A MODIFIED EBULLIOMETER FOR
ACCURATE VAPOR PRESSURE
MEASUREMENT OF
ALCOHOL-GASOLINE MIXTURE
Name : Vika Amidelsi
Rama Oktavian
(2305 100 029)
(2305 100 119)
Advisor : Prof. Dr.Ir. Gede Wibawa, M.Eng.
ABSTRACT
Simple alcohol is used as gasoline oxygenated additives
to enhance the octane number and reduce pollutants from
vechicle exhaut gases. However, alcohol has higher vapor
pressure than gasoline causing raising concerns about the
evaporative emission from the fuel mixtures. As a result, a
qualified experimental data is important to developed
thermodynamic models for accurate prediction of vapor pressure
of fuel oxygenated mixtures. In this work a new simpler
ebulliometer has been developed to measure vapor pressure of
binary system of ethanol-isooctane and 1-butanol-isooctane in the
various compositions and temperatures accurately. Reliability of
this apparatus has been validated by comparing experimental
data with literature data based on Antoine equation for vapor
pressure of pure isooctane and Wagner equation for pure
ethanol, parameter for both equations are obtained from Poling
et al., Mc Graw-Hill International edition (2001) and the mixture
of ethanol-isooctane based on experimental data from Golubkov
et al., IJER 7(2005) 203. An average absolute deviation (AAD)
for vapor pressure of pure isooctane is 1.05%, for pure ethanol is
1.88% and for the mixture of ethanol-isooctane is 1,23%. It shows
that the experimental data is well agreed with literature data. The
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experimental result shows that vapor pressure of ethanolisooctane mixture will increase at low fraction of ethanol in the
range 0-0.3% mass and will be constant in the range 0.4-0.6%. At
the high fraction of ethanol vapor pressure of the mixture of
ethanol-isooctane will decrease in the range 0.7-0.9%. For
mixture of 1-butanol-isooctane system, the vapor pressure
decreased by increasing proportion of 1-butanol concentrations.
Some of activity coefficient models such as Wilson, NRTL,
UNIQUAC equation are used to correlate the experimental data
to obtain binary parameter for both of ethanol-isooctane and 1butanol-isooctane binary systems with AAD value for ethanolisooctane binary system are 3.48%, 3.29%, 6.09% respectively
and for 1-butanol(1)-isooctane binary system are 4.19%, 4.74%,
4.82% respectively.
Key Words: Ebulliometer, Vapor Pressure, Isooctane , Alcohol
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