The American Journal of Engineering and Technology
151
https://www.theamericanjournals.com/index.php/tajet
TYPE
Original Research
PAGE NO.
151-153
10.37547/tajet/Volume07Issue05-13
OPEN ACCESS
SUBMITED
18 March 2025
ACCEPTED
14 April 2025
PUBLISHED
16 May 2025
VOLUME
Vol.07 Issue05 2025
CITATION
Sheraliyeva Ozoda Anvarovna, Nigmatjonov Samugjon Karimjononovich, &
Nurmuhamesov Khabibulla Sadulayevich. (2025). Heat exchange of
granular-fibrous materials in a fluidized bed with superimposition of hot
coolant jets. The American Journal of Engineering and Technology, 7(05),
151
–
https://doi.org/10.37547/tajet/Volume07Issue05-13
COPYRIGHT
© 2025 Original content from this work may be used under the terms
of the creative commons attributes 4.0 License.
Heat exchange of
granular-fibrous materials
in a fluidized bed with
superimposition of hot
coolant jets
Sheraliyeva Ozoda Anvarovna
Associate Professor, Tashkent Institute of Chemical Technologies,
Uzbekistan
Nigmatjonov Samugjon Karimjononovich
Associate Professor, Tashkent Institute of Chemical Technologies,
Uzbekistan
Nurmuhamesov Khabibulla Sadulayevich
Professor, Tashkent Institute of Chemical Technologies, Uzbekistan
Abstract:
In this article, the process of heat exchange
between granular-fibrous materials in a pseudo-
liquefied layer formed by the flow of liquid or gas is
scientifically and technically covered. Based on the
temperature difference between heat carriers (hot
water, steam, gas) and materials, the efficiency of this
process is ensured by the free movement of the heat
carrier in the layer, the expansion of surfaces, as well as
intensive convection. The focus is on parameters such
as heat transfer coefficient, temperature gradient, heat
capacity of the material and flow rate. The possibilities
of process analysis through mathematical modeling
(Fourier, Navy-Stokes equations) and experimental
methods are also considered.
Keywords:
Heat exchange, liquefied layer, granular-
fibrous materials, heat carrier, convection, heat
capacity, temperature gradient, modeling, Fourier,
Navy-Stokes.
Introduction:
Heat exchange between granular-fibrous
materials in a layer diluted (falsely liquefied) with hot
and coolant flows is one of the important and complex
The American Journal of Engineering and Technology
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The American Journal of Engineering and Technology
sections of the thermal technique. This process is
widely used, especially in modern industries
—
chemical, energy, food, pharmaceutical, building
materials production and many other industries. In
such technological processes, the process of heat
exchange plays an important role in order to obtain a
target product, save energy or effectively use thermal
energy.
A dilute layer is such a technological state in which a
high-speed flow of liquid or gas is passed under solid
particles (such as sand, granular or fibrous materials).
In this case, the particles begin to move as if they had
lost their weight, creating an effect similar to that of
them floating in a liquid. This layer is therefore known
as the” pseudo
-liquefied layer". This situation greatly
intensifies the processes of heat and mass exchange,
since the surface of contact between the heat carrier
and the particles and the dynamics of movement
increase.
Granular-fibrous materials, on the other hand,
combine two types of physical structures: the first is
spherical or irregularly shaped granules, while the
second is fibrous or filamentous. The presence of these
two different structures in one layer increases the
complexity of the heat transfer process. Fibers
increase the surface area, but they can be slower to
transfer heat. Granules, on the other hand, can absorb
or transmit heat more quickly. As a result, materials
with different densities, heat capacity, thermal
conductivity and heat dissipation rates are
simultaneously involved in the heat exchange process.
The process of heat exchange is usually carried out
through hot or cold heat carriers
—
such as steam, hot
water, cold air or other gases
—
. When these currents
collide with particles or pass between them, heat is
given or obtained due to the temperature difference.
In particular, convective heat exchange is at a high
level because of the High freedom of movement of the
heat carrier in the pseudo-liquefied layer.
A pseudo-liquefied layer is a technologically complex
but highly efficient system in which solid particles,
either granular or fibrous materials, are passed
underneath at a high rate of fluid or gas flow. As a
result of this flow, the particles come into a state as if
they had lost their weight and begin to move freely,
like substances floating in a liquid. The state of the
layer formed in this way is called "pseudo-liquefied"
because this state shows the same behavior as classical
liquids, but it is actually a layer made up of solid
particles. In the scientific literature, this system is
referred to by the name "fluidized bed" (a term derived
from English).
One of the most important advantages of a pseudo-
liquefied layer is the very intensive nature of heat and
mass exchange processes due to the mobility of the
particles in the layer. It is widely used, especially in the
chemical industry, in catalytic processes, drying,
roasting, granulating, washing, synthesizing or many
other technological processes where rapid transfer of
heat from one substance to another is necessary. It is
also used effectively in the energy sector, such as
activated charcoal, waste recycling, heat exchange
reactors.
