Vacuum glass tubes . Vacuum insulation
Vacuum tube features
Advanced solar selective coatings employ proprietary technologies:
(1) double cermet film structure with the highest photo-thermal efficiency
(2) metal-Aluminum/Copper nitride cermet (one kind of coating: AlN/AIN-SS/Cu) materials deposited by a
novel sputtering technology
- High solar-thermal conversion and low heat loss
- Stable advanced specific coating
- High stagnation temperature up to 300 °C (540 °F)
- Long working lifetime to over 15 years
- High level vacuums ensure operation in cold weather
Advanced solar selective coatings employ proprietary technologies:
(1) double cermet film structure with the highest photo-thermal efficiency
(2) metal-Aluminum/Copper nitride cermet (one kind of coating: AlN/AIN-SS/Cu) materials deposited by a
novel sputtering technology
Vacuum tubes
All glass vacuum tubes are the key component of SEA solar collectors. The vacuum tube is similar to a
conventional Dewar flask and consists of two borosilicate glass tubes, a glass with high chemical and
thermal shock resistance. The outer side of the inner tube is coated with a sputtered solar selective
surface. This coated inner tube is closed at one end and sealed at the other end to the outer tube. The
annular space between the outer tube and inner tube is evacuated to virtually eliminate heat loss by
conduction and convection.
Working with several universities and partner companies, SEA’s R&D and manufacturing facility has
successfully developed the innovative Advanced Solar Selective Coatings in commercial scale, which
achieve high thermal efficiency and good thermal stability. Solar selective coatings absorb most solar
radiation while simultaneously suppressing the thermal emittance loss from coating surfaces. They
vary mainly in their optical property and thermal stability.
Excellent results have been obtained by using DC magnetron sputtering technology. A solar
absorption of 0.94 - 0.96 with an emittance of 0.04 - 0.06 at 100 degree C has been achieved.
All glass vacuum tubes are the key component of SEA solar collectors. The vacuum tube is similar to a
conventional Dewar flask and consists of two borosilicate glass tubes, a glass with high chemical and
thermal shock resistance. The outer side of the inner tube is coated with a sputtered solar selective
surface. This coated inner tube is closed at one end and sealed at the other end to the outer tube. The
annular space between the outer tube and inner tube is evacuated to virtually eliminate heat loss by
conduction and convection.
Working with several universities and partner companies, SEA’s R&D and manufacturing facility has
successfully developed the innovative Advanced Solar Selective Coatings in commercial scale, which
achieve high thermal efficiency and good thermal stability. Solar selective coatings absorb most solar
radiation while simultaneously suppressing the thermal emittance loss from coating surfaces. They
vary mainly in their optical property and thermal stability.
Excellent results have been obtained by using DC magnetron sputtering technology. A solar
absorption of 0.94 - 0.96 with an emittance of 0.04 - 0.06 at 100 degree C has been achieved.
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SEA Groups Ltd.
We harness the power of the sun for our future
We harness the power of the sun for our future
| Solar . Energy . Application |
| Models Weight Structure Outer tube diameter Inner tube diameter Outer Tube thickness Inner tube thickness Tubes length Material of coating Absorption Emittance Vacuum Transmittance of Outer Tube Stagnation temperature (height) Heat-loss coefficient Bearing hailstone ability Pressure-endure ability |
| Ф47×1500 1.35±0.12kg All glass coaxial double-layer tubes Ф47±0.7mm Ф37±0.7mm 1.6±0.15mm 1.6±0.15mm 1542±4mm AlN/AIN-SS/Cu 0.94~0.96 0.04~0.06 P≤5×10-3pa 0.91 270~300 C ≤0.6w/ (m2*C) hailstone diameterФ25mm 1MPa |
| Ф58×1800 2.29±0.18kg All glass coaxial double-layer tubes Ф58±0.7mm Ф47±0.7mm 1.8±0.15mm 1.6±0.15mm 1812±4mm AlN/AIN-SS/CU 0.94~0.96 0.04~0.06 P≤5×10-3pa 0.91 270~300 C ≤0.6 w/ (m2*C) hailstone diameterФ25mm 1MPa |
| Ф58×1920 2.45±0.20kg All glass coaxial double-layer tubes Ф58±0.7mm Ф47±0.7mm 1.8±0.15mm 1.6±0.15mm 1932±4mm AlN/AIN-SS/CU 0.94~0.96 0.04~0.06 P≤5×10-3pa 0.91 270~300 C ≤0.6 w/ (m2*C) hailstone diameterФ25mm 1MPa |
| Ф58×2100 2.67±0.22kg All glass coaxial double-layer tubesФ58±0.7mm Ф47±0.7mm 1.8±0.15mm 1.6±0.15mm 2100±4mm AlN/AIN-SS/CU 0.94~0.96 0.04~0.06 P≤5×10-3pa 0.91 270~300 C ≤0.6 w/ (m2*C) hailstone diameterФ25mm 1MPa |
Normal vacuum tube data and specification
Heat pipes act like a low-resistance thermal conductor. Due to their thermal-physical properties, their
heat transfer rate is thousand's of times greater than that of the best solid heat conductor of the same
dimensions.
The Basic Performance of Heat Pipe
heat transfer rate is thousand's of times greater than that of the best solid heat conductor of the same
dimensions.
The Basic Performance of Heat Pipe
- High Thermal Conductivity - Heat conductivity of heat pipe is much higher than the common
metal. Inside the heat pipe, it transfers heat by gas and liquid phase to change heat. Heat
resistance is very small, so the axial heat conductivity is very high, while the radial heat
conductivity is general.
