Effect of water depth and insulation on the productivity of an acrylic pyramid solar still – An experimental study

Journal Pre-proof Effect of water depth and insulation on the productivity of an acrylic pyramid solar still – An experimental study A. Muthu Manokar, Yazan Taamneh, Abd Elnaby Kabeel, D. Prince Winston, P. Vijayabalan, D. Balaji, Ravishankar Sathyamurthy, S. Padmanaba Sundar, D. Mageshbabu PII:

S2352-801X(19)30390-X

DOI:

https://doi.org/10.1016/j.gsd.2019.100319

Reference:

GSD 100319

To appear in:

Groundwater for Sustainable Development

Received Date: 28 November 2019 Revised Date:

11 December 2019

Accepted Date: 13 December 2019

Please cite this article as: Muthu Manokar, A., Taamneh, Y., Kabeel, A.E., Prince Winston, D., Vijayabalan, P., Balaji, D., Sathyamurthy, R., Padmanaba Sundar, S., Mageshbabu, D., Effect of water depth and insulation on the productivity of an acrylic pyramid solar still – An experimental study, Groundwater for Sustainable Development (2020), doi: https://doi.org/10.1016/j.gsd.2019.100319. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier B.V.

Graphical Abstract

Effect of water depth and insulation on the productivity of an acrylic pyramid solar still – An experimental study Muthu Manokar Aa,∗, Yazan Taamnehb , Abd Elnaby Kabeelc , Prince Winston Dd , Vijayabalan Pe , Balaji De , Ravishankar Sathyamurthyf,f, Padmanaba Sundar Sf , D. Mageshbabug a

Department of Mechanical Engineering, B.S Abdur Rahman Crescent Institute of Science and Technology, Chennai, 600048, Tamil Nadu, India b Department of Aeronautical Engineering,Jordan University of Science and Technology,Irbid,Jordan c Mechanical Power Engineering Department, Faculty of Engineering, Tanta University, Tanta, Egypt d Department of Electrical and Electronics Engineering, Kamaraj College of Engineering and Technology, Virudhunagar, 626001, Tamil Nadu, India e Department of Mechanical Engineering, Hindustan Institute of Technology and Science, Rajiv Gandhi Salai OMR padur, Chennai, 603103, Tamil Nadu, India. f Department of Automobile Engineering, Hindustan Institute of Technology and Science, Rajiv Gandhi Salai OMR padur, Chennai, 603103, Tamil Nadu, India. g Department of Mechanical Engineering, Velammal Institute of Technology, Chennai, Chennai, Tamil Nadu, India.

Abstract Evaporation and condensation rate directly depend on the surface area provided in the solar still. Considering that, pyramid solar still provides greater surface area than basin type still for condensation process and gives out high performance. In this research work, the pyramid solar still is researched by varying the water depth from 1 to 3.5 cm with and without insulation conditions. The performance of the pyramid solar still with insulation is greater than the without insulation. Insulation plays an important role to increase the yield by increasing the water temperature. The yield produced from the pyramid solar still was higher at the lowest water depth of 1 cm for both insulation and un-insulated condition. The freshwater production from the pyramid solar still without insulation is 3.27, 2.93, 2.26, and 1.59 kg/m2 and with insulation is 3.72, 3.40, 2.70, and 2.08 kg/m2 for the water depth of 1, 2, 3, and 3.5 cm, respectively. At 1 cm water depth, the pyramid solar still with and without insulation produced 19.46% and 8.26% higher yield than the single basin type solar still.The daily efficiency of solar still is improved to about 28.5% with insulation whereas, the daily efficiency for solar still without insulation is found as 26.17%. Keywords: pyramid solar still; acrylic collector cover; insulation; water depth; condensation Contents 1 Introduction

2

2 Experimental setup and procedure

3

3 Results and Discussion 3.1 Hourly variations of meteorological data . . . . . . . . . . . . . . . . . . . . . .

4 4

∗

Corresponding author. Corresponding author. Email addresses: [email protected] (Muthu Manokar A), [email protected] (Ravishankar Sathyamurthy) ∗∗

