Granular Heat Storage Using Ambient Air for Solar-Thermal Plants
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Solution Overview
Problem
Current high-temperature heat storage systems face challenges in achieving efficient, cost-effective, and reliable large-scale storage with fast charging and discharging capabilities, high cycle stability, and low investment and operating costs, particularly for solar thermal power plants and seawater desalination applications.
Innovation Solution
A high-temperature heat storage device using a porous and/or granular storage material like sand, gravel, stone, or graphite, which absorbs heat quickly from air flowing through it, with air as the heat transfer medium at ambient pressure, reducing the need for high-pressure systems and allowing for inexpensive and widely available materials, and incorporating an air-to-air heat exchanger for heat recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If PCM storage is used for high-temperature applications, then energy density is improved, but cost and complexity increase due to expensive metal pipes and surfaces required for heat transfer
Solution Approach 1:
The patent replaces expensive metal pipes and heat transfer surfaces with inexpensive, replaceable heat exchange elements made of cheap materials. These elements can be easily replaced when worn out, transforming a high-capital-cost system into one with low capital cost and low operating cost through frequent replacement of consumable components.
Solution Approach 2:
The patent uses porous heat exchange elements that allow direct contact between the heat transfer medium and the storage material, eliminating the need for expensive metal pipes and surfaces while maintaining effective heat transfer through the porous structure.
2Quantity of substance
If sand or gravel storage medium is used with a pipe system, then storage capacity is improved, but heat transfer efficiency deteriorates due to poor heat transfer between pipes and storage medium
Solution Approach 1:
The patent employs porous heat exchange elements that permeate throughout the sand or gravel storage medium, creating extensive contact surfaces for heat transfer. This porous structure allows the heat transfer medium to directly interact with the storage material, dramatically improving heat transfer efficiency compared to conventional pipe systems.
Solution Approach 2:
The patent uses a fluid (liquid or gas) as the heat transfer medium that circulates through the porous heat exchange elements embedded in the storage medium. This hydraulic/pneumatic system enables efficient heat transfer by allowing the fluid to flow directly through the porous structure, maximizing thermal contact between the heat transfer medium and storage material.
3Stability of the object's composition
If concrete storage tanks are used, then structural stability is improved, but heat transfer performance deteriorates due to poor heat transfer between concrete and pipes
Solution Approach 1:
The patent incorporates porous heat exchange elements within the concrete storage tank structure. These porous elements provide extensive surface area for heat transfer between the concrete matrix and the circulating heat transfer medium, overcoming the poor thermal conductivity of concrete while maintaining the structural stability of the tank.
Solution Approach 2:
The patent creates a composite heat exchange system combining concrete structural elements with porous heat transfer materials. This composite structure leverages the structural advantages of concrete while incorporating the superior heat transfer characteristics of porous materials, achieving both structural stability and improved thermal performance.
4Loss of energy
If high pressure steam lines are laid to PCM storage, then heat transfer capability is improved, but cost and complexity increase due to many long and expensive high pressure steam lines
Solution Approach 1:
The patent replaces expensive, long-lasting high pressure steam lines with inexpensive, replaceable heat exchange elements. These elements operate at lower pressures and can be easily replaced when needed, reducing both the capital cost of installation and the complexity of the overall system while maintaining adequate heat transfer capability.
Solution Approach 2:
The patent uses a fluid circulation system with porous heat exchange elements that operate at lower pressures than traditional high pressure steam lines. This hydraulic approach distributes heat transfer medium through the porous structure, achieving effective heat transfer with simpler, less expensive piping and fewer high-pressure 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 solution enables efficient, cost-effective, and reliable high-temperature heat storage with fast charging and discharging, high cycle stability, and minimal pressure losses, optimizing energy transfer and reducing operational costs, while using commercially available components and materials.
Implementation Method 1
The storage module is filled with a porous and/or granular storage material which absorbs the heat from the air flowing through it very quickly and with a small temperature difference
Implementation Method 2
incorporating an air-to-air heat exchanger for heat recovery
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~5
AI summary
Proposed is a cheap and durable high-temperature heat store which utilizes ambient air as a heat carrier medium and which is at least partially filled with a granular and/or porous storage medium (6).