Develop Simple Slope Solar Still And Modify Into Inverted Absorber Solar Still

There is almost no water left on earth that is safe to drink without purification after 20-25 years from today. This is a seemingly bold statement, but it is unfortunately true. Only 1% of Earth's water is in a fresh, liquid state, and nearly all of this is polluted by both diseases and toxic chemicals. For this reason, purification of water supplies is extremely important.
Keeping these things in mind, we have devised a model which will convert the dirty/saline water into pure/potable water using the renewable source of energy (i.e. solar energy). The basic modes of the heat transfer involved are radiation, convection and conduction. The results are obtained by evaporation of the dirty/saline water and fetching it out as pure/drinkable water.
Our main abstract is to design simple type of solar still and develop model of simple and single basin solar still and test of performance of solar still and modify it into inverted absorber type of solar still.

LIST OF FIGURES
Figure No. Figure Description Page No.
Figure No. 1 Basin solar still
Figure No. 2 Wick solar still
Figure No. 3 Multi basin solar still
Figure No. 4 3D Fig. of model
Figure No. 5 CAD model of solar still
Figure No. 6 Photograph of working model
Figure No. 7 Cover of solar still
Figure No. 8 Side wall of insulation
Figure No. 9 Channel
Figure No. 10 Still basin
Figure No. 11 Inverted Absorber Solar Still

LIST OF TABLES
Table No. Table Description Page No.
Table 1 Calculation Table
Table 2 Experiment Table-1
Table 3 Experiment Table-2
Table 4 Experiment Table-3
Table 5 Thermal output per day
Table 6 Thermal CalculationTable-1
Table 7 Thermal CalculationTable-2
Table 8 Thermal CalculationTable-3
Table 9 Comparison experiment and Thermal calculation output
Table 10 Thermal efficiency

List of Graphs:
Graph No. Graph Description Page No.
Graph 1 Distil output v/s Time
Graph2 Vapour Temperature V/S Time
Graph 3 Water Temperature V/S Time
Graph 4 Cover inside Temperature
V/S Time
Graph 5 Total Output V/S Day
Graph 6 heat transfer co-efficient v/s time(24/11/2013)
Graph 7 heat transfer co-efficient v/s time(26/11/2013)
Graph 8 heat transfer co-efficient v/s time(27/11/2013)

LIST OF NOMENCLATURE
h1 - Total heat transfer coefficient from moist air to glass cover, W/m2
h2 - Total heat transfer coefficient from glass cover to ambient, W/m2
Ta - Atmospheric temperature, ??C
Tv - Temperature of water vapour, ??C
Tci - Glass inner surface temperature, ??C
Tco - Glass outer surface temperature, ??C
Tw - Water temperature, ??C
mew ' Distill output of water, kg
Aw ' Surface area of water, m2
V ' Wind velocity, m/s
C ' Unknown constant in Nusselt number expression.
Cp ' Specific heat, J/Kg??C
g ' Acceleration due to gravity, m/s2
Gr ' Grashoff number
hcw ' Convective heat transfer coefficient from water to condensing cover, W/m2??C
hew ' Evaporative heat transfer coefficient, W/m2??C
It ' Total solar radiation, W/m2
Id ' Diffuse solar radiation, W/m2
??hv=Latent heat of vapourizaing of water, J/kg
Lv=Characteristic dimension of condensing cover, m
Kv= Thermal constant in Nusselt number expression
Pci=Partial saturated Vapour Pressure at condensing Cover temperature, N/m2
Pw= Partial saturated Vapour Pressure at water temperature, N/m2
hrw=Radiative heat transfer co-efficient ,W/m2??C
Qew= Rate of evaporative heat transfer
t=time
Greek letters
??= co-efficient of volumetric thermal expansion,K-1
??= Density of humid air,kg/m3
??=Dynamic viscosity of humid air, N
??=Emissivity
?? =stefen-boltzman constant, 5.669??10-8 W/m2K4

TABLE OF CONTENTS
III
ABSTRACT IV
LIST OF FIGURES V
LIST OF TABLES VI
LIST OF GRAPHS VII

Chapter:1 Introduction Page No.
1.1 Introduction 3
1.2 Solar energy 3
1.3 Introduction of solar still 4
1.4 Solar still operation 5
1.5 Advantages 5
1.6 Disadvantages 6
1.7 Application 6
1.8 Types of solar still 6
1.9 Conduction 9
1.10 Convection 9
1.11 Radiation 10
Chapter:2 Design of Solar Distillation Plant 11
2.1 Construction of inverted absorber Solar Still 12
2.2 Dimension of inverted absorber solar still 13
2.3 Details of Different Parts of the System 14
2.4 Inclination angle calculation 19
2.5 Calculation table 20

Chapter:3
EXPERIMENTATION
3.1 Observation table for single slope solar still' 1 21
3.2 Observation table for single slope solar still ' 2 22

3.3
Observation table for single slope solar still ' 3

3.4
Observation table for single slope solar still ' 4

3.5
Observation table for single slope solar still ' 5

3.6 Observation table for single slope solar still ' 6
3.7 Observation table for inverted absorber solar still-1 24
3.8 Observation table for inverted absorber solar still-2
3.9 Observation table for inverted absorber solar still-3
3.10 Total output

