Flat-Plate Collectors
A flat-plate collector (FPC) is a device to collect solar energy and transform it into thermal energy (low-grade energy) by using water as a working fluid. It is a heart of solar thermal devices that has many applications in a medium temperature range ≅10
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Flat-Plate Collectors
Abstract A flat-plate collector (FPC) is a device to collect solar energy and transform it into thermal energy (low-grade energy) by using water as a working fluid. It is a heart of solar thermal devices that has many applications in a medium temperature range ≅100 °C from domestic to preheating to industrial sectors. The hot water available from flat-plate collectors (FPC’s) can be also used to conserve fossil fuel.
Keywords Solar thermal collectors PVT-FPC water collectors Thermal losses Instantaneous efficiency
5.1
Fin efficiency
Introduction
Solar radiation is considered to be in the form of electromagnetic waves as well as photon-carrying energy ðhmÞ. Solar energy can be used broadly by three technological processes, namely: (i) Heliochemical: This process maintains life on Earth by producing food and converting CO2 from the atmosphere into O2 using photons through the process of photosynthesis, i.e., light and dark reaction. (ii) Helioelectrical: In this process photons are used in a semiconductor to produce electricity (Chap. 4); these are known as “photovoltaic converters.” They provide power for many applications including spacecraft. (iii) Heliothermal: This process can be used to provide much of the thermal energy required for solar water/air heating and building heating. It is also referred as a “solar thermal system.” The most important part of the solar thermal system is the flat-plate collector (FPC), which will be discussed in this chapter.
© Springer Science+Business Media Singapore 2016 G.N. Tiwari et al., Handbook of Solar Energy, Energy Systems in Electrical Engineering, DOI 10.1007/978-981-10-0807-8_5
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5.2
5 Flat Plate Collectors
Flat-Plate Collector
The FPC is the heart of any solar energy‒collection system. It is designed for operation in the medium temperature range between 60 and 100 °C. It is used to absorb both the beam and the diffuse solar radiation (Chap. 1) after transmission from the glass cover. The absorber converts it into thermal energy (heat) and then transfers the absorbed thermal energy (heat) into a stream of liquid or gas (Fig. 5.1a). In the present case involves water. It does not require tracking of the Sun. It requires little operation and maintenance. A conventional FPC generally consists of the following components, namely: (a) Glazing: This is transparent material for the short wavelength range (0.23–2.6 μm) and opaque for the long wavelength range ≥2.6 μm. The number of transparent materials used can be more than one (Fig. 5.1a) (b) Tubes and fins: The fluid is allowed to pass through tubes and fins for conducting or directing the heat transfer from absorber to the flowing fluid (Fig. 5.1b).
Fig. 5.1 a Side cross–section view of single glazed flat-plate collector. b Front and cut view of glazed flat-plate collector
5.2 Flat-Plate Collector
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(c) Absorber plate: This is a blackened conducting flat plate, corrugated or grooved, with tubes and fins for the absorption of short-wavelength solar radiation (Fig. 5.1b). (
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