EXPERIMENTAL STUDY ON A STEPPED BASIN SOLAR STILL

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International Journal of Advanced Research in Engineering and Technology

(IJARET) Volume 6, Issue 7, Jul 2015, pp. 24-29, Article ID: IJARET_06_07_004

Available online at

http://www.iaeme.com/IJARET/issues.asp?JTypeIJARET&VType=6&IType=7

ISSN Print: 0976-6480 and ISSN Online: 0976-6499

© IAEME Publication

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EXPERIMENTAL STUDY ON A STEPPED

BASIN SOLAR STILL

Neha Khare, Ajeet Kumar Rai and Vivek Sachan

Department of Mechanical Engineering, SSET, SHIATS – Allahabad,

U. P. India

ABSTRACT

In the present work an attempt has been made to improve the productivity

of a single slope solar still by constructing many steps to the basin of the solar

still. Experimental setup was fabricated and observations were taken in the

premises of SHIATS Allahabad, U.P., INDIA. It is observed that productivity

can be reached up to more than 6 liters per day for 1 metre square area of the

basin when multi-wicks are added to the system. Overall increase in the

production of stepped basin solar still using wick type arrangement in the

basin is 20.5 % more than without using wick arrangement

Key words: Stepped basin solar still, Solar distillation and Solar intensity.

Cite this Article: Khare, N. Rai, A. K. and Sachan, V. Experimental Study on

A Stepped Basin Solar Still. International Journal of Advanced Research in

Engineering and Technology, 6(7), 2015, pp. 24-29.

http://www.iaeme.com/currentissue.asp?JType=IJARET&VType=6&IType=7

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1. INTRODUCTION

Solar distillation is the process of producing potable water from the brackish water,

Since it requires simple technology, it is of low maintenance and can be used

anywhere without environmental pollution. Main problem with this type of system is

the low productivity per unit installation area compared to fuel base desalination

method. Increasing the productivity of the solar still has therefore been the focus of

many researchers. Number of attempts have been made by many researchers to

improve the absorptivity of the basin liner by using different heat absorbers such as

gravel [1], sponge cubes [2], rubber [3], charcoal [4, 5], dyes and ink [6, 7]. Many

researchers experimented with solar still that are coupled to reflectors [8, 9], flat plate

collectors. Velmurugan et al. experimented on fin-type passive solar still and found

that the yield was increased by 52%. Productivity of the solar still increases with

increase in absorber area [10]. Kalidasa Murugvel [11] have used wick materials to

spread the water throughout the basin of a passive double slope solar still to enhance

IJARET

Experimental Study on A Stepped Basin Solar Still


the productivity the still. Rai et al [14, 15] have used latent heat storage materials in

the basin liner to enhance nocturnal output.

In the present work an attempt has been made to improve the productivity of the

solar still by making stepped basin. Performance is further increased by adding wick

to the basin.

2. EXPERIMENTAL SETUP

The experimental setup consists of a passive solar distillation unit with a glazing glass

cover inclined at 26°. Since the geographical location Allahabad lays 26° in northern

hemisphere thus it is justified to take inclination for glass cover to receive maximum

insolation. This tilted glass cover of 3 mm thickness, served as solar energy

transmitter as well as a condensing surface for the vapour generated in the basin.

Basin having area 1.00 m × 1.00 m is made up of Galvanized Iron has an effective

area of 1.00 m2. This solar still consist of stepped base construction having 8 trays of

100 × 12 × 2 cm3 each, placed in the basin of solar still. Trays are blackened, for

having maximum possible absorption of solar energy. The basin of the distiller was

blackened to increase the solar energy absorption. For the better performance of

stepped-type solar still wick material is added on side absorber of the basin. A

distillate channel was provided at end of the basin. For the collection of distillate

output, a hole was drilled in the channel and plastic pipe was fixed through it with an

adhesive (Araldite). An inlet pipe and outlet pipe were provided at the top of the side

wall of the still and at the bottom of the basin tray for feeding saline water into the

basin and draining water from still for cleaning purpose, respectively. Rubber gasket

was fixed all along the edges of the still. All these arrangements are made to make the

still air tight. Water gets evaporated and condensed on the inner surface of glass

cover. It runs down the lower edge of the glass cover. The distillate was collected in a

bottle and then measured by a graduated cylinder.

Thermocouples were located in different places of the still. They record different

temperature, such as glass cover and water temperature in the basin and ambient

temperature. In order to study the effect of salinity of the water lacally available salts

were used at various salinities. All experimental data are used to obtained the internal

heat mass transfer coefficient for single slope still.

