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Experimental investigation on coupling evacuated heat pipe collector on single basin single slope solar still productivity
 

Experimental investigation on coupling evacuated heat pipe collector on single basin single slope solar still productivity

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    Experimental investigation on coupling evacuated heat pipe collector on single basin single slope solar still productivity Experimental investigation on coupling evacuated heat pipe collector on single basin single slope solar still productivity Document Transcript

    • International Journal of Mechanical Engineering (IJMET), ISSN 0976 – 6340(Print), International Journal of Mechanical Engineering and Technologyand Technology (IJMET), ISSN 0976 – 6340(Print) © IAEME ISSN 0976 – 6359(Online) Volume 2, Number 1, Jan - Feb (2011), IJMETISSN 0976 – 6359(Online) Volume 2Number 1, Jan - Feb (2011), pp. 01-09 ©IAEME© IAEME, http://www.iaeme.com/ijmet.html EXPERIMENTAL INVESTIGATION ON COUPLING EVACUATED HEAT PIPE COLLECTOR ON SINGLE BASIN SINGLE SLOPE SOLAR STILL PRODUCTIVITY Hitesh N Panchal Assistant Professor Mechanical Engineering Department L C Institute of Technology, Mehsana Gujarat Email: Engineerhitesh2000@gmail.com Dr. Manish Doshi Member of Institution of Engineer (MIE) Anup Patel Assistant Professor L C Institute of Technology, Mehsana Keyursinh Thakor Assistant Professor L C Institute of Technology, MehsanaABSTRACT Solar still is very important device to convert the available brackish water intodrinkable water. Here work is carried out to know the effect of coupling an EvacuatedHeat Pipe Collector on the solar still. Other different parameters like Water depth, Sundirection and solar radiation to enhance the productivity. It has found that coupling anEvacuated Heat pipe collector with a solar still has increased the productivity by 32%.Also it has found that the productivity is reduced while using higher water depth andsolar insolation is directly proportional to the Productivity.Keywords: Pyranometer, Thermocouples, Evacuated Heat Pipe Collector1. INTRODUCTION O.O. Badran [1] performed experiment on single slope solar still using differentoperational parameters like basin water depth, glass cover thickness, insulating materialsand proved that, productivity of distilled output is increased upto 51% when combined 1
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),ISSN 0976 – 6359(Online) Volume 2, Number 1, Jan - Feb (2011), © IAEMEenhancers such as asphalt basin liner and sprinkler have been applied on single slopesolar still. Kalidasa Murugavel et.al.[2] gave brief report on solar desalination regardingwith various methods of improving the productivity. They suggested that differentmaterials are used in basin solar still to improve the heat capacity, radiation absorptioncapacity and condensation rate. Kalidasa Murugavel at.al [3] used different wickmaterials like light cotton cloth, light jute cloth, sponge sheet of 2 mm thickness anddifferent porous materials like washed natural rocks of different average sizes. He provedthat wick materials could improve the distilled output. M.E. El-Swifty and M.Z.Metias[4], said some sun rays are received by the back plate and side plates of the basin,hence this effect reduces the amount of radiation available to the basin for heating. Sothey used reflecting mirrors. After, Imad Al-Hayek and O O Badran [5]proved that singleslope solar still with reflecting mirror increase the distilled output 20% more than doubleslope solar still. H.A. Tahaineh and O.O. Badran [6] used solar collector coupled withsolar still and investigated that the productivity. They took different parameters like waterdepth, direction of solar still, solar radiation to enhance the solar still productivity. Theyfound that coupling of flat plate collector with solar still can increase the productivityupto 20%.Hazim Mohammed Qibdawey.et.al [7] has presented paper entitled “solarthermal desalination technologies”. He has shown the direct and indirect desalinationtechnologies of solar still like vapour compression, multistage flash evaporation,membrane distillation etc. They said Evacuated glass tube collector is more usefulcompared with flat plate collector. They also suggested that, coupling a CPC can increasethe temperature more than Evacuated glass tube collector and Flat Plate collector. RajeshTripathi. et.al[8] as found the distribution of solar radiation using concept of solarfraction inside the single slope solar still by using Auto Cad 2006 for given azimuth angleand latitude angle. From numerical computations, climate conditions of New Delhi havebeen carried out.M Bouker.et.al [9] has done performance of simple solar still comparedwith coupled one. He tasted for all day productivity under clear sky conditions withdifferent depth levels of brackish water for winter and summer period from Jan to March.2000. He found that productivity in summer period varied from 4.01 to 4.34 L/m2/Dayfor simple basin and 8.02 to 8.07 L/m2/Day for coupled so Tiwari.et.al [10] have donethermal analysis of double effect distillation unit in active operation. He observed that 2
