New solar testing rig – made possible by our super accurate heliostatsPosted: Sunday, 26th August, 2012
There’s a new experimental rig on top of Solar Tower 2 – and it gives CSIRO the ability to do something unique.
This slot-shaped device, shown above, is a way for us to test new components for use in solar receivers. We can install a component for testing into the insulated cavity, illuminate it with concentrated solar energy using our heliostat field, and take accurate measurements of how well the new component operates.
We gave it its first field test a few weeks ago and it performed well. We brought the temperature of the tube we were testing up to 1000°C in a controlled way, monitored the way it transferred heat to air passing through it, and then let it cool again.
Why is this so great? It’s because now we have a facility that can test components or materials at very high temperatures under very controlled conditions. Few other solar fields – or indeed any other type of facility – in the world can do this.
The reason we’ve been able to is because our heliostats can focus more tightly than most, and because our computer control system has smart and accurate control over where the mirrors point. This allows our mirrors to ‘paint’ onto the object a given pattern of light as requested by the experimenters.
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Previously, to carry out experiments like ours, researchers have had to find some other way to mimic the heating effect of hundreds or thousands of ‘suns’ – no mean feat. There are two types of approach to this problem.
The first is to build a ‘solar simulator’ – a collection of (usually) xenon arc lamps whose light is focused into a super intense beam by mirrors. (Xenon lamps are the type used to make the tower of light at the Luxor Casino in Las Vegas, which draws nearly 280 kW of power.) A solar simulator can deliver a high intensity of radiation, with a spectral distribution similar to the sun, over a small area. The German Aerospace Agency DLR, for example, has one about a quarter the power of the Luxor Sky Beam that can deliver about 5000 suns’ intensity over an area the size of a post-it note, and the Paul Scherrer Institute (PSI) in Switzerland has a bigger one that uses half the power of Luxor’s.
The second approach is to use the sun itself as the laboratory – as we have. Usually, though, high-temperature testing with tightly-focused light is carried out in special concentrators called solar furnaces. (DLR and PSI have their own solar furnaces, too, which have been used for a range of things including satellite testing.)
Our new tower-based high-temperature test rig will initially be used for our own receiver component and materials testing. In the future, though, it’ll find use for many more and varied experiments.