ОБРАЗОВАНИЕ НАУКА И ИННОВАЦИОННЫЕ ИДЕИ В МИРЕ
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RESULTS OF PRACTICAL EXPERIENCE OF HEATING A GREENHOUSE
VIA SOLAR WATER HEATING COLLECTORS WITH VACUUM TUBES
(IN KARSHI CITY CONDITIONS)
Toshboev Abdimalik
https://orcid.org/0009-0005-2139-2861
Assistant, Karshi State Technical University
Sultanov Samandar
https://orcid.org/0009-0009-6593-6671
PhD student at Karshi State Technical University.
Sohibov Medxun
https://orcid.org/0009-0007-6557-9948
Master's student at Karshi State Technical University.
Annotation
This article calculates the heat load required to maintain the internal temperature
of the greenhouse and analyzes the possibilities of heating a greenhouse using solar
water heating collectors with vacuum tubes under conditions of external temperature
fluctuations. The article uses as a basis the model of a greenhouse with an area of 50
m², covered with glass.
Keywords:
greenhouse heating, solar energy, evacuated tube collector, solar
water heater, alternative energy sources, practical experience results, thermal
efficiency, environmentally friendly heating method, solar collector system, energy-
saving technology.
In Uzbekistan, year-round cultivation of vegetables and other products in
greenhouses uses artificial heat sources. Compared to traditional fuels, the use of solar
energy can reap environmental and economic benefits, especially through the use of
vacuum tube solar collectors.
ОБРАЗОВАНИЕ НАУКА И ИННОВАЦИОННЫЕ ИДЕИ В МИРЕ
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In winter, there is a need for an efficient source of heat to maintain a greenhouse
microclimate. Solar energy is important as a renewable and cost-effective source. In
order to determine the efficiency of vacuum tube solar water heating collectors under
real conditions, an experiment was carried out in Karshi.
Experience Conditions
Date: February 22, 2025- Location: Karshi city, Kashkadarya region- System:
vacuum collector with 20 pipes, capacity 200 liters- Time: from 09:00 to 15:30-
Outside temperature: 6 °C → 23 °C- Water temperature: 20 °C → 51 °C- Solar
radiation: 342 → 970 W/m² (mixed cloudy and sunny conditions)
Table of experiments (main observations)
Time
External
temperature (°C)
Water
temperature (°C)
Solar
radiation (W/m²)
9:00
6
20
342
9:30
7
22
480
10:00
8
25
627
10:30
9
28
729
11:00
10
30
645
11:30
13
33
860
12:00
17
35
820
12:30
18
38
650
13:00
18
39
400
13:30
18
42
650
14:00
20
44
845
14:30
23
49
970
15:00
22
50
560
15:30
21
51
710
ОБРАЗОВАНИЕ НАУКА И ИННОВАЦИОННЫЕ ИДЕИ В МИРЕ
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Calculation of energy harvest
Thermal energy collected through water (during the whole experiment):
Formula:Q = m · c · ΔTm = 200 kgc = 4186 J/kg·°CΔT = 51 - 20 = 31 °CQ = 200 ×
4186
×31
=
25,951,200
J
≈
7210
Wh
=
7.21
kWh
Result: During the experiment, 7.21 kWh thermal energy was collected.
Correlation with expected energy
Average
solar
radiation:
745
W/m²
Collector area: 2 m²Working time: 6.5 hours
Q = 2 × 745 × 6.5 ≈ 9.67 kWh
Actual:
7.21
kWhTheoretical
maximum:
9.67
kWh
Efficiency: (7.21 / 9.67) × 100 ≈ 74.6%
Figure 1 Solar Water Heating Collectors with Vacuum Tube
Calculation of greenhouse heat load
Heat loss of a greenhouse is calculated by the following formula:
ОБРАЗОВАНИЕ НАУКА И ИННОВАЦИОННЫЕ ИДЕИ В МИРЕ
https://scientific-jl.org/obr
Выпуск журнала №-71
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Q=U
⋅
A
⋅
ΔT
here:
•
Q is heat loss (W),
•
U is the total coefficient of thermal conductivity (W/m²· K),
•
A— heat-conducting level of the greenhouse (m²),
•
ΔT is the temperature difference (K) between the inside and outside.
Information
:
•
Greenhouse area: 50 m²
•
Average height: 2.5 m → Volume ≈ 125 m³
•
Surface area (wall + roof): approx. 130 m²
•
Glass (window) surface: 100% → U=5.7U = 5.7U=5.7 W/cu· K (U-value
of a normal window)
•
Internal temperature: +20 °C
•
External temperature: from +5 °C to −5 °C
Calculations:
External
temperature
(°C)
ΔT
(K)
Q(W)
+5
15
5.7×130×15=111155.7
×
130
×
15
=
111155.7×130×15=11115 W
0
20
5.7×130×20=148205.7
×
130
×
20
=
148205.7×130×20=14820 W
−5
25
5.7×130×25=185255.7
×
130
×
25
=
185255.7×130×25=18525 W
Thus, when the outside temperature drops to −5 °C, the greenhouse heat load
reaches 18.5 kW.
ОБРАЗОВАНИЕ НАУКА И ИННОВАЦИОННЫЕ ИДЕИ В МИРЕ
https://scientific-jl.org/obr
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FIGURE 2:
Solar Greenhouse Heat
Conclusion
This experiment from Karshi showed that 200 liters of water was heated to
31°C in 6.5h and 7.21kWh of energy was collected. Even in partially cloudy weather,
the collector was able to generate enough heat. These results provide a practical
justification for the use of such collectors for heating greenhouses
It is evident from calculations that a greenhouse with an area of 50 m² can
be heated using solar water heater collectors with vacuum tubes. The main advantage
of the system is environmental friendliness and low operation costs. The initial
investment, while high, has long-term cost-effectiveness.
References.
1.
Uzoqov G‘.N., Davlonov X.A. Gelioissiqxonalarning energiya tejamkor isitish
tizimlari. Monografiya, - T.:”Voris”, 2019 - 144 bet.
2.
Узаков Г.Н., Давлонов Х.А., Узакова Ю.Г. Устройство для отопления и
топливо снабжения теплиц. Патент Р. Уз., 2019 г.
3.
QAYTA TIKLANADIGAN ENERGIYA MANBALARI ASOSIDA MOBIL
UYLARNING ENERGIYA TA'MINOT TIZIMLARINI PARAMETRLARINI
SS Yamgirovich, DX Allamurotovich, SM Islom O'g'li… - INTELLECTUAL
EDUCATION TECHNOLOGICAL …, 2024
4.
ОБРАЗОВАНИЕ НАУКА И ИННОВАЦИОННЫЕ ИДЕИ В МИРЕ
https://scientific-jl.org/obr
Выпуск журнала №-71
Часть–7_ июня–2025
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2181-
3187
Sohibov M I, AE Abdixomid o'g'li - academia.edu
5.
Toshboyev Abdimalik, Arziyev Bakhrom, & Sokhibov Medkhun. (2023).
CENTRAL ASIA WITH DIVERSE TOPOGRAPHY AND HYDROLOGIC
CONDITIONS, HYDROPOWER POTENTIAL.
European International Journal of
Multidisciplinary Research and Management Studies
,
3
(11), 151–156. Retrieved from
https://inlibrary.uz/index.php/eijmrms/article/view/26869
