Plywood of 1 CM thickness was used for the fabrication of both solar air heaters The specific area of absorber tray was 151 53 com which has been made of by using a 0. 5 mm thick 22 SSW AAA sheet. The absorber tray was painted dull black to store he maximum amount of solar energy for SSL . To reduce the heat losses, a 2 CM thick layer of glass-wool was placed between the absorber tray and outer cabinet. A single pane transparent float glass of 0. 3 CM thickness and 151 70 com was used for glazing to allow the solar radiation inside the SASH.
The single glazing has been considered effecting elements of the system like as halogen lights, inside wall of ducts for good reflection, and mainly the absorber tray are required to be very clean while performing (a float glass, beneath which the granular carbon is spread of heat storing for long hours) and for efficient irking in good and poor ambient conditions. Dusty transparent glass over storage media and dusty reflective walls will be resulted in lower efficiency of the system.
Double glazing makes the system a little bit complicated in comparison of discussing system and more maintenance and attention will be required The distance between glazing and absorber tray was 10 CM for both heaters. A layer of granular powder of 1 mm was spread on the absorber tray and sealed by 2 mm float glass for so (Fig. 2). The side walls of SASH were tilted at 1 1 50 angle because of receiving DOD amount of solar radiation through its exposed area.
For air supply two similar high velocity table fans (40 W) of "Icing-20 CAR" trademark were used to supply the air inside the SASH. The speed of air supplying was set at 2 m/s for forced convection. The speed of the fan can be controlled by a knob (provided with fan) which was fixed on 3 inbuilt control voice; low speed - 1750 RPM, mid speed - 1980 RPM, and high speed - 2200 RPM. Even this speed can also be varied up to 2500 RPM by supplying a high voltage of current supply, through an external stabilizer.