Multi-stage falling particle receivers
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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 are exacerbated by gravitational acceleration and dispersion.
Innovation Solution
A multi-stage falling particle receiver system that collects and periodically releases particles using flow retarding devices such as troughs and funnels, reducing particle velocity and dispersion, enhancing stability and heat transfer uniformity, and allowing for variable particle flow rates while maintaining high opacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If particles are allowed to fall freely through the receiver, then the system structure is simple and operation is continuous, but particle dispersion increases and residence time decreases due to gravitational acceleration
Solution Approach 1:
The receiver is divided into multiple sections with flow retarding devices (troughs, funnels, or ledges) positioned at different heights. These devices segment the continuous particle flow into discrete stages, allowing particles to be periodically collected and released. This segmentation reduces particle dispersion and increases residence time without requiring complete system shutdown between stages.
Solution Approach 2:
The flow retarding devices create periodic action by collecting particles at regular intervals as they fall through the receiver. This periodic collection and release mechanism creates a rhythmic flow pattern that stabilizes the particle curtain, increases residence time, and improves heat transfer uniformity while maintaining continuous operation.
2Productivity
If particle flow rate is increased to improve productivity, then energy output increases, but particle dispersion and transmittance increase reducing heat capture efficiency
Solution Approach 1:
The flow retarding devices dynamically adjust particle flow characteristics by collecting and releasing particles in a controlled manner. This dynamic control allows the system to maintain optimal particle density and residence time even at higher flow rates, preventing increased transmittance and ensuring consistent heat capture efficiency across varying productivity levels.
3Quantity of substance
If particle falling height is increased to improve energy capture, then more particles are heated, but particle velocity increases causing greater dispersion and reduced residence time
Solution Approach 1:
The falling height is segmented into multiple stages with flow retarding devices positioned at intermediate heights. Instead of allowing particles to fall the entire height in one continuous motion, they are collected and released at multiple intermediate points. This segmentation reduces the velocity gained during each fall segment while still achieving comprehensive heating across the particle population.
4Stability of the object's composition
If flow retarding devices are added to reduce particle dispersion, then residence time increases and heat transfer uniformity improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The flow retarding devices are designed using simple, inexpensive materials and geometries (troughs, funnels, or ledges) that can be easily manufactured and installed. These devices prioritize functional effectiveness over aesthetic or complex structural considerations, using basic shapes that minimize manufacturing complexity while achieving the desired flow control and particle stabilization.
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 dispersion and heat loss, increases opacity, and maintains high energy capture efficiency across a range of flow rates, improving the overall performance and cost-effectiveness of solar energy conversion.
Implementation Method 1
gravitational acceleration that increases downward velocity and dispersion
Implementation Method 2
The particle receivers utilize solid particles as the heat transfer medium to absorb the incident concentrated solar energy
Implementation Method 3
Low particle volume fraction increases the transmittance of the particle curtain. Additionally, solar energy not absorbed by the particles is lost
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.