Thermal heat storage system

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Solution Overview

Problem

Molten-salt thermal energy storage systems face operational complexity and freezing risks due to the use of transfer fluids, which increase costs and reduce efficiency, especially in achieving high temperatures for dispatchable renewable energy storage.

Innovation Solution

A latent heat storage system employing vapor transport under evacuated or low-pressure conditions, using a single storage tank with a heat injection and recovery system, where vaporization and condensation of a volatile fluid like sodium (Na) occur, minimizing temperature deviation and eliminating the need for pumping and secondary tanks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If molten salt is used as transfer fluid pumped between storage tanks and heat exchanger, then thermal energy storage capacity is improved, but operational complexity increases and freezing risk occurs

Engineering Contradiction:
Improvethermal energy storage capacityVSAvoidoperational complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the molten salt transfer fluid system from the thermal energy storage design. By using direct solar heating of the storage medium and natural convection for heat transfer, the system removes the need for pumps, complex piping, and associated control systems that would be required to circulate molten salt, thereby reducing operational complexity while maintaining thermal energy storage capacity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system employs natural convection currents within the storage tank to achieve heat transfer without mechanical pumping. The density differences created by temperature gradients drive spontaneous fluid circulation, allowing the system to self-regulate heat distribution without external mechanical intervention, thus reducing operational complexity

Inventive Principle:
Principle #25Self-service

2Use of energy by moving object

If molten salt is used as transfer fluid in piping systems, then thermal energy transport is achieved, but freezing risk increases requiring heat wrapping or nighttime draining

Engineering Contradiction:
Improvethermal energy transportVSAvoidfreezing risk
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent eliminates external piping systems that would transport molten salt between separate storage tanks and heat exchangers. By integrating the heat exchange function directly within the storage tank and using the storage medium itself as the heat transfer agent through natural convection, the system removes the vulnerable piping infrastructure that would require freezing protection

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the storage tank and heat exchanger into a single integrated system. The heat exchange surfaces are positioned within the storage tank itself, allowing direct thermal interaction between the storage medium and the heat extraction system, thereby eliminating the need for separate piping infrastructure that would be susceptible to freezing

Inventive Principle:
Principle #5Merging (Combining)

3Quantity of substance

If double storage tank layout with hot and cold tanks is used, then acceptable stored energy density and heat exchanger efficiency are achieved, but device complexity and cost increase

Engineering Contradiction:
Improvestored energy densityVSAvoiddevice complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent combines the functions of hot and cold storage tanks into a single integrated storage system. By positioning heat exchange surfaces within the same tank and utilizing natural convection to create thermal stratification, the system achieves both hot and cold storage capabilities in one unit, reducing device complexity and cost while maintaining energy density

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single storage tank system performs multiple functions: it stores both hot and cold thermal energy, acts as the heat exchanger medium, and provides natural convection for heat transfer. This multi-functional design eliminates the need for separate dedicated hot and cold tanks, reducing overall system complexity while maintaining the required energy density

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Use of energy by moving object

If transfer fluid systems with pumps and pipes are used, then thermal energy transport is achieved, but operational complexity and cost increase

Engineering Contradiction:
Improvethermal energy transportVSAvoidoperational simplicity
Core Design Contradiction:
Use of energy by moving objectVSEase of operation

Solution Approach 1:

The system uses natural convection currents driven by temperature-induced density differences to achieve thermal energy transport within the storage tank. This self-driven flow mechanism eliminates the need for mechanical pumps and complex piping systems, greatly simplifying operation and reducing maintenance requirements while maintaining effective heat transport

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces the mechanical pumping system with a natural convection-based thermal circulation system. By utilizing buoyancy forces generated by temperature gradients, the system achieves fluid circulation and heat transport without mechanical intervention, thereby simplifying operation and reducing the need for mechanical components

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

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 approach provides efficient, dispatchable 24-hour power generation with reduced operational complexity, high heat transfer rates, and minimized freezing risks, enabling high-efficiency electricity generation and reducing environmental impact through reduced cooling requirements.

Implementation Method 1

A latent heat storage system employing vapor transport under evacuated or low-pressure conditions

Methodology Applied
Scientific EffectVapor transport: Evaporation

Implementation Method 2

employing vapor transport under evacuated or low-pressure conditions, similar to the principle of the heat pipe

Methodology Applied
Scientific EffectHeat pipe: Heat Pipe

Implementation Method 3

vaporization and condensation of a volatile fluid like sodium (Na) occur

Methodology Applied
Scientific EffectVaporization: Evaporation

Implementation Method 4

A latent heat storage system employing vapor transport

Methodology Applied
Scientific EffectLatent heat: Latent Heat

Implementation Method 5

vaporization and condensation of a volatile fluid like sodium (Na) occur

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3425319B1Thermal heat storage system
Publication Date: 2020.03.25 SUNLIGHT POWER
  • EP3425319B1 patent drawingFigure 1
  • EP3425319B1 patent drawingFigure 2~3
  • EP3425319B1 patent drawingFigure 4

AI summary

A thermal heat storage system is provided, including a storage tank, a heat injection system and a heat recovery system. The storage tank holds a material for thermal storage. The heat injection system is coupled to an intake on the storage tank. The heat recovery system is coupled to an output on the storage tank and also uses vapor under depressurized conditions for heat transfer.