Thermochemical Heat Storage Unit Phase Transition
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Solution Overview
Problem
Existing thermal heat storage units in solar thermal power plants are inefficient in decoupling electrical energy production from solar radiation, as they rely on direct storage methods that are not effective for short-term and medium-term interruptions, such as clouds and nighttime periods.
Innovation Solution
A thermochemical heat storage unit method that involves producing first steam, condensing it into water, pressurizing the water, and then evaporating it into higher-pressure second steam for storage, which is then used during discharging, reducing storage volume and improving energy efficiency by reabsorbing thermal energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If thermal energy is stored using conventional thermal heat storage units (concrete, salt, or high-pressure water), then the storage capacity is sufficient for short-term and medium-term interruptions, but the energy efficiency is low and the storage volume is large
Solution Approach 1:
The patent utilizes phase transitions of water (liquid-vapor) to store and release thermal energy. During charging, steam condenses to water releasing latent heat which is stored. During discharging, water evaporates back to steam releasing the stored thermal energy. This phase transition mechanism enables compact storage with high energy density, directly resolving the contradiction between energy efficiency and storage volume.
Solution Approach 2:
The system changes the pressure parameter of water/steam to control phase transitions and store thermal energy efficiently. By pressurizing condensed water and controlling evaporation at different pressure levels, the system achieves efficient thermal energy storage and release, reducing both storage volume and energy losses compared to conventional thermal storage units.
2Device complexity
If steam is directly stored without pressure increase, then the storage process is simple, but the storage volume is large and energy efficiency is low
Solution Approach 1:
The system implements pressure increase of condensed water as a key parameter change to enable compact steam storage. By pressurizing the water before evaporation, the resulting steam occupies significantly less volume, solving the storage volume problem while maintaining relatively simple process equipment.
3Duration of action of stationary object
If thermal energy is stored for medium-term interruptions (nighttime), then the decoupling of electrical energy production from solar radiation is achieved, but the energy losses are significant
Solution Approach 1:
The patent employs reversible phase transitions of water between liquid and vapor states to store thermal energy for extended periods. The latent heat stored during condensation is efficiently released during evaporation, minimizing energy losses over medium-term storage durations (nighttime periods), thereby achieving effective decoupling of electrical energy production from solar radiation availability.
4Reliability
If conventional thermal storage units are used, then the system can handle short-term interruptions (clouds), but the energy efficiency during charge and discharge is low
Solution Approach 1:
The system utilizes efficient phase transitions of water (condensation during charging, evaporation during discharging) to store and release thermal energy with minimal losses. This mechanism provides reliable handling of short-term interruptions (clouds) while maintaining high energy efficiency, directly addressing the contradiction between reliability and energy loss in conventional thermal storage units.
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 method enhances energy efficiency by reducing the energy required for pressure increase and provides a compact storage solution for high-temperature heat, allowing for efficient storage and retrieval of thermal energy, even during periods without solar radiation.
Implementation Method 1
the first steam (40), with an at least partial release of its thermal energy, is at least partially condensed into water (41) by means of the heat exchanger (4)
Implementation Method 2
the pressurized water (41) is returned to the heat exchanger (4) and, with an at least partial absorption of the thermal energy previously released, at least partially evaporated into second steam (42)
Implementation Method 3
the water (41) is pressurized
Data Source
AI summary
The present disclosure relates to thermochemical heat storage units. The teachings thereof may be embodied in systems and methods for operating, including charging and discharging, a thermochemical heat storage unit. For example, a method for operating a thermochemical heat storage unit may include: producing a first steam and feeding it to a heat exchanger; partially condensing the steam with release of its thermal energy, in the heat exchanger; subsequently pressurizing water condensed from the steam; feeding the pressurized water to the heat exchanger; evaporating the water into a second steam; and storing at least a portion of the second steam in a steam storage unit.