Solar concentrator for a tower-mounted central receiver
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Solution Overview
Problem
Current solar concentrator systems face limitations in achieving high optical concentration, field efficiency, and low self-shadowing losses, particularly with heliostat-based systems, which result in reduced energy conversion efficiency and increased structural costs.
Innovation Solution
A solar concentrator system featuring a mobile, amphitheater-like structure with concave mirrors arranged in tiered arcs on a circular track, allowing each mirror to maintain a fixed position relative to the receiver and articulate minimally to focus sunlight efficiently, combined with a rotatable receiver to optimize sunlight concentration throughout the day.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If heliostat reflectors are positioned on the ground around a tower mounted receiver, then the system can achieve a large collection area, but the collection efficiency is reduced due to obliquity losses and self-shadowing
Solution Approach 1:
The patent transitions from ground-level heliostats operating in a two-dimensional plane to elevated mirrors mounted on a three-dimensional spherical framework. This dimensional change allows mirrors to be positioned at various heights and angles, optimizing their orientation to the sun and receiver while eliminating self-shadowing issues that plague ground-based systems. The spherical geometry provides spatial separation that prevents mirrors from blocking each other's sunlight paths.
Solution Approach 2:
The patent employs a spherical framework to mount the mirrors, where each mirror is positioned on the surface of an imaginary sphere centered on the receiver. This curved, three-dimensional arrangement allows mirrors to maintain optimal angles to both the sun and receiver throughout the day, minimizing obliquity losses. The spherical geometry naturally accommodates the changing solar position while maintaining efficient optical paths.
2Productivity
If heliostat density is increased to improve field efficiency, then more mirrors can be packed into the field, but shadowing losses increase
Solution Approach 1:
By moving from a two-dimensional ground-based arrangement to a three-dimensional spherical framework, the patent dramatically increases the available mounting space. Mirrors can be distributed across the spherical surface at various heights and radial distances from the receiver, allowing high mirror density without mutual shadowing. The vertical dimension provides additional separation space that prevents mirrors from blocking each other's optical paths.
3Loss of energy
If dish collectors are used to achieve high optical efficiency, then the reflector always faces the sun directly, but the structural costs increase and the reflector aperture is limited
Solution Approach 1:
The patent divides the collection system into many small, identical mirror segments mounted on a spherical framework, rather than using a single large dish. Each small mirror has simple, identical support structure, avoiding the need for a complex, large-scale tracking structure. The segmented approach allows the system to achieve large total aperture area while keeping individual mirror supports simple and inexpensive.
Solution Approach 2:
The spherical framework serves multiple functions simultaneously: it provides structural support for the mirrors, defines the geometric arrangement for optimal optical paths, and enables the system to achieve both large aperture area and high concentration ratios. This multi-functional design eliminates the need for separate complex tracking mechanisms required by dish collectors.
4Device complexity
If trough reflectors are used, then the system can achieve simple structure, but the concentration is limited due to single-axis focusing
Solution Approach 1:
The patent uses a spherical framework with mirrors positioned on the surface of an imaginary sphere centered on the receiver. This spherical geometry provides two-degree-of-freedom optical paths, allowing mirrors to focus sunlight from different azimuth and elevation angles onto the receiver. The curved spherical arrangement naturally achieves high concentration ratios while maintaining relatively simple mirror support structures, overcoming the single-axis limitation of trough reflectors.
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 configuration achieves significantly higher optical efficiency (up to 90%) and concentration (2050×) while minimizing obliquity and shadowing losses, enabling cost-effective construction and operation, even in high winds.
Implementation Method 1
A solar concentrator focuses sunlight to a central receiver mounted atop a tower. A mobile, amphitheater-like structure moves on a circular track about the tower and supports an array of concave mirrors that reflect and focus sunlight onto the receiver.
Implementation Method 2
The mirrors are carried in tiered arcs that together approximate the shape of part of a sphere centered on the top of the tower, so the mirrors are all at approximately the same distance from the receiver. Sunlight is focused to the central receiver throughout the day
Data Source
AI summary
A solar concentrator may have a horizontal circular track on the ground, a tower centered on a vertical axis of the track, and a rotatable structure around the track having an upper, concave mounting surface approximating the shape of part of a sphere centered on the top of the tower. Articulated concave mirrors are attached to the rotatable structure, and the mirrors have a focal length approximately equal to the radius of a sphere portion formed by the concave mounting surface. Sunlight is focused at a receiver mounted atop the tower, and the receiver may convert sunlight into thermal or electrical energy. As the position of the Sun changes, sunlight is maintained on the receiver by turning the rotatable structure toward the Sun, turning the receiver about said vertical axis to face the mirrors, and articulating the mirrors toward the receiver in response to the changing elevation of the Sun.