Calibration of a Multi-Facet Vacuum-Membrane Solar Dish Array
摘要
This study investigates the implementation of a novel Hall effect focus control system and alignment calibration method for vacuum-membrane solar dish facets in small-scale concentrating solar power (CSP) systems. The CSP system comprises 42 individual elliptical vacuum-membrane solar dish facets, each with a variable focal length dependent on the membrane depth. Previous research identified membrane displacement as a significant challenge affecting system performance throughout an operating day due to changing environmental conditions, especially ambient temperature. In response, a cost-effective and low power consumption focus control system utilizing a Hall effect depth-sensing method was implemented in the current work and mounted to 42 facets to maintain the membrane depth to within ±2 mm, for a minimum 90% intercept factor. The system’s effectiveness was further enhanced by employing a manual alignment method using a green laser pointer mounted on a movable guide arm, which enabled the precise alignment of each facet at night. This method allowed for accurate alignment of the 42 facets, ensuring that the reflected solar radiation would be directed to the receiver aperture. An initial full-moon validation test demonstrated that the new focus control and alignment methods could achieve a higher intercept factor compared to previous setups, with minimal light spillage outside the receiver aperture. These innovations can significantly improve the performance and efficiency of small-scale CSP systems by maintaining accurate focal lengths and enhancing solar radiation concentration. Future on-sun testing will further validate the effectiveness of the calibration methods and its potential for wider application in small-scale CSP systems.