Chapter:4
Thermal calculation
4.1 Thermal equation 25
4.2 Calculation table 1 (single slope solar still) 27
4.3 Calculation table 2(single slope solar still) 28
4.4 Calculation table 3(single slope solar still) 29
4.5 Calculation table 1 (single slope solar still)
4.6 Calculation table 1 (single slope solar still)
4.7 Calculation table 1 (single slope solar still)
4.8 Calculation table 1(inverted absorber solar still)
4.9 Calculation table 2(inverted absorber solar still)
4.10 Calculation table 3(inverted absorber solar still)
Chapter:5 Comparison
5.1 Comparison of experimental work and calculation 30
5.2 Thermal efficiency 30
Chapter:6 Graphs
6.1 Distil output v/s Time 31
6.2 Vapour temperature v/s Time 31
6.3 Water temperature v/s Time 32
6.4 Cover inside temperature v/s time 32
6.5 Total output v/s day 33
6.6 Heat transfer co-efficient v/s time 34
Chapter:7 Conclusion 35
References 39


CHAPTER-1
INTRODUCTION


1.1 Introduction of solar still:
The first "conventional" solar still plant was built in 1872 by the Swedish engineer Charles Wilson in the mining community of Las Salinas in what is now northern Chile (Region II). This still was a large basin-type still used for supplying fresh water using brackish feed water to a nitrate mining community. The plant used wooden bays which had blackened bottoms using logwood dye and alum. The total area of the distillation plant was 4,700 square meters. On a typical summer day this plant produced 4.9 kg of distilled water per square meter of still surface, or more than 23,000 litres per day. Solar water Distillation system also called 'Solar Still'. Solar Still can effectively purify seawater & even raw sewage. Solar Stills can effectively removing Salts/minerals {Na, Ca, As, Fe, Mn} Bacteria{ E.coli, Cholera, Botulinus}, Parasites ,Heavy Metals &TDS.
Basic principal of working of solar still is 'Solar energy heats water, evaporates it (salts and microbes left behind), and condenses as clouds to return to earth as rainwater'.
1.2 SOLAR STILL OPERATION:
Water to be cleaned is poured into the still to partially fill the basin. The glass cover allows the solar radiation to pass into the basin, which is mostly absorbed by the blackened base. This interior surface use blackened material to improve absorption of the sunrays. The water begins to heat up and the moisture content of the air trapped between the water surface and the glass cover increases. The heated water vapour evaporates from the basin and condenses on the inside of the glass cover. In this process, the salts and microbes that were in the original water are left behind. Condensed water trickles down the inclined glass cover to an interior collection trough and out to a storage bottle.
Feed water should be added each day that roughly exceeds the distillate production to provide proper flushing of the basin water and to clean out excess salts left behind during the evaporation process. If the still produced 3 litres of water, 9 litres of make-up water should be added, of which 6 litres leaves the still as excess to flush the basin.
1.3 ADVANTAGES:
1) Solar energy used for solar still is available in abundance.
2) No prime mover required.
3) Produce pure water.
4) No fossil fuels are required.
5) No skill operators required.
6) Can purify high saline water
7) No elaborated arrangements are needed for transportation, handling and storage of fuels as needed in conventional power plants.
8) It's has low operating and maintenance cost.
9) It's free from pollution.

1.4 DISADVANTAGES:
1) Availability of solar energy varies
2) Solar still process is time consuming.
3) Weather condition is main aspect of solar still. In rain we cannot get any freshwater.

1.5 APPLICATION
It's use in industries, hospitals, and dispensaries, for radiation and battery maintenance, garages and automobile workshops, Laboratory use, marshy and costal area, automobile industries, desert areas and to get fresh portable water.

1.6 TYPES OF SOLAR STILL:
There are four type of solar still:
1) Basin still.
2) Wick still.
3) Diffusion still.
4) Multi basin still.
1.6.1 Basin still:
It consist of shallow, bracken basin of saline/impure water covered with a sloping transparent roof solar radiation that passes through the transparent roof heats the water in blackened basin. Thus evaporating water which gets condensed on the cooler under side of the glass and gets collected as distillate attached to the glass.


Fig.1 basin still

1.6.2. Wick still:

It consists of a wick instead of a basin. The saline/impure water is passed through the wick or absorbed by the wick at a slow rate by capillary action. A waterproof liner is placed between the insulation and the wick. Solar energy is absorbed by the water in the wick which gets evaporated and later condensed on the underside of the glass and finally collected in the condensate channel fixed on the lower side of the bottom surface.

Fig.2 wick still
1.6.3. Diffusion still:
In the simple diffusion desalination process a hot and a cold surface are parallel to each other and separated by a small distance. A diluent gas such as air fills the gap between the two surfaces. The gap thickness is selected to be small in order to suppress heat transfer by convection between the two surfaces.
Solar radiation transmitted through the glass cover and is absorbed on the front surfaces of the partition. When feed water is allowed to flow over hot surface, water vapour diffuses across the gap where it's condensed on cold surfaces. This process is called diffusion desalination.
1.6.4. Multi basin still:
Multi basin still has two basins for water purify. So, productivity of solar still is increase.
It consist of shallow, bracken basin of saline/impure water covered with a sloping transparent roof solar radiation that passes through the transparent roof heats the water in blackened basin. Thus evaporating water which gets condensed on the cooler under side of the glass and gets collected as distillate attached to the glass.


Fig. 3 multi basin still

1.5 CONDUCTION:
Conduction is the transfer of heat from one part of substance to another of the same substance, or from one substance to another in physical with it, without appreciable displacement of molecules forming the substance. In solid the heat is conducted by lattice vibration or by transport of free electrons.
1.6 CONVECTION
Convection is the transfer of heat within a fluid by mixing of one portion of fluid with another. It is possible only in a fluid medium and is directly linked with transport of medium itself. Convection constitutes the macro form of the heat transfer since macroscopic particles of fluid moving in space cause the heat exchange.
1.10.1 TYPES OF CONVECTION
1 Free Convection:-
Free or natural convection occurs when the fluid circulates by virtue of the natural differences in densities of hot and cold fluids; the denser portion of the fluid move downward because of greater force of gravity as compared with the force on the less dense.
2 Forced Convection
When the work is done to blow or pump the fluid , it is said to be forced convection.

