Concrete Thermal Storage with Decoupled Pipe System

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Solution Overview

Problem

Current thermal energy storage solutions face challenges in achieving high heat capacity, reliable, and economical storage due to limitations in materials and vapor pressure issues, especially at higher temperatures.

Innovation Solution

A solid-state thermal energy storage device using concrete as the storage medium, with a pipe system for energy carrier medium and a gap or sliding layer for mechanical decoupling, allowing for increased permeability and efficient heat transfer, and modular connection options for scalable storage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If water is used as heat storage medium, then high specific heat capacity and low costs are achieved, but rapid rise in vapor pressure above 100°C necessitates expensive pressure vessels

Engineering Contradiction:
Improveheat capacityVSAvoidvapor pressure
Core Design Contradiction:
Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical state parameter of the storage medium from liquid (water) to solid (concrete), which fundamentally alters the vapor pressure characteristics. Solid concrete does not exhibit rapid vapor pressure increase at elevated temperatures like liquid water does, eliminating the need for expensive pressure vessels while maintaining thermal storage capability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses ordinary concrete, a cheap and readily available material, instead of expensive specialized heat storage materials. This approach achieves cost-effective thermal energy storage by using a common building material with sufficient thermal properties for the application

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Temperature

If oils are used for higher temperature ranges, then boiling point is increased, but costs increase significantly

Engineering Contradiction:
Improveboiling pointVSAvoidcosts
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent replaces expensive thermal oils with ordinary concrete, a cheap and abundant material. This substitution achieves high-temperature thermal storage without the significant cost increase associated with specialized high-boiling-point liquids, making the system economically viable

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Strength

If steel or cast iron is used for solid reservoirs, then high strength is achieved, but high costs are incurred

Engineering Contradiction:
ImprovestrengthVSAvoidcosts
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent substitutes expensive steel and cast iron with ordinary concrete, a much cheaper material. The concrete structure provides sufficient mechanical strength for thermal storage applications at a fraction of the cost of metallic alternatives, achieving cost-effective solid-state thermal energy storage

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Object-affected harmful factors

If loose mineral materials are used for solid reservoirs, then low costs are achieved, but limited available capacity due to low thermal conductivity occurs

Engineering Contradiction:
ImprovecostsVSAvoidheat capacity
Core Design Contradiction:
Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The patent uses concrete, which is itself a composite material combining cement, aggregates, and water. This composite structure provides both the low cost of mineral materials and improved thermal conductivity through the dense matrix and embedded aggregates, overcoming the limitation of loose mineral materials while maintaining economic advantage

Inventive Principle:
Principle #40Composite materials

5Stability of the object's composition

If pipe system is mechanically coupled to concrete storage medium, then structural stability is achieved, but thermal expansion differences cause damage

Engineering Contradiction:
Improvestructural stabilityVSAvoiddamage resistance
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent divides the thermal storage system into two functionally independent parts: the concrete storage medium and the pipe system. By providing a gap between them, the design allows each component to expand and contract independently according to its own thermal properties, preventing stress buildup and damage while maintaining overall structural integrity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The gap between the pipe system and concrete storage medium acts as an intermediary element that decouples the two components. This intermediate space accommodates differential thermal expansion without transmitting damaging stresses, while still allowing effective thermal energy transfer to the storage medium

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution enables a cost-effective, high-capacity thermal energy storage system with uniform energy input and reduced vapor pressure, allowing for reliable and adaptable thermal energy storage across various applications.

Implementation Method 1

The thermal energy is fed into the solid storage tank via a gaseous or liquid energy carrier medium that is guided within a pipe system

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

storing thermal energy in a solid-state storage device

Methodology Applied
Scientific EffectThermal energy storage: Thermal Energy Storage

Implementation Method 3

a gap or a sliding layer between these two elements. This makes it possible to prevent constraint that, due to different thermal loads and different coefficients of expansion of the solid-state storage and pipe register

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2286168B1Device for storing thermal energy
Publication Date: 2012.05.09 ED ZUBLIN AKTIENGESELLSCHAFT
  • EP2286168B1 patent drawingFigure 1
  • EP2286168B1 patent drawingFigure 2
  • EP2286168B1 patent drawingFigure 3~4

AI summary

The invention relates to a device and a system for storing thermal energy, for example large-scale solar thermal systems. The thermal energy is stored in a monolithic concrete block (2). To this end, the block has a piping system embedded therein for flowing a heat transfer fluid therethrough, said piping system permitting thermal energy to be added to and removed from the storage device. According to the invention, the piping system and the surrounding concrete block are mechanically decoupled. Preferably, this is done without significantly affecting the heat transfer between the concrete and the pipe (6) by way of a thin-walled graphite shell around the pipe.