Thermal Storage System Crystallization Control via Solvent Agitation
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Solution Overview
Problem
Phase change materials (MCPs) used in thermal storage systems, such as polyols and alcoholic sugars, face challenges with slow crystallization and surfusion, which hinder their implementation in large-scale heat storage applications due to difficulties in controlling crystallization during the discharge phase.
Innovation Solution
A thermal storage system design incorporating a solvent circulation system with a crystallization control device that injects a diphasic, insoluble solvent into the tank, generating agitation and nucleation sites to accelerate crystallization, and an external heat exchanger for efficient thermal energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyols or alcoholic sugars are used as MCPs to achieve good enthalpy of state change and environmental compatibility, then energy density and eco-friendliness are improved, but crystallization control becomes difficult due to strong surfusion propensity
Solution Approach 1:
The patent introduces an intermediary substance (nucleating agent or gas bubbles) that mediates between the supercooled liquid MCP and the solid crystal structure. This intermediary provides nucleation sites that facilitate controlled crystallization, solving the problem of difficult crystallization control while maintaining the use of polyols or alcoholic sugars as MCPs.
2Adaptability or versatility
If surfusion capacity is increased to maintain liquid state below crystallization temperature, then operational flexibility is improved, but discharge phase control deteriorates due to difficulty in triggering crystallization
Solution Approach 1:
The patent applies preliminary action by pre-introducing nucleation sites (intermediary substance or gas bubbles) into the system before the discharge phase begins. This preliminary preparation ensures that when crystallization needs to be triggered, the process starts immediately and reliably at the predetermined nucleation sites, rather than waiting for spontaneous nucleation which may be delayed due to surfusion.
3Productivity
If crystallization speed is increased to improve discharge efficiency, then energy release rate is improved, but surfusion management becomes more difficult
Solution Approach 1:
The intermediary substance provides abundant nucleation sites that dramatically increase crystallization speed by providing numerous starting points for crystal growth throughout the MCP volume. This mediator approach achieves high productivity without increasing device complexity, as the nucleating agent works passively to accelerate crystallization without requiring complex control mechanisms.
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 effectively accelerates the crystallization rate of MCPs, improves the efficiency of thermal energy storage and discharge, and reduces the risk of surfusion, enhancing the performance and scalability of thermal storage systems.
Implementation Method 1
injecting a diphasic, liquid / gas solvent... The heating of the solvent causes its boiling generating a bubbling of the solvent in the MCP thus triggering the crystallization of the MCP
Implementation Method 2
The heating of the solvent causes its boiling generating a bubbling of the solvent in the MCP
Implementation Method 3
an external heat exchanger for efficient thermal energy transfer
Implementation Method 4
The heat storage exploiting the latent heat of phase change materials (MCP)
Implementation Method 5
generating agitation and nucleation sites to accelerate crystallization
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a Thermal Storage System (TSS) using a Phase Change Material (PCM) (2) comprising a tank (1) for containing a PCM (2), a circulation system for circulating a solvent in the tank (1) in direct contact with the PCM (2), characterized in that it includes a device for controlling the crystallization of the PCM (2), and an external heat exchanger (9) for transferring thermal energy between the solvent and a heat transfer fluid from an external heat transfer fluid circulation network (20, 21). All TSSs whose PCMs have issues with supercooling and slow crystallization rates are likely to be relevant to the invention. The present invention will find application in urban, rural, or industrial heating and/or cooling networks, as well as in solar energy storage.The invention may also find applications in housing, off-grid thermal transport (trucks, boats, etc.) and thermal management of embedded systems.