solar vacuum tube with copper pipe

vacuum tube with copper pipe 1.CE,ISO9001,CCC 2.USD5.5-8 per pc 3. 15Years Warranty for evacuated tube StrucureAll-glass concetric dual tube geometrGlass materialBorosilicate glassOuter lube biameter and lengthφ=47 ±0.7mm& =1.5mφ=58 ±0.7mm& =1.8mφ=70 ±0.7mm& =2mφ=47 ±0.7mm& =1.5mLnner lube diameter and lengthφ=47 ±0.7mm &=1.8mφ=58 ±0.7mm& =2mGtaded Al-N/Al solar selectuve absorbing coatingConstructionAbsorbingMothod to depositionDC reactive sputteringCoatingAbsorptance>91%PropertiesEmittance<8%(80)VacuumP<5×10-3paStagnation parameter≥230M²/KWSolar radiance exposure for obtaining a preset water temperature≤2.8MJ/M2Average heat loss coefficient≤0.8W/(M3)Lifetime15 years