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),ISSN 0976 – 6359(Online) Volume 2, Number 1, Jan - Feb (2011), © IAEMEincrease of 30% and 20% in efficiency of solar distillation working under active andpassive mode.H.N. Singh.et.al [11] have done experiment on active and passive solar stillfor different climate conditions like Chennai, Jodhpur, Kolkata and Mumbai on the basisof numerical computation. He has found that annual yield significantly depends on waterdepth, condensing cover inclination for both active and passive solar still and annualyield for a given water depth increasing linearly with collector area for active solarstill.Rustam Mamlook.et.al [12] have taken a case study of solar distillation system byfuzzy sets. The study reveals that wind speed, ambient temp, solar intensity, sprinkler,coupled collector, solar concentration, water depth etc. Based on increase of productionresults show that factors were found to affect on yield of solar still. Tiwari et al.[13] havebeen developed a computer model to predict the performance of single slope solar stillbasin on both inner and outer glass temperature. They concluded that there is a significanteffect of operating temperature range on the internal hears transfer coefficients.Voropoluos et.al. [14] Evaluated experimentally and theoretically a simple and efficientmethod for the behaviour of solar stills. Their method relates the main climate data andoperating conditions of the still with distilled water output in daily and night base withlinear equations using characteristics coefficient. Kumar.et.al [15] presented the annualperformance of an active solar still. Analytical expression for water and glass covertemperature and yield has been derived in terms of design and climate parameters.Numerical computations have been carried out for Delhi climate conditions. it has beenobserved that for given parameters, annual yield is optimum when the collectorinclination is 200 and the still glass cover inclination is 100.Rajesh Tripathi.et.al [16] hasused semi cylindrical condensing cover and he has used temperatures of 40 to 80C andfound that there is an increase of about 15% in the evaporative heat transfer coefficientdue to the size of the condensing cover and increase of about 7.5% of evaporative heattransfer coefficient due to change of material. Malik & Sodha.[17] attached a hot waterstorage tank to the solar still and they proved that coupling of hot water storage tankincrease the 10% distilled output of single slope solar still. Our goal for the present investigation on solar still is to design and develop animproved solar still which can use in house of India as well as output of a solar stillthrough Evacuated Heat Pipe Collector under Indian Climate Conditions. 3
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),ISSN 0976 – 6359(Online) Volume 2, Number 1, Jan - Feb (2011), © IAEME2. EXPERIMENTAL SET UP Figure 1 Schematic Diagram of Solar still coupled with Evacuated Heat pipe Collector Present investigation consists of solar still coupled with Evacuated Heat PipeCollector. It has black painted basin of area of 1 square meter filled with brackish watersupplied to it from a collector which preheats the water by use of solar energy, such kindof solar still also called Active Solar still. The evaporating basin is covered by a sheet oftoughened glass having 4 mm thickness which allows the sunrays directed to basin.Angle of tilting the glass cover is 15 degree. A trough running along the bottom side ofthe glass cover ensures the collection of the potable water toward the collecting vessel. The glass also holds the heat inside the still for continuing the evaporation ofwater inside the basin. An inlet pipe is fixed at the rear of the still for feeding the brackishwater. Holes were drilled in the body of still to fix the thermocouples (to measure thevarious temperatures of solar still). An Evacuated Heat Pipe Collector (1.50 m long, 0.5m width and 0.20 m thick) has been used to evaporate the water which is inside the basin.The Evacuated Heat Pipe Collector is made of many parallel tubes having ½ inchdiameter and 1.6 m length.In this Solar still following factors have highly considered for the investigation: • To made simple in construction, maintenance and operation. • To be rigid and firm enough to resist the worst environmental Conditions. • Local materials have used for making low cost solar still. Figure 2 Shows Evacuated Heat Pipe Collector. 4
