Ammonia Thermal Cracker for Alkaline Membrane Fuel Cell Hydrogen Supply

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Solution Overview

Problem

Alkaline Membrane Fuel Cells (AMFCs) face challenges in accessing hydrogen fuel, as compressed hydrogen is not readily available in many areas and handling it is cumbersome, while ammonia, with a higher hydrogen weight percentage, offers a more accessible and efficient packaging solution.

Innovation Solution

An ammonia-operated fuel cell system incorporating an alkaline membrane fuel cell with an ammonia thermal cracker that produces a 75% hydrogen and 25% nitrogen mixture, which is distributed uniformly across the active area using a spiral flow channel, and ammonia is bled into the air feed stream to getter CO2, preventing ionomer carbonation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If compressed hydrogen gas is used as fuel source, then the AMFC can generate electricity, but the hydrogen availability is limited and handling is demanding due to transport regulations and low weight percentage

Engineering Contradiction:

Improvehydrogen weight percentageVSAvoidhandling difficulty

Core Design Contradiction:

Quantity of substanceVSEase of operation

Solution Approach 1:

The patent changes the physical state and composition parameters by using liquid ammonia instead of compressed hydrogen gas. Liquid ammonia contains approximately 17.6 wt% hydrogen compared to about 5 wt% in compressed hydrogen tanks, significantly increasing the hydrogen content per unit mass while improving storage and handling characteristics.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an ammonia decomposition device as an intermediary component that converts liquid ammonia into hydrogen fuel in situ. This mediator resolves the contradiction by providing a storage medium (ammonia) that is easier to handle and store, while still delivering the required hydrogen to the fuel cell through thermal decomposition.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If ammonia is used as hydrogen source, then the hydrogen packaging efficiency is improved and fuel supply is facilitated, but carbon dioxide in the air stream can carbonate the ionomer

Engineering Contradiction:

Improvehydrogen density in storageVSAvoidionomer carbonation

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes carbon dioxide from the air stream before it reaches the cathode by introducing ammonia, which reacts with CO2 to form ammonium carbonate. This extraction of the harmful component (CO2) prevents ionomer carbonation while maintaining the benefits of ammonia-based hydrogen storage.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potentially harmful interaction between ammonia and CO2 into a beneficial process. Instead of allowing CO2 to carbonate the ionomer, the introduced ammonia reacts with CO2 to form ammonium carbonate, effectively using the harmful CO2 as a reactant that gets removed from the system, protecting the fuel cell while utilizing ammonia's dual functionality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If ammonia is bled into the air feed stream to getter CO2, then CO2-related performance losses are prevented, but the system complexity increases

Engineering Contradiction:

Improveperformance stabilityVSAvoidsystem configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the ammonia tank serve multiple functions: it provides hydrogen fuel through the decomposition device and simultaneously provides CO2 gettering by bleeding ammonia into the air feed stream. This multi-functionality reduces the need for separate CO2 removal systems, thereby limiting the increase in system complexity while maintaining performance stability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 allows for extended operation time per tank fill-up and maintains performance comparable to neat hydrogen feeds, even with high ammonia levels, and effectively prevents CO2-related performance losses by utilizing ammonia for CO2 sequestration, enhancing fuel efficiency and reducing the need for additional units.

Implementation Method 1

an ammonia thermal cracker including a combustion chamber, the cracker being in gas communication with an ammonia tank, and configured to provide a supply of H2 directly to the AMFC anode

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

ammonia is bled into the air feed stream to getter CO2, preventing ionomer carbonation

Methodology Applied

Scientific EffectChemical absorption: Absorption (physical)

Implementation Method 3

Alkaline Membrane Fuel Cells (AMFCs) generate electricity using mostly Hydrogen fuel

Methodology Applied

Scientific EffectElectrochemical reaction: Fuel Cell

Data Source

PatentEP2735046B1Use of ammonia as source of hydrogen fuel and as a getter for air-co2 in alkaline membrane fuel cells

Publication Date: 2017.01.11 CELLERA INC

AI summary

Embodiments of the invention provide an ammonia operated fuel cell system including an alkaline membrane fuel cell (AMFC) having an anode, and an ammonia thermal cracker including a combustion chamber, the cracker being in gas communication with an ammonia source, and configured to provide a supply of H2 directly to the AMFC anode.