Absorption Carnot Battery Heat Loss Reduction
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Solution Overview
Problem
Current Carnot battery technologies face challenges with low round-trip efficiency, low energy storage density, and high self-discharging rates due to complex configurations and high heat loss, limiting their suitability for long-term energy storage.
Innovation Solution
A novel absorption-desorption-based Carnot battery system with a four-process cycle, utilizing a solution repository and refrigerant tank with an external vapor-compression heat pump loop, flow regulating devices, and an internal heat loop, achieving high efficiency and flexibility through specific operating modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If current Carnot battery technologies (Brayton PTES, Rankine PTES, LAES) are used, then energy storage capability is achieved, but round-trip efficiency is low and heat loss is high
Solution Approach 1:
The patent merges the heat pump cycle with the absorption-desorption cycle into an integrated system. The heat pump condenser serves as the absorber for refrigerant vapor, and the evaporator serves as the desorber, eliminating separate heat exchangers and reducing heat loss through integrated thermal energy recovery.
Solution Approach 2:
The system recovers thermal energy that would otherwise be discarded. The heat pump recovers heat from the environment or low-temperature sources during charging, and the absorption-desorption process recovers thermal energy during refrigerant condensation and evaporation, converting it into useful work through the expander.
2Reliability
If complex configurations with multiple sub-cycles are used, then energy storage is achieved, but device complexity increases and heat loss increases
Solution Approach 1:
Each component performs multiple functions: the heat pump compressor both compresses refrigerant vapor and drives the absorption-desorption process; the condenser both condenses refrigerant and absorbs heat; the evaporator both evaporates refrigerant and releases heat for power generation. This multi-functionality reduces the number of separate components needed.
Solution Approach 2:
The system divides the energy storage process into four distinct operational modes (charging, discharging, heat pumping, and cooling/heating provision) that can be independently controlled and optimized, allowing complex functionality to be achieved through sequential operation of integrated components rather than simultaneous complex configurations.
3Ease of manufacture
If temperature difference-based energy storage is used, then cost reduction is achieved, but self-discharging rate increases
Solution Approach 1:
The system utilizes phase transitions of the refrigerant (vaporization and condensation) as the primary energy storage mechanism rather than relying solely on temperature differences. The refrigerant absorbs heat during evaporation and releases heat during condensation, providing stable energy storage with minimal self-discharge because the phase change state is thermodynamically stable.
Solution Approach 2:
The system changes the thermodynamic parameters of the refrigerant between phase states (liquid-vapor transitions) to store and release energy. By maintaining the refrigerant in stable phase states within the closed loop system, self-discharging is minimized while still achieving cost-effective energy storage through the use of common refrigerants and absorbents.
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 system achieves a round-trip efficiency of at least 30%, energy storage density of 7.0 kWh/m3, and a self-discharging rate of less than 1% after 80 days, enhancing energy storage capabilities and reducing heat loss.
Implementation Method 1
a solution repository including at least one solution tank for thermochemical energy storage, the solution being reversibly capable storing and releasing refrigerant
Implementation Method 2
an absorption-desorption-based Carnot battery system
Implementation Method 3
an expander and a compressor for heat-power and power-heat energy conversion respectively
Implementation Method 4
During the charging process, the ambient air is compressed and cooled into liquid air, while in the discharging process, the stored liquid air is evaporated with the heating of stored or external heat
Implementation Method 5
an internal heat loop between the solution tank and the refrigerant tank
Data Source
AI summary
The present invention provides an absorption-desorption based Carnot battery designed to achieve a high-efficiency, large-density, and low-loss conversion battery system for power-heat-power purpose. Based on the rational operating strategies, the current Carnot battery system design demonstrates outstanding energy storage density and round-trip efficiency, while the self-discharging loss is minimal even after prolonged standby time. The battery system of the present invention also enables further designs with flexibility in adopting different operating modes for versatile functions to provide electricity, heating, and cooling.