Latent Heat Store Charge Level Determination
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Solution Overview
Problem
Current methods for determining the charge rate of latent heat storage systems are inefficient and unreliable, particularly due to the difficulty in measuring the volume of phase change material in liquid form without causing thermal resistance and requiring numerous sensors, which complicates maintenance and increases costs.
Innovation Solution
A system and method using a measuring fluid with a lower density than the phase change material, allowing for the determination of the charge rate by measuring the height of the fluid in the tank at different states, which simplifies the calculation of the charge rate without the need for extensive sensor networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are placed at different heights to measure liquid/solid front position, then measurement precision of charge rate is improved, but device complexity and maintenance difficulty increase due to numerous sensors
Solution Approach 1:
The invention extracts the measurement function from multiple sensors into a single sensor that measures the free surface height of the measuring fluid. This single measurement point provides sufficient information to determine the charge rate, eliminating the need for a complex network of sensors at different heights while maintaining measurement precision.
Solution Approach 2:
The invention introduces a measuring fluid as an intermediary substance between the heat exchanger and the solid phase change material. This measuring fluid acts as a mediator that translates the charge state into a measurable free surface height, enabling accurate charge rate determination with minimal sensors.
2Power
If solid phase change material adheres to heat exchange surfaces, then heat transfer efficiency is improved during charging, but thermal resistance increases during discharging due to solid layer formation
Solution Approach 1:
The measuring fluid serves as an intermediary layer between the heat exchanger tubes and the solid phase change material. During discharging, this fluid layer prevents direct contact between the solid PCM and the heat exchange surfaces, reducing thermal resistance caused by solid adhesion while allowing efficient heat transfer to continue through the fluid medium.
3Volume of stationary object
If tank headspace is minimized to avoid oversizing, then volume efficiency is improved, but pressure variation measurement reliability deteriorates for charge level determination
Solution Approach 1:
The measuring fluid acts as an intermediary that decouples the charge level measurement from pressure variations in the headspace. By measuring the free surface height of the measuring fluid instead of relying on headspace pressure, the system achieves reliable charge level determination without requiring a large headspace volume.
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 allows for accurate and reliable determination of the charge rate, reducing thermal losses and maintenance complexities while maintaining the system's thermal efficiency and cost-effectiveness.
Implementation Method 1
a measuring fluid (4) intended to be poured into the tank (1) of said storage means, characterized in that it is a fluid having a lower density than the phase change material
Implementation Method 2
a phase-change material whose phase change is accompanied by a volumetric variation
Implementation Method 3
the transition from solid to liquid is accompanied by an increase in volume
Data Source
Figure 1~2
AI summary
The invention concerns a system for determining the charge level of a means for storing latent heat energy, said storage means comprising a reservoir partially filled with a phase change material of which the phase change is accompanied by a volume variation with a heat exchanger embedded in said material, said storage means being in a completely discharged state when the phase change material is substantially totally in a first state and in a completely charged state when the phase change material is substantially totally in a second state, characterised in that the system comprises: - a measurement fluid (4) intended to be poured into the reservoir (1) of the storage means, - means (5) for measuring the height of the measurement fluid in the reservoir, and - means for calculating the charge level of the storage means at a determined time in the operation of same, depending on the difference between the height of the fluid present in the reservoir when the storage means is completely discharged and the height of the liquid at said determined time.