Abstract
This project work is aimed at having a complete analysis and design of a grain
dryer that will utilize Kerosene as its fuel with consideration of pressure build up
for saturated range for our local farmers. The analysis and design has its bases on
the three mode of heat transfer operations, strength of materials and its
availability. The analysis and design of the grain dryer will be of more benefit to
agricultural sectors for the preservation of grains for both food consumption and
future cultivation for a variable temperature. In the course of this analysis and
design mechanisms, some essential mathematical models like Fourier laws of
conduction, heat transfer equations relative to Stefan Boltzman and Stoicheometic
analysis for the combustion of hydrocarbon together with fuel-air ratio were
considered while the grains considered in this analytical design include maize
(main), wheat, groundnut and sorghum. The temperature gradient at (dT/dx)
relative to the wall compo
INTRODUCTION
1.1 BACKGROUND OF STUDY
For decades, other than cash crops, grain crops have played a vital role in
agricultural sector in Nigeria where a greater number of populace are subsistence
farmers by virtue of their occupation. Most of grain crops such as maize, sorghum,
beans wheat to mention but a few, when properly processed yield to other finished
and consumable food with great nutrient for human consumption. For instance,
maize can be processed to obtain quake oat, flakes etc. and eventually, now that
Nigeria is faced with oil and gas degradation, grain crop planting can take its
advantage and at fast exported to earn foreign exchange.
Consequently, the researcher observed a great negligence in areas of adequate
preservation and storage facilities of grain crops by our local farmers thus, leading to
seasonal scarcity and unnecessary wastage of grain crops after each harvesting
season for both consumption and next planting season. Varieties of these grains are
found to be subjected to sunlight as the only drying mechanism but most times there
is always little or no sunshine to dry them. However, the inability for our local
farmers to afford themselves a mechanized storage and preservative grain
equipments may be attributed to the level of abject poverty in Nigeria thus, the need
for the analysis and design of a grain dryer that could be affordable, fuel economy
and efficient in its capacity and operate under the three modes of heat transfer.
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1.2 OBJECTIVE OF THE STUDY
The aim / objective of this project work is to establish a complete analysis and
design a grain dryer with the aid of mathematical models that is capable of utilizing
kerosene as fuel for drying of grains but with a consideration to a pressure build up
for saturated vapor and bearing in mind the state of economy and the scarcity of
petrol (gasoline) as a means of fuel, thus analyzing and designing an affordable and
less problematic grain dryer for our low-income farmers and to create an avenue for
reduction in grain scarcity /wastage thus alleviating the related problems associated
with storage facilities of grains in Nigeria.
1.3 STATEMENT OF PROBLEMS
Before the advent of oil and gas industries in Nigeria economy greater
numbers of the populace are subsistence /commercial farmers by virtue of their
occupation. Several grain crops are grown during each planting season of every year.
A lot of resources in terms of time, manpower and money are being invested so as to
have good returns during the harvesting period. After harvesting, much of the
products are consumed while some are exported to the neighboring countries. In the
process also, some percentage of the yield are kept and preserved for future use in
the next planting season. Consequently some of these grains even before harvesting
are attacked in the field by insects, birds and pest. The most agonizing problem is
lack of preservation and storage facilities which leads to the scarcity of these grains
after harvesting seasons. Farmers have lived with these problems for decades
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thereby drying their grains under unpredicted rising sun as their last resort. During
rainy season, it becomes apparent that preservative of grain crops for both
consumption and farming operations becomes difficult. It is against these backdrops
that the researcher had to embark on this project work with the aim of analyzing and
designing a grain dryer that will use kerosene as fuel for low income farmers.
1.4 RESEARCH QUESTIONS
The researcher deemed it necessary to have the following research questions
at the back of the mind for the proper analysis and design of the grain dryer.
1. What are the major problems of our local farmers?
2. What is the essence of preservation of grain crops?
3. What is the purpose or need for analyzing and designing of grain dryer?
4. Can the grain dryer help to alleviate the problems faced by the local farmers?
5. What sample grain crops will be utilized for the analysis and design of the
grain dryer?
6. What mechanism/models of heat transfer is required for appropriate operation
of the grain dryer.
7. What are the major components of the designed tray dryer?
8. What is the working or operational principle of the designed grain dryer?
9. How can saturated vapour in the designed analysis of the grain dryer be
curbed?
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10. How can the air to fuel ratio be determined in the cause of design analysis of
the dryer?
1.5 SIGNIFICANCE / JUSTIFICATION OF THE STUDY
Literature and statistics together with the present global economic meltdown
have all proved it beyond all reasonable doubt that with the rate of exploration and
world consumption of crude oil, most of the countries of the world will be faced
with starvation or shortage of crude oil as means of generating their foreign revenue,
hence, even the world leading countries such as America, Japan, Great Britain etc
have started embarking or revisiting their agricultural sectors as last resorts to
augmenting their national economy. Nigeria as our country should not be left out in
returning to agricultural sector irrespective of how mechanized or local it could be.
Thus, the analysis and design of the grain dryer will serve as an antidote that will
rekindle or reinforce our local farmers in terms of confidence in storage facility for
preservation of grains rather than depending solely on an unpredictable sunlight for
preservation of grain crops. In the same token, the designed grain dryer will help to
minimize the unnecessary wastage of crucial grains that could have served as
consumable (food or crops for planting seasons).
1.6 LIMITATIONS OF THE STUDY
There are numerous grain dryers that use various types of fuel for its operation
and with different mechanisms in their design analysis. Thus, this project work is
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restricted to the design analysis of grain and depends on the three models of heat
transfer for its operations for local farmers.
1.7 Nomenclature
HUF = Heat utilization factor.
COP = Coefficient of performance
dm/d0 = Drying rate.
q = Heat flow rate
A = Area normal to the direction of heat flow.
h1 = Enthalpy of drying air
h0 = Enthalpy of ambient air.
t2 = Dry bulb temperature of exhaust air.
t0 = Dry bulb temperature of ambient air.
t1 = dry bulb temperature of drying air.
?= Density of air.
Cp = Mean specific heat of dry product.
qx = Rate of convection heat transfer.
qx/A = Heat flux across any surface / total heat transfer
?T = Temperature difference between the surface and fluid.
K = Thermal conductivity.
Wm = Weight on moisture.
Wd = Weight on dry material.
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X3 –X2 = Thickness of insulator.
X2 –X1 = Thickness of inside drying chamber of metal wall.
h = Heat transfer coefficient.
? = Stephan Boltzmann constant.
T = Absolute temperature
? = Relative Humidity.
? = Specific humidity.
Tdp = Dew point temperature.