Newsgroup: it.discussioni.motori
Titolo: Metanolo come carburante per motori a combustione interna

Tempo fa si parlava del metano come potenziale carburante auto e la
discussione era finita sui soliti discorsi di velocità di fiamma, dosi
stechiometriche, tonalità termiche, ecc...
A questo proposito è invece molto più interessante l' uso dle metanolo in
motori a comb int, come è ben descritto in questo studio (viene trattato
anche l' etanolo, ma l' enfasi è maggiormente sul *metanolo*); siccome
allora era venuta fuori un' interessante discussione, sarei curioso di
sapere cosa ne pensate
 
http://www.ethanolboost.com/LFEE%202008-01%20RP.pdf
 in particolare
" The high intrinsic octane numbers of ethanol and methanol are well known.
However, a
much greater effective octane number can be effectively realized through the
knock
resistance provided by the high level of vaporization cooling that occurs
when methanol
or ethanol is directly injected into the engine cylinders. A computational
model is used in
this paper to determine the knock resistance and effective octane number of
these alcohol
fuels when they are directly injected. The model indicates that the
effective octane
numbers are around 160 for ethanol and 180 for methanol. The high
compression ratio,
high degree of turbocharging and aggressive engine downsizing enabled by the
high
effective octane number of methanol could provide an efficiency gain of
30 –35% (for
combined city-highway driving) relative to conventional port fueled gasoline
engines. An
additional gain of around 10% can be obtained by using reforming of methanol
to enable
ultra lean operation at low loads. The combination of these gains could thus
potentially
provide an efficiency gain of 40–45% for direct injection methanol engines.
This
efficiency gain is significantly greater than the typical 25–30% gain of
turbocharged
diesel engines. "
 
e alla fine del testo, sul discorso della più ridotta autonomia del metanolo
vs benzine
 
" The combination of high compression ratio and downsizing provided by
direct methanol
injection together with reformer enabled ultra lean operation at light loads
could provide
an efficiency improvement of 40 to 45% relative to a conventional port fuel
injected
gasoline engine. This increase in efficiency is significantly greater than
representative
efficiency improvements of 25–30 % (combined city and highway driving) for
turbocharged diesel engines with an advanced exhaust aftertreatment system
(that
includes NOx treatment and a particulate filter) and could be achieved at a
lower cost.
 
A 40–45% improvement in efficiency would also provide a significant offset
to the range
disadvantage of methanol fueled vehicles. With this improvement the range
relative to a
conventional gasoline engine with a similar size fuel tank would increase
from
approximately 50% to approximately 70%. "
 

 
giusto per integrare il discorso, oggi in alcuni Paesi si vendono già auto
(tipo saab o volvo) ad etanolo (per la sua maggiore diffusione, ma per il
metanolo è uguale, anzi meglio come si evince dallo studio) a prestazioni 
"differenziate" e maggiorate nell' uso
dell' alcol, per es.
http://www.aci.it/uploads/tx_edicolaaci/40-43_Bioetanolo.pdf
 
 
notare i 175 CV nel funzionamento a benzina e i 200 CV in quello ad etanolo,
nonchè i differenti consumi a benzina (10,8 km/l) vs E85 miscela al 85% di
etanolo (9,3 km/l) che considerando l' inferiore potere energetico dell'
etanolo vs benzina (2/3 circa) indica chiaramente un aumento dell' 
efficienza del funzionamneto ad
etanolo a motore/veicolo inalterato