Field-receiver model validation against Solar Two tests

Validation is a crucial aspect in the reliability assessment of models. Validation accuracy is measured with respect to experimental data. In this regard, there is not any experimental technique with sufficient spatial resolution capable of measuring the incident solar flux onto the receiver of solar power tower plants to model validation. Therefore, the individual optical efficiency of the field and the thermal performance of the receiver cannot be accurately obtained experimentally. To calculate these efficiencies, the development of numerical models is mandatory. Although, numerous receiver models can be found in the literature, the accuracy of most of them is not checked because of the scarcity of experimental data to compare with. In this study, the simulations of a model that includes the heliostat field and an external tubular receiver, taking into account all the receiver tubes, have been compared with available experimental data from Solar Two plant, in order to check its accuracy. It was obtained that the model overestimates 1.42% the total mass flow rate and 0.73% the global efficiency of Solar Two, which is almost negligible. Besides, the field-receiver efficiency can be calculated with confidence using Solar Two experimental data, and then it can be taken into account in the validation of the model. The model error, with respect to the experimental data are of 1.1% at full load and 1.4% at 50% partial load.