Fluidized Bed Heat Exchanger for High-Temperature HTF Generation
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Solution Overview
Problem
Existing thermal energy storage systems based on fluidized beds of solid particles face limitations in maintaining high temperature heat transfer fluid generation, as increasing the minimum particle temperature to achieve desired HTF temperatures significantly reduces thermal storage capacity and may exceed material limits for heat exchangers, making it impractical for high-temperature applications like supercritical CO2 turbines.
Innovation Solution
A device and method for thermal energy accumulation and transfer using a fluidized bed of solid particles, where energy is stored and transferred efficiently by controlling the temperature of the particles through a system involving a receiver, hot and cold tanks, and an external heat exchanger, allowing for continuous generation of high-temperature heat transfer fluid, with the ability to absorb thermal shocks and maintain a homogeneous temperature field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the minimum particle temperature is increased to achieve desired HTF temperatures, then the HTF temperature is improved, but the thermal storage capacity is significantly reduced
Solution Approach 1:
The system divides the particle bed into multiple temperature zones using selective heating and cooling regions. The receiver zone maintains higher temperatures for HTF generation, while other zones operate at lower temperatures for thermal storage, allowing simultaneous optimization of both HTF temperature and storage capacity.
Solution Approach 2:
Different regions of the fluidized bed are assigned different temperature profiles and functional characteristics. The receiver area maintains elevated temperatures for heat transfer fluid generation, while other areas operate at lower temperatures to maximize thermal storage capacity, creating local quality variations throughout the bed.
2Temperature
If the minimum particle temperature is increased to produce high-temperature HTF, then the HTF temperature is improved, but the heat exchanger material stress is increased
Solution Approach 1:
The fluidized bed particles serve as an intermediary thermal mass between the heat source and the heat exchanger. This intermediary layer absorbs and distributes thermal energy, allowing the heat exchanger to operate at moderate temperatures while the particles maintain the capability to generate high-temperature HTF when needed.
Solution Approach 2:
The system performs preliminary heating of particles to storage temperatures, then maintains these particles in a thermal reservoir. When HTF is needed, the pre-heated particles are transferred to the heat exchanger, allowing the exchanger to receive thermal energy without being continuously exposed to maximum temperature stresses.
3Quantity of substance
If the fluid bed maximum temperature is increased to recover thermal storage capacity, then the thermal storage capacity is improved, but the heat exchanger material limits are exceeded
Solution Approach 1:
The system dynamically adjusts temperature profiles in different zones of the fluidized bed based on operational requirements. When thermal storage capacity is needed, cooler zones are activated; when HTF generation is needed, the receiver zone is heated. This dynamic control allows the system to operate within material temperature limits while optimizing performance.
Solution Approach 2:
The system employs periodic cycling of temperature zones, alternating between charging phases (where particles are heated to storage temperatures) and discharging phases (where thermal energy is extracted). This periodic action allows the system to accumulate thermal energy without continuously exposing heat exchanger materials to maximum temperature stresses.
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 ensures efficient and flexible energy use, maintaining high performance and safety by allowing temperature control and extended heat transfer capabilities, suitable for applications like concentrated solar power and hybrid energy systems, while minimizing material stress and cost.
Implementation Method 1
thermal energy is stored in the bed in the form of sensible heat of solid particles
Implementation Method 2
This approximation is acceptable due to the high thermal diffusivity within the entire fluidized bed
Implementation Method 3
such energy can be released to a heat transfer fluid (HTF), such as steam, CO2, supercritical CO2 and the like, by means of said heat exchangers immersed in the bed
Implementation Method 4
heat exchangers are immersed into the particle bed
Implementation Method 5
thermal energy is stored in the bed in the form of sensible heat of solid particles
Implementation Method 6
the ability to absorb thermal shocks and maintain a homogeneous temperature field
Data Source
AI summary
An apparatus for the accumulation and transfer of thermal energy is disclosed including a thermal energy charging device having a bed of fluidizable solid particles received within a casing and acting as heat accumulation means by being exposed to a thermal energy source, heat exchange means operating in counter-current, configured for an exchange of thermal energy between a heated vector mass of the bed particles and an operative fluid, transport means configured for feeding the vector mass of the bed particles from the device to the heat exchange means and for returning part of the vector mass, downstream the heat exchange means, to the device, and a control unit associated with parameter detecting means arranged selected locations of the apparatus to control the flow of the vector mass within the apparatus.