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15Oriental Renaissance: Innovative, educational, natural and social sciences Scientific Journal Impact Factor Advanced Sciences Index Factor
VOLUME 2 | ISSUE 3 ISSN 2181-1784 SJIF 2022: 5.947 ASI Factor = 1.7
УДК 662.472:536.24
SOLAR HEATING MODE WITH FLAT REFLECTORS AND WATER
HEATING ACCUMULATOR
Sh.B. Imomov1, U.A.Hudaynazarov2, B.Sh.Xamdamov3.
1PhD in Engineering Sciences, 2 teacher, 3student, Karshi Institute of Irrigation and Agrotechnology of the National Research University "Tashkent Institute of Irrigation and Agricultural Mechanization Engineers" Karshi, Uzbekistan
imomov-shuhrat@rambler.ru
ABSTRACT
The modes of solar and additional heating of a building with a system of solar reflectors installed on the north side are given.
Keywords: building; northern orientation; reflectors, heating mode, insolation.
РЕЖИМ СОЛНЕЧНОГО ОТОПЛЕНИЯ С ПЛОСКИМИ РЕФЛЕКТОРАМИ И ВОДЯНЫМ АККУМУЛЯТОРОМ ТЕПЛА
АННОТАЦИЯ
Приведены режимы солнечного и дополнительного отопления здания с системой солнечных рефлекторов, устанавливаемых с северной стороны.
Ключевые слова: здания; северный орентация; рефлектори, режим обогрева, инсоляция.
INTRODUCTION
Currently, there is a wide variety of solar heating systems (SHS). The choice of a constructive solution for the SHS is determined by many factors: radiation and meteorological resources of the region, thermal and hydrodynamic and economic indicators. Both water and air SHS have positive and negative sides. The determining factor in the use of air SHS, for all their disadvantages, is their simplicity and low cost.
Standard heat loss Qf1 indoors are determined based on average long-term data:
QS = кЬг (st - С)Fozp ; (1)
where tfn and t^ - standard temperature of indoor and outdoor air, °C
As tnt a comfortable temperature is accepted tnt = 20 оС, tnt - average perennial outdoor air. Actual heat loss QIC indoors are determined by the formula [1]
Qa; (2)
Oriental Renaissance: Innovative, p VOLUME 2 | ISSUE 3
educational, natural and social sciences ISSN 2181-1784
Scientific Journal Impact Factor Q SJIF 2022: 5.947
Advanced Sciences Index Factor ASI Factor = 1.7
where phl- coefficient of actual heat loss:
p =( tn - C) / (tn - C) ; (3)
where taecx - actual outdoor temperature, 0C. The heating season starts on condition
a < QhC . (4)
The proportion of solar radiation relative to heat loss is determined by the replacement coefficient:
f= Qp / Qac. (5)
Coverage of heat losses in the room is provided by the intake of solar radiation and an additional heat source. Additional heating Qhe is determined by the condition of covering the actual heat loss and the receipt of solar radiation:
Qhe+Qp = Qac (6)
From here
Qhe = Kst (Qac - Qp); (7)
where Kst = 1.. .1,5 - safety factor.
With solar heating, heating mode is carried out intermittently. During the period of heat shortage (at tm <200 C), heating is provided due to the accumulated heat Qah and an additional heat source Q .
Heating period To consists of the battery life rde (detente) and the operating time of the additional heat source [2] zad:
The = Tde + Tad . (8)
The daily Tda heating operation mode is
The +Tpa = Tda = 24h ; (9)
where Tpa - pause when there is no heating, at tm > 200 C. Heating duration is expressed as a fraction of the daily period
Ydh =The /Tda (10)
The average daily heating capacity is determined from the equation
QaV = ThpQhe. (11)
From here
Qhae =/dhQhe (12)
To ensure a normal temperature in the room, the condition is necessary
Q-pa - Qav=Qac (13)
Oriental Renaissance: Innovative, educational, natural and social sciences Scientific Journal Impact Factor Advanced Sciences Index Factor
VOLUME 2 | ISSUE 3 ISSN 2181-1784 SJIF 2022: 5.947 ASI Factor = 1.7
Condition (13) can be used to determine the heating duration
Ydh =
Q,
av he
QZ - Qp
Qh
he
Qh
he
Vhßhi - Qp
Kz (Qac - Qp )
(14)
Accumulation time zat, excess heat from solar radiation, coincides with the period of no heating zpa.
In fig. 1 shows the average monthly daily room heating mode.
