Parabolic Trough Mirror Alignment Using Theoretical Image Overlay
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Solution Overview
Problem
Parabolic trough solar concentrators face challenges in accurate mirror facet alignment due to the lack of practical optical alignment techniques, leading to inefficiencies in energy capture and increased installation costs, as existing methods are complex, require sophisticated equipment, and are impractical for large-scale implementations.
Innovation Solution
The Theoretical Overlay Photographic (TOP) alignment method uses off-axis cameras to photograph the receiver image in mirror facets, calculates a theoretical projected image, and adjusts the mirrors to overlay the images, allowing for precise alignment without requiring sun exposure, line-of-sight to a distant observer, or removal of the heat collection element, using low-technology equipment and adaptable for both new installations and existing facilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical fixtures are used to align mirror facets, then alignment can be performed without sophisticated equipment, but alignment accuracy is insufficient due to error stack-up and indeterminate effects
Solution Approach 1:
The patent replaces mechanical alignment fixtures with an optical alignment system using lasers and cameras. The laser provides a reference beam that reflects off mirror facets to their focal points, and cameras capture the reflected images. This optical system eliminates mechanical error stack-up and provides sub-arcminute alignment accuracy, resolving the contradiction between simplicity and precision.
Solution Approach 2:
The patent uses optical copying by capturing images of the heat collection element (HCE) as reflected in each mirror facet. These optical copies are then compared against theoretical projected images to determine alignment deviations. This copying approach allows precise measurement without physical contact, avoiding mechanical errors while maintaining alignment simplicity.
2Manufacturing precision
If optical techniques are used to achieve accurate alignment, then alignment precision is improved, but device complexity and equipment requirements increase
Solution Approach 1:
The patent introduces a laser as an intermediary to create a reference optical path. The laser beam serves as a mediator between the mirror facets and the heat collection element, enabling precise alignment measurement without complex direct measurement systems. This intermediary approach simplifies the overall system while maintaining high precision.
Solution Approach 2:
The mirror facets themselves serve the dual function of both reflecting sunlight to the HCE and reflecting the laser alignment beam. The same optical surface that needs alignment also provides the alignment feedback, eliminating the need for separate alignment markers or additional components. This self-service approach reduces equipment complexity while maintaining alignment accuracy.
3Ease of manufacture
If traditional alignment methods are used, then installation cost is reduced, but energy efficiency decreases due to misalignment and spillage losses
Solution Approach 1:
The patent implements feedback by capturing actual reflected images of the HCE in each mirror facet and comparing them against theoretical projected images. The difference between actual and theoretical positions provides feedback on alignment deviations, which is then used to adjust mirror facet orientations. This feedback loop ensures optimal alignment that minimizes spillage losses while maintaining cost-effectiveness.
Solution Approach 2:
The patent performs preliminary alignment using lasers and cameras before final installation completion. By establishing precise optical alignment beforehand, the system ensures that when the concentrator operates with sunlight, the mirror facets are already optimally positioned to minimize energy spillage, avoiding the need for costly post-installation adjustments or energy losses during operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves accurate mirror alignment, improving energy efficiency, reducing spillage losses, and potentially lowering installation costs by enabling better optical performance and alignment accuracy, even in commercial trough power plants, and is adaptable for various conditions and mirror replacements.
Implementation Method 1
photographing the image of the receiver in a mirror facet with a camera at the off-axis camera position
Data Source
AI summary
A Theoretical Overlay Photographic (TOP) alignment method uses the overlay of a theoretical projected image of a perfectly aligned concentrator on a photographic image of the concentrator to align the mirror facets of a parabolic trough solar concentrator. The alignment method is practical and straightforward, and inherently aligns the mirror facets to the receiver. When integrated with clinometer measurements for which gravity and mechanical drag effects have been accounted for and which are made in a manner and location consistent with the alignment method, all of the mirrors on a common drive can be aligned and optimized for any concentrator orientation.