First National Conference on Advances in Mechanical Engineering (NCAME-2011), 20th - 21st May 2011, UIET, Panjab University, Chandigarh 309 EFFECT OF HEAT INPUT ON THE PERFORMANCE OF A SOLAR STILL AT CONTROLLED AND UNCONTROLLED CONDITIONS Singh Kishan Pal 1 , Hussain S.Q. 2 1 Assistant Professor, Department of Mechanical Engineering, BSACET Mathura, India 2 Assistant Professor, Department of Mechanical Engineering, WIT Sohna, Haryana, India E-mail: kishan.amu@gmail.com meesam.amu123@gmail.com Abstract: Experimental studies on a basin type still, basically application to the solar energy has been carried out at room condition for the purpose of simulation and to provide a substantial feed back for its thermal modeling in the actual conditions of solar energy. The basin holds water maintain at a certain depth which is being heated electrically. Due to evaporation of water, there exist humid air zone above the water level. The vapour on reaching the inclined glass cover condenses and trickles down to collected outside the still. The measurement consists of power input, distillate output and temperatures along the height from the base of basin up to the glass outer and the air surrounding it. Temperature profiles along the height in water depth, humid air region and near the glass cover are quite interesting. Subsequently, the vapour pressure in the system has also been predicted. Effect of heat input on the temperatures of the absorber, the water, humid air vapour and those of glass cover are studied. The distillate output increases with time of heating as well as on increasing the heat input. Efficiency of the still has been studied based upon the total heat input and the heat taken by the water. The efficiency of the still increases with the heat input. Keywords: Solar energy; Solar heating; Heat input; Productivity. 1. INTRODUCTION As we know of total earths 70% is covered by water, but most of it is in the sea as saltwater. Fresh water covers only 3% of the earth surface and much of it lies frozen in the Antarctic and Greenland polar ice. Humans consume fresh water quailable from rivers, lakes underground sources and aquifers. Which are also now facing a big problem of pollutants generated by us, jointly these sources account only for 1% of all the water available on earth. Six billion people depend on this supply and a significant portion of the world’s population now faces water shortage. Now days, 81 countries representing 2.8 billion people, including china, India, Kenya, Ethiopia, Nigeria and Peru, confront chronic water problem. Within a generation from today the world’s population will go up to an estimated 8 billion people and the amount of water will remain the some or may be less. The challenge is as dear and compelling as pristine water cascading down a mountain stream. The method of purification of water for drinking and other use like boiling, carbon filtering, reverse osmosis, ion exchange, electro deionization and distillation. All these method suffer from several shortcoming compared to distillation. Firstly all of the above mentioned methods depend on the conventional sources of energy like fossil fuels which are limited in nature that they generate No x so x co x particulate etc. these pollutants are a major concern from environmental point of view. Also these methods are highly expensive in terns in that they have a high installation and maintenance cost. They also can not be installed and maintained in remote areas. So the only solution is a solar distillation plant. It is a simple and effective method that replicates the way natures brings rain to us. Due to its low installation maintenance cost and its free running cost it is widely being used by people throughout the world. The history of solar distillation plant can be dated back to 1551 when it was used by Arab alchemists. Other scientists and naturalist used still over the coming centuries including Della [1], Lavosier [2], and Muchot [3]. The first “conventional” Solar still plant was built in 1872 by the Swedish engineer charles Wilson in the mining community of las Salinas in what is now northern Chile (Region II). This still was a large basin-type still used for supplying fresh water using brackish feed water to a vitrate mining community. The plant used wooden boys which had blackened bottona using logwood dye and alum. The total area of the distillation plant was 4, 700 square meters. On a typical summer day this plant produced 4.9 kg of distilled water per square meter than 2300 liters per day operational until 1912.