1.11 SOLAR RADIATION
Solar radiation is a general term for the electromagnetic radiation emitted by the sun. this radiation can be captured and converted to useful forms of energy suc as heat and electricity, using a variety of technologies. Solar radiation drives atmospheric circulation. Since solar radiation represents almost all the energy available to the earth, accounting for solar radiation and how it interacts with the atmosphere and the earth's surface is fundamental to understanding the earth's energy budget. Solar radiation reaches the earth's surface either by being transmitted directly through the atmosphere direct solar radiation (direct beam or extra-terrestrial radiation) or by being scattered or reflected to the surface diffuse solar radiation. About 50 present of solar (or short wave) radiation is reflected back into space, while the remaining short-wave radiation at the top of the atmosphere is absorbed by the earth's surface and re-radiated as thermal infrared (or long-wave) radiation.
1.11.1 TYPES OF SOLAR RADIATION
1 Diffuse Solar Radiation:-
Sunlight passes through the atmosphere, some of it is absorbed, scattered, and reflected by air molecules, water vapour, clouds,dust, and pollutants from power plants, forest fires, and volcanoes. This is called diffuse solar radiation.
2. Direct Solar Radiation:-
The solar radiation that reaches the surface of the earth without being diffused is called direct beam solar radiation.
3 Global Solar Radiation:-
The sum of the diffuse and direct solar radiation is called global or total solar radiation.
Solar radiation is a term used to describe visible and near visible (ultra violet and near infrared) radiation emitted from the sun. the different regions are described by their wavelength range within the broadband range of 0.20 to 4.0 microns. Outside the earth's atmosphere, solar radiation has an intensity of approximately 1370 watts/meter2.
The following is a list of the components of solar and terrestrial radiation and their approximate wavelength ranges:
Ultraviolet: 0.20-0.39 microns
Visible: 0.39-0.78 microns
Near-infrared: 0.78-4.00 microns
Infrared: 4.00-100.00 microns

CHAPTER 2
Design of Solar Distillation Plant

2.1. Construction of inverted absorber Solar Still:


Fig.4 3D model of solar still

The base of the solar still is made of mild steel This box is embedded into another box of wood shown in figure . Here length L= 1 m, Breath B= 1m, Height H= 0.47 m. and at opposite side = 0.05 m, Angle ?? = 23. This also contains same box of thermocol inside it between the M.S box and wooden box. The thermocol is having 0.05 m thickness. The channel is fixed such that the water slipping on the surface of the glass will fall in this channel under the effect of gravity. This completes the construction of the model.
The holes for the inlet of water, outlet of brackish water and outlet of pure water is made as per the convenience. We have made the outlet of brackish water at right bottom of the model, outlet of the pure water at the end of the channel and inlet at the right wall above the outlet.

Fig.5 CAD model of single slope solar still

2.2. Dimension of solar still:

Sr. no PARTS DIMENTIONS
1) Base 1??1 m (M.S.Sheet)
2) Height (lower , higher) 0.05(L) 0.47(H)
3) Cover 1.086??1 m (Glass)
4) Insulation Thermocol(0.05m)&wood(0.01m)
5) Channel M.S steel
6) reflector 87*85*80(b*l*h)

2.3. Details of Different Parts of the System:
Different type of part is use in solar still with different type of material and dimension. We use five type of part is use in single slope solar still.
Different type of part that use in our solar still:
1) Top cover
2) Side wall
3) Channel
4) Still Basin
5) Reflector


Fig.6 photograph of working model

2.3.1.Top cover:
The passage from where irradiation occurs on the surface of the basin is top cover. Also it is the surface where condensate collects.
So, the features of the top cover are:
1) Transparent to solar radiation
2) Non-absorbent and Non-adsorbent of water
3) Clean and smooth surface.
The Materials Can Be Used Are:
1) Glass
2) Polythene.
We have used glass (4mm) thick as top cover having rubber tube as frame border.

Fig 7 cover of solar still

2.3.2 Side wall:
It generally provides rigidness to the still. But technically it provides thermal resistance to the heat transfer that takes place from the system to the surrounding. So it must be made from the material that is having low value of thermal conductivity and should be rigid enough to sustain its own weight and the weight of the top cover.
Different kinds of materials that can be used are:
1) Wood
2) Concrete
3) Thermocol
4) RPF (reinforced plastic).
For better insulation we have used composite wall of thermocol (inside) and wood (outside). (Size: wood (k= thermal conductivity=0.6W/m0C):-- 20mm thick, thermocol (k= thermal conductivity=0.02W/m0C):--50mm.

Fig. 8 side wall insulation

2.3.3. Channel:
The condensate that is formed slides over the inclined top of cover and falls in the passage, this passage which fetches out the pure water is called channel.
The materials that can be used are: 1) P.V.C.
2) M.S
3) RPF.
We have used M.S. sheet channel


Fig 9 channel

2.3.4 Still Basin:
It is the part of the system in which the water to be distilled is kept. It is therefore essential that it must absorb solar energy. Hence it is necessary that the material have high absorptive or very less reflectivity and very less transitivity. These are the criteria's for selecting the basin materials. Kinds of the basin materials that can be used are as follows:
1. Leather sheet
2. Mild steel plate,
3. RPF (reinforced plastic)
4. G.I. (galvanized iron).
We have used blackened mild steel sheet (K= thermal conductivity= 300W/m??C) (3mm thick). (SIZE: 1??1 m BOX OF M.S.).

