Solar water heating systems using vacuum tubes made of borosilicate glass with special coating to absorb the solar energy are called as Evacuated Tube Collector system (ETC Systems).
Vacuum tube, as shown in the sketch, is the main component, which absorbs solar energy. The vacuum tube is an assembly of two concentric, borosilicate glass tubes.
Air between the gap of two glass tubes is evacuated. It results in high level of vacuum, which acts as the best insulation to minimize the heat loss from inner tube. The black coating on the inner tube absorbs the solar energy and transfers it to the water. The water on upper side of Vacuum Tube becomes hot and thus lighter, so it starts moving upwards in the tank. At the same time cold water, which is heavy, comes downward from the tank and is stored at the bottom. The phenomenon is called as natural thermosyphon circulation, which occurs in every tube.
Why MACHINOCRAFT ETC Systems
- 3 target magnertron sputtering plating
- Efficiency more than 94%
- Tube length 58mm x 1800mm
- Inner tank 0.5mm SS 304
- Outer cladding SS 304
- PUF insulation
- SS Frame
TECHNICAL
DETAILS
Structure
All glass double tube co-axial structure
Glass Material
High Borosilicate 3.3
External pipe diameter and thickness
58mm / 1.6mm
Internal pipe diameter and thickness
47mm / 1.6mm
Pipe Length
1800mm
Absorptive coating method
3 target magnertron sputtering plating
Specific absorption
>94%
Emittance
<6%
Average heatloss
<0.6W/(m2’C)
Vacuum degree
P<5*10-3Pa
Inner tank
0.5mm SS 304
Outer cladding
SS 304
Insulation
PUF
Frame
SS
Advantages of ETC systems
- Suitable for hard water and Corrosion free
- Less maintenance
- Min life 15yrs
