ETC SOLAR WATER HEATER

ETC WATER HEATER

ETC Water Heater or Evacuated Tube Collectors Water Heater comprises a row of parallel SS tubes. Supported on a frame, they are connected to a header pipe. The header pipe is used in place of a blackened absorbing plate used in Flat Plate Collectors. Unlike FPC, Evacuated Tube Collectors (ETC) do not heat the water directly, they work on the principle of "black-body absorption" which states that the amount of light absorbed will be all the light that hits the surface(black-body). Solar water heating systems which use this principle and vacuum tubes made of borosilicate glass with a special coating to absorb the solar energy are called the Evacuated Tube Collector system (ETC Systems). The vacuum tube is the main component which is an assembly of two concentric borosilicate glass tubes that will absorb solar energy. The air between the gap of two glass tubes is evacuated which results in a high vacuum, which acts as the best insulation to minimize the heat loss from the inner tube. The black coating on the inner tube absorbs the solar energy and transfers it to the water. The water on the upper side of the vacuum tube becomes hot and as the thermosiphon principle states, it gets lighter and starts moving upwards in the tank. At the same time heavy, cold water sinks from the tank and is stored at the bottom.