Solar ETC TubeEvacuated tube are the absorber of the solar water heater ,This type of tube is chosen for it’s reliability , performance and low manufacturing cost Each evacuated tube consists of two glass tubes made from extremely strong borosilicate glass,The outer tube is transparent allowing light rays to pass through with minimal reflection,The inner tube is coated with a special selective coating (AL-N/AL)which features excellent solar radiation absorption and minimal reflection properties The top of the two tubes are fused together and the air contained in the space between the two layers of glass is pumped out while exposig the tube to high temperature ,This “evacuation” of the gasses forms a vacuum which is an important factor in the performance of the evacuated tubes ⅠHigh heat-collecting effciency: The vacuum magnetic-controlled sputtered aluminum-nitrogen-aluminum selective absorption coating has a solar absorptance≥0.93, a heat emittance≤6%,a low heat loss ,and a good thermal-retention effectⅡ Good weather-resistanc:It has a good all-year thermal efficiency and is able to withstand the front impact by the hail of a dianmeter below 25mm and pressure 0.6MpaⅢ Long service life:ensures a service life of 15 years for the evacuated tube☆Properties of all-glass evacuated solar collector tubesItemMeasured ValueSpecification in Chinesestate standardPtance of the solar selective absorbing coatingsα≥0.931α≥0.86(AM1.5)Hemisphere emittanceε≤0.06ε≤0.09(80±5℃)Solar radiance exposure using sun as mediumH≤2.639MJ/m²H≤3.8MJ/m²Ation parameter using air as mediumY≥240 m²℃/KwY≥175 m²℃/KwAverage heat loss coefficientULT≤0.78W/m2℃ULT≤0.9W/m2℃ModelOuter diameter/innerDiameter(mm)Length(mm)Package158/471800/1500/1200Carton247/371800/1500/1200Carton
