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CALCULATION OF EFFICIENCY OF FLAT SOLAR COLLECTORS
Ismoilov Sherzod Gayratovich
Researcher
Islomov Otabek Urolovich
Leading specialist of “UNG training” LLC
https://doi.org/10.5281/zenodo.13751524
Abstract:
The article examines the energy efficiency of the solar water
heating collector. The operation procedure, elements and functions of the solar
water heating collector are described. The methodology and expressions for
calculating the energy efficiency of the solar water heating collector have been
developed.
Keywords:
solar water heating collector, energy efficiency, thermal energy,
energy efficiency of solar collectors, solar hot water systems.
Introduction.
The energy efficiency of solar collectors represents the
ability to convert solar energy into thermal energy. Solar collectors often
convert the sun directly into thermal energy, which offers somewhat lower
energy costs and environmental benefits. To calculate and evaluate the energy
efficiency of solar collectors, you can perform the following steps:
Solar collectors are used to heat industrial and household buildings, supply
hot water for production processes and household needs. The most production
processes that use hot and hot water (30÷90
℃
) together with domestic needs
occur in the food and textile industries, so we focus on the use of solar collectors,
its efficiency and resource saving. needed.
The solar collector is the main element of solar hot water systems [1-5].
Solar collectors are solar energy devices designed to absorb solar radiation
and convert it into thermal energy [6-9].
The efficiency of the heat and hot water supply system largely depends on
the efficiency of the solar collector. All structural features of any solar collectors
should allow maximum absorption of solar energy and minimum heat loss. The
more the collector system absorbs solar energy, the faster it converts this
radiation into heat energy, and the less heat is lost on the way to the heat
accumulator and the pipe to the consumer, the more efficiently this system
works [10-12].
Materials and methods.
A solar water heater (SWH) is a system designed
to capture solar energy and convert it into thermal energy for heating water.
This renewable energy technology can significantly reduce energy bills and
environmental impact compared to conventional water heating methods. Here’s
THEORETICAL ASPECTS IN THE FORMATION OF
PEDAGOGICAL SCIENCES
International scientific-online conference
52
a comprehensive guide on how solar water heaters work, their components,
benefits, and considerations.
Solar water heaters use solar energy to heat water through a collector. The
basic operation involves:
1.
Solar Collectors:
o
Flat-Plate Collectors: These are commonly used in residential
applications. They consist of a flat-plate absorber with a transparent cover to
trap sunlight and a heat-absorbing element.
o
Evacuated Tube Collectors: These collectors have multiple glass tubes
with a vacuum between them, which improves efficiency by reducing heat loss.
2.
Heat Transfer:
o
Direct Circulation Systems: Water circulates directly through the
collectors and into the storage tank. Suitable for areas with moderate freezing
risks.
o
Indirect Circulation Systems: A heat-transfer fluid (like antifreeze)
circulates through the collectors, transferring heat to the water in the storage
tank through a heat exchanger. Ideal for areas with freezing temperatures.
3.
Storage Tank:
o
A well-insulated tank stores the heated water, ensuring it remains hot
until needed.
4.
Controls and Valves:
o
Thermostatic Controls: Regulate water temperature and manage the
operation of the system.
o
Check Valves: Prevent backflow of water.
5.
Pumps (for active systems):
o
Circulation Pump: Moves water or heat-transfer fluid between the
collector and the storage tank.
The housing of flat solar collectors uses thermal insulation, reflective
coating of glass, solid wall, which ensures a long service life. They are simply and
reliably installed flat and on the roof, installed anywhere on the roof and
buildings [15-19].
The efficiency of the solar collector is the ratio of useful heat energy to the
incoming solar energy. In addition to thermal losses, in some cases optical losses
also occur in the device. The optical efficiency determines what percentage of
the radiation through the transparent coating reaches the collector and is
absorbed by the absorber.
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Results.
To evaluate the efficiency and design parameters of solar
collectors for a solar water heating system, we can use the given formulas. These
formulas help determine the collector efficiency, required collector area, and
potential fuel savings from using solar energy. Here’s a detailed explanation and
calculation process for each formula:
As a first approach, the efficiency of solar collectors can be calculated using
the following formula [8]:
η = η
0
−
k
𝚫𝐓
E
, (1)
where, η is the calculated value of FIK, %;
η
0
is the optical efficiency of the
device under normal conditions, %,
k
1
is a coefficient depending on the type of
collector and thermal insulation, ΔT is the temperature difference of the working
div and the ambient temperature,
℃
, E is insulation, W/m
2
.
