Elsevier

Journal of Cleaner Production

Volume 161, 10 September 2017, Pages 881-887
Journal of Cleaner Production

Modified pyramid solar still with v-corrugated absorber plate and PCM as a thermal storage medium

https://doi.org/10.1016/j.jclepro.2017.05.195Get rights and content

Highlights

  • The modified pyramid solar stills using PCM was studied.

  • The improvement in productivity with PCM about 87.4% compared to the conventional pyramid still.

  • The improvement in daily efficiency for the modified pyramid still with PCM reached about 106.85%.

Abstract

A modified pyramid solar still with both v-corrugated absorbers plate and PCM, and the conventional pyramid solar still was designed, constructed and fabricated under the same ambient conditions of Tanta city, Egypt. The performance of the modified pyramid still with both v-corrugated absorbers plate and PCM (modified pyramid still with PCM) are compared to the conventional pyramid still, to describe the improvement in the performance of the modified pyramid still with PCM. The experimental results showed that the accumulated distillate yield for modified pyramid still with PCM is higher than that of conventional pyramid still. The accumulated distillate yield reached approximately 6.6 L m−2 d−1 for modified pyramid still with PCM while its value was 3.5 L m−2 d−1 for conventional pyramid still. The use of v-corrugated absorbers plate and PCM under basin improved the accumulated distillate yield of a modified pyramid still with PCM by 87.4% compared to the conventional pyramid still. Moreover, the modified pyramid still with PCM is superior in daily efficiency (86.41%–88% improvement) compared to the conventional pyramid still in the period from September to October 2016 under the Egyptian conditions. The estimated cost of 1 L of distillate water productivity reached approximately 0.0236 $ L−1 for modified pyramid still with PCM while its value was 0.0262 $ L−1 for conventional pyramid still.

Introduction

Many states in most parts of the globe, in particular of developing countries and is located in the region of the Middle East, suffer from the problem of low amount of distillate water. According to a report of the United Nations, one third of the earth’s population lives in countries that suffer from the problem of the lack of distillate water (United Nations Environment Programme). Brackish water obtained from lakes and rivers and the sea and therefore baler needs cannot be used for the purpose of direct drinking water. Solar desalination is one of the best techniques used to produce the distillate water from brackish water or seawater using solar energy (Al-Kharabsheh, 2003).

Solar stills represent one of different methods used to desalination the seawater and brackish water by using the solar energy. The Solar still uses to produce drinking waters from the salt and brackish water, the factors affecting on the productivity of solar stills are (climatic conditions, operating conditions and design parameters) (Sharshir et al., 2016a, Sharshir et al., 2016b, Velmurugana and Srithar, 2011, Dimri et al., 2008) studied the effects of condensing materials on the performance of solar still. This study showed that, the solar still productivity reached to 3.6, 3.3 and 3 l/m2 for using the copper, glass and plastic as the condensing material, respectively. Castillo-Téllez et al. (2015) experimentally studied the influence of climatic conditions on the productivity of solar still (single and double slope). Also, the effects of forced and natural convection mode were conducted.

Due to the low productivity of the solar stills, a large number of researchers carried out a study different ways to improve the productivity of the solar stills (Badran et al., 2005, Tiris et al., 1998, Voropoulos et al., 2001). The productivity of solar still integrated with solar collector and hot water storage tank was studied (Voropoulos et al., 2003a, Voropoulos et al., 2003b). Abu-Hijleh and Rababah (2003) experimentally studied the effect of the sponge cubes in the basin on the productivity of solar still, the results showed that the productivity improved for use the sponge cubes in basin still. El-Sebaii and El-Naggar (2017) theoretically and experimentally conducted the effect of fin material on the productivity of the finned basin stills. The results showed that, the productivity of the stills are not affected by gender metal fins. Sharshir et al., 2016a, Sharshir et al., 2016b studied the performance of solar still integrated with humidification/dehumidification (HDH) and solar collector. The study showed that, for using the water exit from HDH as feed water to the still, the productivity increased by 242% compared to traditional still. Nishikawa et al. (1998) experimentally studied the behavior of the solar still with vacuum pump integrated with solar PV. Edalatpour et al. (2015) numerically studied the effects of the fluid flow and convection heat transfer coefficient on the single slope still productivity. Edalatpour et al. (2016) conducted the reviews of last numerical studies used to estimate the productivity of different technology of solar stills.

Rubio et al. (2000) conducted the impact water flow rate on performance of a single and double slope stills. In this study a new empirical equation are proposed to calculate the mass flow rate for single slop and double slope stills. Omara and Eltawil (2013) conducted the effect of solar dish with boiler on the productivity of solar still. The results showed that, the still productivity with preheating on solar dish increased by 294% compared to traditional still. Omara et al. (2014) conducted the influence of reflectors on the stepped still performance. The results showed that the reflectors improved the productivity by 125%. El-Agouz et al. (2015) conducted the influence of makeup water on the still performance. They found that, the closed loop makeup water increase the productivity by 57.2% compared to traditional still. Kabeel and Abdelgaied, 2017a, Kabeel and Abdelgaied, 2017b experimentally studied the effect of multi-groups of two coaxial pipes in basin on the productivity of modified still. They found that for increase the thickness of annular gap between two coaxial pipes from 5 to 14.5 mm, the improvement in the daily productivity will decreases from 97.8% to 52.7%. Mahian et al. (2017) theoretically and experimentally investigated the effect of nanofluid on the evaporation rate inside the solar still integrated with two flat plate solar collectors connected in series.

