Multi-Stage Falling Particle Receiver for Stable High-Opacity Heating
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Solution Overview
Problem
Existing falling particle solar receivers face inefficiencies in capturing solar energy due to low particle volume fraction, opacity, and flow instability, leading to increased transmittance and uneven heating, which results in reduced energy conversion and storage capabilities.
Innovation Solution
A multi-stage falling particle receiver system that uses flow retarding devices, such as troughs and funnels, to periodically collect and release particles, reducing vertical and horizontal dispersion, enhancing particle flow stability, and maintaining high opacity, while minimizing material usage and protecting surfaces from erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If particles fall freely through the receiver, then the particle flow rate increases, but the particle volume fraction and opacity decrease due to gravitational acceleration and dispersion
Solution Approach 1:
The receiver is divided into multiple stages with flow retarding devices at intermediate levels. Each stage processes particles sequentially, allowing the system to handle high flow rates while maintaining adequate particle concentration at each level through staged deceleration and redistribution
Solution Approach 2:
Flow retarding devices act as intermediary elements between the particle source and final collection. These devices mediate the particle flow by reducing velocity and redistributing particles, preventing excessive dispersion while maintaining high throughput
2Duration of action of moving object
If particles fall freely through the receiver, then the residence time decreases, but the energy capture efficiency worsens due to reduced heating time
Solution Approach 1:
The heating process is segmented into multiple stages. Particles receive incremental heating at each stage rather than requiring prolonged exposure in a single stage, achieving adequate energy capture with reduced total residence time through distributed heating zones
Solution Approach 2:
The multi-stage configuration ensures continuous heating action throughout the particle descent. Each stage contributes to the cumulative heating process, maintaining continuous energy transfer without requiring extended residence time at any single location
3Loss of energy
If the particle curtain is exposed to concentrated solar energy, then the energy absorption increases, but the flow stability deteriorates due to perturbation and transformation into a wider, unstable curtain
Solution Approach 1:
The particle curtain is divided into multiple smaller curtains by flow retarding devices at each stage. Each segmented curtain is more stable and easier to control, preventing the transformation into a wide, unstable flow while collectively maintaining high energy absorption across all stages
4Quantity of substance
If more particles are used to maintain high volume fraction, then the opacity increases, but the material cost and system complexity increase
Solution Approach 1:
The system uses multiple stages with fewer particles at each level rather than requiring a large volume fraction in a single stage. This segmented approach achieves equivalent overall heating performance with reduced total particle inventory and simplified system configuration
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
The system effectively reduces particle velocity and dispersion, increases heat transfer uniformity, and maintains high opacity, leading to improved energy capture and conversion efficiency while reducing costs and maintenance needs.
Implementation Method 1
The particle receivers utilize solid particles as the heat transfer medium to absorb the incident concentrated solar energy
Implementation Method 2
gravitational acceleration that increases downward velocity and dispersion
Data Source
AI summary
The present disclosure is directed to multi-stage falling particle receivers and methods of falling particle heating. As the particles fall through the receiver, the particles are periodically collected and released by flow retarding devices. The periodic catch-and-release of the particles falling through the receiver reduces particle flow dispersion, increases particle opacity and solar absorption, and reduces erosion and damage to surfaces caused by direct particle impingement.