Thermostatic Fluid Distribution for Thermal Storage Stratification

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Solution Overview

Problem

Existing thermal energy storage devices face challenges in maintaining thermal stratification when dealing with variable temperature heat sources, leading to inefficient energy storage and retrieval, particularly in systems like solar panels where temperature fluctuations affect the distribution and withdrawal of heat transfer fluids.

Innovation Solution

A heat transfer fluid distribution system utilizing thermostatic elements that allow for precise injection and withdrawal of heat transfer fluid at the correct thermal stratum, minimizing thermal destratification and enabling operation with strong temperature gradients without the need for actuators or sensors, and allowing independent control of each thermal stratum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If hot heat transfer fluid is injected into the upper part of the storage device, then the injection system is simple, but thermal stratification is degraded and energy storage density is reduced

Engineering Contradiction:
Improveinjection system complexityVSAvoidenergy storage density
Core Design Contradiction:
Device complexityVSQuantity of substance

Solution Approach 1:

The storage device is divided into multiple thermal strata with different temperature zones. The injection system is segmented into multiple injection levels corresponding to different thermal strata, allowing hot fluid to be injected at the appropriate temperature level rather than always at the top, thus maintaining stratification while keeping the system relatively simple.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The injection system uses movable injection means that can dynamically adjust their position along the storage device height. This dynamic adjustment allows the injection level to adapt to varying hot fluid temperatures, ensuring optimal injection depth and maintaining thermal stratification without requiring a complex fixed multi-level system.

Inventive Principle:
Principle #15Dynamics

2Device complexity

If the injection level is fixed at the upper part, then the device complexity is low, but the system cannot adapt to variable temperature heat sources

Engineering Contradiction:
Improveinjection system complexityVSAvoidadaptability to variable temperature
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The injection means are made movable rather than fixed, allowing them to adjust their position along the storage device. This dynamic capability enables the system to adapt to variable temperature heat sources by injecting at the appropriate thermal stratum level, while avoiding the complexity of multiple fixed injection systems.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The injection system utilizes the temperature difference between the hot fluid and the storage device contents to automatically determine the appropriate injection level. The system self-adjusts by allowing the hot fluid to naturally rise or be injected at the level where it matches the thermal stratum temperature, eliminating the need for complex external control mechanisms.

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If movable injection means are used to adapt to variable temperatures, then adaptability is improved, but device complexity increases

Engineering Contradiction:
Improveadaptability to variable temperatureVSAvoidinjection system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The movable injection means are designed to automatically position themselves based on temperature gradients without requiring external actuators or sensors. The system uses natural convection and temperature-driven fluid dynamics to self-regulate the injection level, achieving adaptability while minimizing added complexity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention replaces complex mechanical actuation systems with thermal-driven natural convection mechanisms. Instead of using motors, sensors, and control systems to move injection points, the system relies on temperature differences to naturally position the injection flow at the correct thermal stratum, significantly reducing mechanical complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Ease of operation

If hot water is injected into the hot zone, then injection is simple, but thermal stratification is disturbed and high temperature energy is lost

Engineering Contradiction:
Improveinjection operation simplicityVSAvoidhigh temperature energy loss
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The storage device is segmented into distinct thermal strata, and the injection system is correspondingly segmented into multiple injection levels. This segmentation allows hot water to be injected at the appropriate temperature level rather than always at the top, preventing mixing with colder zones and preserving high-temperature energy while maintaining operational simplicity.

Inventive Principle:
Principle #1Segmentation

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 ensures high thermal energy storage density by accurately distributing heat transfer fluid during charging and discharging phases, preventing thermal stratification disturbance and optimizing energy recovery while reducing costs and complexity.

Implementation Method 1

each thermostatic system (3a, 3b, 3c, 3d, 3e and 3f) comprises a first thermostat (4a) in contact with the heat transfer fluid of the thermal stratum and a second thermostat (4b) in contact with the heat transfer fluid (F) to be distributed... each thermostat (4a, 4b) comprises an expansion material, able to expand bijectively depending on the temperature applied to the thermostat with which it is associated

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a stratified thermal storage tank comprising a heat transfer fluid for the storage of thermal energy... allowing the distribution of the heat transfer fluid (F) within a target thermal stratum of the thermal storage tank (51) of substantially equal temperature

Methodology Applied
Scientific EffectThermal stratification: Density Gradient

Data Source

PatentEP3392595B1Coolant distribution system for a thermal energy storage device including thermostatic systems
Publication Date: 2020.06.10 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP3392595B1 patent drawingFigure 1~2
  • EP3392595B1 patent drawingFigure 3A~4B
  • EP3392595B1 patent drawingFigure 5A~5I

AI summary

The main object of the invention is a heat transfer fluid (F) distribution system (1) for a thermal energy storage device (50) comprising a stratified thermal storage tank (51), characterized in that it comprises: a heat transfer fluid (F) distribution support (2); at least two thermostatic systems (3a-3f) located at thermal strata having different temperatures, each comprising first and second thermostats, respectively in contact with the heat transfer fluid of the thermal stratum where the thermostatic system (3a-3f) is located and in contact with the heat transfer fluid (F) to be distributed, and passively controlling at least one hydraulic system to allow the distribution of heat transfer fluid (F) within a target thermal stratum of the thermal storage tank (51) of temperature substantially equal to the temperature of the heat transfer fluid (F) intended to be distributed.