Effect of Cow dung cakes inside basin on heat transfer ... · PDF fileEffect of Cow dung cakes inside basin on heat ... The gas is rich in methane and is used in rural areas of India

INTERNATIONAL JOURNAL OF APPLIED ENGINEERING RESEARCH, DINDIGUL Volume 1, No 4, 2011

© Copyright 2010 All rights reserved Integrated Publishing Association

RESEARCH ARTICLE ISSN 09764259

675

Effect of Cow dung cakes inside basin on heat transfer coefficients and productivity of single basin single slope solar still

Hitesh N Panchal 1 , Manish Doshi 2 , Prakash Chavda 3 , Ranvirgiri Goswami 4 1 Research Scholar, Kadi Sarva Vishwavidyalaya University, Gandhinagar, Gujarat

2 Member of Institution of Engineers (MIE) 3 Assistant Professor, Department of Mechanical Engineering, Sankarsinh Vaghela Bapu

Institute of Technology, Gandhinagar 4 Assistant Professor, Department of Mechanical Engineering, M L Institute of Diploma

Studies, Bhandu, Mehsana [email protected]

ABSTRACT

Water has always been a source of energy for man. We use solar energy to change salty or brackish water into drinkable water by soar distillation. Natural fresh water resources are being depleted rapidly, as a result of population growth and socioeconomical development. The increasing demand for water puts enormous strain on the underground aquifer, which results in lower water level and increasing salt content. In this communication, an attempt has made to find the effect of cow dung cakes properly arranged on the surface of absorber in single slope single basin solar still during summer climate conditions of month July, 2010. To know quick distillate output difference, experiment has done by use of two identical solar still, one by use of cow dung cakes on simple absorber plate and other steel absorber plate. Facing of solar stills were 30 degree inclination of condensing cover (inner side glass cover) and constant depth of water 0.03 m. The objective of this paper is to know variation in internal heat transfer coefficients like evaporative heat transfer coefficient, convective heat transfer coefficient and radiative heat transfer coefficient as well as output of solar still. Experiments says that, evaporative heat transfer coefficient is higher in case of solar still consisting of cow dung cakes inside the solar still, compare with other heat transfer coefficient and it is also observed that distillate output is higher about 25 % more of solar still having cow dung cakes

Keywords: cow dung cakes, solar still, Thermocouple, heat transfer Coefficient

1 Introduction

Cow dung (usually combined with soiled bedding and urine) is often used as manure (agricultural fertilizer). If not recycled into the soil by species such as earthworms and dung beetles, cow dung can dry out and remain on the pasture, creating an area of grazing land which is unpalatable to livestock. In many parts of the developing world, caked and dried cow dung is used as fuel. Dung may also be collected and used to produce biogas to generate electricity and heat. The gas is rich in methane and is used in rural areas of India/Pakistan and elsewhere to provide a renewable and stable source of electricity. Cow dung is also used to line the floor and walls of buildings owing to its insect repellent properties for some types of insects (not flies or dung beetles).




676

Figure 1: Cow dung Cakes used in Experiment

In central Africa, Maasai villages have burned cow dung inside to repel mosquito. In cold places, cow dung is used to line the walls of rustic houses as a cheap thermal insulator. Cow dung is also an optional ingredient in the manufacture of adobe mud brick housing depending on the availability of materials at hand. A deposit of cow dung is referred to in American English as a "cow pie", and in British English as a cowpat . Also known as "cow chips" when dry, it is used in the practice of "cow chip throwing" popularized in Beaver, Oklahoma in 1970 another game is Cow Chip Bingo. When cow dung is made in cake form, and then called cow dung cakes. Fig.1. shows cow dung cakes.