Fig.10 still basin

6) Reflector:
Reflector is transfer solar radiation with help of mirror. Mirror is arrange in 11.5 ?? with dimension of 40cms *80cms as shown in fig. And another mirror is place at 20.5 ?? with dimension of 30cms *80cms as shown fig. Solar radiation is reflect to the bottom side of the still and productivity of still increase because solar radiation absorb from top of the still and also from the bottom of the still.
Maximum radiation is reflect to bottom side of the still between 11:00 P.M to 2:00 P.M.

Fig. reflector

2.4 Inclination angle calculation:

1)Latitude:
??= 22??32?? (for Anand)

2)Declination:
??=23.45 sin ((360/365) ?? (285+n))
Where, n =day of the year counted
From 1st January.

3) Hour angle:
??= cos ??1 (- tan(??-??) ??tan ??)

4)Average radiation in day:

H0=24/?? ?? 1353 ?? ((1+0.033 cos (360??n/365)) ??(cos??.Cos?? .sin??+
((2'?/260).cos??.cos??))

2.5 CALCULATION TABLE:

Sr.No. Inclination Angle(??) Declination Angle(??) Hour Angle(??) H0
w/m2-day
1 23?? -8.48?? 90.101 9758.255
2 24?? -8.48?? 90.250 9758.179
3 25?? -8.48?? 90.399 9758.035
4 26?? -8.48?? 90.549 9757.823
5 27?? -8.48?? 90.699 9757.545
6 28?? -8.48?? 90.849 9757.200
7 29?? -8.48?? 91.000 9756.785
8 30?? -8.48?? 91.152 9756.298
9 31?? -8.48?? 91.304 9755.743
10 32?? -8.48?? 91.457 9755.115

Based on the calculations we performed from the above equations we get the above calculation table.
Based on the above calculations of H0 (Intensity of solar radiation) we select glass cover inclination angle as 23??

CHAPTER 3:
EXPERIMENTATION
3.1.OBSERVATION TABLES FOR SINGLE SLOPE SOLAR STILL ' (24/11/2013):

TIME Ta
(0c) Tv
(0c) Tw
(0c) Tci
(0c) Tco
(0c) Water output(ml)
9:00 -10:00 34.8 58.7 59.1 57.3 41 90
10:00 -11:00 35.2 65.7 68.2 63.9 45 210
11:00- 12:00 35.3 66.8 68.9 64.2 41 300
12:00-13:00 36.8 68.7 72.6 66.9 44.6 360
13:00-14:00 36.8 69.7 73.7 68.9 44.8 530
14:00-15:00 36.3 65.5 68.8 63.9 41.5 610
15:00-16:00 35.3 58.8 62.2 56.8 39.1 350
16:00-17:00 33.2 48.2 53.4 47.4 35.5 290

3.2.OBSERVATION TABLES FOR SINGLE SLOPE SOLAR STILL ' (25/11/2013):

TIME Ta
(0c) Tv
(0c) Tw
(0c) Tci
(0c) Tco
(0c) Water output(ml)
9:00 -10:00 27.0 39.1 46.1 39.2 30.1 80
10:00 -11:00 30.1 42.1 51.2 41.2 35.4 140
11:00- 12:00 33.3 54.2 59.2 53.1 36.8 220
12:00-13:00 36.4 60.1 63.3 58.1 38.6 280
13:00-14:00 36.8 64.4 68.4 62.6 42.7 310
14:00-15:00 36.7 65.1 67.4 63.3 41.1 370
15:00-16:00 34.0 58.1 60.3 56.8 39.2 290
16:00-17:00 32.3 46.7 49.4 44.6 35.9 210

3.3.OBSERVATION TABLES FOR SINGLE SLOPE SOLAR STILL ' (27/11/2013):
TIME Ta
(0c) Tv
(0c) Tw
(0c) Tci
(0c) Tco
(0c) Water output(ml)
9:00 -10:00 35.0 60 56.3 58.8 41.7 100
10:00 -11:00 36.1 65.5 67.6 63.8 42.1 220
11:00- 12:00 38.2 73.3 75.8 71.6 44.6 420
12:00-13:00 38.6 78.6 80.5 76.9 46.8 615
13:00-14:00 37.3 76.0 78.9 74.2 45.1 600
14:00-15:00 37.0 74.3 75.8 72.9 48.4 590
15:00-16:00 36.6 61.8 65.4 59.9 44.6 410
16:00-17:00 34.8 52.7 54.6 50.5 40.2 300

3.4.OBSERVATION TABLES FOR SINGLE SLOPE SOLAR STILL ' (5/04/2014):
TIME intensity Ta
(0c) Tv
(0c) Tw
(0c) Tci
(0c) Tb
(0c) Tco
(0c) Water output(ml)
9:00 -10:00 84.81309

35.6

50.8 50.1 44

51.1 40.3 90
10:00 -11:00 117.1614

38.5

59.1 58.3 50.1

60.1 49.1 220
11:00- 12:00 882.5645

39.5

60.5 60.1 50.7

60.4 49.1 310
12:00-13:00 853.6018

39.1

64.1 63.9 55.2

65.1 53.1 370
13:00-14:00 766.201

40.2

68.1 67.9 57.9

69.1 56.8 540
14:00-15:00 659.3446

40.5

70.1 69.5 58.9

71.1 57.8 610
15:00-16:00 466.8107

37.5

62.3 61.3 52

63.1 50.1 360
16:00-17:00

110.1514

34.2

55.3 54.3 43.3

56.1 41.1 300

Average wind speed on date 05/04/2014 = 2.1 m/s
Experiment held between 10.00 A.M to 5 P.M
Average humidity of the is 35%
Average solar intensity of the day is 5.5
TDS of inlet water: 254ppm TDS of outlet water: 55ppm

