Development product of a multi-layer solar distillation system connected to tubular solar collectors by using gravel

Solar distillation occurs within a device called the (solar still). There are many types of solar still. In this study, the addition of modern technology for solar still was used. Experimental tests have conducted in (Baghdad), the capital of (Iraq). On the other hand, (MAT LAB) program was used to formulate mathematical formulas. The study was conducted during (July) and (August) and extended during the testing day from (5:30 am) to (10:00 pm). Coarse and fine gravel added to the solar still basins to develop its product. The percentage of increase in the production of solar still with the presence of gravel was (47%), the percentage increase in night productivity was (64%). (paper)