LCST Heat Storage Tank Layout Without Evaporation Condensers
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Solution Overview
Problem
Existing heat storage apparatuses, such as those described in Japanese Patent Applications JP 2014-181879 A and JP 10-325617 A, require evaporation condensers or fractionators to return the state of water or mixed solutions to a heat-releasable state, resulting in large apparatus sizes due to the need for evaporation and condensation or fractional distillation processes.
Innovation Solution
A heat storage apparatus comprising a first tank, a second tank positioned above the first tank, and an on-off valve connecting them, using a heat storage solution that separates into a first liquid and a second liquid at a lower critical solution temperature, allowing for heat absorption and release without the need for evaporation condensers or fractionators, with the first liquid having a higher density than the second liquid, enabling heat storage and release by controlling the valve operation based on temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If evaporation condenser or fractionator is used to return water or mixed solution to heat-releasable state, then heat storage and release can be achieved, but apparatus size becomes large
Solution Approach 1:
The invention changes the physical-chemical parameters of the heat storage solution by selecting a system with lower critical solution temperature (LCST) characteristics. This allows the solution to undergo liquid-liquid phase separation at specific temperature ranges, enabling heat storage and release without requiring evaporation-condensation equipment. The parameter change from using water or mixed solutions to using an LCST-type heat storage solution resolves the contradiction between heat storage capability and apparatus size.
Solution Approach 2:
The invention utilizes liquid-liquid phase separation and mixing transitions instead of vapor-phase transitions. When the heat storage solution is heated above its LCST, it separates into two immiscible liquid phases, storing heat. When cooled below LCST, the phases mix together, releasing heat. This phase transition mechanism eliminates the need for evaporation condensers and fractionators, significantly reducing apparatus size while maintaining effective heat storage and release.
2Reliability
If evaporation and condensation process is used, then heat-releasable state can be restored, but device complexity increases
Solution Approach 1:
By changing the thermal parameters of the heat storage medium to one with LCST characteristics, the invention simplifies the device structure. The heat release capability is maintained through temperature-controlled phase separation and mixing, eliminating complex evaporation-condensation equipment and reducing overall device complexity.
Solution Approach 2:
The invention replaces complex vapor-phase evaporation-condensation processes with simpler liquid-liquid phase separation and mixing. The phase transition occurs directly in the liquid state at the LCST, requiring only temperature control rather than sophisticated evaporation condensers and fractionators, thus reducing device complexity while preserving heat release capability.
3Reliability
If fractional distillation is used to return mixed solution to heat-releasable state, then heat storage function is maintained, but apparatus size and complexity increase
Solution Approach 1:
The invention changes the fundamental parameters of the heat storage system by using an LCST-type solution that undergoes liquid-liquid phase separation. This parameter change eliminates the need for fractional distillation equipment, maintaining heat storage function through simpler temperature-controlled phase transitions and significantly reducing apparatus structure complexity.
Solution Approach 2:
The invention utilizes liquid-liquid phase separation at the lower critical solution temperature instead of vapor-phase fractional distillation. The heat storage function is maintained through the reversible phase separation and mixing process, which occurs directly in the liquid state and requires no complex distillation apparatus, thereby reducing device complexity while preserving thermal energy storage capability.
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 configuration eliminates the need for evaporation condensers or fractionators, reducing apparatus size while maintaining effective heat storage and release capabilities, as demonstrated by the separation and mixing of specific liquid pairs like tetra-n-butylphosphonium trifluoromethanesulfonyl leucine aqueous solution and water, which absorb and release heat efficiently.
Implementation Method 1
a heat storage solution which has a characteristic of absorbing heat and separating into a first liquid and a second liquid having a lower density than the first liquid at a lower critical solution temperature or higher
Implementation Method 2
the first liquid and the second liquid have a characteristic of releasing heat and mixing with each other at a temperature lower than the lower critical solution temperature
Implementation Method 3
a heat storage apparatus in which an evaporation condenser or an evaporation fractionator for returning the state of water or a mixed solution to a heat-releasable state is not necessary
Data Source
AI summary
A heat storage apparatus includes: a first tank; a second tank that is provided above the first tank; an on-off valve; and a heat storage solution that is accommodated in the first tank and the second tank. The heat storage solution has a characteristic of absorbing heat and separating into a first liquid and a second liquid having a lower density than the first liquid at a lower critical solution temperature or higher, the first liquid and the second liquid have a characteristic of releasing heat and mixing with each other at a temperature lower than the lower critical solution temperature, and when the heat storage solution separates into the first liquid and the second liquid, the first liquid is accommodated in the first tank and the second liquid is accommodated in the second tank.