One method of using alternativefuels in diesel engines
is by adopting amixed combustion process called dualfu
elling w h er e alt ernativ e fu eI s uc h as natural gas (Ir{ G)
is induc e d into the cylinder as a primary fuel with air
and is subsequently isnited with a pilot injection of
dieselfuel. The ignition delay in a dualfuel (DF)
engine is differentfrom that in a diesel engine because
the primaryfuelalters the properties of the charge,
r e duc e o xy g e n av ailable and under go e s pr e -ignitio n
r e ac tio n s durin g c o mp r e s s io n. V ario u s c o nclu sio n s of
DF ignition delay have beenreachedusing different
engines. In the presentwork a constantvolume
combustionvessel (CVCV) has beenusedto study the
ignition delay of aDF combustionpFocess.
E xp erim e nt s hav e b e e n p e rform e d to inv e s tigat e th e
i gniti o n d e lay p e rio d at dffi r e nt initial t e mp e r atur e s
andpressures. The results obtainedwere usedto modify
the Hu and Milton'ss DF ignition delay correlation.
The proposed coruelation predicts a delay periodfor a
wide range of initialtemperatures andpressures. The
trends exhibitedby the correlation are consistentwith
DF ignition delay engine tests datafrom other
researchersl'2. In particular, it explains why some
reported tests results show that ignition delay is always
rising while others show that it decreases temporarily
before rising againto very highvalues. The rising of
ignition delay occurs withlow pilot diesel quantities
and the latter with high one s.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001053 |
| Date | January 2003 |
| Creators | Mbarawa, MM |
| Publisher | The SA Mechanical Engineer |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Rights | The SA Mechanical Engineer |
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