In the present study, optical and thermal modelling is applied with the aim to contribute to the identification of the proper form of the overall performance equation of Parabolic Trough Collectors (PTC). Numerical experiments are performed for a range of operational parameter values that refer to medium temperatures. The computational data are used for assessing the capability of existing and new forms of the characteristic equation to better correlate the overall efficiency. Parameters under consideration include the end-loss factor, the Incidence-Angle Modifier (IAM) and the thermal losses.

Results indicate that IAM models affect the correlation of the optical performance. Regarding thermal losses, a new model is proposed. It involves a term representing the radiation flux to the ambient, as dictated by the corresponding transport mechanism. Since thermal losses comprise a small amount of the incident flux to the receiver, the corresponding terms slightly affects the correlation of the overall performance, which is shown to be affected more by IAM modelling. The comparison between IAM models indicates that a correlation based on a second-order polynomial function of the incidence angle, even though leading to comparable correlation coefficients values, produces one order of magnitude lower standard deviation of the sample.

在本研究中，应用光学和热建模的目的是有助于识别抛物槽收集器（PTC）整体性能方程的正确形式。针对涉及介质温度的一系列运行参数值进行了数值实验。计算数据用于评估特征方程的现有形式和新形式的能力，以更好地关联整体效率。考虑的参数包括最终损耗因子，入射角修正器（IAM）和热损耗。

结果表明，IAM模型会影响光学性能的相关性。关于热损失，提出了一种新模型。它涉及一个术语，代表由相应的传输机制决定的到环境的辐射通量。由于热损耗仅包含少​​量入射到接收器的入射通量，因此相应的项会稍微影响整体性能的相关性，这显示出受IAM建模的影响更大。IAM模型之间的比较表明，即使导致可比较的相关系数值，基于入射角的二阶多项式函数的相关也会使样本的标准偏差降低一个数量级。