3.5..OBSERVATION TABLES FOR SINGLE SLOPE SOLAR STILL ' (06/04/2014):
Intensity Ta
(0c) Tv
(0c) Tw
(0c) Tci
(0c) Tb
(0c) Tco
(0c) Water output(ml)
9:00 -10:00 648.7439

36.5

51.1 50.1 45

52.1 40.3 90
10:00 -11:00 647.8088

38.5

59.1 58.2 50.1

60.1 49.1 210
11:00- 12:00 859.4653

39.7

60.5 60.2 50.7

60.8 49.1 300
12:00-13:00 875.8397

39.4

65.5 64.2 56.1

66.5 54.2 350
13:00-14:00 795.5866

39.5

70.1 69.1 60.2

70.5 58.2 530
14:00-15:00 656.1906

40.3

69.1 68.8 58.9

70.1 57.8 610
15:00-16:00 797.258

36.5

63.5 62.3 53.2

64.5 51.2 350
16:00-17:00 655.4512

38.1

54.5 54.3 43.3

56.1 41.1 290

Average wind speed on date 06/04/2014 = 2.20m/s
Experiment held between 10.00 A.M to 5 P.M
Average humidity of the is 40%
Average solar intensity of the day is 5.5
TDS of inlet water: 260ppm TDS of outlet water: 49ppm

3.6.OBSERVATION TABLES FOR SINGLE SLOPE SOLAR STILL ' (08/04/2014):

TIME Intensity Ta
(0c) Tv
(0c) Tw
(0c) Tci
(0c) Tb
(0c) Tco
(0c) Water output(ml)
9:00 -10:00 688.7527

34.1

49.5 49.2 44

50.1 39.3 90
10:00 -11:00 845.2543

36.2

58.1 57.4 49.1

59.2 48.5 170
11:00- 12:00 907.0516

38.1

62.3 61.3 49.9

62.8 47.3 280
12:00-13:00 912.1774

38.8

63.5 63.1 53.9

64.5 53.2 340
13:00-14:00 853.9289

38.1

67.9 67.4 57.3

68.5 56.7 530
14:00-15:00 703.338

38.5

67.5 67.3 58.9

68.5 57.4 620
15:00-16:00 489.9818

34.5

64.1 63.3 55.3

65.1 53.2 320
16:00-17:00 109.3056

33.5

55.9 55.3 45.3

65.9 42.5 290

Average wind speed on date 08/04/2014 = 2.15m/s
Experiment held between 10.00 A.M to 5 P.M
Average humidity of the is 38%
Average solar intensity of the day is 5.5
TDS of inlet water: 250ppm & TDS of outlet water: 51ppm

3.7. OBSERVATION TABLES FOR INVERTED ABSORBER SOLAR STILL ' (12/04/2014):

TIME Intensity Ta
(0c) Tv
(0c) Tw
(0c) Tci
(0c) Tb
(0c) Tco
(0c) Water output(ml) efficiency
9:00 -10:00 475.7123

36.5

55.9 55.6 48.3

56.5 45.3 190

20.56%
10:00 -11:00 862.2702

38.1

66.9 65.6 58.3

67.3 57.3 310

29.83%
11:00- 12:00 926.8478

40.1

70.8 70.3 62.5

71.3 60.4 460

49.63%
12:00-13:00 914.2334

40.5

75.1 74.3 66.3

76.1 65.1 670

55.66%
13:00-14:00 813.4034

41.3

77.1 76.3 68.3

77.9 67.3 700

14:00-15:00 724.1636

40.1

71.6 71.3 62.3

72.3 60.3 660
15:00-16:00 482.3081

37.3

64.1
63.1 52.3

65.1 50.6 430
16:00-17:00 123.8524

38.2

59.5 59.1 47.8

60.1 46.3 390

Average wind speed on date 12/04/2014 = 2.1 m/s
Experiment held between 10.00 A.M to 5 P.M
Average humidity of the day is 39%
Average solar intensity of the day is 5.5
TDS of inlet water: 262ppm TDS of outlet water: 55ppm

3.8.OBSERVATION TABLES FOR INVETRED ABSORBER SOLAR STILL ' (13/04/2014):

TIME Intensity Ta
(0c) Tv
(0c) Tw
(0c) Tci
(0c) Tb
(0c) Tco
(0c) Water output(ml)
9:00 -10:00 686.747

36.5

58.3 58.1 50.1

59.1 49.3 190
10:00 -11:00 846.6906

38.5

66.2 65.8 59

66.7 57 290
11:00- 12:00 686.906

40.1

73.1 72.6 65.1

73.5 64 480
12:00-13:00 902.9878

41.3

80.3 80.2 73.9

81.5 72.4 650
13:00-14:00 933.5984

43.3

80.0 79.9 73.2

80.1 71.3 680
14:00-15:00 848.4804

40.2

73.1 72.9 65.3

73.9 63.1 610
15:00-16:00 545.5855

39.2

65.3 65.2 55.6

66.2 54.3 450
16:00-17:00 89.57723

37.5

60.5 59.3 48.2

60.2 47.8 370

Average wind speed on date 13/04/2014 = 2.2 m/s
Experiment held between 10.00 A.M to 5 P.M
Average humidity of the is 36%
Average solar intensity of the day is 5.5
TDS of inlet water: 259ppm TDS of outlet water: 52ppm

3.9. OBSERVATION TABLES FOR INVETRED ABSORBER SOLAR STILL ' (14/04/2014):

TIME intensity Ta
(0c) Tv
(0c) Tw
(0c) Tci
(0c) Tb
(0c) Tco
(0c) Water output(ml)
9:00 -10:00 477.77

