R. Jayaprakash

Experimental Study on Various Solar Still Designs

Humankind has depended for ages on underground water reservoirs for its fresh water needs. But these sources do not always prove to be useful due to the presence of excessive salinity in the water. In this paper, the fabrication of seven solar still designs such as spherical solar still, pyramid solar still, hemispherical solar still, double basin glass solar still, concentrator coupled single slope solar still, tubular solar still and tubular solar still coupled with pyramid solar still and their performance evaluation in converting brackish water into fresh water for drinking are presented. The experiment was constructed and tested during January to May 2011. All the solar stills were operated in the same climatic conditions to analyze the influence of the modifications on the productivity. From the observations, the compound parabolic concentrator-assisted tubular solar still shows the maximum yield.

Synthesis of ZnO Nanostructures by Microwave Irradiation Using Albumen as a Template

ZnO nanostructures have been successfully prepared by a microwave irradiation method. The role of albumen as a template in addressing the size and morphology of ZnO has been investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG-DTA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. A heterogeneous mixture of Zn(OH)2 and ZnO was obtained in absence of albumen. Pure ZnO nanostructures, consisting of rod- and whisker-like nanoparticles embedded in a sheet matrix, were obtained in the presence of albumen. Optical and photoluminescence (PL) properties of the synthesized samples were also compared. Results obtained indicate that the microwave-assisted method is a promising low temperature, cheap, and fast method for the production of ZnO nanostructures.

Experimental Study on a Compound Parabolic Concentrator Tubular Solar Still Tied with Pyramid Solar Still

Water is a nature’s gift and it plays a key role in the development of an economy and in turn for the welfare of a nation. Non-availability of drinking water is one of the major problem faced by both the under developed and developing countries all over the world. Around 97% of the water in the world is in the ocean, approximately 2% of the water in the world is at present stored as ice in polar region, and 1% is fresh water available for the need of the plants, animals and human life [1]. Researchers have been carried out in this method by Nij‐ meh, et al., [2], they have been investigated the regenerative, conventional and double-glasscover cooling solar still theoretically and experimentally. Several system parameters were also investigated with respect to their effect on the productivity, namely, water with and without dye in the lower basin, basin heat loss coefficient, and mass of water in the basins and mass flow rate into the double-glass cover. Thermal performances of a solar still cou‐ pled with flat plate heater along with an evaporator-condenser have been analyzed by Rene Tchinda, et al., [3]. They reported that the theoretical solar still productivity is in reasonably good agreement with the experimental distillation yields. Thermal performances of a regen‐ erative active solar distillation system working under the thermosyphon mode of operation have been studied by Singh and Tiwari for Indian climatic condition. It is concluded that (i) there is a significant improvement in overall performance due to water flow over the glass cover and (ii) the hot water available due to the regenerative effect does not enhance the out‐ put. They derived expressions for water and glass temperatures, hourly yield and instanta‐ neous efficiency for both passive and active solar distillation systems [4]. Chouchi et al., [5] have designed and built a small solar desalination unit equipped with a parabolic concentra‐ tor. The results show that, the maximum efficiency corresponds to the maximum solar light‐

Augmentation of distillate yield in “V”-type inclined wick solar still with cotton gauze cooling under regenerative effect

Abstract Water flowing over bare glass is not evenly distributed over the width of the glass cover. Effective temperature reduction in the glass cover is not possible in this case. Thin cotton gauze is used over the glass cover to solve this problem. The amount of water required to cool the glass cover is low and the flowing water is collected and fed into a hot water reservoir. Water from the hot water reservoir is directed to the wick absorber by a drip valve. The system was tested in two ways (i) regenerative effect with cotton gauze (ii) regenerative effect without cotton gauze. The inclined wick absorber ensures that the surface is always wet due to capillary action and there were no dry spots. Excess flow in the wick absorber is pumped back to the hot water reservoir. Due to low thermal inertia of the wick and regenerative effect, the system has quick start-up times, as well as higher operating temperatures. This resulted in higher distillate yield than simple solar stills. Since the hot water reservoir remained warm enough during the night hours, a reasonable amount of nocturnal distillate output was also obtained. Optimum inclination of the wick absorber was found to be 20° and mass flow rate through the wick absorber was 200 ml/minute. The system with cotton gauze produced distillate yield of 6,300 ml/m2 whereas the system without cotton gauze produced distillate yield of 5,600 ml/m2.

Performance Analysis of “V”- Type Solar Still with Tilt Wick and Effect of Wick Coverage

Abstract Solar distillation has yet to achieve widespread acceptance due to various technical difficulties and maintenance requirements which might not be acceptable or feasible for local communities. Emphasis has now shifted on the assimilation of locally available materials and expertise for optimum output. Coimbatore and nearby areas in South India have cotton waste material because the textile industry has flourished over the past ten years. A new design of wick and the performance of the solar still are parametrically analyzed in this paper. A “V”-type solar still of 1.5 m2 was constructed for experimental verification and data collection. The glass temperature, ambient air temperature and solar radiation were recorded during the sunny days. The effect of the tilt angle in the Coimbatore climatic conditions is also presented in this paper. The system was tested in two ways: (1) tilt basin fully covered by wick and, (2) tilt basin partially covered by the wick. Since the partial coverage of the wick yielded higher output and would be lower cost, this is the superior arrangement. The optimum tilt of the wick was found to be 25°. The system with tilt basin fully covered by wick produced distillate yield of 3,365 ml (m2-day) whereas the system with tilt basin partially covered by wick produced distillate yield of 3,640 ml (m2-day).