How Evacuated Tube Solar Thermal Collectors Work
We all know the sun’s energy can be converted into heat; just get into your car on a summer’s day after it has been left in the sun. The principal of a solar thermal collector is very similar. It takes the light energy from the sun and converts it to useful energy in the form of hot water.
To do this, the collector is mounted on your roof in a southerly direction. It needs to be out of the shade as much as possible to collect the maximum amount of sunlight. InFloor will examine the design of your house, the purpose you are using solar thermal for and weather data from your area to determine how steep your collector should be tilted. This will allow it to collect the most sun when you need the energy.
An evacuated tube collector uses a series of glass tubes with a special coated copper plate inside to collect the energy from the sunlight. The sun shines through the glass, hits the collector plate and is transformed into thermal energy. This energy is used to warm a water-glycol mixture that is flowing through a manifold above the tubes.
The key to the efficiency of Thermomax evacuated tubes is the vacuum. Hot water running through the collector will be cooled by the outside air on a cold day and thus lose energy to the environment. The vacuum in the tubes works like a Thermos™ to keep the water warm. Visit our page on evacuated tube advantages find out more about what make Thermomax so unique and efficient.
Once you have hot water, there are many uses for it. See our applications to find out what you can do with solar thermal!
How a Heat Pipe Works:
The Thermomax solar thermal collectors use a heat pipe to transfer the heat from the evacuated tube to the manifold. This is a second sealed system that allows for dry connections at the manifold and a limiting device. Inside the evacuated tube, there is a copper pipe that is welded to the collector plate. Inside this pipe is a small amount of water.
When the sun strikes the collector plate, it heats the copper tube that then heats the water at the bottom of the tube. The temperature gets so high that the water boils and water vapor evaporates and is carried upwards because it is lighter than the air in the tube. At the top, the tube is pushed into the manifold, where water is flowing over the end of the tube. The water vapor hits the end of the tube which is colder, causing it to condense. The heat is transferred to the antifreeze mixture in the manifold and the water flows back down to the bottom of the tube to be boiled again. See the below animation:
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Solar Thermal Components