Determination of Diffilsion Coefficient of Transparent Liquid Solutions using Moire Deflectometry and online Monitoring of Liquid Quality by Ray Defectionand Online
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Date
2006-06
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Addis Ababa University
Abstract
In this thesis the diffusion coefficients of coffee, caffeine and sugar were investigated.
The technique cmployed is Moire deflectometry. New technique of on-line monitoring of
the quality of liquor in the process of manufacturing is also introduced. The diffusion
coefficient of caffeine was found to decrease with an increase in the caffeine
concentration at constant temperature. The diffusion coefficient of grinded and sieved
raw coffee at a concentration of 4.11mg/ml in distilled water, at temperature of 22°C was
(3.05±0.16) x JO.6cm2/s. This value of diffusion coefficient is less than the value of the
diffusion coefficient of caffeine at the same concentration and temperature, in distilled
water, which is (6.13±0.16)xl0·6cm2/s. The main factors that are expected to have
contributed to this difference are the fact that coffee is a mixture of many ingredients, as
wcll as the particle size of the grinded raw coffee. Diffusion coefficient of 10% sugar
solution in distilled water at a room temperature of 24°C was also measured and the value
found is (6.68 ± 0.07) xlO·6cnfls. On-line monitoring of a liquid quality in the process of
manufacturing is also found applicable in controlling a liquid quality. This was applied to
sugar solution that was made to flow through a horizontal diffusion tank and expected
result was found. The qualitative aspect about any change in the index of refraction of
liquid that passes through a horizontal tank with diffusion column can easily be observed
by a person at work; only by referring to ray deflections that correspond to the optical
density of the medium
Key words: coffee, caffeine Moire deflectometry, diffusion coefficient, and index of
refraction
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Keywords
Coffee; Caffeine Moire Deflectometry; Diffusion Coefficient ;and index of Refraction