Characteristic equation of a passive solar still

The characteristic equation has been used for experimental results of a passive solar still to generate linear and non-linear characteristic equations for winter and summer conditions. The different angles of inclination of condensing cover (15°, 30°, 45°) have been chosen for winter and summer conditions both. It has been observed that the passive solar still with inclination of 45° gives better performance both in winter and summer respectively. Different water depths (0.04, 0.08, 0.12, and 0.16 m) have also been taken for solar still with 30° inclination angle for summer weather condition. Comparisons of instantaneous gain and loss efficiencies at 0.01 and 0.04 m water depths for a 15° inclination angle have also been made to show the effect of water depth on the performance of solar stills. It was found that a lower water depth gives better efficiency, which is in agreement with many investigators. The instantaneous gain and loss efficiency curves have been simultaneously analyzed to give a better understanding of the performance of solar stills. The proposed method will be used to standardize the design and operational parameter of a passive solar still, i.e. angle of inclination and water depth for highest yield for a given climatic condition.