Taamneh and Taamneh (2012) experimentally conducted the productivity of pyramid still. They found that, the productivity of pyramid still increased by 25% compared to conventional still. Kianifar et al. (2012) experimentally studied the behavior of a pyramid type still. The results showed that the exergy efficiency of pyramid still higher than that of traditional still, while the cost reduced by 8–9% compared to traditional still. Kabeel et al., 2016a, Kabeel et al., 2016b experimentally conducted the influence of cover angles on the behavior of pyramid still. The resulted show that, the optimal angles equal to the latitude angle. Sathyamurthy et al., 2014a, Sathyamurthy et al., 2014b conducted the factors influences on the behavior of pyramid still. The study showed that the productivity increased by 15.5% for increase the wind speed from 1.5 to 4.5 m s−1.

The Phase Change Material (PCM) represents a thermal storage medium use to improve the still productivity. Kabeel and Abdelgaied (2016) experimentally studied the influence of PCM on the still productivity. The result showed that, the use of PCM improved the still productivity by 67.18%. Kabeel et al., 2016a, Kabeel et al., 2016b experimentally conducted the influence of hot air injection on the behavior of still with PCM. They conducted that, the productivity improved by 108% for using hot air injection with PCM. Kabeel and Abdelgaied, 2017a, Kabeel and Abdelgaied, 2017b experimentally studied the performance of modified still with PCM under basin coupled with oil serpentine loop from cylindrical parabolic concentrator. The results showed that the productivity increased by 140.4% as compared to the conventional still. Sathyamurthy et al., 2014a, Sathyamurthy et al., 2014b experimentally studied the productivity of triangular pyramid still with and without thermal storage medium. They found that, the use of the thermal storage medium improved productivity of triangular pyramid still by 35% compared to the case without in thermal storage medium. Sathyamurthy et al. (2016) studied the effect of different PCM material on the performance of triangular pyramid still. They conducted that, the use of PCM improved the productivity of pyramid still.

From previous studies it is clear that a large proportion of researches use the different techniques to improve the productivity of conventional still, while a limited number of researchers studied the factors affecting on the productivity of pyramid still. With the knowledge that, the productivity of pyramid still more than that of the conventional still. The objective of the present experimental work improved the productivity of the pyramid still, by using v-corrugated absorbers plate and Phase Change Material (PCM) as a thermal storage medium. The performance of the pyramid still with v-corrugated absorbers plate and PCM (modified pyramid still with PCM) are compared to conventional pyramid still, to describe the improvement in the performance of the modified pyramid still with PCM. The modified pyramid still with PCM and the conventional pyramid still are designed, constructed and tested at the same ambient conditions.

Section snippets

Experimental work

In the present experimental work, the test-rig has been designed and constructed to investigate the effect of v-corrugated absorbers plate and Phase Change Material (PCM) on the performance of the modified pyramid still under the Egyptian conditions. The performance of the modified pyramid still with both PCM and v-corrugated absorber plate are compared with conventional pyramid still at the same climate conditions of Tanta city, Egypt. Fig. 1 shows the schematic diagrams of the conventional

Experimental procedure and data analysis

The experimental facility has been designed and constructed in the Tanta University-Egypt (Latitude 30.47 °N and longitude 31°E) to investigate the effects of PCM and v-corrugated absorber plate on the productivity of the modified pyramid still. The depth of the basin water for the both conventional pyramid still and modified pyramid still remain constant at average value 2 cm along the working days. The starting time work at 8:00 a.m. and contained to 9:00 p.m., during the period from

Experimental results

The solar radiation, temperatures of ambient and the basin water for the modified pyramid still with PCM and conventional pyramid still are shown in Fig. 3. As shown in this figure the solar radiation and ambient temperature increase to the maximum value at midday and decrease after that. The maximum temperature of basin water for modified pyramid still with PCM and conventional pyramid still are 77 °C and 71 °C respectively in 1:00 p.m. This result shows that the temperature of basin water for

Economic analysis

Cost analysis of a two pyramid stills are described in this section. The average accumulated distillate yield along the year can be estimated as 5.73 L m−2 d−1 and 2.58 L m−2 d−1 for the modified pyramid still with PCM and conventional pyramid still, respectively. Take the working days per year are 340 d, where in Egypt the sun ascends along the year. The total cost of distillate water per liter (TC/L) is estimated using Equation (3).TCL=Total annual  cost

Conclusions

In the present experimental work, the modified pyramid still with PCM and the conventional pyramid still are constructed and tested under the same ambient conditions of Tanta University, Egypt. The present work aims to improve the accumulated distillate yield of the pyramid still, by using v-corrugated absorbers plate and Phase Change Material (PCM) as a thermal storage medium under basin. The performance of pyramid still with both v-corrugated absorbers plate and PCM (modified pyramid still

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