You May Also Be Interested In:
All glass evacuated tubes are the key component of solar collectors. The evacuated tube is similar to a conventional Dewar flask and consists of two borosilicate glass tubes, a glass with high chemical and thermal shock resistance. The outer side of the inner tube is coated with a sputtered solar selective surface. This coated inner tube is closed at one end and sealed at the other end to the outer tube. The annular space between the outer tube and inner tube is evacuated to virtually eliminate heat loss by conduction and convection.
Sunna developed the rotary three-layering magnetron sputtering technology and used it to produce Double M-ALN cermets coatings tube which has the advantages of highest thermal efficiency(0.96) , lowest emittance rate(<=0.05/200) and working effectively in the high temperature(350-4000) in contrast to the normal selective coating evacuated tube. The corresponding film structure is ALN / M-ALN (LMVF) / M-ALN (HMVF) / Cu.
LMVF: Low Metal Volume Fraction.
HMVF: High Metal Volume Fraction
1. Absorption layer
2. Ceramic anti-reflection
3. Metal infrared reflector
Advantages over normal vacuum glass tube:
1) Higher heat efficiency: 12% higher heat absorbent ratio than normal vacuum tube.
2) Resisting ageing and attenuation: Normal vacuum tube could have problems such as film ageing and attenuation under high temperature exposure(250 degree Celsius) for a long time while the three- target vacuum tube can endure high temperature of 400 degree Celsius, therefore the service life can be significantly prolonged.
High solar-thermal conversion and low heat loss
Stable advanced coating up to 3800
Long time warranty to 15 years
High level vacuum ensure operation under cold weather