Monthly fresh water yield analysis of three solar desalination units a comparative study in the south Algeria climatic condition Houcine Moungar 1,2* , Ahmed Azzi 2 , Youcef Sahli 1 , Abdelkarim Haida 1 1 Unité de recherche en énergies renouvelables en milieu saharienne (URERMS) Centre de développement des énergies renouvelables (CDER), Adrar 01000, Algérie 2 Unité de recherche en matériaux et énergies renouvelables (U.R.M.E.R) Université Abou Bekr Belkaïd, Tlemcen 13000, Algérie Corresponding Author Email: houcinemgn@gmail.com https://doi.org/10.18280/ijht.360423 ABSTRACT Received: 22 July 2018 Accepted: 14 September 2018 The Purpose of the paper is studied three types solar distillers, double slope with and without immersed fins and the simple solar distiller. A monthly comparative study is investigated experimentally, for a long period of the year. Further, the wind speed influence, the distance between fins, the fins height, the fins number and thickness, on the solar distiller’s production, is investigated theoretically. From the obtained results, it is noted that for the wind speed greater than 3.5 m/s, a decrease in the productivity is caused by the cooling of the outer walls, and this induces some heat losses, especially at the front and rear walls of the solar still. The distance between fins has no significant effect on the still productivity. Moreover, increasing the fins height, from 2 to 5 cm, increase the productivity; however, when the height changes from 6 to 8 cm, the distillate production goes down. A larger fins number lead for rise the produced distilled water amount. Therefore, one should use the maximum number of fins, while taking into consideration the feasibility of the assembly. Increasing the water mass makes the productivity to go down. The obtained results on June 11, 2016, show that the proposed system productivity was about 15 to 27 % higher than that of a simple one, under the following conditions, i.e. Mw = 42.61 kg, h1 = 3.6 cm, Vw = 3.5 m/s, lw = 5 cm and Nfins = 12. The total annual cost estimation proof clearly that the payback period is less than a years. As well as, it has been found that the increasing lifetime and the interest rate decreasing caused a decrease in the distilled water unit price. Keywords: solar still, distilled water, shadow, immersed fins, solar irradiation flux 1. INTRODUCTION Water is the cheapest and the most expensive is missing, is one of the necessary elements for every living thing on earth life on the earth. The population growth, the economic development, water needs are increasing to response the human live exigency. These increases are inversely proportional to the resources. Fresh water represents only 3% from the total amount of water available on earth. Only 1 % of this quantity is usable, the rest is in the glace form or buried underground. Arid regions are characterized by droughts; they are poor in superficial water, which is generally saline. This is the case of some regions in southern Algeria, namely BOUDA, ABADLA, etc. Hence, these areas have a saline or brackish water usually, withe sunning duration exceeds 14 (h/day) and radiation intensity exceeds 1200(w/m²), especially in the summer period. Using the solar desalination process could offer economic, environmental and social benefits for the drinking water supply system in these regions. In the last ten years, several research works have investigated, experimentally and theoretically, the parameters influencing different solar distiller’s configurations productivity. Bechki et al. [1] Studied the effect of shadow of an intermittent partial coverage on the efficiency of a single basin double slope solar still. The daily production in the first series was found equal to 6.01 (l/m 2 /day). This quantity was improved by 33.7% in the second series. The third one consisted of reducing the temperature of the transparent cover by means of shadows of the intermittent glass cover on the north side. This procedure allowed an additional 12% improvement in the daily production of distillate Kabeel et al. [2-3] Conducted an experimental and theoretical study on two types of solar stills, namely a conventional inclined solar still and a cascade solar still, which were tested simultaneously. They also examined the influence of the depth and width of the tank on the performance of the solar still. The cascade solar still was supplied with hot water coming from an evacuated tube solar collector. To increase the heat exchange surface, they used a wick on the vertical sides of the cascade distiller. In this case, the daily efficiencies, for one liter of distillate, for the cascade and conventional solar distillers was found to be approximately; 53 and 33.5%, respectively. Conducted a theoretical study on a single basin double slope solar still. The first cover glass, transparent and oriented towards the south, acts as an evaporator; the second one is tinted and oriented towards the north, and acts as a condenser. They added a black dye into the basin of the distiller in order to improve the absorption of the plate and to increase the evaporation surface. Then, they studied the influence of climate and geometric parameters on the productivity of the distiller. They also carried out frequent instantaneous cooling of the transparent International Journal of Heat and Technology Vol. 36, No. 4, December, 2018, pp. 1330-1335 Journal homepage: http://iieta.org/Journals/IJHT 1330