determination in parabolic trough plants using the time offset of temperature gradients

The absence of flow measurements in the loop of a parabolic trough solar field makes it impossible to easily determine flow for the purpose of calculating the performance of a loop. This proof-of-concept study uses the temperature signals of the heat transfer fluid, measured at the parabolic trough collectors to determine the runtime of a temperature signal and thus, to infer the runtime of the fluid. It is not dependent on additional measurement instrumentation and only requires data analysis using the available measurement equipment. The approach can be applied to existing parabolic trough loops at nearly no additional costs and could also be used in other pipe flows in process engineering applications. The method is validated in a realistic application scenario with data from the parabolic trough power plant Andasol-3 and shows a mean absolute percentage error of 6.15% compared to the measured subfield mass flow.