Performance and Emissions of a SI Engine using Methanol-Water Blends 2013-01-1319
Using liquid alcohols, such as methanol and ethanol, in
spark-ignition engines is a promising approach to decarbonize
transport and secure domestic energy supply. Methanol and ethanol
are compatible with the existing fuelling and distribution
infrastructure and are easily stored in a vehicle. They can be used
in internal combustion engines with only minor adjustments and have
the potential to increase the efficiency and decrease noxious
emissions compared to gasoline engines. In addition, methanol can
be synthesized from a wide variety of sources, including renewably
produced hydrogen in combination with atmospheric CO₂.
Presently, during the production of ethanol or methanol a
dehydration step is always applied. This step accounts for a
significant part of the entire production process' energy
consumption and thus, from an economical point of view, methanol
and ethanol could become more interesting alternative fuels if the
costs related with dehydration could be reduced.
Also, methanol and ethanol are prone to absorb water when they
are exposed to the atmosphere for a considerable amount of time,
for example, during transport or storage.
The present study gives insights into the advantages that could
exist with methanol-water blends and compares the brake thermal
efficiencies and engine-out emissions from a production-type
four-cylinder SI gasoline engine running on gasoline, pure methanol
and methanol-water blends. Methanol-water blends of 2.5% v/v, 5%
v/v and 10% v/v water are tested. It is shown that the brake
thermal efficiency does not differ significantly for all methanol
fuels and is still higher than the efficiency on gasoline.
NOx emissions are reduced substantially for the fuels
with higher water content.