Preprint submitted to Ground water for sustainable development

December 14, 2019

3.2 3.3 3.4 3.5

Hourly variations of water and basin temperature for the PSS with and without insulation condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Variations of the accumulated yield for the PSS with and without insulation condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Variations of thermal efficiency of the PSS with and without insulation condition Comparison of productivity and thermal efficiency of different passive pyramid solar still . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4 Conclusions

6 6 8 9 11

1. Introduction Water, an essential life saving renewable source, fulfils our needs from the ancient time to till date and also in future. Only 1% of the available water is freshwater, which is suitable for domestic purposes. Because of the unbelievable growth of population and industrialization, the available freshwater source is in the dangerous condition of moving from renewable source to a finite source. This condition can be avoided and the need and demand of the people can be satisfied only if the salt water, which is hugely available, is converted into drinking water by desalination process using solar stills (Khechekhouche et al. (2019); Kumar et al. (2019); Balachandran et al. (2019a,b)). Management and recreation of freshwater resource draw extra attention in today’s scientific world. Freshwater can be recreated by processes other than natural hydrological cycle is one of the important development which gives us the confidence to meet the growing demand. Various researches are going on worldwide on the conversion of saltwater into freshwater (Sathyamurthy and El-Agouz (2019); Madhu et al. (2019); Manokar et al. (2019a,b, 2018); Panchal et al. (2019); Madhu et al. (2018); ElAgouz et al. (2018); Nagarajan et al. (2017)). Most of the research work state that solar energy based desalination technology is the effective technique to produce fresh water with low cost (Kulandaivel and Karuppiah (2014)). Solar desalination technique is proven to be the best suitable method for the recreation of the freshwater from saltwater in isolated locations where scarce for electrical energy and other resources exist. Single Slope Solar Still (SSSS) and Pyramid Solar Still (PSS) are designed by Fath et al. (2003) for the comparative analytical study of thermal performance, productivity and efficiency. Based on Dunkle relations, annual average daily productivity was calculated and it was found that 2.6 L/m2 /day and the PSS and SSSS produced 30, 33% annual average daily efficiency, respectively. The PSS attached with the parallel multi-shelf arrangement in the basin was designed by Kabeel (2007) and his experimental setup produced 90 to 95% higher fresh water than corrugated or horizontal beds. Kabeel (2009) also designed a solar still with concave wick evaporation surface and tetra sided pyramid shaped collector. It produced the fresh water of about 4.1 L/ day m2 with an average daily efficiency of 30% which is 200% higher than the conventional solar still. Passive and Active Pyramid Solar Still (PPSS and APSS) was fabricated for a comparative analysis by Kianifar et al. (2012). The only difference in both the still is, the APSS has a small fan, which runs in negligible power, at the side wall. Based on the research, it was reported that the APSS produced a higher productivity of 3.14 L/m2 , 1.88 L/m2 at 8cm water depth during the summer and winter, respectively. Taamneh and Taamneh (2012) also analyzed the PSS with fan and without the fan, fixed at the collector surface. The PSS with fan gave 25% higher yield than the PSS without fan due to the circulation of the air in the interior of the solar still. Arunkumar et al. (2012) researched the PSS, the PSS integrated with the Concentrated Coupled Collector (PSS - CPC) and hemispherical solar still (HSS). The freshwater production from the PSS, PSS - CPC, and the HSS were 3300, 6928 and 2730 mL/m2 per day, respectively. Based on the comparative study of the PSS and Single Basin Solar Still (SBSS), Algaim et al. (2013) found that the PSS produced maximum fresh water of 7368 2

