Solar Water Heater Vacuum tubes with Glass Heat Pipes
Glass heat pipes, all sealed, no metal or moving parts. 1.5 meter by 47 mm outside diameter, sealed glass heat pipe condenser bulb ends, high efficiency, no moving parts. Robust enough to be shipped, no corrosion. Dirty or corrosive water OK.
May be used with passive solar water heaters or active systems with panels and pumps. Solar energy is trapped on the black absorber surface, which is deposited on the inner glass using thin-film technology. Vacuum tube is composed of an inner tube, an outer tube, a selective absorption layer, a vacuum space, and an absorption layer. The outer wall of the inner tube has the selective absorption layer, which absorbs 98% of the suns energy. The space between outer tube and inner tube is vacuum space, no conductive heat transfer to the outside, even if the outside temperature is -40 C. At the bottom of the outer tube ,there is an absorption layer used to keep the vacuum. Suitable for use with active panel, pumped systems with remote tank or passive systems with tank and tubes together. A vacuum separates the absorption surface from the outside environment, eliminating conductive or convective heat transfer.
-99 % heat conduction
·Lifetime greater than 10 years
·Vacuum ensures no heat loss
-No corrosion, since no metal parts
The inside of the glass tubes are coated with a special black absorber that absorbs nearly all the energy of the sunlight falling on it. A double wall with vacuum keeps the absorption layer pristine. The liquid in the heat pipe boils and the steam travels up to the top of the heat pipe. The top bulb of the heat pipe (the condenser bulb) is in contact with cool water, which causes the vapor to condense. The drops of condensed liquid (a salt of potassium) then drip down the heat pipe. This cycle repeats so long as sunlight keeps heating the pipe and the top of the pipe is cool enough to condense the vapor.
How it works:
There are two tricks to the high efficiency of this solar heater. First, a vacuum prevents any conductive or convective heat loss to the environment from the absorber. Second, heat pipes ensure one-way heat transfer from the absorber to the water: the water can not heat the absorber. The selective coating in the inner cover of the evacuated tubes ensures high energy absorption and low heat radiance losses. The liquid in the inner glass heat pipes changes into vapor which then rises up the heat pipe. When heat is exchanged between the condenser end of the heat pipe and the cold water in the tank or panel header, it turns into liquid again, then comes down to the base of the heat pipe. This cycle continuously repeats as long as the sun shines.
Quasi-tracking in four seasons: as the sun tracks across the sky, same absorber area faces sun, since absorber surfaces are cylindrical. The collector will be in operation as long as sun shines. The solar water heater can be in service all year round even in cold climate areas since heat pipes transfer heat in one direction only within the collector and the vacuum prevents convective heat losses.
1.5 meters long, 20 tubes per box