38.1

57.9 56.7 47.8

58.3 47.1 200
10:00 -11:00 838.0324

39.5

60.1 59.4 49.2

61.1 48.4 330
11:00- 12:00 910.579

40.8

64.2 63.1 51.2

65.1 49.1 570
12:00-13:00 901.2625

41.3

66.4 65.4 53.6

66.8 51.2 710
13:00-14:00 818.683

42.3

70.5 70.4 60.1

70.9 58.6 730
14:00-15:00 686.7607

40.5

69.8 68.8 59.3

70.3 57.3 610
15:00-16:00 500.84

38.5

66.1 65 54.3

67.5 53.3 510
16:00-17:00 100.12

35.2

58.1 57.1 47.2

60.1 44.1 330

Average wind speed on date 14/04/2014 = 2.1 m/s
Experiment held between 10.00 A.M to 5 P.M
Average humidity of the is 38%
Average solar intensity of the day is 5.5
TDS of inlet water: 257 ppm TDS of outlet water: 47pp

3.4. Total output per day:
1)single slope solar still:
DATE OUTPUT
(ml) DATE OUTPUT
(ml)
05/04/2014 2800 24/11/2013 1900
06/04/2014 2730 25/11/2013 2300
08/04/2014 2640 27/11/2013 2900
Average 2723.33
Average 2366.66

2) inverted absorber solar still:
DATE OUTPUT
(ml)
12/04/2014 3810
13/04/2014 3720
14/04/2014 3990
Average 3840

CHAPTER 4 :
HEAT TRANSFER CALCULATION

4.1 Thermal equation:
Assumption:-
' The system is in quasi steady state condition.
' No leakage of vapour in solar still.
' The connected pipes are perfectly insulated.
' The fraction of energy absorb by glass cover is insignificant.
' The thermal energy capacity of the glass cover insulation and the conductive materials are negligible.
' The radiative convective evaporative heat losses are linearized during the time interval??t.
' The heat transfer coefficients are constant during time interval.
' The physical properties of water and vapour are constant in operating temperature range of the proposed system.

A number of studies in the literature are available to examine heat transfer process of the still. The most widely acceptable study was made by Dunkel model. The modes of heat transfer inside the still between the water surface and the glass cover are convection accompanied with evaporative mass transfer in the form of water vapour and radiation. The radiation heat transfer is very small if compared with other two heat transfers, and the production of still is not affected significantly by the heat transfer. The evaporative heat transfer is responsible for the transportation of water mass from water surface to cover. This evaporative heat transfer increase with the vapour pressure difference between the water and glass: and is responsible for bulk motion of air inside the still. This bulk motion increases the convection heat transfer. Hence the convection and evaporation heat transfer inside the still are interrelated.

The general equation of convective heat transfer is,
Qcw =hcw (Tw 'Tci )Aw
Where h is the convective transfer coefficient. Dunkle models have been used to evaluate internal,
hcw= 0.884(??T' )(1/3)
Kumar and Tiwari have developed thermal model for evaluation of internal heat transfer coefficient which is free from Dunkle's shortcoming. In this model linear regression analysis method is used for evaluation of c and n which is given below. The following relation gives the non-dimensional Nusselt number related by the convective heat transfer coefficient:-
Nu= (hew ??Lv)/Kv
Where, Gr and Pr are the Grashof and Prandtl numbers respectively. The unknown constant C and n as given in equation (5) will be determined by linear regression analysis using experimental data. The Gr and Pr are given by the following expressions:
Gr= (??gL3v??2??t)/??2
Pr = (??Cp)/Kv
After that we get,
Dunkle's equation for evaluation of internal heat transfer coefficient is as given below,
??T= (Tw-Tci) +((pw 'pci)(Tw +273)(268.9??10 -pw))
Here temperature dependant physical properties of vapour are given in below page and evaporative heat transfer coefficient is given as:

hew =(0.0016 ?? hcw ?? (Pw-Pc )/(Tw-Tci))

So evaporative heat transfer rate can be given as :
Q=hew (Tw-Tci)AW
But as above mentioned here that only evaporative heat transfer causes and contributes to water distillation. Here heat transfer for other sections is not presented.
So here solar still is to produce distilled water output given by:
mew= Qew ?? t ?? A/??h

Thermal calculation table 1 single slope solar still (24/11/2013):

Pci Pw hcw hew hrw Qew mew
9:00 -10:00 6709.634 9864.143 1.938 13.513 5.835 216.208 0.262
10:00 -11:00 7671.460 12711.356 2.245 18.412 6.035 290.910 0.352
11:00- 12:00 13942.509 18626.716 2.042 25.517 6.616 571.581 0.693
12:00-13:00 16799.782 22496.909 2.129 31.835 6.863 786.325 0.953
13:00-14:00 21790.488 28272.089 2.180 39.644 7.196 1018.851 1.235
14:00-15:00 22496.909 27047.954 1.963 34.970 7.186 919.711 1.115
15:00-16:00 16641.723 19603.369 1.727 23.781 6.761 501.779 0.608
16:00-17:00 9414.013 11633.743 1.762 14.890 6.079 201.015 0.243

Thermal calculation table 2 single slope solar still (25/11/2013):

Pci Pw hcw hew hrw Qew mew
9:00 -10:00 17039.324 19422.550 1.605 22.231 6.770 424.612 0.515
10:00 -11:00 23118.173 26808.725 1.803 32.813 7.199 728.449 0.883
11:00- 12:00 23434.357 28901.972 2.051 38.827 7.263 1083.273 1.314
12:00-13:00 26453.324 33953.280 2.261 48.412 7.470 1355.536 1.644
13:00-14:00 28901.972 35595.165 2.168 49.195 7.572 1421.736 1.724
14:00-15:00 23118.173 28775.031 2.076 39.001 7.250 1064.727 1.291
15:00-16:00 16641.723 21395.544 2.015 28.866 6.820 666.805 0.809
16:00-17:00 10530.896 12836.312 1.685 15.804 6.217 251.284 0.305

