PCM Thermal Storage Condenser Separation
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Solution Overview
Problem
Thermal storage systems using Phase Change Materials (PCMs) face challenges such as low thermal conductivity, volume expansion issues, and evaporation problems due to high saturation vapor pressure, leading to heat loss and potential clogging of pipes and equipment.
Innovation Solution
A thermal energy storage device with a tank containing a two-phase solid-liquid PCM and a heat transfer fluid exchanger, featuring a gas headspace and a condenser as separation means to separate evaporated PCM from the gas overhead, preventing uncontrolled leakage and condensing the PCM to prevent damage and material loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If PCM is used for thermal energy storage, then energy density is improved, but PCM evaporation and loss occur due to high saturation vapor pressure
Solution Approach 1:
An inert gas (nitrogen or carbon dioxide) is introduced as an intermediary substance to displace oxygen and prevent PCM evaporation and oxidation. The gas creates a protective atmosphere in the headspace, reducing PCM loss while maintaining high energy density storage capability
Solution Approach 2:
The patent creates an inert atmosphere by filling the headspace with nitrogen or carbon dioxide gas. This inert environment prevents PCM molecules from escaping into the vapor phase and being lost, while allowing the system to maintain its high energy density through efficient thermal storage
2Reliability
If PCM volume expansion is accommodated by gas headspace, then reliability is improved, but PCM evaporation and leakage increase
Solution Approach 1:
The inert gas atmosphere in the headspace prevents PCM evaporation during volume expansion cycles. When PCM expands from solid to liquid phase, the inert gas provides a non-reactive environment that prevents molecular escape and leakage, maintaining system reliability
Solution Approach 2:
The inert gas acts as a mediator between the expanding PCM and the external environment, allowing volume changes while preventing harmful evaporation and leakage interactions with oxygen and moisture
3Power
If tube exchanger is used for heat transfer, then heat transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The tube exchanger serves multiple functions simultaneously: it provides the primary heat transfer interface between the heat transfer fluid and PCM, acts as a structural support element within the tank, and defines the geometric configuration for optimal thermal contact. This multi-functionality justifies the increased structural complexity by delivering superior heat transfer efficiency
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 effectively reduces PCM loss and prevents equipment damage by separating and recovering the PCM, maintaining system integrity and efficiency during thermal energy storage and retrieval processes.
Implementation Method 1
a condenser as separation means to separate evaporated PCM from the gas overhead, preventing uncontrolled leakage and condensing the PCM to prevent damage and material loss
Implementation Method 2
Latent storage uses Phase Change Materials (PCM) to store heat. Thermal storage is achieved using the enthalpy of change of state. It is the enthalpy of phase change, most often during the change of solid/liquid state, which is stored. This energy, which is absorbed during fusion and released during solidification, results from the establishment, or the rupture, of interatomic or intermolecular bonds.
Implementation Method 3
During charging, the heat transfer fluid reaches a temperature above the melting temperature of the PCM and transfers energy to it, which causes it to melt; during the discharge, the heat transfer fluid enters at a temperature lower than the melting temperature of the PCM and recovers the energy previously stored, which leads to the solidification of the PCM.
Data Source
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AI summary
The invention relates to a device for storing thermal energy comprising a vessel (1), at least one two-phase solid-liquid phase-change material (PCM) (2) contained in the vessel (1), and a thermal energy exchanger with a heat-transfer fluid comprising at least one tube (3) in which a heat-transfer fluid is capable of flowing, configured to carry and/or recover thermal energy to and/or from the PCM (2), the tube (3) being at least partially immersed in the PCM (2) and comprising a gaseous ceiling (4) of inert gas including one portion arranged in the vessel (1) above and in contact with the at least one PCM (2), characterised in that it comprises a separation means arranged in the gaseous ceiling (4) outside of an area of maximum occupation of the PCM (2) in the most expanded phase thereof for separating the two solid and liquid phases, the separation means being configured so as to separate from the gaseous ceiling (4) a fraction of the at least one solid-liquid PCM (2) which evaporates during the phase changes. The field of the invention relates to thermal storage systems (TSS) using phase-change materials (PCM). The invention relates, in particular, to the integration of a thermal storage system in concentrating solar power plants, for example for plants with direct steam generation, or even to the recovery of free heat from industries.