Electric Heat Pipe Using Partial Pressure for Power Generation
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Solution Overview
Problem
Existing thermo-electrochemical heat engines face challenges in achieving high efficiency levels and practical utility due to low power density, impractical pressure ratios, and inefficiencies in heat conversion, particularly when operating over a wide range of heat source temperatures.
Innovation Solution
The Johnson Electric Heat Pipe (JEHP) employs a housing with a wick, phase change heat recuperator, and two-phase working fluid to maintain a constant overall pressure, utilizing a non-condensable gas partial pressure differential across an electrochemical cell, coupled with a heat source and sink, to generate electrical energy through evaporation and condensation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a direct heat to electricity converter uses an ionizable gas and a non-condensable gas to create a partial pressure differential across an electrochemical cell, then electrical energy is generated, but the non-condensable gas accumulation dissipates the pressure differential resulting in impractically low power density
Solution Approach 1:
The patent employs phase transitions of the working fluid (evaporation at the hot end and condensation at the cold end) to drive the non-condensable gas partial pressure differential across the electrochemical cell. The phase change mechanism enables continuous circulation and maintains the pressure differential, preventing dissipation and enhancing power density.
Solution Approach 2:
The patent utilizes changes in physical parameters (temperature, pressure, phase state) of the working fluid to control the partial pressure differential. By varying temperature between the hot and cold ends, the system maintains a sustainable pressure differential that drives electrical energy generation without dissipation.
2Loss of energy
If a Johnson Thermo-Electrochemical Engine uses two electrochemical cells operating at different temperatures with a recuperative heat exchanger, then heat conversion efficiency is improved, but the voltage differential is limited to a small range (0.05V in low heat source temperature applications)
Solution Approach 1:
The patent employs phase transitions (evaporation and condensation) to generate a larger partial pressure differential compared to conventional heat exchangers. This phase change mechanism enables a greater voltage differential across the electrochemical cell, overcoming the limitation of small voltage ranges in traditional JTEC engines while maintaining improved heat conversion efficiency.
3Power
If the working fluid is compressed in the low temperature cell by supplying current at a voltage sufficient to overcome the Nernst potential, then hydrogen is driven from the low pressure side to the high pressure side, but resistive losses in efficiency associated with the impedance of two proton conductive MEA connected in series cause limited practical utility
Solution Approach 1:
The patent replaces the electrical compression mechanism (which causes resistive losses) with a thermodynamic compression mechanism driven by phase transitions and partial pressure differentials. This substitution eliminates the need for current supply to overcome Nernst potential, thereby reducing resistive losses while maintaining effective hydrogen compression.
4Productivity
If a nozzle is used to increase flow velocity levels beyond flow promoted by gas partial pressure differentials alone, then convective heat transfer and gas mixing are improved for higher power generation rates, but entropy increases associated with high turbulence and shock waves significantly impact efficiency
Solution Approach 1:
The patent utilizes pneumatic principles by employing partial pressure differentials of non-condensable gas to drive flow through the electrochemical cell. This approach achieves effective flow velocities and convective heat transfer without relying on high-velocity nozzles, thereby avoiding entropy increases from turbulence and shock waves while maintaining high power generation rates.
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 JEHP achieves a Carnot equivalent thermodynamic cycle, enhancing power density and efficiency by recuperating latent heat and maintaining a consistent pressure differential, thereby improving energy conversion efficiency.
Implementation Method 1
Heat from the source evaporates two phase working fluid to produce a portion of the mixed gas with low partial pressure of non-condensable gas
Implementation Method 2
heat rejected to the heat sink condenses working fluid to produce a portion of the mixed gas with high partial pressure of non-condensable gas
Implementation Method 3
The phase change heat recuperator recuperates a substantial portion of two-phase working fluid heat of condensation for use as two-phase working fluid heat of evaporation
Implementation Method 4
A Johnson Electric Heat Pipe (JEHP) direct heat to electricity converter is disclosed having a housing containing a first wick
Implementation Method 5
The conversion of heat energy or chemical energy to electrical energy, or visa-versa, may be accomplished in a variety of ways
Implementation Method 6
The ions are conducted through an electrolyte separator
Implementation Method 7
Heat from the source evaporates two phase working fluid
Data Source
AI summary
A Johnson Electric Heat Pipe direct heat to electricity converter includes a housing containing a wick, a vapor exchange recuperator, a two-phase working fluid, an ionizable non-condensable gas, preferably hydrogen or oxygen, and an electrochemical cell. The heat pipe is coupled to a heat source and a heat sink. The gas phase of the two-phase working fluid and the non-condensable gas exist at partial pressures within a constant pressure system. Heat from the source evaporates two-phase working fluid resulting in low partial pressure of non-condensable gas. Heat rejected to the heat sink condenses working fluid, resulting in high partial pressure non-condensable gas. The non-condensable gas partial pressure differential is applied across the electrochemical cell whereby non-condensable gas expands through the electrochemical cell and generates electrical energy. The vapor exchange recuperator recuperates a substantial portion of two-phase working fluid heat of condensation for use as two-phase working fluid heat of evaporation.