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You take what looks like a simple container filled with water and you put it in the sun and the water starts heating up and even boiling; fast! The brilliant equations created by the National University of Lesotho (NUL) Physics students are doing their magic.

Thaane ‘Mokose and Molibeli Rakauoane are able to use equations, which they took months to create, to bend sun’s rays to heat water quickly in a solar thermal kettle.

This kettle can also control the water temperature without any use of electricity whatsoever!

The work of this brilliant twosome, who are supervised by Dr Naleli Matjelo, is published in the International Research Journal of Engineering and Technology with the topic, “Design and Simulation of a Fluid-filled D-Shaped Lens for Solar Thermal Applications,” Volume: 08, Issue 06. As they seek to commercialise this work, their designs are now under both the NUL Energy Research Centre and the NUL Innovation Hub.

This is how it got rolling.         

They first spent quite some time developing highly complex equations. This is the hard part and they spent most of the time here. These equations are used to guide a curved surface of a material of choice, polycarbonate in this case. With these equations, “we are able to know when we have reached the point where the polycarbonate can concentrate the sun’s rays into one line as we curve it,” they said.

That point is a line on a metal rod, especially a copper or any black metal. They used copper in their construction of the material because it readily distributes heat.

Now they take a container, any container is okay, and they place the curved polycarbonate over it. From there they do something odd. They fill the container with water to the brim. Yes, to the brim. It is at this point that they are doing something interesting.

They are creating a lens using both water and polycarbonate.

Those who know a thing or two about lenses will recall that they can be thick. “In our case, our polycarbonate is not thick, but we increase its thickness by coupling it with water. That’s why we fill the container with water to the brim.”

When the sun’s rays pass through this polycarbonate-water lens, they get directed to a specific line on the metal rod, guided by the complex equations they have created. When these rays hit the rod, the rod heats up, in which case warm water surrounding it moves away from it, only to be replaced by colder water, which also gets warmed up upon reaching the rod. A current is created until all the water is hot or even boiling.

This is where things get thrilling!

The way the water behaves as it gets heated makes it easy for these folks to control its temperature. Yes, without using any electronic devices!

This is how!

As the water gets heated up, it creates bubbles (turbulence). The bubbling interferes with the sun’s rays that are directed to the metal rod to heat it up. So the metal rod, with less directed rays coming in, gets its temperature lowered. As the temperature is lowered, the bubbling itself is reduced. Then the sun’s rays now hits the metal rod better in which case the temperature increases, again. As temperature increases, the bubbling begins and the process repeats itself.

This keeps the temperature of the water around a certain desired value.

To ensure that this happens in a controlled manner, pressure in the container can be upped or lowered manually.

All this work is happening because we live in challenging and exciting times all at once!

For a long time, the human race has burned fossil fuels such as oil and coal like there is no tomorrow, just so it can create heat and electricity itself. The problem with fossil fuels is that the amount of carbon they release to the atmosphere is higher than the amount the earth is designed to absorb. So the extra carbon remains in the atmosphere, warming our beloved planet in the process.

“This is why we are turning our attention to the sun,” said the brilliant duo “In its purest form, the sun provides the cleanest energy there is”. Energy from the sun, fortunately, happens to come free. With that energy, you can do everything you used to do with coal and oil, in fact, the energy in coal and oil actually comes from the sun.

However, harnessing the sun’s energy doesn’t come easy. It’s not like you just trap it at will. Rather, you sweat like these folks.

The beauty of concentrating suns rays to heat water, as opposed to using normal solar water heaters, is that this approach heats water fast.

One of the first applications of this appliance will be to use it in greenhouses to supply extra heat for agricultural production in Winter.

So let’s watch this story as it unfolds.

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