An Experimental Study of a Solar Still: Application on the sea water desalination of Fouka

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1 Available online at Poedia Engineeing 33 (2012 ) ISWEE 11 An Expeimental Study of a Sola Still: Appliation on the sea wate desalination of Fouka Hanane.Abuideh, Adel.Deliou, Bahim.Abbad, Fatma Alaoui, Djilali.Tassalit and Zahia.Tigine * Sola Equipement Develpement Unit,UDES,National oad N 11,P.O.Box386,Bou-Ismail, 42415, Tipaza, Algéia. Abstat Today, seawate and bakish wate desalination is a subjet of onen of many eseahes all ove the wold. The eouse to the desalination by distillation using sola enegy epesents an appeiable element of the wate esoue and onstitutes a ealizable, simple, pofitable, opeational solution tehnially. The pesent study, whih is essentially expeimental, is inteested in the effet of the intenal paametes on a double slope plane sola still. In this wok, the sola still was oneived and ealized by ou team of eseah. The expeiments wee aied out at diffeent onditions. The vaiation of the diffeent opeating paametes of the sola still has been studied. It is found that the distillate podution ate ineases when the diffeene between the tempeatue of wate and glass deeases. Distillated wate was also, influened by the pesene of wind and the limati hanges whih deease the amount of diffuse sola enegy eeived by the bakish wate. The aveage yield of distilled wate was 4 L/m 2 /day Published by Elsevie Ltd. Seletion and pee-eview unde esponsibility of ISWEE 11 Open aess unde CC BY-NC-ND liense. Keywods: Desalination, distillation,,sola enegy, sola still, Sea wate, effiieny, eletial ondutivity, ph. 1. Intodution Many developing ounties show an ineasing inteest to the sea wate and bakish wate desalination by sola distillation. Sola enegy is available, fee ost and non-extinguishing in natue. In the last few yeas, many eseahes wee inteested in the sea wate and bakish wate desalination using sola enegy. This themal poess is an effiient solution to pue wate saity in the wold. In fat, thee ae many types of sola stills, some of them have been developed and ommeialized [1, 2, 3]. Till today, many expeimental and theoetial studies ae undetaken in ode to modify the sola still using diffeent onfiguations and impove its yield [4, 5, 6]. The study of many eseahes undetaken in this ontext, indiate that the yield of the sola still depends on the diffeent extenal and intenal opeating paametes and that the podued wate quantity vaies aoding to the type of the sola still. * Coesponding autho. addess:phyzahia@yahoo.f Published by Elsevie Ltd. Open aess unde CC BY-NC-ND liense. doi: /j.poeng

2 476 Hanane.Abuideh et al. / Poedia Engineeing 33 ( 2012 ) Nomenlatue Q Q ev Q Q ga Q ga Q bw Q bw Qis a Qis a d Qb is Amount of enegy flux tansfeed by onvetion fom wate to glass (W) Amount of enegy flux tansfeed by adiation fom wate to glass (W) Amount of enegy flux tansfeed by evapoation fom wate to glass (W) Amount of enegy flux tansfeed by onvetion fom glass to ambient (W) Amount of enegy flux tansfeed by adiation fom glass to ambient (W) Amount of enegy flux tansfeed fom bottom to wate (W) Amount of enegy flux tansfeed by ondution fom insulato to ambient (W) Amount of enegy flux tansfeed by adiation fom insulato to ambient (W) Amount of enegy flux tansfeed by onvetion fom insulato to ambient (W) Amount of enegy flux tansfeed by ondution fom vat to insulato (W) g Global effiieny of sola still (%) I g Global sola adiation (W m 2 ) T Tempeatue ( C) ρ Density of wate (kg/m 3 ) e T W T ig T og T b T v T a T is U L t L v m Eletial ondutivity (µs/m) Wate tempeatue ( C) Inne glass tempeatue ( C) Oute glass tempeatue ( C) Vat tempeatue ( C) Vapo tempeatue ( C) Ambient tempeatue ( C) Insulato tempeatue ( C) Fato of the global losses Absoption oeffiient Latent heat of evapoation of wate (J/kg) Rate of the distillate (kg/s) A aea of glass (m 2 )

