Energy-matrices, exergy, economic, environmental, exergoeconomic, enviroeconomic, and heat transfer (6E/HT) analysis of two passive/active solar still water desalination nearly 4000m: Altitude concept

Parametric study of an active and passive solar distillation system: Energy and exergy analysis

The solar stills were developed to fulfil the freshwater need of the growing population. The paper presents the recent modifications made in still to improve their productivity like the application of phase change materials (PCM), connecting flat-plate collector (FPC), use of nanoparticles, stepped solar still, and attaching separate condenser in the still. Active solar stills are found more productive than passive ones and the thermal efficiency of active solar stills lie in the range of 50–70%, which is far better than passive still having 20–55% thermal efficiency. According to the literature studied in the paper, the maximum productivity of active solar still is 10 litres per day and in passive solar stills, it is 6 litres per day. The different approaches used to carry out the heat and mass transfer analysis of single and double slope active and passive solar stills are also discussed in the paper.

Water scarcity is an issue that stems from the overconsumption and misuse of fresh water supplies, which leads to shortages and decreased quality of life. It most affects developing countries that do not have the infrastructure in place to mitigate these factors. Solar still become most suitable method for water purification in these types of places due to its cheapness and easily made from locally available materials. Current paper concentrate on a detailed techno-economic and enviroeconomic analysis of distinct configurations of active and passive solar distillation stills. Distilled water production, cost per litres, environmental cost comparison has been done between different types of passive and active solar still. Active solar still has a higher system cost compared to passive solar due to the addition of thermal energy by different components and mechanisms. Based on the results, minimum cost per litre is obtained for passive conventional solar still with the spherical ball as heat storage material and in case of active solar still, with PV module, reflectors, air-cooling technique are 0.0136 $/l and 0.0092 $/l, respectively. On the basis of energy, the highest environmental cost was found for AMSSFS air-cooled with evacuated mode (1456.38 $), while the lowest was found for active solar stills with N - Flat Plate Collectors (44 $).

One of the basic requirements for all living things in this world is the availability of pure drinking water. Nowadays, the world is facing a huge water crisis, and clean water sources are being contaminated by man-made pollution and overexploitation. Water demand will grow in the future with population growth and increased urbanisation and industrialisation. Desalination is one of the oldest technologies used for water purification. Conventional desalination techniques utilise electric power, which is not economic, and also it has an indirect adverse effect on the environment due to the pollutants generated during power plant operations. Even today, underdeveloped countries and developing countries face a huge water scarcity because of unplanned mechanism and pollution created by man-made activities. Water desalination without affecting the ecosystem is the need of the hour. Water purification using solar energy has become more popular because of its eco-friendly nature and low cost. A solar still is a commonly used device for water purification, and it does not require any electricity for its functioning and it is the most suitable device for the urban and rural areas. The solar still is mainly classified into two groups, namely, the passive solar still and active solar still. The passive solar still is simple in design, low cost, low maintenance, but the yield is very low. Active solar still consists of additional components to supply the thermal energy and therefore, the yield is high. In the last three decades, many new passive and active solar stills are developed all over world, and research works are still going on to improve the system performance and other aspects of solar stills. Looking into its importance in the present and future, this chapter creates a comprehensive knowledge and research advances in various designs of solar still. This chapter also covers the principle of solar distillation and advantages of solar stills in crunchy manner.

Water is one of the essential sources for the endurance of human on the earth. As earth having only a small amount of water resources for consumption purpose people in rural and urban areas are getting affected by consuming dirty water that leads to water-borne diseases. Even though ground water is available in small quantity, it has to be treated properly before its use for internal consumption. Brackish water contains dissolve and undissolved contents, and hence it is not suitable for the household purpose. Nowadays, distillation process is done by using passive and active solar stills. The major problem in using passive solar still is meeting higher demand for fresh water. The fresh water production from passive solar still is critically low to meet the demand. To improve the productivity of conventional solar still, input feed water is preheated by integrating the solar still to different collector panels. In this review article, the different parameters that affect the rate of evaporation in an active solar still and the different methods incorporated has been presented. In addition to active distillation system, forced convection technique can be incorporated to increase the yield of fresh water by decreasing the temperature of cover. Furthermore, it is identified that the yield of fresh water from the active desalination system can be improved by sensible and latent heat energy storage. This review will motivate the researchers to decide appropriate active solar still technology for promoting development.

Solar distillation is a promising method for clean water supply to rural communities where the quality of water is poor and sunshine is abundant. Due to a lower yield of water distilled in a passive solar still, it is not popularly used and commercialized. Various active methods were developed to overcome this problem. A newly designed solar still coupled with an evacuated tube collector (active solar still) and passive solar still for comparison purposes were fabricated and tested at Solar Energy Park, Tamilnadu College of Engineering, Coimbatore (Latitude: 11°N; Longitude: 77°E and an altitude of 409 m above sea level), Tamilnadu, India. Experiments were conducted under various meteorological conditions from June 2009 to March 2010. It has been found that maximum daily distilled water production of 7.03 and 3.225 kg obtained in active and passive solar stills, respectively, at a water depth of 0.04 m. It has also been observed that the efficiency of an active solar still is lower than the passive solar still in high temperature operations.

