Serial Ammonia Cracking Units for Stable On-Board Hydrogen Supply
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Solution Overview
Problem
Existing technologies face challenges in efficiently generating hydrogen from ammonia on-board vehicles due to the need for high heat input, which is difficult to provide with limited electrical supply, and the inefficiency of ammonia combustion in internal combustion engines, leading to inconsistent combustion and storage safety issues with hydrogen.
Innovation Solution
An on-board ammonia cracking system that combines a heat exchange cracking unit and an electric cracking unit, utilizing exhaust heat and an expansion valve to maintain ammonia in a gaseous state, ensuring cracking occurs efficiently at varying engine conditions, with hydrogen produced as a co-fuel for internal combustion engines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If ammonia is combusted directly in internal combustion engines, then zero CO2 emissions are achieved, but combustion is inconsistent and combustion rate is too slow
Solution Approach 1:
The patent introduces hydrogen as an intermediary substance that facilitates consistent combustion. Hydrogen is produced through catalytic cracking of ammonia in a cracking unit, and this hydrogen then serves as a reliable ignition source that initiates and sustains combustion of ammonia in the engine, resolving the inconsistency issue while maintaining zero CO2 emissions
2Productivity
If hydrogen is stored on-board for use as fuel, then combustion efficiency is improved, but storage safety issues arise
Solution Approach 1:
The system generates hydrogen on-demand through catalytic cracking of ammonia stored in the vehicle's ammonia tank. The cracking unit converts ammonia to hydrogen and nitrogen when hydrogen is needed for combustion, eliminating the need for separate hydrogen storage tanks and associated safety concerns, while still providing efficient combustion
3Productivity
If ammonia cracking is performed using electrical heating, then hydrogen production is achieved, but energy consumption exceeds available electrical supply
Solution Approach 1:
The patent replaces electrical heating with a catalytic cracking process that uses a catalyst bed to facilitate the decomposition of ammonia into hydrogen and nitrogen. This chemical catalysis method requires minimal or no electrical energy input, allowing hydrogen production to proceed within the constraints of the vehicle's available electrical supply while maintaining high productivity
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 system effectively generates hydrogen for internal combustion engines, addressing inefficiencies and safety concerns by utilizing exhaust heat and electric heating to crack ammonia, providing a stable fuel source with zero CO2 emissions.
Implementation Method 1
an expansion valve coupled to the ammonia inlet of the heat exchange cracking unit, the expansion valve configured to maintain the ammonia in a gaseous state as the ammonia enters the heat exchange cracking unit
Implementation Method 2
a heat exchange cracking unit coupled to the ammonia tank, the heat exchange cracking unit receives exhaust from the internal combustion engine via the exhaust inlet
Implementation Method 3
the ammonia undergoes a cracking process in the heat exchange cracking unit
Implementation Method 4
the ammonia exits the heat exchange cracking unit via the gas outlet and flows to the electric cracking unit, and the ammonia subsequently undergoes the cracking process in the electric cracking unit
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 a fuel source for an internal combustion engine. The invention provides an expansion valve configured to maintain ammonia in a gaseous state prior to introduction into a cracking system that comprises a heat-exchange cracking unit and electric cracking unit coupled in series which enables reliable hydrogen generation under varying engine operating conditions.