Apricus Tech Area

tech-area

The Apricus solar collector is designed to provide a high solar thermal conversion across both domestic and commercial applications.

The evacuated tube technology enables solar energy to be absorbed and converted into heat for water heating. The Apricus collectors use a “twin-glass tube” due to its excellent reliability and efficiency. Each evacuated tube consists of two glass tubes made from extremely strong borosilicate glass. The outer tube is transparent allowing light rays to pass through with minimal reflection. The inner tube is coated with a special selective coating (AI-N/AI) which features excellent solar radiation absorption and minimal reflection properties. The top of the two tubes are fused together and the air contained in the space between the two layers of glass is pumped out while exposing the tube to high temperatures. This “evacuation” of the gasses forms a vacuum, which is an important factor in the performance of the evacuated tubes.

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Why a vacuum?

As you would know if you have used a glass lined thermos flask, a vacuum is an excellent insulator. This is important because once the evacuated tube absorbs the radiation from the sun and converts it to heat, we don’t want to lose it!! The vacuum helps to achieve this. The insulation properties are so good that while the inside of the tube may be 150oC / 304oF , the outer tube is cold to touch. This means that evacuated tube water heaters can perform well even in cold weather when flat plate collectors perform poorly due to heat loss (during high Delta-T conditions)

Evacuated Tube Basic Specifications

Length (nominal)

1500mm /1800mm

Outer tube diameter

58mm

Inner tube diameter

47mm

Glass thickness

1.6mm

Thermal expansion

3.3×10-6 oC

Material

Borosilicate Glass 3.3

Absorptive Coating

Graded Al-N/Al

Absorptance

>92% (AM1.5)

Emittance

<8% (80oC)

Vacuum

P<5×10-3 Pa

Stagnation Temperature

>200oC

Heat Loss

<0.8W/ ( m2oC )

Maximum Strength

0.8MPa

To learn more about the application of the Apricus solar collectors please select from the menu on the left hand side.