Materialkrav för komponenter i förbränningsmotorer för vätgas
Typ
Examensarbete på kandidatnivå
Bachelor Thesis
Bachelor Thesis
Program
Publicerad
2023
Författare
Abda, Deler
Andersson, Joel
Andersson, Svante
Kåhre, Hugo
Jönsson, Henrik
Torslén, Melker
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Because of the current climate crisis hydrogen gas is investigated as a fuel for internal
combustion engines. Hydrogen gas has the potential to be an environmentally friendly
fuel since it can be produced with renewable electricity and it does not release
carbon dioxide during combustion. One problem with hydrogen is that it embrittles
many metals and thus potentially limits the material selection that could be used
to construct a hydrogen powered engine. The purpose of the study is to investigate
how hydrogen can affect materials and components in hydrogen powered internal
combustion engines. Hydrogen embrittlement can be attributed to several mechanisms,
these mechanisms are more thoroughly described during this project. This
generally leads to for instance reduced ductility and fatigue limit for the affected
materials. Different crystal structures have different susceptibility to this effect, for
instance hydrogen diffusion is higher in BCC metals and BCC metals are embrittled
to a greater extent compared to FCC metals. Different types of piston engines with
internal combustion was further investigated to determine what engine type is more
suited to being powered by hydrogen gas. This was done in order to determine components
which are more relevant to study further. Spark ignition was percieved to
be advantageous since hydrogen gas requires significantly higher compression than
is currently used in compression ignition egnines. The effect of hydrogen on the
alloys most commonly used in conventional internal combustion engines was studied.
High strength steel, in general, embrittles to a higher extent compared to, for
instance, aluminium and austenitic stainless steels. However, the variation is large
even between different alloys within the same alloy group. Finally, components with
direct exposure to hydrogen were studied as well as their requirements and which
alloys they usually consist of. Exactly how fatigue limit and service life for different
components would be affected could not be determined. Investigating this would
require experiments with hydrogen powered engines for long periods of time. A conclusion
is that components in proximity to the combustion chamber are critical to
study further, partially because of the high concentrations of hydrogen and partially
because of the high mechanical and thermal stresses.