Introduction to Flat Plate Collectors:
Flat-plate collectors are a very helpful device for low to medium temperature heat collection from the sun. They can be used for a lot of uses including a variety of thermal desalting process from low to medium capacities. Flat-plate collectors enclose simple characteristics: they are simply assembled, and effortlessly operated.
The plan of any system that shifts solar radiant power into thermal energy is the sensible application of the thermal energy itself. Solar Thermal Energy application can be able to direct as heat or indirect by using the heat to force a heat engine to produce useful mechanical energy or to use the thermal energy for electrical energy production. For this cause unique devices are used called solar thermal collectors. The principle of a solar thermal collector is to absorb the radiant energy of the sun and to convey the significant heat to a fluid which in turn relocates the thermal energy to the place of relevance. In familiar, solar collectors are classified according to their thermal output temperature which establishes also the field of their application.
For solar applications to be suitable, this transport headed for a lower temperature stage is important. While high-priced high concentrating solar systems are essential to generate quantities of steam or oil with temperatures of more than a few hundred degree Celsius, temperatures below 150°C can be created by high efficiency standard collectors without or with just low concentration of the solar radiation.
Flat-plate collectors are planned for applications require low to moderate temperatures in general up to 110°C higher than ambient temperatures. The simplest flat plate collectors are the solar ponds and the solar stills which function by direct utilization of the incident solar radiation acting simultaneously as solar energy converters. The importance of flat-plate collectors is that their thermal performance.
Solar Collector Applications
Solar collectors are very popular for setting up in a region where there are high irradiation intensities and clear sunshine days. They can be installed simply in individual houses for domestic hot water, in hotel buildings and in municipal installations, such as athletic centres for hot water use and for heating swimming pools.
Huge mercantile installations with high capacity are used in industry to produce process water or, in solar desalination plants to produce moderate temperature water, as feed to low or medium temperature distillation plants. In general they are useful tools for hot water production.
The higher temperatures required which will be achieved by the minimisation of the collector U-value (Heat loss coefficient). It is in the nature of the things that this minimisation of the U-value which increases the stagnation temperature. Solar Thermal Collectors which are used in thermal process heat applications (Range: up to 150°C), must reach stagnation temperatures greater than 300°C. So all the parts of the thermal collector such as selective absorber coatings for the black absorber medium, insulation materials for the backside of the absorber have to be able to endure high temperatures.
In addition to thermal radiation losses the air inside the collector, consistently at atmospheric pressure, is transferring energy primarily by convection as well as by conduction. Hence the collectors itself have to be insulated against the surroundings. Likewise the Back side of the collector also insulated with a variety of temperature and humidity resistant thick materials offered on the market, the front of the collector is more awkward since it is out in the open to solar radiation. Transparent insulation materials in addition high transmittance for solar radiation with low heat conductance are required to achieve more temperature.