Introducing Solar Vacuum Tube Collectors –
Solar vacuum tube collectors comprise a number of rows of parallel transparent glass tubes connected to a header pipe. The header pipe is where heat transfer fluid containing 50% Propylene Glycol circulates and absorbs heat energy generated by vacuum tubes.
The glass tubes are cylindrical. The angle of sunlight remains perpendicular to the heat-absorbing lines. As a result, the collectors work efficiently even during low sunlight conditions like early morning, late afternoon or during cloudy weather. Solar evacuated tube collectors are mainly used in areas with cold, cloudy winter weather, i.e. most parts of Canada and the northern area of the United States.
How Do Vacuum Tubes Work in Residential Solar Water Heaters?
As discussed above, solar evacuated tube collectors comprise single or multiple rows of parallel, transparent glass tubes supported on a frame. Every tube has a different diameter varying between 25mm-75mm and length between 1500mm-2400mm depending on the manufacturer.
Every vacuum tube has a thick glass external tube and a thinner glass internal tube – known as a twin-glass tube or a thermos-flask tube. The tube’s special coating ensures solar energy absorption by inhibiting heat loss. The tubes are made from borosilicate or soda lime glass, which is strong and high-temperature resistant. As a result, they have high transmittance for solar irradiation.
A flat or curve-shaped aluminium or copper fine is connected to a metal heat pipe running through the inner tube in every glass tube. The fin has a selective coating that helps transfer heat to the fluid that circulates through the pipe. The sealed copper heat pipe transfers the solar heat energy through the convection of the internal heat transfer fluid to a hot bulb which heats a copper manifold present inside the header tank indirectly.
The copper pipes are attached to a standard manifold connected to a storage tank. They heat the hot water during day time, and hot water can be used at night or the next day because of the insulating properties of the storage tank.
The vacuum tube has amazing insulation properties so that the internal tube may be as high as 150 degrees Celsius, and the external tube is cooler to touch. That means the evacuated tube residential solar water heaters can work well and heat water to fairly high temperatures even during cold weather conditions.
Evacuated tube solar water heaters can be an effective alternative to flat plate collectors for residential water heating, especially in areas where the weather often remains cloudy. Vacuum tube residential solar water heaters are more efficient and modern than flat plate collectors as they can be able to extract heat energy from the surrounding air on a humid, dull overcast day and don’t require direct sunlight for their operation.
With the vacuum inside the glass tube, the system’s total efficiency in every area remains much higher. In addition, the system performs better even when the sun is not at an optimal angle.
Bottom Line –
Contact a solar system supplier working near you and better understand residential solar water heaters. They will suggest whether a residential solar water heater is worth the investment for your home.
Author Information –
This article is written by Latitude51 Solar, which provides residential solar water heaters working with solar evacuated tube collectors for maximum efficiency and performance in the long run.