A.A. ElSebaii et.al, 2009 made mathematical model for an active single basin solar still (ASS) with and without a sensible storage material under the basin liner of the still. Sand is used as a storage material due to its availability and used in climate condition of Algeria in summer and winter conditions. He proved that use of sensible heat storage medium can also increase the distillate output of solar still and also depends on climate conditions of summer and winter. In summer conditions, due to high amount of direct radiations, distillate output is higher and for winter conditions due to diffused conditions, distillate output is lower compared with summer conditions. N.H.A. Rahim, 2003. A new approach is proposed to store excess heat energy in horizontal solar desalinations tills during daytime for the continuation of the process at night. This technique divides the horizontal still into evaporating and heat storing zones and combines the advantages of shallow and deep stills. He studied over one year and exhaustive data were collected, analyzed and presented. To show the effectiveness of the system, its performance was compared with that of the shallow still. The heat storing capacity of the system during the daytime was found to be an average of 35.7%. G. N. Tiwari et.al, 2007. Made thermal models of all types of solar collector integrated active solar stills are developed based on basic energy balance equations in terms of inner and outer glass temperatures. They used hourly yield, hourly exergy efficiency, and hourly overall thermal efficiency of active solar stills are evaluated for0.05m water depth. All numerical computations had been performed for a typical day in the month of 07December 2005 for the climatic conditions of New Delhi (288350N, 778120E, 216m above MSL).




677

Thermal model of flatplate collector integrated with active solar still was validated using the experimental test setup results. Total daily yield from active solar still integrated with evacuated tube. Hiroshi Tanaka,2009. made basin type solar still with internal and external reflectors was constructed and then examined in outdoor experiments in winter in Kurume, Japan. The external reflector was inclined slightly forward to make the reflected sunrays hit the basin liner of the still effectively. The daily productivity of a basin type still can be increased about 70% to 100% with a very simple modification using internal and external reflectors. V. Velmurugan and K. Srithar, 2007 , he integrated the Solar stills with a mini solar pond. In a mini solar pond, He was found that the optimum value of salinity in the mini solar pond is 80 g/kg of water. Effect of sponge cubes in the still, effect of integrating mini solar pond with the still and combination of both are discussed. The average daily production of solar still is found to be increased considerably, when it is integrated with a mini solar pond. Salah Abdallah et.al, 2009. found that, there is a strong need to improve the single slope solar still thermal performance and increase the production rate of distilled water. Different types of absorbing materials were used to examine their effect on the yield of solar stills. These absorbing materials are of two types: coated and uncoated porous media (called metallic wiry sponges) and black volcanic rocks. Four identical solar stills were manufactured using locally available materials. The first three solar stills contain black coated and uncoated metallic wiry sponges made from steel quality AISI 430 type, and black rocks collected from Mafraq Area in northeastern Jordan. The fourth still is used as reference still which contains no absorbing materials (only black painted basin). The results showed that the uncoated sponge has the highest water collection during day time, followed by the black rocks and then coated metallic wiry sponges. On the other hand, the overall average gain in the collected distilled water taking into the consideration the overnight water collections were 28%, 43% and 60% for coated and uncoated metallic wiry sponges and black rocks respectively. B. Selva Kumar et.al, 2008. made thermal performance of a “V” type solar still with a charcoal absorber is analyzed and distilled water collection output is estimated. The internal heat transfer and external heat transfer modes are studied. The efficiency of the still is estimated under four ways. The overall efficiency of the still is 24.47% without charcoal, 30.05% with charcoal, 11.92% with boosting mirror and 14.11% with boosting mirror and charcoal. The performance ratio of the still, variation of the Nusselt number (Nu) and the Grashof number (Gr) are presented. The experimental properties of the still are also estimated. The experimental data for the four studies under similar climatic conditions are compared. The main advantage of the “V” type solar still is due to centre collection and all the condensation are easily directed to the outlet. So the distilled yield is collected without any hindrance. Abdul Jabbar et.al, 2009. made many experimental and numerical studies, the most important parameters investigated were solar radiation, cover tilt angle, brine depth, and using dyes with the brine. To gives the effect of above parameters on the productivity of the basin type solar still using the available data given by the different investigators. The correlations developed illustrate that the still productivity could be influenced by the brine depth alone by up to 33% and by the tilt angle alone by up to 63%. A cover tilt angle of about 30° gives the highest productivity. The still productivity could be enhanced by adding dark soluble dye to the brine by up to 20%. The still productivity increases with the increase of insulation thickness of the still and the solar radiation received. Salah Abdullah et.al, 2008. found that, there is a strong need to look at various possible designs that can be implemented to improve the single slope solar still performance through increasing the production rate of distilled water. Design modifications were introduced to the