Thermal calculation table 3 single slope solar still (27/11/2013):

Pci Pw hcw hew hrw Qew mew
9:00 -10:00 12464.631 19332.687 2.183 41.353 6.670 756.760 0.918
10:00 -11:00 23013.605 24846.311 1.431 25.132 7.141 588.089 0.713
11:00- 12:00 32517.962 34990.341 1.547 36.612 7.648 1050.764 1.275
12:00-13:00 40768.164 43771.506 1.640 47.148 8.005 1499.306 1.819
13:00-14:00 36363.9 39251.502 1.623 42.369 7.825 1306.306 1.588
14:00-15:00 34394.430 36519.358 1.468 36.259 7.724 939.108 1.139
15:00-16:00 19243.186 21006.839 1.435 21.676 6.903 372.827 0.398
16:00-17:00 12228.344 13675.003 1.409 15.077 6.345 188.463 0.229

Thermal calculation table 4 single slope solar still (05/04/2014):

Pw Pci hcw hew hrw Qew mew
9:00 -10:00 12042.92 8865.039 1.910687 8.416663 5.383416 82.4833 0.131564
10:00 -11:00 17859.43 12042.92 2.221775 18.01823 5.752718 165.7677 0.264406
11:00- 12:00 19422.55 12403.61 2.349378 22.42672 5.816522 246.6939 0.393486
12:00-13:00 23118.17 15423.23 2.369072 27.23857 6.039628 294.1766 0.469223
13:00-14:00 27654.15 17527.35 2.560828 39.38914 6.22431 437.2195 0.697382
14:00-15:00 29673.86 18367.83 2.645003 45.71368 6.297019 534.85 0.853106
15:00-16:00 20529.61 13217.64 2.364717 24.07975 5.88316 269.6932 0.430171
16:00-17:00 14772.64 8552.326 2.359337 17.20096 5.473309 227.0527 0.362158

Thermal calculation table 5 single slope solar still (06/04/2014):

Pw Pci hcw hew hrw Qew mew
9:00 -10:00 12042.92 9329.152 1.805057 7.248341 5.408537 71.03374 0.113301
10:00 -11:00 17775.9 12042.92 2.211699 17.73521 5.750059 161.3904 0.257424
11:00- 12:00 19512.78 12403.61 2.3588 22.7474 5.819204 252.4962 0.402741
12:00-13:00 23434.36 16098.68 2.32431 26.33908 6.072236 263.3908 0.420118
13:00-14:00 29157.31 19512.78 2.501611 39.29289 6.321799 428.2925 0.683143
14:00-15:00 28775.03 18367.83 2.574933 41.56807 6.277236 457.2488 0.729329
15:00-16:00 21493.69 14010.09 2.368849 25.31886 5.942193 281.0394 0.448268
16:00-17:00 14772.64 8552.326 2.359337 17.20096 5.473309 227.0527 0.362158

Thermal calculation table 6 single slope solar still (08/04/2014):

Pw Pci hcw hew hrw Qew mew
9:00 -10:00 11519.09 8865.039 1.805679 6.9597 5.360608 68.90103 0.1099
10:00 -11:00 17119.83 11462.14 2.214674 17.14959 5.702783 152.6314 0.243453
11:00- 12:00 20529.61 11924.75 2.513319 27.75524 5.827715 388.5734 0.619789
12:00-13:00 22293.07 14491.26 2.392851 26.91024 5.982727 266.4114 0.424936
13:00-14:00 27047.95 17039.32 2.556498 38.34889 6.193817 410.3331 0.654497
14:00-15:00 26928.11 18367.83 2.416969 33.32616 6.235027 329.929 0.526249
15:00-16:00 22496.91 15497.04 2.297427 24.5747 6.025859 248.2045 0.395895
16:00-17:00 15497.04 9472.475 2.308348 17.16298 5.54991 219.6862 0.350408

Thermal calculation table 7 inverted absorber solar still (12/04/2014):
Pw Pci hcw hew hrw Qew mew
9:00 -10:00 16563.18 10743.83 2.250665 17.26553 5.650647 165.7491 0.264376
10:00 -11:00 18801.07 11519.09 2.394668 22.7064 5.758488 249.7704 0.398393
11:00- 12:00 22293.07 12711.36 2.583414 32.1545 5.910714 450.1629 0.718027
12:00-13:00 24736.98 14283.31 2.628492 37.26233 6.037771 529.1251 0.843974
13:00-14:00 30865.19 19422.55 2.645688 47.65061 6.35593 562.2772 0.896853
14:00-15:00 28775.03 18713.72 2.543561 40.36647 6.288314 464.2144 0.740439
15:00-16:00 24295.95 14772.64 2.544914 33.97714 6.045607 397.5325 0.634079
16:00-17:00 16879.3 10425.82 2.331776 19.14179 5.645688 248.8433 0.396914

Thermal calculation table 8 inverted absorber solar still (13/04/2014):
Pw Pci hcw hew hrw Qew mew
9:00 -10:00 17692.71 12042.92 2.201558 17.45404 5.747402 153.5955 0.244991
10:00 -11:00 25184.93 18453.77 2.234817 25.58998 6.19582 225.1919 0.359189
11:00- 12:00 33953.28 24405.56 2.459785 43.88267 6.560305 377.391 0.601953
12:00-13:00 46770.76 35900.95 2.535068 65.10486 7.043531 507.8179 0.809989
13:00-14:00 46195.27 34840.53 2.574202 66.95659 7.013468 575.8266 0.918465
14:00-15:00 34394.43 24626.07 2.477322 45.2604 6.574728 443.552 0.707482
15:00-16:00 24515.6 15720.31 2.468404 31.91469 6.086278 347.8701 0.554866
16:00-17:00 18713.72 10960.53 2.454195 23.91374 5.729768 275.008 0.438648

