Analysis and Simulation Study of Flow and Thermal Performance in the U-tube Solar Collector

In this study,the energy balance equations for each part of U-tube solar collector were established.In order to analyze the collector thermal efficiency in detail,a computational fluid dynamics model was developed for different operating conditions.The flow and thermal performance was evaluated by means of the computational model for changing inlet flow velocity,different solar irradiance and varied configuration.Simulation results presented that faster incoming flow rate,lower solar irradiance or bigger U-tube diameter will lead to lower outlet temperature,whereas slower incoming flow rate,higher solar irradiance or smaller U-tube diameter result in higher thermal efficiency.Furthermore,within the specified range,the flow structure in the U-tube uninfluenced by the inlet flow rate.