Experimental and theoretical method for the determination of the daily output of a solar still: input-output method

In the present work the thermal behavior of a typical solar still is examined experimentally and theoretically and its basic characteristics are analyzed. It is concluded from a larger number of experimental measurement that the operation of such stills during daytime is characterized by three phases: (1) starting, (2) pseudo steady-state, and (3) saturation. A mathematical equation is formed for the instantaneous simulation of the solar still during the pseudo steady-state phase. From this the equation in its integrated form determines satisfactorily the daily output by the daily solar radiation (solar energy input), the average ambient air temperature during the day, T_a(av), and the temperature of the water in the basin at the beginning of the day, T_win, as parameters. This method is called the “input-output” method.