678

conventional solar still, involving the installation of reflecting mirrors on all interior sides, replacing the flat basin by a stepwise basin, and by coupling the conventional solar still with a sun tracking system. The inclusion of internal mirrors improved the system thermal performance up to 30%, while stepwise basin enhanced the performance up to 180% and finally the coupling of the stepwise basin with sun tracking system gave the highest thermal performance with an average of 380%. A.E. Kabeel, 2009A.E. Kabeel. used different surfaces for evaporation and condensation phenomenon play important roles in the performance of basin type solar still. In the present study, a concave wick surface was used for evaporation, whereas four sides of a pyramid shaped still were used for condensation. Use of jute wick increased the amount of absorbed solar radiation and enhanced the evaporation surface area.. A concave shaped wick surface increases the evaporation area due to the capillary effect. Results show that average distillate productivity in day time was 4.1 lit/m2 and a maximum instantaneous system efficiency of 45% and average daily efficiency of 30% were recorded. The maximum hourly yield was 0.5 lit/h. m2 after solar noon. An estimated cost of 1 litter of distillate was 0.065 $ for the presented solar still. S. Shanmugan et.al, 2008. used a booster mirror (acrylic) is attached with just above the glass cover of solar still, which will reflect solar radiation in excess to water and it is possible to adjust the booster mirror for perfect reflection depending upon the sun moving angle. Low rates of distillation have been observed with the existing unit. A notable result has been observed with a boosted distillation unit (4.2 L/m 2 /d at 890 W/m 2 max.). The arrangements have been made by commercial Al sheet material and insulated with a thermocol sheet.

Cow dung cakes are easily available in country like in India, and evaporative heat transfer coefficient should be higher in solar still. Hence major aim of this research paper is to investigate the effect of cow dung on evaporative heat transfer coefficient as well as distillate output of the solar still. To know above aspects, two identical solar stills have taken, hence which solar still gives higher output that can be easily determined.

2. Mathematical Modeling

Performance of solar still based on productivity, efficiency as well as internal heat and mass transfer coefficient. Hence performance directly proportional to internal heat transfer coefficient and distillate output from solar still. Internal heat and mass transfer coefficient in the solar still based on three parameters called convection, radiation and evaporation, hence there are three heat transfer coefficient called convective heat transfer coefficient, radiative heat transfer coefficient and evaporative heat transfer coefficient.

2.1.Convective Heat transfer Action of buoyancy force due to density difference of humid air due to temperature

difference is the major reason behind the convective heat transfer coefficient in solar still. The convective heat transfer coefficient of water surface to condensing glass cover is given by :

) ( g w cw cw T T h q − = …………………………………………………………………………(1)

Heat transfer coefficient cw h can be calculate by following equation




679

3 1

3 ) 10 9 . 268 (

) 273 )( ( ) [( 884 . 0

w

w g w g w cw

P

T P P T T h

− ×

+ − + − = …………………………………………… .(2)

2.2.Radiative Heat transfer

Solar energy is responsible for the formation of pure water from the solar still. Radiative heat transfer is also responsible through solar energy. Rate of radiative heat transfer from water surface to condensing cover is given by:

) ( g w rw rw T T h q − = …………………………………………………………………………(3)

Radiative heat transfer coefficient rw h is given by:

