| abstract |
The present invention generally relates to solar water heaters, in particular to solar water heaters using glass vacuum tubes as both solar energy collector and thermal energy storage device, without a hot water storage tank. To improve the efficiency of thermal energy storage, a novel medium for thermal energy storage is disclosed, which utilizes the heat of solution of aluminum sulphate, comprising water and 40% to 47% of Al 2 (SO 4 ) 3 . The working temperature range of such energy storage medium is between 50° C. and 100° C. The energy storage medium is contained in plastic capsules, submerged in water and placed in glass vacuum tubes. |