Tube collectors have an empty glass tube as absorber and are therefore also called vacuum tube collectors. The vacuum reduces the heat losses, so that this type of collector achieves a higher degree of efficiency.
HL 314 can be used to demonstrate the principal aspects of solar thermal domestic water heating in a system with components used in real world applications. Radiant energy is absorbed and converted into heat in a commercially available evacuated tube collector. Heatpipes located inside the absorbers enable heat transfer to a heat transfer fluid in the solar circuit. Subsequently another heat exchanger feeds the heat into the hot water circuit and into the storage tank. A solar controller controls the pumps for the hot water and solar circuits. The solar circuit is protected by an expansion tank and a safety valve. The trainer has been designed so that it is possible to carry out a complete preheating as part of a practical experiment.
The temperatures in the storage tank, at the outlet from and the inlet to the collector are measured, as is the flow in the solar circuit. The measured values are recorded via the integrated data logger. Additionally, as in practice, the temperatures of the inlet and return are displayed on the solar circulation station.
The solar controller is operated via an integrated WLAN router. The user interface can be displayed on any number of terminals via a web browser. Different user levels with different functions can be selected. A LAN/WLAN connection with the local network allows the evaluation of the recorded measured values on a PC. An additional producer software of the solar controller is supplied for this purpose.
In order to ensure there is sufficient illuminance, the system should be operated with solar radiation or the optionally available HL 313.01 Artificial light source.