] ) 273 ( ) 273 [( 2 2 + + + = g w effect rw T T h σ ε ………………………………………………… (4)

Here,

4 2 8 / 10 669 . 5 K m W − × = σ …………………………………………………………………(5)

1 ) 1 1 1 ( − − + = w g

effect ε ε ε ……………………… ………………………………….………(6)

9 . 0 = = w g ε ε

2.3.Evaporative heat transfer

When solar energy is incident inside the solar still, water evaporates and converted into steam. Hence, evaporative heat transfer is given by following equation

) ( g w ew ew T T h q − = ………………………………………………………………………..(7)

Evaporative heat transfer coefficient is given by

) ( ) (

10 27 . 16 3

g w

g w cw ew T T

P P h h

−

− × × × = − ………………………………………………………(8)




680

Total heat transfer coefficient from water surface to condensing cover is given by following equation

ew rw cw w h h h h + + = 1 ………………………………………………………………………(9)

2.4. Energy balance

Figure 2: Energy flow in Single basin single slope solar still

When solar energy is incident inside the basin water, heat transfer mechanism starts. Fig.2. Shows the energy flow in single slope single basin solar still. Energy balance equation can be written with following assumption

1. There is no vapor leakage in solar still 2. It is an air tight basin, hence no heat loss. 3. Heat capacity of cover and absorbing material, insulation is negligible. 4. There is no temperature gradient across the basin water and glass cover of solar still. 5. Water level inside the basin maintained at constant level. 6. Only film type condensation is occurs in place of drop type condensation.

• Energy balance for glass cover

eg rg ew cw rw g q q q q q t I + = + + + ) ( ) ( ' α …………………………………………………..(10) • Energy balance for basin water




681

cw ew rw w

w w b q q q dt T MC q t I + + + = + ) ( ) ( ' α …………………………………………... (11)

• Energy balance for basin

) ( ( ) ( '

s

ss s cb w b A A q q q t I + + = α …………………………………………………………..(12)

• Heat transfer coefficients

V h g 8 . 3 7 . 5 1 + = …………………………………………………………………… …..(13)

• Hourly yield of solar still is given by:

3600 × = L q m ew

w …………………………………………………………………………(14)

• Efficiency of solar still is given by

) (t I q ew = η ……………………………………………………………………………… ..(15)

3. System Description

Figure 3: Three dimensional model of single slope solar still

3.1.Experimental set up description

Figure 2. shows the three dimensional view of single slope solar still. Fig.3 shows the experimental set up single slope solar still It is consists of condensing cover having angle of 30 degree. The bottom surface of solar still was painted carbon black for greater absorptivity.




682

Here experiment is done for various water depths. To avoid spilling of basin water into distillate channel

Figure 4: Experimental set up of Solar Stills

and to prevent the contact of distillate channel with glass cover as well as with water level, the height of lower vertical side of still was kept at 0.20 m, where as highest vertical side was kept of 0.80 m. The effective basin area of each still is kept at 1 m x 1 m and it is made of fiber reinforce plastic of 5 mm thickness. It is made of layers of corrugated sheets with special chemicals in such a way that air is entrapped between its corrugated cavities, which provide a higher desirable water quality for solar still material. Condensing cover made of plane glass of 3 mm is fixed to top of vertical wall of stills using a rubber gasket on both side of glass and clamp fixed iron frames made of angles. To ensure the non leakage of vapor to the atmosphere, eight crew tighten clamps are used on still. The output from the still is collected at end of smaller vertical side of the basin. A plastic pipe is connected to this channel to drain the water into mirror jar.

3.2.Procedure of measurement

The experiment was performed at Ahmedabad, India for different depths of water. All experiments started from 10 am morning to 5 pm evening. In each day, experiment one water depth was used. During the experiment, when switching over from one water depth to other , solar still remains idle, minimum for a day to attain steady state condition prior to start of experiments for all five depths. The following parameters were measured for every hour.




