Actively focused lightweight heliostat
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Solution Overview
Problem
Existing heliostats require a large number of flat or concave reflectors to achieve high sunlight concentration, leading to mechanical complexity and high costs, and their fixed shapes result in suboptimal performance throughout the day due to varying solar angles.
Innovation Solution
A heliostat with an elastically deformable frame and bracing struts equipped with actuators that actively adjust the reflecting surface's shape to maintain optimal curvature and orientation throughout the day, using a dual-axis mount to focus sunlight on a fixed target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a large number of small flat heliostats are used to achieve high sunlight concentration, then the concentration ratio can be maintained, but the mechanical complexity and system cost increase significantly
Solution Approach 1:
The heliostat field is segmented into fewer, larger individual heliostats with active shape control capabilities. Each heliostat is divided into multiple independently controllable mirror segments that can be dynamically adjusted to maintain optimal focus, replacing the need for many small static heliostats.
Solution Approach 2:
The heliostats incorporate active shape control mechanisms that dynamically adjust the mirror surface geometry in real-time to maintain precise focus on the receiver. This dynamic adaptation allows each heliostat to compensate for geometric aberrations and maintain high concentration ratios.
2Quantity of substance
If larger heliostats with concave reflector surfaces are used to reduce the number of units, then fewer heliostats are needed, but the mechanical complexity and cost of the reflector structure increase
Solution Approach 1:
The large concave reflector is segmented into multiple smaller mirror panels that can be independently actuated. This segmentation allows the complex concave shape to be achieved through coordination of simple panel adjustments rather than requiring a single complex molded structure.
Solution Approach 2:
The reflector structure incorporates active shape control mechanisms that allow the mirror surface to dynamically change its curvature and orientation. This enables a relatively simple support structure to achieve complex optical paths through real-time geometric adjustment.
3Device complexity
If fixed toroidal curvature is used to simplify the mount design, then the mount structure is simplified, but image degradation occurs at times other than midday
Solution Approach 1:
The heliostat incorporates active shape control that dynamically adjusts the mirror surface geometry throughout the day to compensate for changing solar angles. This allows a simpler mount structure to achieve precise imaging at all times by actively correcting geometric aberrations rather than requiring a complex fixed mount design.
Solution Approach 2:
The system changes the geometric parameters of the reflector surface in real-time based on the sun's position. By dynamically adjusting curvature radii, orientation angles, and segment positions, the system maintains optimal imaging quality across different times of day despite using a simplified mount structure.
4Manufacturing precision
If active shape adjustment mechanisms are added to change toroidal radii throughout the day, then imaging quality is improved, but the device complexity and cost increase
Solution Approach 1:
The active shape control system divides the mirror into multiple independently actuated segments. Each segment can be adjusted individually using simple actuators, avoiding the need for a single complex continuous shape adjustment mechanism. This segmentation enables precise control with simpler, more reliable components.
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 design improves sunlight concentration and reduces spillage, allowing for higher receiver temperatures and lower construction costs while maintaining efficient energy collection with a smaller number of heliostats.
Implementation Method 1
A heliostat is a device generally in a fixed location, with a mirrored surface to reflect solar energy toward a fixed target
Implementation Method 2
an elastically deformable frame on which the reflecting surface is mounted... The actuation of the at least one actuator in response to the electronic control system causes compression or tension of at least one of the at least four bracing struts to thereby control a shape of the reflecting surface and the elastically deformable frame
Data Source
AI summary
A heliostat includes a reflecting surface: an elastically deformable frame on which the reflecting surface is mounted: a truss structure behind the elastically deformable frame that includes at least four bracing struts with first ends attached to the elastically deformable frame and second ends attached to at least one node located centrally behind the frame: at least one actuator connected to at least one of the at least four struts at the at least one node: an electronic control system configured to communicate with the least one actuator; and a dual-axis mount to support and orient the above assembly. The actuation of the at least one actuator in response to the electronic control system causes compression or tension of at least one of the at least four bracing struts to thereby control a shape of the reflecting surface and the elastically deformable frame in at least low order bending modes.