Traditionally, teplopriёmniki solar heating systems are strictly directed south orientation. Since teplopriёmniki are integral architectural and structural parts of the building, in many cases, urban planning, architectural, and other relief. Reasons, the southern orientation of the building itself, or teplopriёmnika not always possible.
The use of flat reflectors installed on the north side of the building, to extend the capabilities and uses of solar energy, increase the density of solar radiation in the plane teplopriёmnika [1].
To determine the thermal balance and thermal regime of the building + reflectors, pre-installed:
1) radiation and shadow modes of flat reflectors [2];
2) the thermal efficiency of the system and eksergeticheskaya flat reflectors [1, 3];
3) The model is composed of the heat balance of the building + reflectors.
In drawing up the heat balance, the following conditions:
- Interacting components: the internal and external air, the building envelope, the system of flat reflectors;
- The impact of interior space on the heat balance is not considered;
- The walls, the ceiling, the floor is considered as a multi-layered windows and doors — both single-walled enclosures;
- The walls, combined with control and tambour premises are treated as multi-fencing with an air gap;
- With respect to the environment is seen as building a stand-alone object.
In general, the heat balance of the space is defined by:
Qпг = Qтп; (1)
where Qпг — total absorbed heat of solar radiation entering the room, W;
Qтп — total heat loss in the room watts.
The total solar radiation, which took place in the premises:
Qпр = Qпр4 + Qпр5. (2)
Суммарная солнечная радиация, поступающая через окно Qпр5 and svetoproem Qпр3, It is given by:
Qпр5 = (Sпр5 + Dпр5) F5; Qпр3 = (Sпр3 + Dпр3) F3; (3)
where Sпр and Dпр — density held direct and diffuse solar radiation W/м2; F5 and F3 — the surface area of the glass window and svetoproema m2.
Direct solar radiation in svetoproem comes from reflectors:
Sпр3 = Sпр0 + 2 Sпр1 sinг; (4)
where Sпр0, Sпр1 — direct solar radiation, coming from the middle and right + left reflectors, W/м2; г- The angle of incidence to the plane of the heat, hail.
Solar radiation entering the room, and is absorbed by the inner surfaces of the heat receiving:
Qпг5 = Апр Qпр5; Qпг4 = Ат Qпр3; (5)
Апр — reduced coefficient of absorption of solar radiation by internal surfaces of the room; Ат — Absorption coefficient of solar radiation heat receiving.
The total heat loss in a room:
Qтп = Qто + Qв; (6)
where Qто — heat loss through the fence, W; Qв — heat loss by infiltration of air watts.
The use of reflectors installed on the north side of the building, provides an increase in the density of solar radiation in the plane teplopriёmnika in 1.7–2 times.
The temperature regime of the premises considered in the period of least solar radiation (averages for December 19–22, 2009) and the period of the lowest outdoor temperature (20–23 January 2010) in terms of Karshi. In the period from 10–11 hours to 15 hours and the room temperature is higher than the standard value ti = 20 ° C. During this period it is necessary to accumulate excess heat of solar radiation. Study room temperature in the building + reflectors allows to predict the effectiveness of the system of reflectors installed on the north side of the building during the heating season.
References:
1. Imomov Sh.B, Kim V.D, Khayriddinov B. E. Thermal efficiency of flat reflectors installed on the north side of the building, passive solar heating systems // Solar technology. -T.: Fan. 2003. № 4, p. 39–44
2. Imomov Sh.B, Kim V.D, Khayriddinov B. E. Shading flat reflectors to passive solar heating systems. // Solar technology. 2003. № 2. p. 50–53.
3. Imomov Sh.B. Exergy efficiency of the system of flat reflectors installed on the north side of the building. //Science, Development and Youth. Scientific-practical conference materials. Karshi-2008. Nasaf, c. 245–247.
