Thermochemical Storage Pressure Control
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Solution Overview
Problem
Current thermal energy storage systems using thermochemical materials (TCMs) face challenges with energy density, temperature output, and system/material demands, particularly in conventional closed systems requiring high vacuum and large heat exchanger materials, and open systems limited by low output temperatures due to heat capacity constraints.
Innovation Solution
A closed cycle thermal energy storage system using a TCM reactor separated from the heat exchanger, with forced convection of an air/water mixture and adjustable pressure control between reduced and overpressure, allowing for tuned temperature differences and reduced heat losses, avoiding high vacuum and atmospheric pressure constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional closed systems operate at high vacuum to maintain water vapor pressure equilibrium, then the thermochemical reaction can proceed, but the system size increases and energy density decreases
Solution Approach 1:
The patent changes the pressure parameter from high vacuum (conventional closed systems) to controlled reduced pressure (1-100 mbar), allowing the system to maintain thermochemical reaction equilibrium while significantly reducing system size and improving energy density
Solution Approach 2:
The system dynamically adjusts pressure between charging (reduced pressure to facilitate dehydration) and discharging (controlled pressure for hydration), optimizing reaction equilibrium at different operational phases rather than maintaining static vacuum conditions
2Loss of energy
If conventional closed systems use large amounts of heat exchanger material to exchange heat with TCM, then heat transfer efficiency improves, but system cost and environmental footprint increase
Solution Approach 1:
The patent extracts the heat exchanger from direct contact with the TCM, separating the heat exchange function from the reaction zone. This reduces the amount of heat exchanger material needed while maintaining efficiency through the controlled pressure environment that enhances heat transfer
3Ease of operation
If open systems operate at atmospheric pressure with large heat capacity, then system simplicity improves, but output temperature decreases
Solution Approach 1:
The patent changes the pressure parameter from atmospheric pressure (open systems) to controlled reduced pressure (1-100 mbar), enabling the system to maintain simplicity while achieving higher output temperatures by reducing the heat capacity of the gas phase and improving heat transfer efficiency
4Reliability
If conventional closed systems maintain high vacuum levels, then water vapor pressure equilibrium is maintained, but non-condensable gases accumulate and stop the reaction
Solution Approach 1:
The patent changes from maintaining high vacuum (conventional closed systems) to controlled reduced pressure (1-100 mbar), which prevents non-condensable gas accumulation from stopping the reaction while still maintaining water vapor pressure equilibrium for the thermochemical reaction
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 design enhances energy density, temperature control, and system efficiency by actively managing pressure and convection, reducing the impact of non-condensable gases and minimizing heat exchanger material needs, while maintaining high output temperatures and energy storage capacity.
Implementation Method 1
an adjustable pressure control system for actively controlling the pressure of the air/water mixture to produce a desired temperature difference across the TCM reactor
Implementation Method 2
a fan for circulating air in the system
Implementation Method 3
an evaporator/condenser for controlling the vapor pressure of water in the air/water mixture
Implementation Method 4
a TCM reactor containing a TCM... The TCM discharging 112 involves the release of heat 114 by the TCM 100 and the sorption of water 116
Implementation Method 5
a heat exchanger for transferring heat from the air/water mixture
Data Source
AI summary
A closed-cycle thermal energy storage system includes a thermochemical reactor [400] containing a solid thermochemical material, a heat exchanger [402], a fan [406] for creating forced convection of an air/water mixture circulating around the closed cycle, an evaporator/condenser [408], and a pressure control system that includes a pressure sensor [422], a controller [424], and a pump [404]. The pressure control system actively controls the pressure of the air/water mixture to produce a desired temperature difference across the thermochemical reactor [400]. The adjustable pressure control system controls the pressure of the air/water mixture to a first pressure (e.g., between 10 mbar and 1 bar) during a hydration phase and a second pressure (e.g., between 1 bar and 10 bar) during a dehydration phase.