Sealed Central Fuel Pipe Nozzle for Hydrogen Flashback Prevention
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Solution Overview
Problem
Existing nozzle assemblies for engines designed for liquid fuels like kerosene or diesel are inadequate for injecting gaseous fuels such as hydrogen, as they risk premature auto-ignition and flashback due to the mixing of fuel and air within the nozzle, which is not suitable for gaseous fuels with shorter ignition delay times and higher flame speeds.
Innovation Solution
A nozzle assembly with a central fuel pipe sealed against air inflow, allowing fuel to be introduced into the combustion space without premixing, using a feed reservoir and passage openings to ensure even distribution and swirling of the fuel flow, combined with separate air ducts for mixing downstream of the nozzle end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fuel and air are mixed within the nozzle as in conventional liquid fuel injection, then atomization and combustion efficiency are improved, but flashback and premature auto-ignition risk increases for gaseous fuels
Solution Approach 1:
The nozzle is segmented into distinct functional zones: a central sealed fuel pipe for pure fuel transport, an intermediate mixing zone where fuel and air first contact, and a combustion zone downstream. This spatial segmentation prevents premature mixing in the fuel supply path while enabling controlled combustion downstream, resolving the contradiction between combustion efficiency and flashback prevention.
Solution Approach 2:
A sealed central fuel pipe acts as an intermediary barrier that physically separates fuel from air during transport. This intermediary structure allows fuel to be delivered to the mixing zone without direct contact with air or hot combustion gases, eliminating the flashback pathway while maintaining reliable fuel supply for efficient combustion.
2Reliability
If a sealed central fuel pipe is used to prevent flashback, then flashback and auto-ignition risk are reduced, but the complexity of the nozzle structure increases
Solution Approach 1:
The fuel pipe is nested within the nozzle body structure, with the sealed central fuel conduit integrated into the nozzle's longitudinal axis. This nesting arrangement allows the fuel supply system to be contained within the existing nozzle geometry, achieving flashback prevention through the sealed pipe while minimizing additional external complexity.
Solution Approach 2:
The central fuel pipe serves multiple functions simultaneously: it acts as a sealed barrier against flashback, a conduit for fuel transport, and a structural element of the nozzle assembly. This multi-functionality reduces the need for separate components, thereby limiting the increase in overall structural complexity while achieving reliable flashback prevention.
3Reliability
If fuel is injected without premixing with air, then flashback risk is reduced, but mixing efficiency and combustion stability must be maintained downstream
Solution Approach 1:
The nozzle performs preliminary actions in a controlled sequence: first, fuel is delivered through the sealed pipe to the mixing zone; second, air is introduced to create a controlled mixture; third, the mixture proceeds to the combustion zone. This preliminary structuring of the mixing process ensures that when fuel and air do mix, it occurs under controlled conditions that maintain combustion stability while preventing flashback upstream.
Solution Approach 2:
Different regions of the nozzle have different mixing qualities: the central fuel pipe region maintains pure fuel (no mixing), the intermediate zone provides controlled partial mixing, and the combustion zone allows full mixing. This local differentiation of mixing quality ensures flashback prevention in the fuel supply region while maintaining combustion stability in the combustion region.
Data Source
AI summary
The invention relates to a nozzle assembly for a combustor of an engine, including at least one nozzle for injecting fuel into a combustion chamber of the combustor, wherein the nozzle has a nozzle main body which extends along a nozzle longitudinal axis and a nozzle holder connected to the nozzle main body and having at least one fuel supply line. The nozzle main body comprises a central fuel pipe extending along the nozzle longitudinal axis and sealed against an in-flow of air, in which fuel supplied via the at least one fuel supply line can be guided within the nozzle main body up to a fuel outlet opening of the fuel pipe provided at a nozzle end of the nozzle, via which the fuel can be introduced into the combustion chamber.