System and method for thermal energy storage and transfer based upon a bed of fluidized particles
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Solution Overview
Problem
Thermal energy storage systems based on fluidized beds of solid particles face limitations in energy charging and discharging phases, as the heat transfer efficiency decreases over time, leading to incomplete heat extraction and storage, particularly when dealing with high-temperature heat transfer fluids like supercritical CO2, which requires operating at extreme temperatures that can be costly and impractical due to material limitations.
Innovation Solution
A system comprising multiple fluidized particle beds arranged in series, allowing the heat transfer fluid to flow through the compartments in opposite directions during charging and discharging phases, enabling each compartment to operate at different temperature ranges, thereby maintaining a temperature gradient that enhances heat transfer and storage capacity without increasing the mass of solid particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fluidized bed is used for thermal energy storage, then the system structure is simple, but the heat transfer efficiency decreases over time and latent heat cannot be recovered
Solution Approach 1:
The single fluidized bed is divided into multiple fluidized beds arranged in series, with each bed serving a specific temperature zone. This segmentation allows the system to maintain temperature gradients and sustain heat transfer efficiency throughout the charging and discharging cycles, preventing the efficiency degradation that occurs in single-bed systems.
Solution Approach 2:
The patent introduces a temporal dimension to the heat transfer process by implementing alternating charging and discharging cycles across different beds. While one bed is charging, another is discharging, creating a continuous and efficient thermal energy storage system that overcomes the time-dependent efficiency loss in conventional single-bed systems.
2Ease of operation
If the entire fluid bed is operated isothermally, then the system operation is simple, but the thermal energy storage capacity is limited
Solution Approach 1:
Different regions of the multi-bed system operate at different temperatures, with each fluidized bed maintaining a specific temperature range suited to its position in the series. This local temperature differentiation maximizes the thermal energy storage capacity by utilizing the full temperature potential of the heat transfer fluid while keeping each individual bed's operation relatively simple.
Solution Approach 2:
The system exploits changes in the heat transfer fluid's physical parameters, particularly phase changes (such as condensation and evaporation), to dramatically increase storage capacity. By allowing the HTF to undergo phase transitions as it passes through the series of beds, the system captures both sensible and latent heat, multiplying the energy storage capacity without proportionally increasing system complexity.
3Power
If high temperature materials are used to handle supercritical CO2, then the heat transfer capability is improved, but the system cost increases due to material limitations
Solution Approach 1:
The system segments the high-temperature heat transfer process across multiple beds, allowing each bed to operate at optimized temperature levels. This reduces the requirement for expensive high-temperature materials throughout the entire system, as only specific beds nearest to the heat source require such materials, while downstream beds can use more economical materials.
Solution Approach 2:
The multi-bed fluidized bed system acts as an intermediary between the supercritical CO2 heat source and the thermal energy storage medium. This intermediate system gradually transfers heat through multiple stages, reducing thermal stresses and allowing the use of more cost-effective materials in the storage beds while still achieving high overall heat transfer capability.
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 configuration allows for a higher amount of thermal energy to be transferred and stored, enabling the recovery of latent heat and maintaining efficiency in heat conversion processes, such as generating high-temperature steam, while avoiding the need for extensive material upgrades or increased module sizes.
Implementation Method 1
heat exchangers are generally immersed into the fluidized bed, so that the thermal energy storage and transfer functions can be integrated into a same device
Implementation Method 2
the heat transfer fluid (HTF) to cross said modules in serial thermal sequence to charge thermal energy therein
Implementation Method 3
heat can be released from it to a heat transfer fluid (HTF), such as steam, CO2, supercritical CO2, or other, by means of heat exchangers immersed in the fluidised bed
Implementation Method 4
the entire fluid bed—due to its high thermal diffusivity—can be assumed to be isothermal, i.e. equated to a mass wherein all particles have the same temperature
Implementation Method 5
it is higher at the beginning of the charging phase (left vertical arrow in the diagram) and smaller at the end (right vertical arrow). As a consequence, the heat transfer from high temperature steam to the bed particles becomes smaller and smaller during the charging time. This fact constitutes a limit in the operation and performance of the thermal energy storage system, since the latter does not extract and store the entire potential heat content of the steam. In some circumstances, for example, the arrangement considered cannot be able to recover the latent heat of the steam
Data Source
AI summary
A heat storage and transfer method, having: providing a plurality of heat storage and transfer modules, arranged thermally in series, each module of the plurality having a bed of fluidizable solid particles as a heat storage and transfer means; adducting a flow of a heat transfer fluid (HTF) to cross the modules in serial thermal sequence; fluidizing each of the beds of fluidizable solid particles so as to foster heat exchange between the bed particles with said heat transfer fluid, the arrangement being such that the heat transfer fluid can cross the modules in sequence according to opposite directions, to transfer or extract thermal energy, respectively, from the beds of particles.