Halogen-based thermo-electrochemical converter
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Solution Overview
Problem
Existing thermo-electrochemical converters, such as AMTEC and JTEC, suffer from inefficiencies due to entropy loss, reliability issues, and limited utility, particularly at high temperatures, and require large membrane electrode assembly surface areas for high current levels, making them difficult to manufacture.
Innovation Solution
A thermo-electrochemical converter using halogen-based working fluids, such as bromine or iodine, operates on a closed-loop Rankine cycle with membrane electrode assemblies (MEAs) to maintain a constant pressure ratio, converting thermal energy into electrical energy efficiently by evaporating and condensing the working fluid across temperature gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional fuel cells or batteries are used, then chemical energy can be converted to electrical energy, but the amount of available reactants is limited by the battery casing, restricting energy production
Solution Approach 1:
The system divides the working fluid handling into separate functional components: an evaporator for phase change, a condenser for condensation, and membrane electrode assemblies for electrochemical conversion. This segmentation allows each component to be optimized independently, enabling continuous operation with large quantities of working fluid without being constrained by a single battery-like casing.
Solution Approach 2:
A halogen-based working fluid acts as an intermediary substance that carries energy between the heat source, evaporator, condenser, and electrochemical cells. The working fluid circulates continuously, absorbing heat in the evaporator, releasing heat in the condenser, and enabling electrochemical reactions in the MEAs, thereby decoupling the system from direct chemical reactant storage limitations.
2Duration of action of stationary object
If battery type electrochemical cells are recharged by applying reverse polarity current, then the cell can be recharged, but the cell is typically not usable during the recharging process
Solution Approach 1:
The system maintains continuous useful action through a closed-loop circulation of the halogen-based working fluid. While electrochemical reactions occur in the MEAs, the working fluid continuously evaporates in the evaporator and condenses in the condenser, ensuring uninterrupted energy conversion and eliminating idle periods associated with recharging batteries.
Solution Approach 2:
The working fluid serves itself by automatically circulating through the evaporator, condenser, and electrochemical cells based on temperature and pressure gradients. The phase change process self-regulates the fluid's movement and energy transfer, eliminating the need for external recharging operations and maintaining continuous system operation.
3Power
If conventional fuel cells operate with continuous supply of chemical reactants, then energy production can be sustained, but the system requires complex infrastructure for reactant supply and product removal
Solution Approach 1:
The halogen-based working fluid performs multiple functions simultaneously: it acts as a heat transfer medium in the evaporator and condenser, serves as an electrolyte in the membrane electrode assemblies, and enables both thermal and electrochemical energy conversion. This multi-functionality eliminates the need for separate reactant supply and product removal infrastructure required by conventional fuel cells.
Solution Approach 2:
The system merges the thermal cycle (evaporation-condensation) with the electrochemical conversion process into a single integrated system. The working fluid circulation loop combines heat exchange functions with electrochemical reaction functions, eliminating the need for separate infrastructure for reactant supply and product removal that would be required in conventional fuel cell systems.
4Power
If membrane electrode assembly surface area is increased to achieve high current levels, then power output increases, but manufacturing difficulty increases
Solution Approach 1:
The system changes the operating parameters by using a halogen-based working fluid with favorable electrochemical properties, enabling high current densities at lower surface areas. The unique properties of halogen-based fluids allow for more efficient electrochemical reactions, reducing the required MEA surface area while maintaining high power output, thereby simplifying manufacturing.
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 converter achieves higher voltage and efficiency by minimizing entropy loss and maintaining a constant pressure ratio, utilizing a closed-loop system with halogen-based fluids, even at low waste heat temperatures, thus overcoming manufacturing challenges and improving power generation.
Implementation Method 1
evaporating and condensing the working fluid across temperature gradients
Implementation Method 2
operates on a closed-loop Rankine cycle with membrane electrode assemblies (MEAs) to maintain a constant pressure ratio, converting thermal energy into electrical energy efficiently by evaporating and condensing the working fluid across temperature gradients
Implementation Method 3
evaporating and condensing the working fluid across temperature gradients
Implementation Method 4
Each MEA includes a nonporous membrane capable of conducting ions of the working fluid
Implementation Method 5
porous electrodes on either side of the electrolyte separator or PEM are used to couple the electrons involved in the chemical reaction through an external load via an external circuit
Implementation Method 6
converting thermal energy into electrical energy efficiently by evaporating and condensing the working fluid across temperature gradients
Data Source
AI summary
A method of generating electrical energy using an electrochemical direct heat to electricity converter operating on the Rankine cycle is provided. The converter includes a working fluid, a high temperature electrochemical cell including a first membrane electrode assembly, a low temperature electrochemical cell including a second membrane electrode assembly, an evaporator coupled to the first electrochemical cell, a condenser coupled to the second electrochemical cell, and an external load. The method involves introducing the working fluid at the first membrane electrode assembly as a liquid, expanding the working fluid through the first membrane electrode assembly and evaporating it into a vapor, and cooling and condensing the vapor back into a liquid at the second membrane electrode assembly.