Comparative analysis of thermal and dynamic performance of glass evacuated tube solar collectors with U-pipe, filling pipe, and spiral pipe: an experimental study
摘要
This study aimed to enhance the performance of evacuated tube collectors in solar water heating systems by investigating and comparing three thermal energy transfer methods: Filling pipe, U-pipe, and Spiral pipe. The research uniquely explores the spiral pipe’s performance for the first time, providing a comprehensive comparative analysis of its thermal and dynamic properties against the other methods under experimental conditions. Experiments were conducted at 2.5, 4.5, and 7.5 L min−1 fluid flow rates to evaluate thermal efficiency, exergy efficiency, pressure drop, and friction coefficient. Results demonstrated that the spiral pipe, at a flow rate of 2.5 L min−1, achieved the highest fluid temperature (84.1 °C), thermal efficiency (60.8%), and exergy efficiency (46.8%). The U-pipe configuration exhibited the lowest pressure drop across all flow rates; while, the spiral pipe showed a maximum pressure drop of 1.3 bar at 7.5 L min−1. Additionally, the filling pipe at 2.5 L min−1 recorded the highest friction coefficient of 0.52. These findings underscore the spiral pipe’s superior thermal and exergy performance, particularly at lower flow rates, while highlighting trade-offs with increased pressure drop at higher flow rates. This research advances the understanding of evacuated tube solar water heater designs, emphasizing the potential of spiral pipes to improve system efficiency and performance significantly.