Thermal calculation table 9 inverted absorber solar still (14/04/2014)

Pw Pci hcw hew hrw Qew mew
9:00 -10:00 15720.31 11015.3 2.100028 13.82537 5.634682 142.4013 0.227136
10:00 -11:00 24960.08 17859.43 2.279946 26.70005 6.171014 221.6104 0.353477
11:00- 12:00 30730.81 21691.16 2.432284 38.62452 6.420337 382.3827 0.609915
12:00-13:00 36519.36 25754.77 2.55301 51.85948 6.644241 477.1072 0.761004
13:00-14:00 39751.54 28147.55 2.608343 59.61765 6.761032 536.5588 0.855832
14:00-15:00 32097.75 21493.69 2.56461 46.03164 6.443343 506.348 0.807644
15:00-16:00 22293.07 13411.99 2.510476 30.13516 5.939958 376.6895 0.600834
16:00-17:00 18540.07 10743.83 2.463479 23.89001 5.714064 305.7922 0.48775

CHAPTER 5:
COMPARISON OF CALCULATION AND EXPERIMENTAL OUT COME :

5.1 Comparison experimental and thermal calculation output:
SS:
DATE EXPERIMENTAL
(liters) CALCULATION
(liters)
5/4/2014 2.800 3.601
6/4/2014 2.730 3.416
8/4/2014 2.640 3.325

IASS:
DATE EXPERIMENTAL
(liters) CALCULATION
(liters)
12/4/2014 3.810 4.703
13/4/2014 3.720 4.635
14/4/2014 3.990 4.893

5.2 EFFICIENCY:
IASS:
DATE THERMAL EFFICIENCY STILL EFFICIENCY
12/4/2014 81.23% 41.1%
13/4/2014 80.49% 40.2%
14/4/2014 81.16% 43.3%
SS:
DATE THERMAL
EFFICIENCY STILL
EFFICIENCY
5/4/2014 78.08% 28.9%
6/4/2014 79.77% 36.6%
8/4/2014 79.91% 34.5%

CHAPTER 6:
Graphs

6.1 single slope solar still :

6.1.1 Graph 1: Distil output v/s Time:

6.1.2 GRAPH-2 TV V /S Time:

6.1.3 GRAPH-3 TW V /S Time:

6.1.4 GRAPH-4Tci V /S Time:

6.1.5 GRAPH-6TOTAL OUTPUT V/S DAY:

6.1.6 heat transfer co-efficient v/s time
Date :5/4/2014, 24/11/2013

Date :6/4/2014, 25/11/2013

Date:8/4/2014,27/11/2013

6.2. inverted absorber solar still:
6.2.1. GRAPH- 1: Distil output v/s Time:

6.2.2 GRAPH- 2 TV V /S Time:

6.2.3 GRAPH- 3 TW V /S Time:

6.2.4 GRAPH- 4Tci V /S Time:

6.2.5 heat transfer co-efficient v/s time:
Date:12/04/2014

Date:13/04/2014

Date:14/04/2014

Chapter 7
Conclusion
7.1 comparison of inverted absorber solar still with other:
Model Input water Output water Insulation
single slope solar still 20 litres 2.730 litres Thermocol,
Wood
Inverted absorber solar still 20 litres 3.720 litres Thermocol,
Wood
Pyramid solar still 20 litres 1.223 litres Saw dust
Double slope solar still 20 litres 0.735 litres Thermocol

7.2 Theoretical and Experimental comparison:

Output 5/4/2014 6/4/2014 8/4/2014
Experimental
Output 2.800 2.730 2.640
Theoretical output
3.6014 3.416 3.325

Output 12/4/2014 13/4/2014 14/4/2014
Experimental
Output 3.810 3.720 3.990
Theoretical output
4.703 4.635 4.893

' From this Project we can conclude that inverted absorber solar still is better than pyramid solar still ,single slope solar still and double slope solar still.
' Still Efficiency and Thermal Efficiency of Inverted Absorber Solar Still is higher than Single Slope Solar Still.

References:

1)Al- karaghouli A, alnaser w. performance of single and double solar still applied energy 78(2004) 347-357

2) Badran.o experimental study of the enhancement parameters on a single slop solar still, desalination 209(2007)136-143

3) Tiwari g., shukla.s. Computer modelling of passive/active solar stills by using inner glass temperature desalination 154(2003) 171-185

4) Tiwari .g, tripathi r, Effect of water depth on internal heat and mass transfer for active solar stilldistillation desalination 173 (2005)187-200

5)Shrivastav .p , Agrawal .s. experimental and theoretical analysis of single sloped basin type solar still consisting of multiple low thermal inertia floating porous absorbersdesalination 311(2013)198-205

6)Dev.R, Abdul-wahab.S, Tiwari.G performance study of the inverted absorber solar still with water depth and total dissolved solid applied energy 88(2011)252-264

7)Sain.M, Sharma.V,Rajpoot.M Experiment study of inverted absorber solar still with water Depth and Total Dissolve solid ijetae 3(2013)

8)Elango.T, Murugavel K, Hansen.R A review of different method to enhance the productivity of the multi-effect solar still Renewable and sustainable energy reviews 12(2013)248-250
9) Dev.R, Tiwari.G Characteristic equation of the inverted absorber solar still desalination 269(2011)67-77
10) Jaferpur.K, Soltanieh.M, Feilizadeh.M A new radiation model for a single slope solar still desalination262(2010)166-173

Source: ChinaStones - http://china-stones.info/free-essays/engineering/simple-slope-solar.php



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