Types of solar collectors
The solar thermal collectors are devices capable of capturing solar radiation and sending a fluid, for later use
The solar collectors are divided into two main groups:
1. Solar Collectors without concentration: They do not exceed the 70 ° C, so they are used in applications of low temperature. An example of an application would be producing hot water.
2. The Solar Collectors with concentration: Are the ones that using the methods of concentrating optics, are capable of raising the fluid´s temperature over 70 ° C. These are applied in the solar thermal medium and high temperature. We can find examples of these solar thermal plants in Almeria (Spain), Grenoble (France) and California.
1. Solar Collectors without concentration
These collectors are characterized by not having methodic concentration of solar energy, so that the relationship between the collector and the surface is almost the absorption unit.
- Flat plate solar collector:
Generally flat-plate collector acts as a receptor that gathers energy from the sun and warm up a plate. The energy stored in the plate is transferred to the fluid. Usually, these collectors have a transparent cover glass or plastic taking advantage of the greenhouse effect, consisting of a series of copper tubes, which exposed to the sun absorb solar radiation and it is transmitted to the fluid passing through its interior. Its application is the production of hot water, air conditioning and heating of swimming pools.
Its main feature is to have the air as a heat carrier fluid. They have a maximum temperature limit (convection processes have a minor influence on the air) and work better for a normal road, but in contrast with a low heat capacity and the process of heat transfer between plate and the fluid is bad. Its main application is the heating.
Those have a double deck envelope, sealed, insulated inside and outside. Its aim is to reduce losses due to convection. They are more expensive, in addition to losing the effect of vacuum with the passage of time. Its main application is the production of sanitary water, heating pools and air conditioning.
They have a cylindrical symmetry, consisting of two concentric tubes; A glass exterior and one interior painted with black paint or selectively. The fluid flows through the internal tube. Its main application the heating.
- Conical or spherical Collectors:
Its main feature is that the unit simultaneously captures and storages. Its receiving area is conical or spherical with a cover glass in the same geometry. With these geometries it ensures that the surface gets illuminated throughout the day, in the absence of shade, is constant. The installation is very simple, but there are problems with the stratification of water and the receiving surface is small. Its main application is the production of hot water through solar energy.
2. Solar Collectors with concentration:
These use special systems in order to increase the intensity of radiation on the absorbing surface and thus achieve high temperatures in the heat carrier fluid. The main complication is the need for a monitoring system to ensure that the collector is permanently oriented towards the Sun.
Cylindrical Switch: Its surface reflector is half a cylinder. Its main application is the production of steam at thermal power stations
Switch paraboloids: Its surface reflector has the geometry of a paraboloid, Its main application is the production of steam at a thermal power station.
Once again we see that solar energy is beneficial to all. |