683

Table 1: Hourly average values calculated using 8 hours experimental data for 0.03 m of water depth having cow dung cakes on absorber plate at 15 th July, 2010

Sr. No. Time (Hr)

Solar Insolation I(t)

Outer glass cover Temp. Tco

Inner glass cover Temp. Tci

Ambient Temperature Ta

Temp of water Tw

Distillate mass Mw Kg.

1 10:00 400 39 37 18 22 0.0

2 11:00 463 47 43.2 20 30.2 0.030

3 12:00 700 50 47.8 22.1 35 0.10

4 13:00 680 52.5 50.2 23.12 43.6 0.182

5 14:00 700 51.2 48.6 23.1 46.9 0.240

6 15:00 600 47.2 45 25 45 0.200

7 16:00 420 45 41.7 26.2 42 0.190

8 17:00 150 43 40.6 26.8 39.7 0.179

Table 2: Hourly average values calculated using 8 hours experimental data for 0.03 m of water depth having cow dung cakes on absorber plate at 15 th July, 2010

Sr. No. Time (Hr)

Solar Insolation I(t)

Outer glass cover Temp. Tco

Inner glass cover Temp. Tci

Ambient Temperature Ta

Temp of water Tw

Distillate mass Mw Kg.

1 10:00 400 42 39 18 25 0.0

2 11:00 463 49 45.2 20 32 0.039

3 12:00 700 52 49.8 22.1 37 0.120

4 13:00 680 54 52 23.12 45 0.192

5 14:00 700 57 52 23.1 49 0.269

6 15:00 600 54.2 48 25 51 0.240

7 16:00 420 48 42.5 26.2 45 0.220

8 17:00 150 45 42 26.8 42 0.190




684

• Outer glass cover temperature • Inner glass cover temperature • Vapor temperature • Water temperature • Ambient temperature • Distillate output • Solar insolation

Water, glass and vapor temperatures were recorded with help of calibrated copper constantan thermocouples and digital temperature indicator having least count of 0.1 degree Celsius. The ambient temperature was measured by calibrated mercury in glass thermocouple having least count of 1 degree Celsius. The distillate output was recorded with help of calibrated Pyranometer of least count of 2 mW/cm 2. Table 1 and Table 2 represent the data recorded without and with cow dung cakes inside the solar still.

4. Result & Discussion

It is well known fact in solar desalination that the amount of distillate output gained will be higher for the higher temperature of evaporative surface and lower for the condensing surface. In other words, higher value of evaporative surface temperature and lower value of condensing surface temperature leads to rise in distillation output. Experiment is conducted from, to investigate the effect of cow dung cakes on heat transfer and productivity of solar still.

Hourly measurements were made for various thermocouple put at various locations for temperatures like hot water temperature, vapor temperature, inner glass cover temperature and outer glass cover temperature. Experiments, starts from morning 10 am and ends at Evening 5 pm. Readings have taken in Ahmedabad. Table 1 shows the readings of various thermocouples, mass of distillate output, solar insolation and time interval of One hour from 10 am to 5 pm shows in simple solar still. Table 2 shows same variables but solar still consists of cow dung cakes.

Figure 5 shows the comparative analysis of solar stills. Fig shows that solar still possess higher distillate output at 2 pm, means up to 2 pm distillate output is increases and it is gradually decreases after 2 pm. highest output at particular date is 0.129 liter for solar still having steel absorber plate and 0.139 liter for cow dung cakes. Because the cow dung cakes used as a energy storing materials, hence due to energy storing ability, distillate output is higher. Higher distillate output possess higher evaporative heat transfer coefficient. Hence figure 5 graph between evaporative heat transfer coefficient and time




685

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18

10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00

Time (Hr)

Distil

late o

utpu

t

solar still having steel absorber plate solar still having cow dung cakes

Figure 5: Comparative analysis of distillate output of solar stills having steel absorber plate and cow dung cakes

