Investigation of Solar Collector Irradiated from Both Sides

I. Ziemelis, H. Putans and L. Kancevica

Research Institute of Agricultural Machinery, Latvia University of Agriculture,
Institute Street 1, LV–2130, Ulbroka, Riga region, Latvia
e-mail: Imants.Ziemelis@llu.lv; Liene.Kancevica@llu.lv

Abstract:

The ordinary flat plate solar collector receives solar radiation only from one side of its surface. Another side is covered with a heat barrier. The solar collector with reflectors has been developed and examined to track the sun. The absorber of this type of a collector was irradiated from both sides. The experimentally obtained energetic parameters of the collector tracking the sun have been compared to those of the ordinary flat plate solar collector. In order to complete the experiment, a special stand has been developed. The experimental investigation has been carried out at the intensity of radiation 2,000, 1,000 and 500 W m ^-2in different combinations. The temperature has been measured in certain points of different parts of the collector by several thermocouples. With the aid of a multi-meter, the obtained results were collected to the memory of a computer, and later processed and analyzed. When a collector surface is tracking the sun, the heat energy produced by the collector is 1.4 to 1.5 times higher in comparison with a stationary solar collector of the same size. A solar collector tracking the sun and irradiated from both sides depending on the reflection quality of the reflector’s material is able produce about 2.5 times more heat energy then a stationary flat plate solar collector irradiated only from one side.

Key words:

The comparative material investigations of solar collector

J. Palabinskis, A. Aboltins, A. Lauva and N. Karpova-Sadigova

Latvia University of Agriculture, Liela iela 2, Jelgava, LV – 3001, Latvia;e-mails: Janis.Palabinskis@llu.lv; Aivars.Aboltins@inbox.lv; Aigars.Lauva@inbox.lv;Nadezda.Karpova@llu.lv

Abstract:

The prices of energy resources used for grain drying are increasing year by year. In order to reduce costs, research into methods of saving energy in grain drying is in progress in the Research Laboratory of Grain Drying and Storing of the Faculty of Engineering, the LUA. Equipment for experimental research into the materials of solar collectors was built in the research laboratory for research purposes in 2005. The construction of the equipment allows for simultaneous comparative studies of two materials. The experimental data are metered and recorded in the electronic equipment REG. Cell polycarbonate PC (bronze, henceforth referred to as polycarbonate) with absorbers steel-tinplate and black-coloured wood was researched in comparison to the polyvinylchloride film (henceforth referred to as a film). The researches were made with different air velocities. The air heating degree ∆T in the solar collector is dependent on solar radiation I and air velocity v in the solar collector. In the experimental equipment, which is 1.5 meters in length, the air was heated to ∆T = 6°C at the velocity v = 0.5 m s-1.For theoretical investigation of the air heating power in solar systems the mathematicalmodel is applied; the solution can be used for estimation of different materials /absorbents/ and their heat source.

Key words:

air, film, material, polycarbonate, radiation, sun, temperature