ml/2 /day and the SBSS produced the distillate water of about 5570 mL/m2 /day. Ahmed et al. (2014) recorded in their studies that the PSS produced the higher yield than the SSSS and DSSS because it received more direct solar radiation. Kabeel et al. (2016) experimentally proven that changing the collector cover angle has a huge impact on Still’s performance. They set square PSS with three different collector cover inclination angles of 30.47◦ (System-A), 40◦ (System-B) and 50◦ (System-C). Based on the experiment they stated that the PSS with the inclination equal to the latitude of the place, System A (300), received more solar energy which increases the performance of the still. It showed 41% higher performance than System C (50o ) and 18% higher yield than system B (40◦ ). System C gave comparatively very less yield because its collector cover angle is higher than the latitude angle of the place. Triangular shaped solar still with variations such as still with Phase change materials (PCM) and without PCM was investigated by several researchers (Ravishankar et al. (2013); Sathyamurthy et al. (2014b,a, 2016)). Sathyamurthy et al. (2014a) also studied the effect of water mass in the PSS. Effect of water mass in the solar still is studied by many researchers (Murugavel et al. (2008b); Ahsan et al. (2014); Suneja and Tiwari (1999); Zurigat and AbuArabi (2004); Tripathi and Tiwari (2005); Tiwari and Tiwari (2006); Phadatare and Verma (2007); Murugavel et al. (2008a); Murugavel and Srithar (2011); Murugavel et al. (2010)). Effect of insulation thickness is studied by Khalifa and Hamood (2009), and the effect of insulation on solar still productivity is experimentally investigated by Elango and Murugavel (2015) and Al-Hamadani and Shukla (2014). It is seen that very fewer experiments were focused on the use of acrylic sheet as a collector cover material to enhance the condensation rate. Hence the main objective of this research work is fabricating the PSS with acrylic sheet as a collector cover. Experiments were conducted by varying the water depth (1cm, 2cm, 3cm and 3.5 cm) with and without insulation conditions. 2. Experimental setup and procedure The schematic diagram of the PSS without and with insulation is shown in Figure. 1. The basin of the still is made of a galvanized iron sheet with an area of 0.25m2 and the collector surface of the still made by an acrylic sheet. The transmission of the acrylic material is 2% higher than the normal glass material. It has the higher impact strength and clear than the glass. In the first experimentation, the PSS without insulation has been carried out. In the second experimentation, 4mm thickness thermo cool has been used as an insulation to prevent the heat losses from the solar still to the atmosphere. Experiments were carried out from 9 am to 5 pm. The freshwater production by the PSS is collected at the inner surface of the collector surface by attaching a small glass piece obstruction. The condensed water is collected by using a flexible hose pipe and the water is transferred into the measuring jar. The thermocouples were used to measure basin, water, glass and atmosphere temperatures. Solar power meter and Anemometer were used to measure the solar intensity and wind speed, respectively. Table 1: Accuracy and error limits for different measuring instruments

Sl. no 1 2 3 4

Instruments

Accuracy

Range

Thermocouple Solar power meter Anemometer Measuring jar

±1◦ C ±1 W/m2 ±0.1 m/s ±10 mL

0–100◦ C 0–2500 W/m2 0–15 m/s 0–1000 mL

3

% error 0.50% 2.50% 10% 10%

Figure 1: Illustrative diagram of the PSS with and without insulation conditions

3. Results and Discussion 3.1. Hourly variations of meteorological data Fig. 2 (a-c) shows the hourly variation of the solar intensity, wind velocity and ambient temperatures during the experimental day of the PSS in two different experimental conditions such as the PSS with and without insulation conditions with respect to time. During the testing of the PSS without insulation conditions, the average solar intensity for every day is recorded in the range from 710 to 730 W/m2 and it is recorded that the maximum solar radiation during the experimentation is 965 W/m2 at 1 PM on 18.04.2017. Throughout the testing of the PSS with insulation conditions, the average solar intensity for every day is recorded in the range from 800 to 820 W/m2 and it is recorded that peak solar radiation during the experimentation is 995 W/m2 at 1 PM on 26.04.2017. The daily average wind speed during the testing of the PSS without insulation was recorded as 1.5 to 2 m/s and with insulation was recorded as 1.4 to 1.6 m/s. It is noted that during the operation of the PSS under the condition of without insulation there is a higher wind speed and it increased the heat transfer rate from the collector surface to the environment which resulted in enhancement in condensation rate. It is noted that the ambient temperature for the period of the midday is the highest and the maximum temperature is recorded as 39◦ C. The daily average ambient temperature during the testing of the PSS without and with insulation was recorded as 34 to 35◦ C and 35 to 36◦ C, respectively.