0 2 4 6 8 10 12 14 16

10:00

11:00

12:00

13:00

14:00

15:00

16:00

17:00

Time (Hr)

evap

orative he

at

tran

sfer coe

fficien

t (watt

per meter squ

are)

solar still having steel absorber plate

solar still having cow dung cakes

Figure 6: Comparative analysis of evaporative heat transfer coefficient of solar stills having steel absorber plate and cow dung cakes

Figure 6 shows the comparison of evaporative heat transfer coefficient of solar still having steel absorber plate and cow dung cakes. Every person, who works in area of solar still always try to increase the evaporative heat transfer coefficient, hence in this research work, comparison is made and it is shown in graph that, evaporative heat transfer coefficient is higher in cow dung cakes compared with steel absorber plate. In cow dung cakes, uniformly distributed at entire absorber plate, and due to physical property, called porosity, solar radiation falls on them as well as water, hence evaporative heat transfer coefficient will be higher, evaporation is higher and distillate output will be more.




686

Figure 7: Solar insolation incident on glass cover measured by pyranometer

Figure 7 shows the change in solar insolation during clear sky conditions (15 th July, 2010). It is observed from the fig that, solar radiation was high at noon and also power gain was varied. It is lower in the morning due to low ambient temperature and lower solar radiation and increases at noon due to higher ambient temperature and higher solar radiation falling on glass cover.

0 10 20 30 40 50 60 70

10:00

11:00

12:00

13:00

14:00

15:00

16:00

17:00

Time (Hr)

Water temperature in

celcius

solar still with steel absorber plate solar still with cow dung cakes

Figure 8: basin water temperature variation in cow dung cake solar still and steel absorber plate solar still

0 200 400 600 800 1000 1200

10:00

11:00

12:00

13:00

14:00

15:00

16:00

17:00

Time (Hr)

Solar insolatio

n (W

att

per m

eter squ

are)




687

0 10

20 30 40 50

60 70

10:00

11:00

12:00

13:00

14:00

15:00

16:00

17:00

Time (Hr)

Vapor Temperature in Celcius

with steel absorber plate with cow dung cakes

Figure 9: Vapor temperature variation in cow dung cake solar still and steel absorber plate solar still

Figure 8 and Figure 9 shows the variation of water temperature as well as vapor temperature through typical day of 15 th july, 2010 during 10 am to 5 pm. Fig.6 & 7 shows that, an increase in water temperature during early hours of the day until it reaches the maximum water temperature around noon. Water temperature was around 32 degree Celsius for steel absorber plate solar still at early morning and upto 66 degree Celsius at mid noon. For cow dung solar still. Therefore, at mid noon period, the thermal performance increased proportionally. This shows that, increase of surrounding ambient temperature of the still and higher solar radiation. For vapor temperature, it was lower upto 48 degree Celsius for steel absorber plate solar still and highest at 64 degree Celsius for cow dung solar still.

5. Conclusion

The performance of two identical single slope single basin solar still was investigated. The experimental result clearly shows that, thermal performance of cow dung solar still is considerably higher compared with steel absorber plate solar still. By use of cow dung type solar still increases distillate output of 25% more compared with steel absorber plate solar still.

Nomenclature

Ac – Area of cover, m 2 Ac – Area of basin liner, m 2 As — Area of basin liner, m 2 Ass — Area of solar still sides, m 2 hcw—Convective heat transfer coefficient from water to cover, W/ m 2 /C




