Experimental Investigation of Solar Desalination System Using Evacuated Tube Collector

Soft water is very essential for life, without soft water human as well as an animal cannot survive into nature. In the world, about 97 % of the earth's water is salt water into the ocean and 3 % fresh water contained in the groundwater, lakes, and rivers. Many researchers have studied the solar desalination system which mainly classified into membrane method, distillation method, RO, MED, MSF those methods need to consume fossils fuel and electric power. Section I discussed published literature till date reports with use of ETC to desalination system. Section II Literature review Section III discuss in detailed experimental results and results, and discussion is made in section IV conclusion and future scope is made in section V. In this set-up, solar energy was used solar desalination to solve the problem of shortage of fresh water. Solar energy can be directly used for a heating process to desalination work.

Solar desalination system widely investigated by many researchers. Praveen Hunashikatti et al., [1] are working on development on desalination unit using solar still coupled with evacuated tubes for domestic use. Soteris A. Kalogirou [2] mainly studies seawater desalination using renewable energy sources. This paper also includes a review of various systems that use renewable energy sources for desalination. Ashok Kumar Rajput et al. [3] mainly discusses the monthly averages of a sunshine hour and monthly variation of entire solar radiation are estimated. This paper also discusses the potential of estimation and utilization the solar energy and to solve the energy deficit in Pune district throughout the year. Their study shows that thermal and economic analysis of desalination system, he had used low-temperature multi-effect desalination system, they concluded that through multi-effect distillation method achievement for maximum thermal performance [4]. Jiang, et al., [5] was studied the compound parabolic concentrator of the novel mid temperature to retain certain temperature of water for desalination. Their results show that an evacuated tube CPC solar array can achieve 50 % efficiency at 200 ⁰C under a one sun condition. Gude, Veera Gnaneswar [6] mainly studies low-temperature desalination using solar collector augmented by thermal energy storage. This paper aims to provide a comprehensive review of all the indirect solar desalination technologies along with plant-specific technical details also economic feasibility and cost [7]. Affecting parameters for each desalination technology are also reviewed. Abhijeet Auti [8-9] mainly works on domestic solar water desalination system using parabolic concentrator they found that condensate water efficiency for finned system and 6 hours in a day to get 20 liters of soft water using parabolic concentrator also works on optical efficiency by varying different parameters. This paper mainly discusses the design and manufacturing of absorber for solar desalination system [10]. It is observed that absorber is more efficient for entire experimentation. Kedar et al. [11] mainly studies theoretical approach for hybrid solar desalination system using evacuated tube collector and compound parabolic concentrator. Their work mainly focuses on a theoretical and experimental study of a double slope still with fins immersed in a basin [12]. Their results show increasing the mass of water in the basin makes the productivity to go down. Satyamurthy et al. [13] carry out detailed experimental study on a conventional single slope solar still with sand heat energy storage for improving the yield of fresh water, their results show that solar still with and without energy storage materials was found to be 5.1 and 1.9 kg/m² day respectively. The paper mainly includes thermal analysis, for double slope solar still, was carried out based on internal and external heat transfer and energy balance equations to predict its performance [14]. They have mainly evaluated regarding recorded temperatures, instantaneous and internal thermal efficiencies, and system productivity. This paper mainly focuses on an overview of present desalination status and fresh water demand, fuel requirements, solar energy availability, thermal desalination technologies and solar thermal technologies of Oman has been presented in the paper [15]. The paper of Kedar et al. mainly focus on thermal analysis of evacuated tube collector as well as design and analysis of compound parabolic concentrator [16-17].

It can be observed from the literature survey that most of the studies carried out by the earlier researcher for analytical, experimental and numerical investigations. The present work involves an experimental investigation of a solar desalination system with evacuated tube collector to an objective of getting a maximum amount of soft water using the single effect boiling which will be useful for drinking purpose. Thus it should be noted that phenomenon of heat transfer from the evacuated outer surface of the tube to the inner surface of the tube and then water to enhance the formation of the steam goes for condensation to forms maximum soft water.

However inherent limitations of the experimental measurements and water flow through an evacuated tube with single effect boiling to form soft water is not found in the literature. The feature responsible for high heat rate and enhance the flow rate of water, temperature distribution for different environmental and climatic conditions of Pune city. Through this experimental investigation of evacuated tube collector, chemical analysis of the inlet and outlet water sample carried out as per (IS-10500:2012) drinking water standard. Chemical analysis shows distillate as well below the limit of drinking water specification.

Operation of the entire system is similar to the natural thermosyphon solar water heating system. Solar radiations strike on glass cover, penetrate into inner glass tube and water. Water heated to a higher temperature and converted into steam. Due to a difference in the volatility on the internal surface of the surface condenser. Eventually leaving back the salt and chemical contaminants water drip down to the channel and in collected into Jar/bottle. The collected water is free from any chemical contaminants which are fit for drinking and industrial applications.

Experiments are carried out for different days as per environmental and climatic conditions of Pune city which is located in Weston reason of INDIA. The chemical analysis of both the initial hard water sample and a final water sample was compared with Indian Standard (ISO-10500-2012). The experiments are carried out from Morning 6:30 AM to evening 5:30 PM for various parameters such as temperature, wind velocity, water flow rates and intensity of solar radiation. The glass cover and condenser plate are cleaned daily to ensure that parameters not affected by dust.

In the present work, a solar desalination system developed with the help of evacuated tube collector system. This system is fabricated and tested for environmental and climatic conditions of Pune city. Based on various experiments conducted and the above discussion the following conclusion is drawn: -

1. An experimental investigation using evacuated tube collector system to get 25-27 liters of soft water per day which is useful for drinking and industrial application. Usually, in case of rural areas water for bathing is heated by burning wood, leaves or cow dung, which deals with emission of carbon dioxide, carbon monoxide to atmosphere and water is observed at high temperature in range 75℃-90℃. This eco friendly system does not depends upon any conventional sources of energy for its operation. Future work will be specifically targeted to increase distillate water using hybrid energy system.
2. The developed system is successful in reducing the excess hardness, total dissolved solids, chemical contaminants of inlet water sample. The chemical composition of distillate obtained satisfied as per drinking water standard (IS 10500:2012).