This paper presents an exergetic analysis for passive and active solar distillation systems. The analysis is based on mass, energy and exergy balance equations, which has not been attempted in the past for active solar stills. In the present paper, it has been tried to compare the hourly exergy and thermal efficiency of passive and active solar stills. The values of hourly exergy and thermal efficiency of passive solar still are 0.1?0.8% and 2?17% while those for active solar still are in the range 0.1?1.1% and 3 15%, respectively. In case of active solar still, the effect of water depth and number of collectors on overall exergy and thermal efficiency have been obtained.

This present work is aimed to examine the effect of mass flow rate on distillate output and performance of a solar still in active mode. Outdoor experiments were conducted at the coastal town, Kakinada (16°93′N/83°33′E), Andhra Pradesh, India. A solar still with a 30° of fixed cover inclination, 1 m2 of effective basin area, and a flat-plate collector (FPC) with an effective area of 2 m2 were used. An attempt was also made earlier in passive mode to optimize the water depth for the same solar still for maximum yield and distillation efficiency. For the passive still, it is observed that the capacity of heat storage and heat drop are significant parameters that affect the still performance. For the selected still design, the study reveals that 0.04 m water depth is the optimum value for specific climatic conditions. In the active solar still, with the optimum water depth, different flow rates of 0.5, 1 and 1.5 L/min are considered through FPC. It is observed that both the mass flow rate and the variation of internal heat transfer coefficients with the mass flow rate have a significant effect on the yield and performance of the still. The experimental results show that the combination of 1.5 L/min mass flow rate and an optimum water depth of 0.04 m leads to a maximum yield for the active solar still. The enhanced yield of the active solar still is 57.55%, compared with that of the passive solar still, due to increase in area of radiation collection and more heat absorption rate.

Life cycle cost analysis of single slope hybrid (PV/T) active solar still

Improving the double slope solar still performance by using flat-plate solar collector and cooling glass cover

This paper comprehensively reviews the use of phase change materials (PCMs) as latent heat storage systems to improve the productivity of solar stills. Previous studies on enhancing the productivity of active and passive solar stills with PCM are also presented. These studies show that a passive solar still with PCM shows a productivity improvement of up to 120% compared with a solar still without PCM. Meanwhile, the productivity improvement of an active solar still with PCM could reach as high as 700%. These results indicate that productivity increases along with an increasing PCM mass and a decreasing saline water mass. The PCM is also observed to be less effective in daytime than in night-time. It is also shown that organic PCMs (such as paraffin) were mostly used in studies on productivity improvement, whilst very few studies have examined the effects of inorganic and eutectic types of PCM.

Monthly performance of passive and active solar stills for different Indian climatic conditions

Solar distillation systems have been found economically feasible in desalination of saline water. It is a simple and cost-effective low-carbon technology. Free of cost, non-polluting, non-exhaustible solar energy is used to produce distilled water inside a solar still. In this article, the usual economic analysis model has been modified by incorporating the factor of equivalent cost of environmental degradation and high-grade energy savings for solar stills. The unit cost of desalination of saline water is estimated to be US$ 0.034/L corresponding to 30.42% energy efficiency of a passive solar still. It decreases to US$ 0.024/L using the modified model. Double-slope passive solar stills desalinate at a lowest cost of US$ 0.007/L. Due to higher capital cost of active solar stills, the unit cost of desalination of saline water is higher even if productivity is more. Effects of variation of energy efficiency, useful life, capital cost, etc. are also studied. The payback periods of the passive solar still are found to be in the range of 1.1 to 7.6 years if the selling price of distilled water decreases from US$ 0.18 to 0.04/L.

Improvement techniques of solar still efficiency: A review

The accessibility of potable water has always been a serious challenge, and the need for both potable water and other resources is increasing year by year. The desalination technique, which uses solar still to produce freshwater while having limited resources, is useful not only in arid areas but also in more developed areas. The distillate output value of a conventional solar still can vary from 1.5 to 4 L/m2/day, which is not enough to consume daily. As a result, an attempt has been made in this article to review the modifications that were categorised based on the various designs of solar stills and summarized based on their maximum productivity and efficiency. Active and passive solar stills were discussed based on recent advancements. It is found from the study that MESS and TSS can be suitable designs for industrial applications, and SSSS and DSSS can be used with different designs for domestic applications. Moreover, in recent studies, the use of weir cascade and rotating wick designs showed maximum thermal efficiency of 76.69% and 84%, respectively. Highlights Based on design developments, all the major designs of solar stills are analysed and comprehensively reviewed. The recent work in active and passive solar stills showed major advancements in design and performance for better distillate yield. Diverse designs of solar still demonstrated significant performance enhancement and gain in efficiency and a new design of solar still can be developed for solving major agricultural groundwater problems. The applicability of various energy storage materials is also examined, and the use of wicks and paraffin wax led to significant improvements in the performance of solar stills. Compared to other designs of solar stills, tubular and multi-effect solar stills showed the maximum productivity and can be utilised for diverse industrial applications. Single- and double-slope solar still can be utilised for domestic applications in arid and more developed areas. The weir cascade and rotating wick design showed maximum thermal efficiency when compared with other major designs of solar still.