Intermediate Storage Tank Heat Exchange for Round-Trip Efficiency
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Solution Overview
Problem
Thermoelectric energy storage systems face limitations in round-trip efficiency due to thermodynamic irreversibilities, particularly high heat transfer losses across large temperature differences, which result in increased capital costs and reduced efficiency.
Innovation Solution
A thermoelectric energy storage system with a transcritical cycle and a heat exchanger design that includes multiple storage tanks and an internal stream splitter to modify the flow rate of the thermal storage medium, minimizing temperature differences between the working fluid and the thermal storage medium during charging and discharging cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heat transfer occurs across large temperature differences in conventional heat exchangers, then heat transfer rate increases, but round-trip efficiency decreases due to thermodynamic irreversibilities
Solution Approach 1:
The heat exchanger is divided into multiple sections with intermediate storage tanks positioned between them. This segmentation allows the heat transfer process to occur in stages across smaller temperature differences, reducing thermodynamic irreversibilities while maintaining overall heat transfer effectiveness.
Solution Approach 2:
Intermediary storage tanks are introduced between heat exchanger sections to act as thermal buffers. These intermediaries enable heat transfer to proceed through multiple smaller temperature steps rather than one large temperature difference, thereby improving round-trip efficiency while still achieving the required heat transfer rate.
2Loss of energy
If multiple storage tanks and stream splitters are added to minimize temperature differences, then round-trip efficiency improves, but device complexity increases
Solution Approach 1:
The system is segmented into modular sections with intermediate storage tanks and stream splitters. This modular segmentation allows for systematic management of temperature gradients while keeping each section relatively simple, balancing complexity with efficiency improvements.
Solution Approach 2:
Stream splitters dynamically adjust flow distribution to optimize temperature differences during different operating conditions. This dynamic control allows the system to maintain high efficiency across varying loads without requiring overly complex fixed infrastructure.
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 enhances round-trip efficiency by minimizing temperature differences and optimizing heat transfer, thereby reducing energy losses and capital costs while maintaining high efficiency.
Implementation Method 1
heat transfer losses across large temperature differences
Implementation Method 2
heat exchanger design that includes multiple storage tanks and an internal stream splitter to modify the flow rate of the thermal storage medium
Implementation Method 3
Thermal energy can be stored in the form of sensible heat via a change in temperature or in the form of latent heat via a change of phase
Implementation Method 4
Thermal energy can be stored in the form of sensible heat via a change in temperature or in the form of latent heat via a change of phase
Implementation Method 5
a thermoelectric energy storage system with a transcritical cycle and a heat exchanger design
Data Source
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AI summary
A system and method for storing electric energy in the form of thermal energy is described. A thermoelectric energy storage system comprises a working fluid circuit for circulating a working fluid through a heat exchanger (16) and a thermal storage medium circuit for circulating a thermal storage medium, the thermal storage medium circuit having at least one hot storage tank (24), one intermediate temperature storage tank (22) and one cold storage tank (20) connected together via the heat exchanger (16). The flow rate of the thermal storage medium in the heat exchanger (16) is modified in order to minimize temperature difference between the working fluid and the thermal storage medium during charging and discharging cycles.