PCM Thermal Storage SOC Estimation Using Surface and Outlet Temperature
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Solution Overview
Problem
Determining the state-of-charge (SOC) of phase-change-material-based thermal energy storage devices (PCM-TES) is challenging due to the latent heat of fusion being released at a single melting temperature, requiring sophisticated methods that are often computationally expensive or invasive.
Innovation Solution
A method involving surface and outlet temperature-based measurements using minimal instrumentation (two temperature sensors) to calculate SOC, combining these methods based on the device's operating condition, allowing for non-invasive, accurate, and fast SOC assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If enthalpy-based methods with power sensors (flow sensors, temperature sensors at inlet/outlet) are used to determine SOC, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential measurement elements needed for SOC determination. Instead of using comprehensive power sensors with flow sensors and multiple temperature sensors, the invention uses only outlet temperature measurements combined with a simplified thermal model, removing unnecessary components while maintaining adequate measurement precision
Solution Approach 2:
The patent replaces complex, expensive enthalpy analysis systems with a simpler, more economical approach using basic temperature sensors and computational algorithms. The simplified method achieves comparable SOC determination accuracy without requiring sophisticated sensor arrays or complex calculation engines
2Device complexity
If volume-based methods with pressure sensors are used to determine SOC, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent replaces mechanical volume-based measurement (pressure sensors detecting PCM expansion) with a thermal field-based approach. By measuring outlet temperature and using thermal energy balance equations, the system determines SOC without mechanical sensors, achieving both simplicity and precision
Solution Approach 2:
The patent changes the measurement parameter from mechanical (pressure/volume) to thermal (temperature). This parameter transformation allows SOC determination through temperature-based thermal models, combining the simplicity of single-parameter measurement with the precision of thermodynamic calculations
3Measurement precision
If temperature-based methods with multiple sensors are used to determine SOC, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the critical temperature measurement point (outlet temperature) needed for SOC determination. Instead of placing multiple temperature sensors throughout the PCM tank, the invention uses a single outlet temperature measurement combined with thermal model calculations to achieve accurate SOC assessment
Solution Approach 2:
The patent introduces a thermal model as an intermediary between the simple outlet temperature measurement and the SOC determination. This mathematical model acts as a mediator that transforms the single temperature reading into accurate SOC information, eliminating the need for multiple physical sensors
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
Enables precise and cost-effective SOC determination for PCM-TES under various conditions, including high charging and discharging rates, with reduced computational complexity and minimal system disruption.
Implementation Method 1
They exploit the latent heat of fusion at a specific melting temperature
Implementation Method 2
phase change material for storing thermal energy
Implementation Method 3
measuring at least one surface temperature at the storage module
Implementation Method 4
The PCM-TES may be charged with a heat transfer fluid, HTF
Data Source
Figure 1~2
Figure 3~5
AI summary
The disclosure relates to a method for determining a state-of-charge, SOC, of a phase-change-material-based thermal energy storage device, PCM-TES (1), with a storage module (9) that comprises a phase change material (3) for storing thermal energy, comprising a sensor for measuring at least one surface temperature (Ts) at the storage module (9) of the PCM-TES (1) as a first temperature; a determining an operating condition of the PCM-TES (1); and if the operating condition is determined to be an active condition where a heat transfer fluid is flowing through an outlet (11) of the PCM-TES (1): a measuring a liquid temperature (Tl) at the outlet (11) of the PCM-TES (1) as a second temperature; a calculating at least one first SOC-value SOCsurface with a first chosen function of the first temperature; a calculating a second SOC-value SOCoutlet with a second chosen function of the second temperature; a determining the SOC of the PCM-TES SOCtotal with a third chosen function of the at least one calculated first SOC-value SOCsurface and of the calculated second SOC-value SOCoutlet in order to determine the SOC of the PCM-TES (1) in a simple and reliable way.