It can be concluded that the flat plate
It can be concluded that the flat-plate glazed ASTFs have a higher conversion factor. This is because the solar efficiency is mostly applied to low heat NHS-SS-Biotin of water pipes (or air ducts) and low heat transfer within the heat exchange units. In the other side, the limitation of heat transfer capacity is also inherently related to the working fluid, as the commonly used antifreeze fluid could lose its chemical nature leading to change of state from the liquid to gas, which may generate a range of problems: (1) an increased pressure drop and a reduced heat transfer ; (2) roof based ASTFs seem to be more adaptable to the simply shaped buildings, owning to their larger outer skin area; (3) overheating is sensitive to most plastic and silicone parts and may cause unsatisfactory stagnation phenomenon for the ASTF components when being integrated into buildings. Normally, well-insulated glazed flat-plate collectors achieve maximum stagnation temperature of 160–200 °C, while the evacuated tube solar collectors have the maximum stagnation temperature of 200–300 °C.