- Good Isothermal Performance - When heat pipe is working, the working fluid temperature
inside it at saturation. The saturated working fluid temperature is the same, but it will absorb or
release more heat, therefore, the heat pipe can transfer more heat under isothermal
circumstances. Theoretically, whose outside behavior in the isothermal performance of heat
pipe is very good. The axial temperature of heat pipe is almost the same.
- Reversibility of Heat Flow - A heat pipe with wick, if only the capillary force is enough, it will begin
transfer heat, so that it make the temperature of two ends tends to equal.
- Thermo-diode - The heat pipe without wick like gravity-assisted heat pipe in solar water heater, in
the absence of wick structure, the working fluid inside the pipe can just recycle by gravity, and the
heat transferred from the bottom to the top and will not reverse so that get the heat loosed during
night and winter.
- Thermal Switches Property - When the heat pipe temperature is lower than the freezing point of
working fluid, the heat pipe will stop working. When the heat pipe temperature is higher than the
critical temperature, the pipe is filled with steam, there is no phase change heat transfer process
inside the pipe, heat pipe will stop working, therefore, the heat pipe working temperature is
between the freezing point and critical point.
- Variability of Heat Flow - Heat pipe can change the heat transfer area of the two ends
independently, that is input heat through smaller heating area but output heat by larger cooling
area, or vice verse; by doing this to change the heat flow density, resolve some difficult problem
about heat transfer.
1-Outer Tube, 2-Aluminum fins,
3-Heat Pipe, 4-Vacuum insulation,
5-Inner Tube
3-Heat Pipe, 4-Vacuum insulation,
5-Inner Tube
| 1-Heat Pipe, 2-Glass tube top hold, 3-Inside Glass tube cover, 4-Heat conductive aluminum fins, 5-Vacuum space, 6-Solar outer glass tube, 7-Getter (glass mirror) |
Vacuum insulation
SEA Groups tubes pull the best vacuum in the industry (meaning the space
within the glass tube contains no air). The better the vacuum within the tube, the
fewer molecules there are providing heat losses. The vacuum also safeguards
the collector against the effects of humidity and condensation. The lower the
heat losses of the tube, the higher the efficiency and the better the collector can
add heat to a hot system. SEA Groups collectors can add heat to a system
already at 60-80 ° C (140-176° F), making them also applicable for space
heating applications.
SEA Groups tubes pull the best vacuum in the industry (meaning the space
within the glass tube contains no air). The better the vacuum within the tube, the
fewer molecules there are providing heat losses. The vacuum also safeguards
the collector against the effects of humidity and condensation. The lower the
heat losses of the tube, the higher the efficiency and the better the collector can
add heat to a hot system. SEA Groups collectors can add heat to a system
already at 60-80 ° C (140-176° F), making them also applicable for space
heating applications.
Copyright © 2010 SEA Groups Ltd.
Heat pipe
Vacuum tube with heat pipe
Heat pipes are inserted into the aluminium absorbers forming assemblies, which in turn are inserted
into the glass vacuum tube, which forms the normal vacuum tube with heat pipe. The vacuum tubes are
made of borosilicate glass that is strong and has a high transmittance for solar irradiation. As
described in the Vacuum tube section, the glass tubes are evacuated to vacuum pressure of <5x10-3 or
10-5 pa In order to reduce the convection heat loss.
The heat pipe employs an evaporating-condensing cycle. The evaporator section is tightly bonded to the
absorber plate, where it captures the heat from the absorber and evaporates the liquid to steam, which
moves up to the condenser section. The condenser protrudes out from the evacuated tube and is
inserted into the heat exchanger manifold. There this steam will be condensed by water flowing through
the manifold. Latent heat energy will be released to the process water through this phase change of
vapor to liquid. In vacuum tube with heat pipe solar collectors, the condensation zone is at a higher level
than the evaporation zone. The transport medium condenses and returns to the evaporation zone under
the influence of gravity. This process is repeated continuously thereby heating the water in the solar loop.
The heat pipe vacuum tube provide the advantages from both the vacuum tube and the heat pipe to be a
effective solar energy absorbing component. The heat pipe vacuum tube successfully prevented from
the defects of tube block and low power output caused by water fouling and deposits of mud dirt. The
vacuum tube with heat pipe is easy to install, just plug the heat pipe with the vacuum tube into the
collector manifold, and it perfectly solves the common issue of the all-glass vacuum tube solar water
heater, which cannot run if one of the tubes is broken.
into the glass vacuum tube, which forms the normal vacuum tube with heat pipe. The vacuum tubes are
made of borosilicate glass that is strong and has a high transmittance for solar irradiation. As
described in the Vacuum tube section, the glass tubes are evacuated to vacuum pressure of <5x10-3 or
10-5 pa In order to reduce the convection heat loss.
The heat pipe employs an evaporating-condensing cycle. The evaporator section is tightly bonded to the
absorber plate, where it captures the heat from the absorber and evaporates the liquid to steam, which
moves up to the condenser section. The condenser protrudes out from the evacuated tube and is
inserted into the heat exchanger manifold. There this steam will be condensed by water flowing through
the manifold. Latent heat energy will be released to the process water through this phase change of
vapor to liquid. In vacuum tube with heat pipe solar collectors, the condensation zone is at a higher level
than the evaporation zone. The transport medium condenses and returns to the evaporation zone under
the influence of gravity. This process is repeated continuously thereby heating the water in the solar loop.
The heat pipe vacuum tube provide the advantages from both the vacuum tube and the heat pipe to be a
effective solar energy absorbing component. The heat pipe vacuum tube successfully prevented from
the defects of tube block and low power output caused by water fouling and deposits of mud dirt. The
vacuum tube with heat pipe is easy to install, just plug the heat pipe with the vacuum tube into the
collector manifold, and it perfectly solves the common issue of the all-glass vacuum tube solar water
heater, which cannot run if one of the tubes is broken.
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