The efficiency of modern solar collectors is expressed by the following
formula [20-22]:
η = η
0
− k
1
𝚫𝐓
E
g
− k
𝚫𝐓
𝟐
E
g
, (2)
E
g
- amount of total solar radiation falling on the collector, W/m
2
.
For a certain amount of hot water, we can calculate the working area of the
required solar collector using the following formula.
𝐀 =
𝟏,𝟏𝟔𝐆(𝐭
𝐜.𝐰..
−𝐭
𝐡.𝐰.
)
𝛈 ∑ 𝐠
𝐢
𝐢
, (3)
here, G – amount of water, kg;
𝐭
𝐜.𝐰..
, 𝐭
𝐡.𝐰.
-temperatures of cold and hot
water,
℃
;
∑ g
i
i
– the amount of total solar radiation falling on the surface of 1 m
2
per day, Wh/m
2
; η-energy efficiency solar collector.
It is also recommended to calculate the efficiency of solar collectors using
the following formula:
η = 0,8c {θ −
9U[t
1
+t
2
2−t
e
⁄
]
η ∑ g
i
i
}
, (4)
here, U is the loss coefficient, the passport characteristic of the solar
collector, W/m
2
·K; in the absence of passport data, 8 W/m
2
·K for single-glazed
collectors and 5 W/m
2
·K for double-glazed collectors can be obtained; t
1
and t
2
are temperatures of the working div at the inlet and outlet of the solar
collector,
℃
;
t
e
-ambient temperature,
℃
.
In case of uneven consumption of hot water by months in devices without
accumulator tanks, the calculation of the working area of solar collectors should
be carried out according to the value of daily consumption of hot water every
month and should take the largest part of the obtained working areas. Hourly
THEORETICAL ASPECTS IN THE FORMATION OF
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productivity of solar collectors g
i
, kg/m
2
is determined by the following 5
formulas [23]:
g
i=
0,86U
ln
tmaxi−t1
tmaxi−t2
, (5)
The equilibrium temperature of each hour
t
maxi
is determined by the
following formula
t
maxi
=
q
θi
U+t
ei
, (6)
q
θi
- absorbed solar radiation intensity, W/m
2
;
t
ei
– ambient temperature,
℃
.
The calculation of saving fuel resources due to the use of solar energy
should be carried out according to the following formula:
B = 0,0342
Q
сh
⁄
, (7)
where, Q is the total amount of heat Q, GDj/year, the amount of heat
produced in the solar collector during the year;
сh
– Efficiency of the modified
heat source.
Conclesuons.
When developing methods for calculating the efficiency of
solar collectors, take into account the meteorological characteristics of the area,
the amount of solar radiation, geographical latitude and albedo, insolation,
annual precipitation, ambient temperature, air humidity, absolute pressure,
cloud density, air dust level and aerosol amounts is appropriate.
These calculations provide a comprehensive approach to designing and
evaluating the performance of solar water heaters. Adjusting inputs and
formulas based on specific system parameters and conditions will yield accurate
and useful results.
References:
1.
Uzakov G.N., Toshmamatov B.M., Khusenov A.A., Nurmanov Sh.Kh.
Geothermal systems for autonomous heat supply of local facilities // Alternative
energy, 2021, T. 3. No. 3. P. 41-46.
2.
Toshmamatov B.M., Rakhmatov O.I., Valiyev S.T., Nurmanov Sh.Kh. Hybrid
heat power based on geothermal energy corrects heat-technical
parameters//Alternative energy, 2023, T. 9. No. 2. Pages 72-82.
3.
Uzakov G.N., Davlanov Kh.A., Toshmamatov B.M., Kamolov B.I. Analysis of
hybrid heating systems for residential buildings using renewable energy
sources//Alternative energy, 2023, T. 8. No. 1. P. 9-15.
4.
Uzakov G.N., Davlanov Kh.A., Toshmamatov B.M. Energy efficient systems
and technologies using alternative energy sources//Alternative energy, 2021, T.
1. P. 7-19.
THEORETICAL ASPECTS IN THE FORMATION OF
PEDAGOGICAL SCIENCES
International scientific-online conference
55
5.
Kudratov J., Toshmamatov B. Justification of heat-technical parameters of
hybrid heat and hot water supply system//European international journal of
multidisciplinary research
6.
and management studies. Volume 03 Issue 09. (2023).
7.
Toshmamatov B.M., Valiev S.T. Calculation of the parameters of the solar
heat supply system for a medical and health center. Alternative Energy. 2022. Т.