Another important aspect in the process of heat
exchange in a dilute layer is the dynamics of movement
of particles in the layer and the mobility of different
materials relative to each other. Especially when
granular and fibrous materials are present in the same
layer, due to their different density, shape, size, and
thermal conductivity, the thermal distribution in the
layer may not be the same. This causes temperature
fluctuations in local zones within the layer.
The process is also influenced by the chemical
properties of the heat carrier, which is injected as a gas
or liquid. For example, if a heat-carrying gas contains
reactive components, they can chemically react with the
material, causing thermal separation or absorption. In
these cases, heat exchange takes place not only on a
physical basis, but in conjunction with chemical
processes, which complicates the model and
calculations. At the same time, automated monitoring
and control systems for liquefied layers are being used
in modern heat exchange systems. Such systems
measure temperature, pressure and flow rate in real
time, keeping the process in optimal condition. This
technology is particularly important in the energy
facilities, Petroleum and chemical industries, providing
safety and efficiency.
Granular-fibrous materials are special substances used
in these processes. They contain particles of two
physical properties: the first are granular particles,
which are usually spherical or granular, smooth, with a
clear center of gravity, and easy to move; the second are
fibrous materials that are structurally more complex,
brittle, layered, in some cases shaped like fabrics.
The presence of granular and fibrous particles in a mixed
state in one layer has a significant effect on the
processes of thermal conductivity, temperature
distribution and energy exchange. For example,
granular particles can absorb and transfer heat faster
due to their higher density, while the contact surface
with the heat carrier increases due to the greater
surface area of the fiber. For this reason, in such
complex systems in a pseudo-liquefied layer, the
temperature field may not be uniformly distributed, but
this simultaneously increases the intensity of the heat
The American Journal of Engineering and Technology
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The American Journal of Engineering and Technology
and mass exchange process.
For optimal results in these systems, layer height, flow
rate, particle diameter, their density, heat capacity,
and many other factors are carefully analyzed. Such
systems are simulated in many cases on the basis of
mathematical models, and advanced control systems
are introduced in the process of their control. Thus, the
interaction of fake liquefied layer and granular-fiber
materials is an important technological solution to
ensure high efficiency and energy efficiency in many
areas of the industry.
When the heat exchange process is carried out in the
presence of granular-fibrous materials and using heat
carriers in a liquid or gaseous state, the effectiveness
of this process is determined through a number of
physical parameters. In particular, this process is
mainly based on the temperature difference of hot and
cold substances. That is, a hot carrier medium
–
which
can usually be in the form of steam, hot water, or hot
gas
–
and a temperature difference between the
granular-fibrous materials in a relatively cold State, this
difference causes heat flow to occur.
The presence of a diluted (falsely liquefied) layer
makes this process more intensive. The reason is that
in this layer, each particle, either granular or fibrous
elements, moves relatively freely between them, while
through the spaces between them, heat carriers can
move with great speed. This action, in turn, expands
the contact surface of the heat carrier with the
particles and greatly accelerates the process of heat
from one particle to another. As a result, the
distribution of heat occurs quickly and a stable
temperature field can be formed throughout the layer.
There are basic physicochemical factors that
determine the effectiveness of heat exchange. One of
them is the temperature gradient, which indicates the
magnitude of the temperature difference between the
heat carrier and the acceptor. The larger the
temperature difference, the stronger the heat flux. The
next important factor is the coefficient of heat
transfer. This indicator depends on the quality of
contact, surface and other conditions between the
particle and the heat carrier medium. The specific heat
capacity of a material, on the other hand, indicates
how much energy is required to raise or lower the
temperature. In addition, the flow rate of the heat
carrier is also of particular importance, which
determines at what speed and in what direction the
heat carrier moves inside the layer.
Mathematical modeling is widely used for in-depth
analysis and management of this process. This typically
uses differential equations representing heat transfer
processes, such as complex systems such as the Fourier
equation (heat dissipation), the Navy-Stokes equations
(motion of liquids and gases). With the help of such
equations, the temperature distribution in the layer, the
interaction of heat flow and gas-liquid flows can be
theoretically determined.
In addition, through experimental studies, cases such as
fluid motion, convection, thermal radiation (radiation)
and transfer of energy through the surface are studied
in detail under real conditions. With specialized
laboratory equipment, fluid motion and heat transfer
mechanisms with temperature sensors, heat flow
meters, and high-speed cameras are analyzed visually
and digitally. This data, on the other hand, serves as the
basis for the design, optimization and efficient
management of heat exchange systems in later practical
production conditions. Thus, the heat exchange process
is analyzed in depth, both theoretically and practically,
in a way that is applicable to the needs of the industry.
CONCLUSION
In conclusion, the process of heat exchange in the
diluted layer is an integral part of industrial
technologies. This process is widely used in fields such
as chemistry, energy, pharmaceuticals, ensuring high-
efficiency energy transfer between materials and heat
carriers. Through an in-depth study of its theoretical and
experimental foundations, it will be possible to design
modern thermal systems, increase energy efficiency and
optimize technological processes.
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