An improvement approach for the solar collector by optimizing the interface of assembling structure

The heat pipe evacuated tube solar collectors were widely used in building heating. The defects in the assembling process caused by the roughness of solid materials have a severe effect on the thermodynamic performance of the solar collector. To enhance the efficiency of the solar collectors, an improvement approach by filling the gaps in the interface between assembling structures using thermal interface materials is proposed. The interface between heat pipe and fin is a major contributor to the heat resistance in collector tubes, thus affecting the utilization efficiency of solar energy. Three thermal greases were selected, and then the interface after filling the gaps was characterized and analyzed. To verify the effectiveness of the new improvement approach, two experimental setups including a solar collector and a solar heating system were built. Experimental results show that the average collection efficiency of the solar collector increases by 4.8% compared with that of the unprocessed one. Moreover, the optimization of the interface enhances the sensitivity and response speed of the collector on solar irradiance, and shortens the startup time by 27.2% of the solar heating system. The work provides a promising way to upgrade the solar collector with heat pipe evacuated tube. • An improvement approach for the solar collector by optimizing the interface of assembling structure is proposed. • Contact heat transfer of assembling structure is considered in thermal model. • Introduction of thermal grease in solar collector enhances its thermodynamic performance. • Improving assembling interface increases collector sensitivity and start speed. • Effectiveness of the new approach is verified by two experimental setups.