4

Figure 2: Variations of (a) solar intensity (b) wind velocity and (c) ambient temperature

5

3.2. Hourly variations of water and basin temperature for the PSS with and without insulation condition Figure. 3 (a,b) shows the variations of water temperature of the PSS without and with insulation effect for different water depth condition. From the experimental results of the PSS without insulation, it is found that the water depth at 1cm reaches the maximum water temperature (60◦ C) at 1 P.M and after that, it is decreased and it reached 35◦ C at 5 P.M. At 2cm water depth, water temperature reaches its maximum (58◦ C) at 1 P.M and it reached 43◦ C at 5 P.M. When the water depth increases from 1 cm to 2 cm there is a maximum temperature drop of up to 9.4% during the morning time and the maximum temperature rise of up to 23% during the evening time because of storage effect of basin water. Further water depth is increased as from 1 to 3cm and 1 to 3.5cm; it is observed that when the water depth is increased above 2cm, water temperature decreased because of increasing the water volume in the basin. The maximum water temperature of 57 and 55◦ C is recorded for the water depth of 3 and 3.5cm, respectively. There is a maximum water temperature drop of up to 22.6% and 47.2%, and maximum water temperature grows up to 31 and 21.6% are observed for without insulation condition at the water depth of 3 and 3.5cm, respectively as compared to the 1cm water depth. The daily average water temperatures of 45, 46, 44 and 42◦ C is recorded at the water depths of 1,2,3 and 3.5 cm, respectively for the PSS without insulation conditions. From the experimental results of the PSS with insulation, it is found that water depth at 1cm reached the higher water temperature (62◦ C) at 1 P.M and after that, it is decreased and reached 39◦ C at 1 P.M. At 2 cm water depth, water temperature reached its highest value (60◦ C) at 2 P.M and it reached 46◦ C at 5 P.M. When the water depth is increased from 1 to 2cm there is a maximum temperature drop of up to 14% during the morning time and the maximum temperature rise of up to 18% during the evening time because of storage effect. Further water depth is increased from 1to 3 cm and 1to 3.5 cm; it is observed that water temperature decreases because increasing in water volume in the basin. The maximum water temperature of 58 and 56◦ C is recorded for the water depth of 3 and 3.5 cm, respectively. There is a maximum water temperature drop of up to 27.3 and 37.5% and maximum water temperature grows up to 26 and 17% are observed for without insulation condition at the water depth of 3and 3.5 cm, respectively as compared to the 1cm water depth. The daily average water temperatures of 48,49,46 and 44◦ C is recorded for the water depth of 1,2,3 and 3.5 cm, respectively for the PSS with insulation conditions. Variations of basin temperature for the PSS without and with insulation are shown in Figure. 4 (a,b). The maximum basin temperature of 58 and 60◦ C is recorded for without and with insulation conditions, respectively at 1cm water depth. When the water depth increased, the basin temperature decreased because of increasing the volume of basin water and heat storage effect. There is a maximum basin temperature drop of up to 18, 28 and 38% of water depth of 2, 3 and 3.5 cm, respectively as compared to the 1cm water depth at with insulation conditions and maximum basin temperature drop of up to 20, 27 and 40% for the water depth of 2, 3 and 3.5 cm, respectively as compared to the 1cm water depth at without insulation conditions. Insulation increases the basin temperature by reducing the heat transfer rate from the bottom of the still basin to the atmosphere and increasing the water depth decreased the basin temperature because of storage effect.

3.3. Variations of the accumulated yield for the PSS with and without insulation condition The daily accumulated yield produced from the PSS without and with insulation is shown in Figure. 5 (a,b). The daily freshwater production from the PSS without insulation is about 0.81kg (3.27 kg/m2 ), 0.73kg (2.93 kg/m2 ), 0.56kg (2.26 kg/m2 ), and 0.39kg (1.59 kg/m2 ) for the water depth of 1, 2, 3 and 3.5cm, respectively. When the water depth increased from 1 to 2cm, 6

Figure 3: Variations of water temperatures for acrylic pyramid solar still (a) without insulation and (b) with insulation conditions with respect to time

