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Candidate of technical science
Assankulov Nurlan Arynrashitovich
M.Kh. Dulaty Taraz State
University, 080000, Taraz, Republic of
Kazakhstan
Investigation of drying kinetics of maize in drum dryers
The article provides a
comparative estimate of the rate of drying fine grain corn and grain core
fractions in order to improve the uniformity of drying of maize grain in the
drum dryers. Had studied the kinetics of drying of fine-grained maize varieties
VIR 156 artificial but moistened to 17, 21% based on dry matter (DM) of grain.
The results can be used for practical purposes the duration of convection
drying of maize grain.
The purpose
of work - a comparative estimate of the rate of drying corn and fine grain core
fractions in order to improve the uniformity of drying of maize grain in the
drum dryers.
We studied
the kinetics of drying of fine-grained maize varieties VIR 156 artificially
humidified to 17, 21% based on dry matter (DM) of grain. To compare the rate of
drying corn took the main fraction with a moisture content in respect to the
weight of grain DM 17, 21%. Experiments were performed twice on an
experimental dryer drum set at a
temperature of drying agent 90 and 110 0C (Alpeisov E.A., 1996).
Dried fine grain corn were weighed with an
accuracy of 0,1 g every 5 minutes. Initial grain moisture content was
determined by the ISO 71161985 and then calculated The magnitude of the
moisture WC per MW. Based on these experiments was built drying
curves represent a graphical relationship between WC and drying time
τ (see Figure
1). Drying rate curves obtained graphical differentiation of the curves of
drying.
Figure 1
shows
that
for
fine grain
maize
with increased
WC
as well as
for
corn grain
core
fractions,
characterized by the
presence of
two periods of drying
constant
and
falling
drying rate.
At the
beginning
of the first period there
is a
short warm-up area of
grain, duration of which
is determined by t ac and the
original WC.
Drying rate in the first period is
determined by the equation:
where N - the
constant drying rate.
In the second period drying rate decreases and
the rate of drying is characterized by K = χN is a generalized coefficient, including the
processes of hydraulic conductivity and water yielding capacity. The proportionality
factor χ is called
the relative ratio of drying.
K-value was determined directly in the second
period of drying curve. The results of determining the values of N, K and χ are given in Table.
Comparative evaluation of drying fine corn and
corn fractions of core show that the rate of drying of fine-grained maize by
20-25% above the rate of drying of corn grain core fractions, which is
explained with respect to the larger surface area of small grains, as well as
differences in biochemical composition and properties.
Table
|
Material type |
ta.c,îÑ |
N, %/h |
K,1/h |
χ, 1/% |
N, %/÷ |
K, 1/h |
χ, 1/% |
|
|
WC =17 |
% |
WC =21 |
% |
|||
|
Fine-grained
corn |
90 |
3,00 |
0,165 |
0,055 |
4,20 |
0,218 |
0,052 |
|
110 |
4,20 |
0,235 |
0,056 |
5,60 |
0,291 |
0,052 |
|
|
Corn
main fraction |
90 |
2,50 |
0,143 |
0,057 |
3,50 |
0,175 |
0,050 |
|
110 |
3,50 |
0,203 |
0,058 |
4,50 |
0,230 |
0,051 |
|
The results can be used for practical purposes
the duration of convection drying of maize grain.
References
1. Alpeisov E.A. (1996)
Intensification of the process of drying and cooling of oilseeds: Dis. Doct.
Tekhn. Science .- St. Petersburg, 429 p.
2. Assankulov N.A. (2007) Intensification of drying
and cooling of wheat grain in the combined unit. Dis. Cand. Tekhn. Science .- Almaty, 156 p.