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),ISSN 0976 – 6359(Online) Volume 2, Number 1, Jan - Feb (2011), © IAEME Schematic Diagram of the system is shown in figure 1A rectangular trough isfixed at the downstream end of the slope for collection of the potable water. The solarstill is filled each morning and days production is collected at the time interval of 1 Hour.Silicon rubber is used as sealant to prevent the heat losses inside the solar still as well asleakage losses. The side walls and base of the solar still are insulated with locallyavailable material called “Rock Wool” having thermal conductivity of 0.034 W/m2 K of 5cm thick. A constant Head tank was used to control the brackish water inside the solarstill. Depth of water level was maintained 2 cm during the period of investigation work.The solar still has been designed installed and operated at Ahmedabad. Figure 2 Evacuated Heat pipe Collector3. RESULT & DISCUSSION In this Research paper I report on daily experimentation of a single slope solarstill and same still coupled with evacuated Heat pipe collector. The system was operatedcontinuously for several months of year 2010 (April to October) under different climateconditions with good and low sunshine. The work aimed to enhance the solar still outputthrough improving the still operations condition by using Evacuated Heat pipe Collector.The temperatures of brackish water, glass cover (Inner glass cover and outer glass cover),vapor temperature and ambient temperature were recorded continuously. This solar still unit mounted on angled iron stand which is movable to make anyadjustment to the angle of axis of still to enhance enhanced solar radiation for betteroutput. The standard orientation of the solar still was assumed to be towards south toreceive maximum solar insolation. 5
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),ISSN 0976 – 6359(Online) Volume 2, Number 1, Jan - Feb (2011), © IAEME The influence of climate conditions and mainly the solar insolation on the solarstill production is investigated without coupling an evacuated heat pipe collector i.e. solarstill alone. The variations of daily solar still output and average solar radiations fordifferent days in September are shown in figure 3 4000 3500 Daily yield in ml 3000 2500 Series1 2000 Series2 1500 1000 500 0 25 52 59 62 65 3 4 6 0. 0. 0. 0. 0. 0. 0. 0. Average Solar radiations (Kw./Square meter) Figure 3 Relation of the solar insolation and solar still output during September, 2010. Figure 3 shows that solar still productivity is proportional to the solar insolationor radiation (Direct radiation + Diffused radiation), which depends on climate conditionsof each day. The effect of coupling a solar still with evacuated heat pipe collector isshown in figure 4. From figure 4, it can be concluded that, 800 700 600 Solar still coupled Yield in ml 500 with evacuated Heat pipe collector 400 Alone solar still 300 200 100 0 0 0 0 0 0 0 :0 :0 :0 :0 :0 :0 10 11 12 13 14 15 Time (Hr.) Figure 4 Comparison of yield between alone solar still and coupled solar still There is proportionality in fresh water production (yield) with respect to the basinwater temperature. The higher the temperature of water, higher output will be from thesolar still as fresh water or distilled water. This productivity is expected as a result ofcoupling an evacuated heat pipe collector with solar still because of supply of artificialheat source with solar radiation. Coupling an evacuated heat pipe collector with solar stillhas higher efficiency compared with alone solar still, because increase in temperature ofwater inside the basin, increase the rate of evaporation and condensation so higher 6
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),ISSN 0976 – 6359(Online) Volume 2, Number 1, Jan - Feb (2011), © IAEMEdistilled water. Comparison between efficiency of alone solar still and solar still coupledwith evacuated heat pipe collector is shown in figure 5 70 60 alone solar still Efficiency (% ) 50 40 30 solar still coupled with evacuated heat 20 pipe collector 10 0 0 0 0 0 0 0 :0 :0 :0 :0 :0 :0 10 11 12 13 14 15 Time (Hr) Figure 5 Comparison of efficiency between alone solar still and coupled solar still The percentage of improvement in daily productivity due to coupling anevacuated heat pipe collector (3029 mL)) is calculated and found to be 30% more thanthat when the solar still was operated alone (2300 mL) Figure 6 Shows the results ofexperiments performed during month of September to determine the optimum angle forthe solar still by changing the solar sill direction few degrees towards the east and westfrom the geographic south to detect the optimum angle that will give the best yield. Suchdeviation is required as the movement of the sun varies in direction between summer andwinter. From the productivity of the solar still, it can be seen that the optimal angle isfound to be 15 degree to the west of the geographic south during the winter season inAhmedabad. These results show that, tracking the sun is one of the best methods toincrease the yield from the solar still. 