On-Board Ammonia Cracking with Dual Catalyst Units for Cold Start
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Solution Overview
Problem
The challenge of efficiently generating hydrogen on-board vehicles for use in internal combustion engines due to the difficulties in storing hydrogen and the need for additional control mechanisms with ammonia-fueled engines, as well as the limitations of electrified vehicles in terms of raw material sourcing and environmental impact.
Innovation Solution
A system comprising an ammonia tank, a heat exchange catalyst unit, and an electric catalyst unit, where ammonia is cracked into hydrogen using exhaust gas heat and/or electric heating, depending on temperature conditions, to provide a stable fuel source for internal combustion engines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hydrogen is stored on-board in compressed form, then hydrogen availability for fuel is improved, but safety issues and storage complexity increase
Solution Approach 1:
The system pre-generates hydrogen from ammonia using waste heat before the engine needs it, storing it in a buffer tank. This preliminary hydrogen production eliminates the need for high-pressure hydrogen storage while ensuring hydrogen availability when needed.
Solution Approach 2:
Ammonia serves as an intermediary substance that converts stored chemical energy into hydrogen fuel on-demand. Instead of storing hydrogen directly, the system stores ammonia and uses it as a precursor to generate hydrogen through catalytic cracking, reducing safety risks associated with compressed hydrogen storage.
2Object-generated harmful factors
If ammonia is used as fuel in internal combustion engines, then CO2 emissions are reduced, but combustion consistency deteriorates due to slow burn rate
Solution Approach 1:
The system extracts hydrogen from ammonia through catalytic cracking and uses the extracted hydrogen as the actual fuel in the engine. This separates the storage medium (ammonia) from the combustion fuel (hydrogen), allowing ammonia to be stored safely while hydrogen provides consistent combustion.
Solution Approach 2:
The system changes the chemical composition of the fuel by converting ammonia (NH3) into hydrogen (H2) through controlled thermal cracking. This parameter change in fuel composition transforms the slow-burning ammonia into fast-burning hydrogen, ensuring consistent combustion across varying engine conditions.
3Reliability
If ammonia cracking is performed using electric heating, then hydrogen production reliability is improved, but energy consumption increases
Solution Approach 1:
The system uses the vehicle's own waste heat from the exhaust manifold to drive the ammonia cracking process. This self-service approach captures otherwise wasted thermal energy and repurposes it for hydrogen generation, eliminating the need for additional electric heating and reducing overall energy consumption.
Solution Approach 2:
The system converts the harmful waste heat from the exhaust system into a useful resource for driving ammonia cracking. By capturing thermal energy that would otherwise be lost and using it for hydrogen production, the system transforms a waste product into a beneficial input, improving energy efficiency.
4Quantity of substance
If ammonia is stored as liquid, then storage density is improved, but vaporization control complexity increases
Solution Approach 1:
The system extracts gaseous ammonia from the liquid storage tank through controlled vaporization and immediately directs it to the cracking catalyst. By extracting only the necessary gaseous portion and processing it immediately, the system minimizes the need for complex vaporization control while maintaining efficient use of the liquid ammonia supply.
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
Enables efficient on-board hydrogen generation from ammonia, addressing storage and control issues while reducing environmental impact by utilizing existing engine heat and minimizing the need for secondary fuels and raw materials.
Implementation Method 1
the gaseous ammonia undergoes a cracking process in the heat exchange catalyst unit if the exhaust gas has reached a temperature sufficient to perform ammonia cracking
Implementation Method 2
the gaseous ammonia exits the heat exchange catalyst unit and flows to the electric catalyst unit and undergoes the cracking process in the electric catalyst unit if the exhaust gas has not reached a temperature sufficient to perform ammonia cracking
Implementation Method 3
the heat exchange catalyst unit includes a plate heat exchanger
Data Source
AI summary
The present invention relates, in general, to systems and methods for generating hydrogen from ammonia on-board vehicles, where the produced hydrogen is used as fuel source for an internal combustion engine. The present invention utilizes an electric catalyst unit operating in series with a plate-type heat exchange catalyst unit. The electric catalyst unit is used to initiate an ammonia cracking process on-board during a cold start or low load operating condition of the internal combustion engine, where the ammonia cracking process occurs in the heat exchange catalyst unit once exhaust gas from the internal combustion engine has been heated to a threshold temperature suitable to perform the ammonia cracking process.