688

hw — Convective heat transfer coefficient from basin liner to water, W/ m 2 /C hcb — Convective heat transfer coefficient

from bottom insulation to ambient, W/ m 2 /C

hrb — Radiative heat transfer coefficient from bottom insulation to ambient, W/ m 2 /C

hrw — Radiative heat transfer coefficient from water to cover, m 2 /C

hew— Evaporative heat transfer coefficient from water to cover, m 2 /C

h1w— Total heat transfer coefficient from water to cover, m 2 /C

h1g — Total heat transfer coefficient from cover to atmosphere, m 2 /C

I(t) — Total solar radiation, W /m 2 Ki — Thermal conductivity of insulating

material, W/m/C L — Latent heat of vaporization, J/kg Li — Thickness of insulation, m (MC)w — Heat capacity of water mass in

basin, J/m 2 /C Mew— Distillate output from still, L/m 2 /day Pg — Partial pressure at cover temperature,

N/m2 Pw— Partial pressure at basin water temperature,

N/m 2 qcw— Convective heat transfer from water

to cover, W/m 2 qrw — Radiative heat transfer from water to

cover, W/ m 2 qew— Evaporative heat transfer from water

to cover, W/ m 2 qloss — Overall heat loss from water surface

to ambient through top and bottom, W/ m 2 qcb — Heat transfer from base to ambient by conduction, W/m2 qs — Side heat loss to ambient by conduction,

W/ m 2 qcg — Convective heat loss from cover to

ambient, W/ m 2 qrg — Radiative heat loss from cover to

ambient, W/ m 2 Ta — Ambient temperature, C Tg — Cover temperature, C Tw — Basin water temperature, C




689

Greek α’g — Solar flux absorbed by cover α’w — Solar flux absorbed by basin water α’b — Solar flux absorbed by basin geff — Effective emissivity, dimensionless gg — Emissivity of cover, dimensionless gw — Emissivity of water , dimensionless σ — StefanBoltzmann constant ηi — Instantaneous efficiency, %

6. References

1. A.A. ElSebaii, Yaghmour S.J, F.S. AlHazmi, Adel S. Faidah, F.M. AlMarzouki and A.A. AlGhamdi Active single basin solar still with a sensible storage medium, Desalination 249, pp 699–706.

2. N.H.A. Rahim,2003, New method to store heat energy in horizontal, Renewable Energy, 28, pp 419–433.

3. G. N. Tiwari, Vimal Dimri, Usha Singh, Arvind Chel and Bikash Sarkar G. N. Tiwari et.al, 2007, Comparative thermal performance evaluation of an active solar distillation system, Int. J. Energy Res.31, pp 1465–1482.

4. Hiroshi Tanaka,2009, Experimental study of a basin type solar still with internal and external reflectors in winter, Desalination 249, pp 130–134.

5. V. Velmurugan and K. Srithar, 2007, Solar stills integrated with a mini solar pond – analytical simulation and experimental validation, Desalination 216 , pp 232–241.

6. Salah Abdallah, Mazen M. AbuKhader and Omar Badran Salah Abdallah et.al, 2009, Effect of various absorbing materials on the thermal performance of solar stills, Desalination 242, pp 128–137.

7. B. Selva Kumar, Sanjay Kumar and R. Jayaprakash B. Selva Kumar et.al, 2008, Performance analysis of a “V” type solar still using a charcoal absorber and a boosting mirror, Desalination 229, pp 217–230.

8. Abdul Jabbar N. Khalifa, Ahmad M. Hamood Abdul Jabbar et.al, 2009, Performance correlations for basin type solar stills, Desalination 249, pp 24–28.

9. Salah Abdallah, Omar Badran and Mazen M. AbuKhader Salah Abdullah et.al, 2008, Performance evaluation of a modified design of a single slope solar still, Desalination 219, pp 222–230.

10. A.E. Kabeel, 2009, Performance of solar still with a concave wick evaporation surface, Energy 34, pp 1504–1509.




690

11. S. Shanmugan, P. Rajamohan and D. Mutharasu, 2008, Performance study on an acrylic mirror boosted solar distillation, Desalination 230, pp 281–287.

Documents

Effect of Cow dung cakes inside basin on heat transfer ... · PDF fileEffect of Cow dung cakes inside basin on heat ... The gas is rich in methane and is used in rural areas of India