7

Figure 4: Variations of basin temperatures for acrylic pyramid solar still (a) without insulation and (b) with insulation conditions with respect to time

there is a 13.3% drop in the freshwater production. Further, it is also found that there is a 33.3 and 65.6% drop of fresh water production rate for the water depth of 3 and 3.5cm, respectively as compared to the 1cm water depth. The daily freshwater production from the PSS with insulation is about 0.93kg (3.72 kg/m2 ), 0.85kg (3.40 kg/m2 ), 0.67kg (2.70 kg/m2 ), and 0.52kg (2.08 kg/m2 ) for the water depth of 1, 2, 3 and 3.5cm, respectively. From the investigational results, it is noticed that an increasing the water depth resulted in decreases in the freshwater production rate. The PSS with insulation increases the daily freshwater production rate up to 12.2, 14, 16 and 16.4% for the water depth of 1, 2, 3 and 3.5 cm, respectively as compared to the PSS without insulation. 3.4. Variations of thermal efficiency of the PSS with and without insulation condition From the thermal efficiency calculation, it is found that minimum water depth in the PSS produced the maximum hourly thermal efficiency and also it is found that the thermal efficiency of the PSS is higher for the water depth at 3 cm for both without and with insulation conditions. 8

The maximum hourly thermal efficiency of the PSS without insulation is 60.93, 44.42, 39.26, and 31.34% and with insulation is 69.04, 55.52, 47.45, and 40.97% for the water depth of 1, 2, 3, and 3.5 cm, respectively. It is found that the daily average thermal efficiency of the PSS without insulation is 26.17, 23.44, 18.48 and 15.38%, with insulation is 28.50, 26.92, 22.82, and 18.95% for the water depth of 1, 2, 3, and 3.5 cm, respectively.

Figure 5: Variations of accumulated yield for pyramid solar still (a) without insulation and (b) with insulation conditions

3.5. Comparison of productivity and thermal efficiency of different passive pyramid solar still The overall thermal efficiency of the solar still depends on the daily accumulated yield, daily solar intensity, latent heat of vaporization and condensation and the area of absorber/condensing surface. Mathematically it is expressed a X ηdaily = X

mew × L

I(t) × A × 3600

(1)

9

The comparison of different PPSS based on their yield and thermal efficiency is tabulated in the Table 2. The freshwater production rate and the thermal efficiency of the PPSS vary from locality to locality. The PSS made of the glass has the highest efficiency of 66.5% (Ahmed et al. (2014)). The PSS with minimum water depth and triangular pyramid-shaped solar still has increased the productivity (Murugavel et al. (2008b); Ahsan et al. (2014)). The efficiency of the proposed PSS without insulation was about 26.17% and it has a maximum distilled water production of 3.27 kg/m2 , similarly, the PSS with insulation was about 28.50% and it has a maximum distilled water production of 3.72 kg/m2 . There is a 12.1% and 8.17% increase in yield and thermal efficiency was achieved in the case of the PSS with insulation as compared to the without insulation.

Table 2: Comparison of the productivity and thermal efficiency of different passive pyramid solar stills

S.No Type of passive pyramid solar still 1

2

3

4 5

6 7 8 9 10

11

12

Theoretical studies on pyramid-shaped solar still (Fath et al. (2003)) Multi-shelves solar glass pyramid system (Kabeel (2007)) Solar still with a concave wick evaporation surface Kabeel (2009) pyramid solar still (Kianifar et al. (2012)) pyramid solar still (Taamneh and Taamneh (2012)) Glass pyramid solar still (Algaim et al. (2013)) pyramid solar still (Ahmed et al. (2014)) square pyramid shaped solar still (Kabeel et al. (2016)) pyramid solar still Ravishankar et al. (2013) triangular pyramid shaped solar still (Sathyamurthy et al. (2014a)) Acrylic pyramid solar sill without insulation (present study) Acrylic pyramid solar sill with insulation (present study)

Location

Egypt

Maximum productivity (L/m2 /day) 2.6

Egypt

2.5

Egypt

4.1

Mashhad, Iran Tafila, Jordan

2.72

Basra city Iraq Kingdom of Bahrain Egypt

Thermal ciency(%) 30%

NA

30%

NA

2.485

40.2

7.368

66.5

4.24

NA

4.14

NA

India

4.3

NA

India

4.2

NA

India

3.27

26.17

India

3.72

28.5

10

effi-

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Highlights •

Experiments are carried out on conventional pyramid solar still with and without insulation.

•

Insulation the improves the daily distillate yield from 12 to 16% as compared to the PSS without insulation.

•

Distillate yield of 3.72 and 3.27 kg/m2 is produced from the PSS with and without insulation at 1cm water depth.

Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: