JTEC Converter with MEA Stack and Recuperative Heat Exchanger
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Solution Overview
Problem
Conventional mechanical and thermo-electrochemical heat engines face reliability issues and inefficiencies due to the corrosive nature of alkali metal working fluids and limited utility, especially at high temperatures, and existing JTEC systems struggle with hydrogen leakage and the need for numerous cells in series to achieve practical output voltage levels.
Innovation Solution
The development of a Johnson Thermo-Electrochemical Converter (JTEC) system with a high-density MEA stack configuration using ion-conductive membranes and electrodes with additives for enhanced conductivity, coupled with a recuperative heat exchanger to approximate the Ericsson cycle, allowing for efficient heat-to-electricity conversion over a wide range of temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mechanical heat engines are used, then electrical power can be produced through thermodynamic cycles, but reliability problems and efficiency losses occur due to mechanical moving parts
Solution Approach 1:
The patent replaces mechanical moving parts (pistons, turbines) with an electrochemical system using ion-conductive membranes and electrodes. The working fluid (hydrogen) is pumped through the membrane by electrochemical reactions rather than mechanical compression, eliminating reliability issues associated with mechanical components while maintaining the thermodynamic cycle for power generation.
2Reliability
If AMTEC cells are used to avoid mechanical moving parts, then reliability improves, but the system suffers from corrosive working fluids and limited utility at high temperatures
Solution Approach 1:
The patent changes the working fluid from corrosive alkali metals to hydrogen, which is non-corrosive and environmentally benign. This parameter change maintains the electrochemical pump mechanism while eliminating the harmful corrosive effects that limited the utility and lifespan of AMTEC systems.
3Power
If JTEC systems use numerous cells in series to achieve practical output voltage, then power output improves, but device complexity and hydrogen leakage risks increase
Solution Approach 1:
The patent employs thin-film ion-conductive membranes that enable high ionic conductivity in a compact format. This allows achieving practical power output with fewer cells by increasing the surface area and ionic conductivity of individual membrane elements, thereby reducing overall system complexity and minimizing potential leakage points.
4Use of energy by moving object
If conventional fuel cells are used, then continuous electrical current can be maintained, but the system requires separate electrical sources for recharging and becomes unusable during recharging
Solution Approach 1:
The patent creates a self-service system where the electrochemical cell performs both power generation and working fluid compression functions. The electrochemical reactions that generate electricity also simultaneously compress the hydrogen working fluid, eliminating the need for separate recharging operations and external electrical sources.
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 JTEC system achieves efficient heat-to-electricity conversion with reduced reliability issues and improved efficiency by utilizing a high-density MEA stack configuration and recuperative heat exchanger, enabling operation over a wide temperature range and minimizing the need for multiple cells in series.
Implementation Method 1
The membranes are conductive of ions of the working fluid
Implementation Method 2
The electrodes include additives to promote electronic conductivity and a catalyst to promote the desired electrochemical reactions
Implementation Method 3
coupled with a recuperative heat exchanger to approximate the Ericsson cycle
Implementation Method 4
The conversion of heat energy or chemical energy to electrical energy, or visa-versa
Data Source
AI summary
A direct heat to electricity engine includes solid state electrodes of an electrochemically active material that has an electrochemical reaction potential that is temperature dependent. The electrodes are configured in combination with electrolyte separators to form membrane electrode assemblies. The membrane electrode assemblies are grouped into pairs, whereby each membrane electrode assembly of a given pair is ionically and electronically interconnected with the other. One membrane electrode assembly of a given pair is coupled to a heat source with the other to a heat sink. One membrane electrode assembly of the pair is electrically discharged while the other is electrically charged, whereby the net and relative charge between the two remains constant because of the electronic and ionic interconnection and the difference in temperature of the membrane electrode assemblies, and thereby voltage, results in net power generation.