Modular PCM Tube Battery for Stable Thermal Discharge
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Solution Overview
Problem
Existing thermal energy storage systems lack modularity and compactness, making them inflexible for various heating and cooling applications, and often struggle to maintain a constant discharge rate and temperature due to reliance on surface area for heat transfer.
Innovation Solution
A compact and modular thermal energy battery design featuring densely packed, vertically arranged plastic tubes filled with phase-change materials (PCMs) that expand during freezing, allowing for expansion without bursting, and utilizing a heat transfer fluid with a freezing point below the PCM's to maintain a constant charge and discharge cycle, ensuring predictable thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If thermal energy storage systems are designed as monolithic integrated systems, then they provide sufficient heat transfer surface area, but they lack modularity and adaptability for different applications
Solution Approach 1:
The thermal energy storage system is segmented into multiple independent tubes, each containing phase-change material. These modular tubes can be individually arranged and configured to achieve the required heat transfer surface area while maintaining adaptability for different applications. The segmentation allows the system to be scaled and adapted without requiring complete system redesign.
Solution Approach 2:
The phase-change material tubes are nested within an outer container that holds the heat transfer fluid. This nested configuration maximizes the heat transfer surface area within a compact volume while maintaining modularity. The tubes are arranged vertically and densely packed, allowing efficient thermal energy storage and release capabilities.
2Quantity of substance
If phase-change material expands during freezing, then storage capacity increases, but tube integrity may be compromised causing bursting
Solution Approach 1:
The tube structure incorporates localized expansion accommodation features at specific positions to handle the phase-change material expansion during freezing. The top portion of each tube includes an unsealed section that allows controlled expansion of the phase-change material without compromising the overall tube integrity. This local quality adjustment resolves the conflict between maximizing storage capacity and maintaining structural strength.
3Productivity
If heat transfer relies on surface area contact, then heat exchange occurs, but discharge rate becomes variable and unpredictable
Solution Approach 1:
The system uses a liquid heat transfer fluid circulating through the outer container to exchange thermal energy with the phase-change material tubes. This hydraulic heat transfer mechanism provides more consistent and predictable heat exchange rates compared to surface-area-dependent conduction, as the fluid flow can be controlled and maintained at steady rates, ensuring stable discharge performance.
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 enables a constant rate of discharge and temperature output, allowing multiple batteries to be connected for scalable thermal energy storage banks, adaptable to various applications, and efficient energy transfer, enhancing energy efficiency and flexibility.
Implementation Method 1
a phase-change material that changes from solid to liquid and vice-versa
Implementation Method 2
Energy is stored when the PCM transitions from liquid to solid form and is released when the PCM transitions back from solid to liquid form
Implementation Method 3
The tubes are arranged vertically and span most of the height of the tank. In an embodiment, the tubes are sealed and submersed in a heat transfer fluid (HTF) contained within the walls of the well-insulated tank
Implementation Method 4
Since PCMs will expand during freezing, the tubes must allow for this expansion to occur without bursting
Data Source
AI summary
This invention provides a thermal energy battery having an insulated tank containing a multitude of densely packed plastic tubes filled with a phase-change material (PCM, such as ice) that changes from solid to liquid and vice-versa. Energy is stored when the PCM transitions from liquid to solid form, and released when the PCM transitions back from solid to liquid form. The tubes are arranged vertically, span the height of a well-insulated tank, and are immersed in heat transfer fluid (HTF) contained within the tank. The HTF is an aqueous solution with a freezing point temperature below the freezing point temperature of the chosen PCM. The HTF remains in liquid form at all times during the operation of the battery. Diffusers located allow the HTF to be extracted uniformly from the tank, pumped and cooled by a liquid chiller situated outside the tank and then and inserted back into the tank.