Yijiarenheat pipeevacuated tubes consist of two glass tubes made from extremely strong borosilicate glass. The outer tube is transparent, which allowslight rays to pass through with minimal reflection. The inner tube is coated with a special selective coating (CU/SS-ALN) which features excellent solar radiation absorption when compared to conventional flat plate collector systems. 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 exposing the tube to high temperatures by 420 C degree. This "evacuation" of the gasses forms a vacuum and is the essential factor in the performance of the evacuated tubes. When the evacuated tube equipped with super efficiency heat pipe which made of TU1 copper,it become as heat pipe evacuated tube,this type tube is widely used for pressurized solar thermal system.heat pipe vacuum tube data :