3500 3000 2500 Y i e l d (m L ) 2000 Series1 1500 1000 500 0 0 10.W 10.E 15.E 15.W 20.E 15.W Direction (In degree) Figure 6 Effect of solar still direction on yield. 7
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),ISSN 0976 – 6359(Online) Volume 2, Number 1, Jan - Feb (2011), © IAEME Time versus water depth 1200 Distillted Output (m m ) 1000 800 1.5 cm water depth 600 2.5 cm water depth 400 4 cm water depth 200 0 0 0 0 0 0 0 :0 :0 :0 :0 :0 :0 10 11 12 13 14 15 Time ( Hr) Figure 7 Effect of various depths on solar still Figure 7 shows the productivity of the solar still as a function of basin waterdepth, it is known that the productivity decreases with the increase of the water depth.This increase in still productivity as a depth decrease could be attributed to the lower heatcapacity. (Lower heat capacity, higher the yield from the solar still).It can be concludedthat the output of the solar still is maximum for the least water depth in the basin. Figure7 shows the comparison between various water depths.4. CONCLUSION The operation of a solar still coupled with evacuated Heat pipe collector has beeninvestigated experimentally. Comparison of the productivity between coupled solar stilland alone solar still was studied. It has found that productivity of coupled solar still wasfound to be 30% higher than alone solar still. It also shown that present solar still designleads to higher distillate water output (yield) due to higher temperature of basin.REFERENCES[1] O.o.Badran. Experimental study of enhancement parameters on a single slope solar still productivity, Desalination, 209(2007) 136-143.[2]K.Kalidasa Murugavel, Kn.K.S.K. Chockalingam, Srithar K. Progress in improving the effectiveness of the single basin passive solar still, Desalination 220 (2008) 677- 686.[3]K.Kalidasa Murugavel, Kn.K.S.K. Chockalingam, Srithar K. An experimental study of single basin double slope simulation solar still with thin layer of water in the basin, Desalination 220 (2008) 687-693. 8
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),ISSN 0976 – 6359(Online) Volume 2, Number 1, Jan - Feb (2011), © IAEME[4]O.O. Badran, Al-Tahaineh A. H. The effect of coupling a flat plate collector on the solar still productivity. Desalination 183 (2005) 137-142.[5]Hazim Mohammed Aiblawey, Banat Fazwi. Solar thermal desalination technologies, Desalination 220 (2008) 633-644.[6]Tripathi Rajesh, G.N. Tiwari. Performance evaluation of a solar still using the concept of solar fractionation, Desalination 145 (2003) 122-128.[7]Bouker M, Harmin A. Effect of Climate conditions on the performance of a simple basin solar still : A comparative study. Desalination 137 (2001) 15-22.[8]G.N. Tiwari, S.A. Lawrence, Thermal Evaluation of High temperature distillation under an active mode of operation, Desalination, 85 (1992) 135-145.[9]Singh H N, G N Tiwari. Monthly performance of passive and active solar stills for different climate conditions, Desalination, 168 (2004) 145-150.[10]Manmook Rustum, Omar Badran. Fuzzy sets implementation for the evaluation of factors affecting solar still production, Desalination 203 (2007) 394-402.[11]G.N. Tiwari, S.K. Shukla and I.P Singh, Computer modeling of passive/active solar stills by using inner glass temperature, Desalination, 154 (2003) 171-185.[12]k. voropoulos, E. Mathioulakis and V Belessiostis, Analytical simulation of energy behaviour of solar stills and experimental validation, Desalination, 153 (2002) 87-94.[13]S. Kumar, G. N. Tiwari and H.N, Singh, Annual performance of an active solar Distillation system, Desalination 127, (2000), 79-88.[14]Rajesh Tripathi, G.N. Tiwari, Effect of size and material of a semi cylindrical condensing cover on heat and mass transfer for distillation, Desalination, 111 (2002) 145-149.[15]G. N. Tiwari, R Tripathi, Study of heat and mass transfer in indoor conditions for distillation, Desalination, 154 (2003) 161-169.[16]J.A. Duffie, W.A. Beckman. Solar engineering of thermal processes 2nd edition. New York, Wiley, 1991.[17]M.A.S. Malik, G.N. Tiwari, A. Kumar and M.S. Sodha, Solar distillation. Pergamon press limited Oxford, 1982, 20-150. 9