Figure 1 Photographic view of stepped basin solar still

Neha khare, Ajeet Kumar Rai and Vivek Sachan


2.1. Productivity and efficiency of the still

The hourly productivity Ph is calculated using the following equation [12]

�� = ℎ�� − �� × 3600 ��⁄ (1)

The daily productivity Pd as well as the daily efficiency without and with wick are

calculated using the following formulas

�� = ��,�� ∑ ��∆ × 100"%$ (2)

�� = ��,�� ∑ ��∆ × 100"%$ (3)

Where is the daily average of the latent heat of vaporisation of water and ∆% is the

time interval during which the solar radiation is measured.

Exergy efficiency of the system can be calculated by using the following

expressions [13]

��& = '&�(�) +, -, +. �� /+01( / 200'&�(�) 23-, + �� /+01( / 200 (4)

45+, -, = 45�61- = 7��89:: /.�<= × ">1 − ?1@AB8

?�@AB8C (5)

Where is hourly yield of solar still (kg/h), L is the latent heat of vaporization (j/kg),

Ta is the ambient temperature (°C) and Tw is the water temperature (°C).

45+, -, = 45�61- = 7��89:: /.�<= × ">1 − ?1@AB8

?�@AB8C (6)

Where Exsun (solar still) is the exergy input to the solar still through radiation and can

be obtained from the following equation

45/,3"DEFGH D%IFF$ = J/ × K"%/$ × L1 − M8 × >?1@AB8

?/@AB8C + =8 × >?�@AB8

?OCMP (7)

Where As is the area of basin in solar still (m2). I (ts) is the solar radiation on the

inclined glass surface of solar still (W/m2) and Ts is the sun temperature, 6000 K.

3. RESULTS AND DISCUSSIONS

Figure 2 shows variation in solar intensity with respect to time of the day experiments

were carried out of several days in the month of may and june with and without wick

in the stepped basin. Variation of solar intensity in Figure 2 with the time of the day in

the month of may with and without wick. The value of maximum intensity reaches

1200 W/m2 at around 12 o’clock for the day when wicks are used in the stepped

basin. Whereas maximum intensity of 1000 W/m2 reaches around 1 o’clock on the

day when stepped basin was used without multi-wick.

Figure 3 shows variation of wind velocity with respect to time of the day with and

without multi-wick arrangement.

Experimental Study

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Figure 2 Variation of the Solar Intensity with time of the Day

Figure 3 Variation of Wind Velocity with t

Figure 4 Variation of Temperature with Time of the Day



Variation of the Solar Intensity with time of the Day

Variation of Wind Velocity with time of the Day

Variation of Temperature with Time of the Day

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Variation of the Solar Intensity with time of the Day

Neha kha

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Figure 4 shows variation of temperature of different component of solar still with

respect to the time of the day. Water temperature without wick is more than the water

temperature with wick in

when wicks were attached to the basin. This due to the fact that due to addition of

wicks to the basin, rate of evaporation increases, which causes the temperature of the

water to decrease. Glass temperature with wick is more due to high solar intensity on

the day.

Figure 5 Variation of the Productivity with Time of the Day

Figure 5 shows the variation of productivity with respect to time of the day. For

two different cases (1) basin with wick (2) basin without wick. It is observed that

productivity with multi-wick arrangement is higher than without wick arrangement.

Use of wick to the basin increases day time productivity by 14 %. Night time

productivity of distil water u

using wick. It is due to thermal inertial effect of the wick material. Overall increase in

the production of stepped basin solar still using wick type arrangement 20.5 % than

without using wick arrang

4. CONCLUSION

A single-slope solar still is

measured in the Allahabad climatic conditions of U.P India. Energy efficiency 60% is

obtained for stepped basin solar still, which is further increase

wicks are added to the basin. Exergy efficiency of the system is calculated as 10.7 %

for without wick and 10.2 % for multi

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Neha khare, Ajeet Kumar Rai and Vivek Sachan


4 shows variation of temperature of different component of solar still with


spite of the fact that the solar intensity is more on the day



ease. Glass temperature with wick is more due to high solar intensity on

Variation of the Productivity with Time of the Day

5 shows the variation of productivity with respect to time of the day. For

(1) basin with wick (2) basin without wick. It is observed that

wick arrangement is higher than without wick arrangement.


productivity of distil water using wick to the basin increases by 50.5 % than without



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[email protected]

4 shows variation of temperature of different component of solar still with


spite of the fact that the solar intensity is more on the day



ease. Glass temperature with wick is more due to high solar intensity on

Variation of the Productivity with Time of the Day

5 shows the variation of productivity with respect to time of the day. For

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wick arrangement is higher than without wick arrangement.


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EXPERIMENTAL STUDY ON A STEPPED BASIN SOLAR STILL

Engineering

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