SOLAR HEATING THROUGH PARABOLIC DISH TYPE REFLECTOR
Parabolic dish type solar water heaters, harness, harvest, and utilize the solar radiation, for our day to day use, and in this case, an important utility, for day to day house-hold.
A simple sketch as above, illustrates the working principle, of dish type parabolic solar water heater. In the vertical sectional view, the dish profile, and the central heat absorbing water tube, is shown. The manner of heat absorption, by the heat reflecting surface of the reflector, is shown through various arrows, emanating from the dish surface, and impinging on to the central water tube outer surface. Both the dish as well as the water tube is painted in black color, to maximize heat absorption during the solar incidence rays period.
The central water tube is made of copper with minimum wall thickness, available in the market, and of maximum diameter, to increase the water holding capacity. Further the dwelling time, of cold water inside the copper tube, is increased by locating identical, similar shaped washers. These washers are inserted inside the copper tube from the top, one over the other. Spacing of 25 mm, is given between adjacent washers, and are located from outside, by radial screws, driven from the outside surface of the copper tube. Depending up on the hot water temperature requirement, the in-between space between adjacent washers can suitably be adjusted. Care should be taken to see that no water leaks from the set screw points, made in the copper tube. To further help in temperature absorption and regulation, the inflow of cold water to the copper tube can be regulated and controlled through a flow regulating and check valve, to the cold water supply lines from the water tank.
The heated water from the dish type solar water heater is then taken directly to the hot water supplying geysers, already installed in the house. As these geysers have a flow regulating mechanism, that can be utilized to advantage. Further, this provision will enable the user, to timely switch on the conventional electrical power, when by chance the solar heating of water is inadequate, as during the days of monsoon weather.
The design is flexible to suit available space in the open terrace floor of existing building. We have to just ensure that cold water flows to the solar water heater by gravity with out any interruption, under all circumstances. The materials used for the dish type collector as well as the copper tube are weather -friendly, and can withstand the normal corrosion of atmospheric weather conditions, including rain. The curved surface, as such does not allow water to stick to the surface, and the rain water that falls on the curved surface is let ourt through the annular clearance between the copper tube and dish.