IMPROVING THE EFFICIENCY OF THE SOLAR STILL USING ELECTRICAL HEATERS POWERED BY SOLAR PANEL AND AN OUTSIDE CONDENSER SOLAR PANEL AND AN OUTSIDE CONDENSER

Abstract

Water and energy are two important factors that govern the lives of humanity and promote civilization. In Egypt we have a big problem in the fresh water and the energy. The main objective of this study was increased the fresh water produce by new design of the solar still using electrical heaters powered by solar Panel and an outside condenser. In order to reach the objective of the study two types of distiller units was design, the first one was conventional unit and the second a new model of solar still with heaters and separating the condensation unit from the evaporation unit. To improve the thermal efficiency of the proposed hybrid solar still (PV / T) systems, the cooling process was carried out to the condenser and the thermal energy generated was recovered during the condensation process. Measurements included that, All the temperatures (saline water, preheated water, basin water, basin, glass cover, panel, ambient), the solar irradiance, Voltage and current, electricity generated from photocells, Water vapour pressure, glass cover transmission, solar radiation, fresh water production, over all thermal efficiency of the still. The experiments are carried out in the eight typical clear sunny days. The results showed that the maximum and the minimum irradiance were 7488 W/m2.day and 7140 W/m2.day. That the maximum solar energy (26.959 MJ/m2/day), and minimum solar energy (25.704 MJ/m2/day). The maximum ambient temperature was (42 °C). It also found that the minimum specific energy consumption was 3.820 MJ/L that means the maximum utilization of energy with the proposed hybrid active (PV/T) solar still with heater and divided feed. The maximum specific energy consumption was 7.483MJ/L, it was found for the conventional solar still without heater and Total feeding rate with minimum energy efficiency.-1136-The proposed hybrid saved about 49% of the energy consumption to produce a liter of pure water. The minimum productivity of fresh water was estimated about 3.435 l/m2day, it was provided in the system of conventional solar still. The maximum productivity of fresh water in the system of proposed hybrid active (PV/T) solar still with heater and divided feed was estimated about 8.571 l/m2day. The increasing rate in the productivity about 149.50% was achieved using by using proposed solar still. The overall thermal efficiency was increased by 36% of the proposed hybrid active (PV/T) solar still is much higher than the conventional. The fresh water produced from the new design of distiller unit with highly efficiency can be use within Hydroponics in coastal area. 1. INTRODUCTION ater and energy are two important commodities that govern the lives of humanity and promote civilization. In Egypt we have a big problem in the fresh water and the energy. We need large amounts of water for the reclamation of new land to meet the needs of the growing amounts of food. The process of desalination of seawater using solar energy will provide additional quantities of water that can be exploited to expand the reclamation and cultivation of new lands (horizontal expansion) especially in the coastal areas. Increasing the production of fresh water can be done by improving the efficiency of the seawater desalination process There are many factors that effect on the productivity of solar distillers. These factors include the intensity of solar radiation, wind speed, ambient temperature, temperature difference between distillation and water cover in distillation basin, water surface area, water depth, water feeding temperature, absorption plate area and glass cover angle Nafey et al., (2000). Some factors cannot be change because they are natural factors as the intensity of solar radiation, Wind speed and environmental temperature. Other factors can be change to increase the productivity of solar distillers. Many studies are still conducted to improve the productivity of distillates from solar energy Tripathi et al., (2006).