Thermal Energy Storage Thermocline Partial Extraction
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Solution Overview
Problem
Thermocline degradation in thermal energy storage systems reduces efficiency and increases costs, as existing methods either keep the thermocline inside the container, leading to flattened temperature gradients, or push it out, causing thermal loss and inefficiency, with no consensus on optimizing energy storage systems considering both efficiency and cost effectively.
Innovation Solution
A method that partially extracts the thermocline from the TES system by controlling the temperature gradient within a specific interval (Tmin+0.25ΔT to Tmin+0.65ΔT) to maintain a steep gradient while minimizing thermal loss, synchronized with low electricity prices for optimal profitability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the thermocline is kept inside the TES container, then the temperature gradient is maintained, but the gradient flattens over time leading to thermocline degradation
Solution Approach 1:
The patent extracts the thermocline from the TES container by heating the TES medium until the temperature at the end of the container exceeds the minimum temperature in the container. This partial extraction prevents the thermocline from degrading within the container while maintaining system efficiency by avoiding complete extraction that would cause thermal losses.
2Reliability
If the thermocline is pushed out of the TES container, then thermocline degradation is reduced, but thermal energy is lost
Solution Approach 1:
The patent applies partial action by heating the TES medium only until the temperature at the end of the container exceeds the minimum temperature, rather than continuing to heat until complete thermocline extraction occurs. This partial extraction approach maintains system efficiency while minimizing thermal energy losses associated with complete thermocline removal.
3Stability of the object's composition
If charging continues until the entire TES medium reaches maximum temperature, then the thermocline is completely extracted, but system efficiency decreases
Solution Approach 1:
The patent uses feedback control by monitoring the temperature at the end of the TES container and comparing it to the minimum temperature in the container. Charging is stopped when this temperature exceeds the minimum temperature, providing a feedback-based stopping criterion that prevents over-heating and maintains optimal system efficiency while achieving sufficient thermocline extraction.
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 balances thermocline control and cost considerations, maintaining a steep temperature gradient while reducing thermal losses and optimizing energy storage efficiency and profitability by adjusting the thermocline control temperature based on electricity prices, thereby enhancing the overall performance of the thermal energy storage system.
Implementation Method 1
thermal energy is transferred from the working fluid to the first TES medium by flow of the working fluid from the upper end to the first TES medium
Implementation Method 2
a compressor configured for raising the temperature of the gas during a charging period by compressing the gas
Data Source
AI summary
A method of operating an energy storage system (100), the system (100) comprising a thermodynamic cycle including a first thermal energy storage container (5) and an energy converter (1, 2, 3) for converting between electrical energy and thermal energy of the working fluid in the thermodynamic fluid cycle. For controlling the thermocline in the system without large thermal energy loss, it is pushed only partially out of the first thermal energy storage container (5).