3 Hanane.Abuideh et al. / Poedia Engineeing 33 ( 2012 ) Intodution Many developing ounties show an ineasing inteest to the sea wate and bakish wate desalination by sola distillation. Sola enegy is available, fee ost and non-extinguishing in natue. In the last few yeas, many eseahes wee inteested in the sea wate and bakish wate desalination using sola enegy. This themal poess is an effiient solution to pue wate saity in the wold. In fat, thee ae many types of sola stills, some of them have been developed and ommeialized [1, 2, 3]. Till today, many expeimental and theoetial studies ae undetaken in ode to modify the sola still using diffeent onfiguations and impove its yield [4, 5, 6]. The study of many eseahes undetaken in this ontext, indiate that the yield of the sola still depends on the diffeent extenal and intenal opeating paametes and that the podued wate quantity vaies aoding to the type of the sola still. In ode to impove the podutivity of a sola still of hot-box type, L. Cheaed [7] aied out a systemati ompaison between a simple sola and sola wate-heate still. Aoding to the obtained esults, one an onlude that wate tempeatue has an impat on the daily podution of the still and its effiieny. Bilal A. Akash et al [8] have studied expeimentally the effiieny of a sola still fom diffeent inlination angles of the ove 15, 25, 35, 45 et 55. They noted that the maximum wate podution is obtained with an inlination angle of 35. The expeimental esults obtained, indiate that the wate salinity affets the podution of the distillate, even at a low onentation. H. Al-Hinai et al [9] used a mathematial model to foeast the podutivity of a simple sola still subjeted to vaious limati paametes and also to the opeational and oneption paametes of the egion of Oman.They noted that the optimum design onditions of the sola still gives an aveage annual sola yield of 4,15 kg/m 2 pe day. Othe studies elated to stills equipped with intenal and extenal efletos wee made by Hioshi Tanaka [10] N. Abdul Jabba Khalifa et A. Hussein Ibahim [11] Hioshi Tanaka et Yasuhito Nakatake [12] [13]. A theoetial and expeimental study was pesented by V. Velmuuga et al [14] with some modifiations on the still (fin, sponge, and wik) in ode to examine the effet of these mateials on the podutivity of the system. They noted that the expeimental analysis is in onfomity with the theoetial esults. The maximum deviation is of 10% and the podutivity impoved fom 1, 88 to 2, 8 kg/m 2. The aim of this wok is to examine the effet of wate tempeatue, the ambient tempeatue and the limati onditions in the town of Bou Ismail-Algeia (loated 36 38' N in latitude and 2 41' E longitude) on the opeating haateistis of the system. The obtained esults allow us to pesent the evolution of diffeent tempeatues, the quantity of distillate vesus time and the physio-hemial analysis of the distillate. 2. The opeating piniple The opeating piniple of a sola still used fo wate desalination involves phase hange wate vapo.it pemits the sepaation of the wate onstituents into salts deposits and distilled wate. In fat, the sola flow tansmitted though the glass ove ahieves the absobe, whih in etun emits themal adiations, this fat heats wate. Unde the influene of heat, the vat s sea wate evapoates suessively leaving only wate s moleules, a dissolved salt deposit and all othe esidues in seawate. The obtained vapo ondenses and the distilled wate steams on the inteio fae of the inlined slope glass put in dains whih dives it into a stoking tank. The diffeent heat fluxes intevening in the heat tansfes whih ou within the still beome expliit by many physial phenomena. The vaious modes of tansfe of the exhanged heat between the bine and the glass ae done by onvention Q, by adiation Q and by evapoation though the glass is a ev Q. The still is a system whih exhanges the heat with the outside Q ga by onvention and bottom and side insulating walls ae done by ondution adiation Q. In what follows we detemine the heat tansfe piniple inside and outside the still fig.1. The absobe: the wate laye eeives both by ondution and onvetion a heat flux tansmits by ondution a flux d Qb is to the insulato. d Qis a and Qbw the absobe and fom

