Solar Vacuum Heat Collector Tube

Product Description

One of the best solar inventions ever, the solar vacuum heat collector tube developed by researchers at the University of Sydney, is the most efficient absorber of radiant energy on the market. These tubes do their daily job as solar water heaters on the roofs of hundreds of thousands of homes. Consisting of a strengthened borosilicate glass tube with double walls, the area between the inner and outer walls are evacuated . This acts as a thermos to keep heat from escaping into the atmosphere via conduction and convection .  The glass is strong and can withstand impacts of 25 mm hail stones.

While the outer wall is fully transparent to allow solar energy to easily pass through, the inner layer is treated with a selective black optical coating that absorbs IR radiation with minimal reflection .  As the tubes are round, they act as passive tracking solar collectors, maximizing their performance. These properties allow the tube to transfer radiant heat to water even on overcast days with subdued sunlight. 
In full sunlight pasteurization temperatures (65 °C +) can be reached in less than an hour and water should boil in 90 minutes.

We have had these shorter tubes specially made as they are much easier and safer to handle than the longer commercial tubes. Now teachers can visibly demonstrate the high levels of radiant energy available to us.

Size: 58 mm (outer diam.) x  0.5 m    [Inner diam. 44 mm]   Tube holds 650 ml water.

Teach:  Conduction, convection, absorbance, radiation, renewable energy, thermal energy, IR radiation. 
These tubes are tough enough for use in classroom demonstrations. Set one up in the sun and record the temperature increase in one class period.  On a sunny day the water should boil before the end of a double period, but with a reflective surface such as the Aussie Solar Cooker below it, the water will boil in 50 minutes. See video below. Even on overcast days you will get a dramatic temperature increase pointing at the presence of IR radiation.  Students can calculate the amount of radiant energy supplied by the sun, using  Q = mcΔt  Then measure the glass surface area exposed to the sun and determine the sun's radiance per sq m.   An invaluable resource to any school science lab.

Age: 12+ with adult supervision (glass & hot water!)
Indicated price is for one 0.5 m tube.

The standard application of these tubes are for solar radiant heat collection for domestic hot water use. A copper pipe is inserted down the glass tube and this conducts heat to a header area where heat energy is exchanged with the cold water. If you would like to purchase a complete DIY highly efficient solar water heating system, then we recommend you contact UltimateSolar in Melbourne. The photo below is UltimateSolar's twenty 1.8 m tube system with 165 l water storage tank.