T, h
31 28 25 22 19 16 13 10 7
XI
XII
month, h
IV
X
I
II
Drawing. 1. Average monthly room heating mode: 1 and 2 - periods of the beginning and end of heating xhe; 3 and 4 - the period of the beginning and end of
heat accumulation rat
DISCUSSION AND RESULTS
Heating rhe is provided up to line 1 and above line 2 (heat deficit coverage). There is no heating zpa during the time between lines 1 and 2. This period is the of heat accumulation rat - the period between lines 3 and 4. The accumulation mode above line 4 is impractical, since after line 4, the accumulated heat is cooled prematurely.
1 mode. During the period of insolation, a large excess of solar radiation occurs and the air temperature in the room significantly exceeds the standard value tm >> tst = 200 C. Decrease of indoor air temperature to tSt ~20 0C provided with active aeration and ventilation of the room, as well as active accumulation of excess solar heat rah. At night, a short period of heat occurs and the room temperature drops below the standard value tm < t*t. Lack of heat at night zhn replenished only by heat Qa, accumulated in the daytime. This regime is observed in October and April.
497
Oriental Renaissance: Innovative, p VOLUME 2 | ISSUE 3
educational, natural and social sciences ISSN 2181-1784
Scientific Journal Impact Factor Q SJIF 2022: 5.947
Advanced Sciences Index Factor ASI Factor = 1.7
2 mode. During the period of insolation, there is an excess of solar radiation, the air temperature in the room exceeds the standard value tm > t*t. During this period, it is necessary to actively accumulate excess solar heat zah and ensure that the room temperature drops to t*n . At night, the resulting heat deficit reduces the room temperature below the standard value tm < t*t. Due to the heat accumulated during the daytime Qah and additional heat source Qhe its deficit at night is compensated t0. This regime prevails in November, February and March.
3 mode. During the period of insolation, there is no excess heat of solar radiation, the air temperature does not exceed the standard value tm < t*t. During the day, it is necessary to replenish the heat deficit To due to additional heat source Qhe. This regime is observed in December and January.
Рerimental studies show that after the maximum value of the air temperature at the outlet of the SC toc(after 13 h), as a result of the temperature drop toc, heat is transferred from the upper layers of the packing to the lower layers. Further, a general decrease in the heat accumulator temperature occurs, which leads to a premature cooling of the accumulated heat. On the basis of experimental data, it was found that the temperature of the air coming from solar collector in heat accumulator, falls below the maximum value toc (at 13 o'clock) by 87 ... 90% (at 14 ... 16 hours), further heat accumulation is ineffective as the mass-average temperature of the heat accumulator begins to drop. Fuel consumption for additional heating is determined by the formula
Bad = Qh ■ Kst /Qnhvk ; (15)
where Kst - fuel reserve factor equal to 1,1.1,2; Qnh - lower heat of combustion of fuel (natural gas) [3], kJ / m3; - efficiency of the heating installation, for gas fuel 0.8. Fuel savings due to solar heating are determined by the following condition:
Bs = Bhi - Bad ; (16)
where Bhl - fuel consumption for heat losses, m3
CONCLUSION
Fuel (gas) savings for the heating season is 58%. Electricity consumption for the operation of the fan for pumping air in the heating system is determined by the periods of accumulation xa and heating to, in accordance with formulas (8) and (9). With air flow in the system G = 0,17m3/ s = 612m3/ s = 612m3/ s; system pressure loss ZAP=110 Pa the installed power of the fan motor is Nins = ll8kWt. We accept
Oriental Renaissance: Innovative, educational, natural and social sciences Scientific Journal Impact Factor Advanced Sciences Index Factor
о
R
VOLUME 2 | ISSUE 3 ISSN 2181-1784 SJIF 2022: 5.947 ASI Factor = 1.7
axial fan VO 4M 300-220/50: performance G = 300...l650m3 /h , total pressure АР=110 Pa, rotation frequency n = 1340rev/min , engine power N = 0,l2kWt, with speed regulator. Electricity consumption for ventilation during the heating season is Wv = 490kWt• h/y. Energy consumption for ventilation accounts for 9.3% of solar and auxiliary heating energy.
REFERENCES
1. Виглин Е.С. Тепловой режим малоэтажных домов при периодичесом отоплении. //Системы вентиляции, отопления и теплоснабжения. -М.: 1985, №4, С.89-104.
2. Ш.Б. Имомов, В.Д. КИМ. Экспериментальное исследование теплового режима здания с системой рефлекторов, устанавливаемых с северной стороны. //Гелиотехника. -Ташкент: Фан, 2009, №2, С. 30-33
3. Теплотехнический справочник. Том 1. -М.: Энергия, 1975, -774 с.
