Porous Interface Thermal Storage Tank Stratification

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Solution Overview

Problem

Current thermal energy storage systems face challenges in maintaining thermal stratification within storage devices, leading to inefficiencies in heat transfer and energy storage due to convective movements and mismatched injection/withdrawal temperatures, particularly during fluctuating demand periods.

Innovation Solution

A thermal energy storage device with a nested tank configuration and porous interfaces allows for direct injection and withdrawal of heat transfer fluid, utilizing differences in density to maintain stratification and minimize thermal destratification, employing an annular porous medium for efficient heat distribution and withdrawal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If heat transfer fluid is injected and withdrawn directly in conventional thermal storage systems, then heat transfer efficiency is improved, but thermal stratification is destroyed due to convective movements and jet effects

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidthermal stratification
Core Design Contradiction:
Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent employs porous distribution elements (diffusers) made of porous materials through which the heat transfer fluid is injected. The porous structure breaks up the fluid jet into numerous small streams, reducing the kinetic energy and velocity of the injected fluid. This prevents the formation of strong convective currents and jet effects that would otherwise destroy thermal stratification, while still allowing efficient heat transfer to occur through the distributed fluid injection throughout the storage tank.

Inventive Principle:
Principle #31Porous materials

2Productivity

If injection velocity is increased to improve charging power, then productivity is improved, but thermal destratification is caused due to increased jet effects and turbulence

Engineering Contradiction:
Improvecharging powerVSAvoidthermal stratification
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The porous distribution elements fragment the high-velocity injection into many low-velocity streams, allowing high charging power to be achieved without high local jet velocities that would cause turbulence and destratification.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The injection system is segmented into multiple distribution elements spaced throughout the tank, each injecting fluid at low velocity. This segmentation distributes the total charging power across many locations, achieving high overall productivity while maintaining local flow conditions that preserve thermal stratification.

Inventive Principle:
Principle #1Segmentation

3Stability of the object's composition

If distribution system complexity is increased to maintain thermal stratification, then thermal storage quality is improved, but device complexity increases

Engineering Contradiction:
Improvethermal stratificationVSAvoiddistribution system complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The use of porous distribution elements provides an elegant and relatively simple solution for maintaining thermal stratification. These porous diffusers can be integrated into existing tank structures and require no external control systems or complex mechanisms, achieving thermal storage quality improvement with minimal increase in device complexity.

Inventive Principle:
Principle #31Porous materials

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 enhances energy efficiency by maintaining thermal stratification during charging and discharging, increasing the Richardson number and reducing dimensionless permeability, thereby improving the flow rate and charging/discharging power while preventing thermal destratification.

Implementation Method 1

at least one porous interface (53) formed in a part of the wall of the first internal thermal storage tank contained in the second external heat transfer fluid distribution tank, fluid communication is thus achieved between the first internal thermal storage tank and the second external heat transfer fluid distribution tank via at least one porous interface

Methodology Applied
Scientific EffectPermeation: Permeation

Implementation Method 2

utilizing differences in density to maintain stratification and minimize thermal destratification

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentEP3435018B1Device for storing thermal energy having an internal tank and a coolant distribution system
Publication Date: 2021.08.18 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP3435018B1 patent drawingFigure 1~2
  • EP3435018B1 patent drawingFigure 3~4
  • EP3435018B1 patent drawingFigure 5~7

AI summary

The main object of the invention is a thermal energy storage device (50), characterized in that it comprises: a first internal stratified thermal storage tank (51), and a heat transfer fluid distribution system (10) comprising a second external heat transfer fluid distribution tank (52) in which the first tank (51) is contained at least in part and at least one porous interface (53) formed in a part of the wall of the first tank (51) contained in the second tank (52), a fluidic communication being thus achieved between the first tank (51) and the second tank (52) by means of said at least one porous interface (53) so as to allow the distribution of heat transfer fluid.