5. № 2. С. 26-34.
8.
Uzakov G.N., Davlanov H.A., Toshmamatov B.M.E. Energy-efficient systems
and technologies using alternative energy sources. Alternative Energy. 2021.
Vol. 1. Pp. 7-19.
9.
Uzakov G.N., Aliyarova L.A., Ibragimov U.Kh., Toshmamatov B.M. Study of a
combined water-air solar collector under laminar hydrodynamic conditions.
Alternative Energy. 2021. Vol. 1. Pp. 33-40.
10.
Toshmamatov B.M., Rakhmatov O.I., Mamedova D.N. The auger shaft
drumli pyrolysis kurilmasining samaradorligini baholash. Muqobil Energetika.
2021. Vol. 1. P. 73-79.
11.
Uzakov G.N., Davlanov Kh.A., Toshmamatov B.M., Kamolov B.I. Analysis of
hybrid heating systems for residential buildings using renewable energy
sources. Alternative Energy. 2023. Vol. 8. No. 1. P. 9-15.
12.
Uzakov G.N., Davlonov Kh.A., Toshmamatov B.M. Efficient methods for
processing municipal solid waste to obtain alternative fuels. Alternative Energy.
2021. Vol. 3. No. 3. P. 28-35.
13.
Toshmamatov B.M., Uzakova G.N. Analysis of the heat balance of a solar
installation for processing municipal solid waste. Alternative Energy. 2021. Vol.
3. No. 3. P. 36-40.
14.
Uzakov G.N., Toshmamatov B.M., Khusenov A.A., Nurmanov Sh.Kh.
Geothermal systems of autonomous heat supply of local objects. Alternative
energy. 2021. Vol. 3. No. 3. P. 41-46.
15.
Toshmamatov B.M., Rakhmatov A.R., Valiev S., Safarova S.U., Boyitova A.
Analysis of air conditioning schemes based on evaporative air cooling using
solar energy. Alternative energy. 2022. Vol. 5. No. 2. P. 11-15.
16.
Toshmamatov B.M., Valiev S.T., Boyitova A.O. Calculation of changes in the
parameters of the conditioned air state in energy-saving two-stage evaporative
air cooling systems. Alternative Energy. 2022. Vol. 5. No. 2. P. 77-85.
17.
Sattorov B., Davlonov Kh., Toshmamatov B. and Arziev B. Increasing
energy efficiency combined device solar dryer-water heater with heat
accumulator. BIO Web of Conferences , 71 024 71 024 (2023)
THEORETICAL ASPECTS IN THE FORMATION OF
PEDAGOGICAL SCIENCES
International scientific-online conference
56
18.
B. Toshmamatov, I. Kodirov and Kh. Davlonov. 2023 Determination of the
energy efficiency of a flat reflector solar air heating collector with a heat
accumulator. E3S Web of Conferences 402, 05010.
19.
B. Toshmamatov, S. Shomuratova, S. Safarova. 2023 Improving the energy
efficiency of a solar air heater with heat accumulator using flat reflectors. E3S
Web of Conferences 411, 01026.
20.
Toshmamatov B.M., Shomuratova S.M., Mamedova D.N., Samatova S.H.Y.,
Chorieva S. 2022 Improving the energy efficiency of a solar air heater with a heat
exchanger – Accumulator. 1045(1), 012081.
21.
Toshmamatov B, Davlonov Kh, Rakhmatov O, Toshboev A 2021 Recycling
of municipal solid waste using solar energy IOP Conf. Series: Materials Science
and Engineering 1030 012165. doi:10.1088/1757-899X/1030/1/012165.
22.
Aliyarova L A, Uzakov G N, Toshmamatov B M 2021 The efficiency of using
a combined solar plant for the heat and humidity treatment of air IOP Conf.
Series: Earth and Environmental Science. 723 052002. doi:10.1088/1755-
1315/723/5/052002.
23.
G N Uzakov, S M Shomuratova and B M Toshmamatov 2021 Study of a
solar air heater with a heat exchanger – accumulator IOP Conf. Series: Earth and
Environmental
Science.
723
(2021)
052013.
doi:10.1088/1755-
1315/723/5/052013.
24.
T A Faiziev and B M Toshmamatov 2021 Mathematical model of heat
accumulation in the substrate and ground of a heliogreenhouse IOP Conf. Series:
Earth and Environmental Science. 723 032006. doi:10.1088/1755-
1315/723/3/032006.
