Solar Collectors – more details
The vacuum tube solar collectors – represent a non-electric water heater using solar energy. They are established by 12 parallel-arranged SC-tubes in the so-called solar collectors. Each one of these tubes is insolated by the means of double tube, fabric vacuumed between the layers. On the inside of glass tube is applied a selective coat that caches the solar radiation.
The CAU 12 solar collectors are direct-instantaneous type. It means that the coolant in the installation – water or antifreeze, usually in a solution of propylene glycol – is heated directly in copper tubes, placed in the solar collector’s vacuum tubes.
The inlet pipe goes in a collector, to which are brazed 12 copper tubes with welded on them aluminum absorber in the shape of a double X. In their lower end through a copper U-knee, the copper tubes are brazed to another 12 copper tubes, which are respectively brazed to the outlet tube’s collector. These tube couples are placed inside the vacuum tube. The dihedral vacuum tubes are made of borosilicate glass (resistance to hail with grains size up to 25 mm.) with applied selective coating.
The coating is respectively applied on the inside and the outside wall of the inlet glass tube. The factory vacuum guarantees it’s long life – to 25 years. The whole construction of collectors and pipes is installed on a frame made of stainless steel. Replacement of a damaged glass tube does not affect the work of the whole system and it can be made easily. The pipe construction provides minimal wind load.
Because of its unique heat exchanger shape – U-pipe with double X absorber – the CAU collectors can be installed under any angle to horizon. Therefore they don’t need a reflector and don’t need to be cleaned from snow and they barely keep dust. They can be also installed on well lit by the sun wall, maximum near the boiler.
Their major advantage over the other offered type collectors (heat pipe) is that in case of a breakdown of the circulator pump the coolant in them is evaporating, passes through the system’s safety valve and in the vacuum tubes remain only dry copper tubes, that can’t be damaged. Also their higher CPA – the measured power of one CAU 1 collector has reached 1,95 kW in effective area of the collector 1,92 m2.
