Characteristic equation of the inverted absorber solar still Original Research Article

The inverted absorber solar still (IASS) is a box type solar still in which a curved reflector has been placed under the basin to heat it from both top and bottom sides. Because of this, the high water temperature can be obtained in the IASS in comparison to that of the single slope solar still (SS). In this communication, an attempt has been made to develop linear and non-linear characteristic equations of the IASS based on derived analytical expressions of instantaneous gain (ηi) and loss (ηiL) efficiencies by using experimental data for the climatic condition of Muscat, Oman. The results show that the behaviour of the IASS is non-linear as expected. These results have also been compared with obtained characteristic equations of the SS under similar operating and climatic conditions. On the basis of economic analysis of the IASS and SS, the annual costs of distilled water per kg-m2 have been found to be Rs. 0.95/- and Rs. 0.54/- respectively.