4 478 Hanane.Abuideh et al. / Poedia Engineeing 33 ( 2012 ) The bine: the bine yields by adiation the flux Q the hange phase a flux Q ev and by natual onvetion the flux Q, on the ondensation sufae (the inteio glass of the still). The Glass: fom the inne side, the glass eeives the flux by onvetion evapoation Q flows ev Q ga and Q ga. Q, by adiation, by evapoation duing Q and by. Consequently, fom the inne side, the glass diffuses to the ambient ai the equivalent sum of two The insulato: the insulato eeives by ondution a flux Qis a and Qis a espetively by adiation and onvetion. d Qb is fom the absobe and an yield to the outside 3. Expeimentation 3.1 Desiption of the expeimental devie Fig. 1. The opeating piniple and heat exhanges of a sola still The expeimental measuements ae pefomed on a sola still of hapel type ealized and oneived by ou team of eseah at UDES. The system onsists of a wate-tight apaity sumounted by a glazing (fig.2). The basin of the still that is made of mateials with glass fibes and a esin laye, epesents the lowe pat of the sufae 1,39 m 2 painted in blak in ode to aptue the maximum sola enegy.the absobe is oveed with sea wate of 3m in depth, haateized by a salinity of 37,7 g/l. The side and the lowe walls ae insulated by a glass woolen laye of 40mm of thikness and a themal pefomane = w/m C to minimize the heat loss into the outside. The whole of the devie is fixed on a metal suppot. Fig.2. An oveview of the expeimental devie

5 Hanane.Abuideh et al. / Poedia Engineeing 33 ( 2012 ) Instumentation In ou expeiment, we used the sea wate of Fouka whih has a density of = kg/m 3, an eletial ondutivity of 56, 6 ms/m and a ph =8, 01 at a tempeatue T=23, 3 C. The Vaious tempeatues wee measued by themoouples of K type onneted to a data logge of fluke type fo the aquisition of the data whih wee eoded on a memoy boad pogammed fo a time inteval of 30 minutes. The themoouples dispositions ae pesented in fig.3. The measuements of the distilled wate haateistis (salinity, eletial ondutivity, ph, TDS) wee pefomed using a ondutivimete of Inolab type (Cond level 1). The global sola iadiation on a hoizontal plane was measued by means of a pyanomete type CMP11 «Kipp & ZONEN» whose ange of sensitivity is inluded between 7 and 14 μv/w/m². The adiation data wee eoded in the weathe station of UDES. The distillate wate was olleted evey hou and was measued using a gaduated test tube. 4. Results and disussion Fig.3. The themoouples position in a sola still The systematization of the expeimental tests, allowed us to epesent the evolution of the vaious tempeatues vesus time, the daily quantity of the distillate, the ph vaiation, the eletial ondutivity, the sola iadiation and the global effiieny of the last two days (30/06/2010 and 06/07/2010) whih ae epesented in the fom of uves. The day of 30/06/ 2010 was sunny, windy, with a lea sky and a maximal tempeatue of T a = 32 C.On the ontay the day of 06/07/2010 was sunny, a little bit windy fom 13 PM with a maximal tempeatue of T a =30, 6 C this has an impat on the quantity of the distillate. The daily podution of distilled wate (30/06/2010 and 06/ 07/2010) was espetively 5 and 5, 38 lite/day. 4.1 Tempoal evolution of the sola adiation Ig The vaiation of sola adiation eeived by an inlined glazing sufae θ=23º duing the expeimental tests is shown in Figue 4. The esults show that the sola adiation beomes pepondeant and moe intense between 12 PM and to 13 PM and deease fom 16 PM beause the town of Bou-Ismail is loated in a littoal iumfeene whih is maked by a long sunstoke time duing July and June. The measuements of sola iadiation obtained show a slightly signifiant deviation between the day of 30/06/2010 and 06/07/2010 fom 9 AM to 13 PM, this explains the inease of the daily podution 7.6 %. These esults indiate that the podution of the distilled wate depends stongly of the inidental sola enegy.

6 480 Hanane.Abuideh et al. / Poedia Engineeing 33 ( 2012 ) Fig.4. The evolution of the distillate vesus the time 4.2. Evolution of the tempoal distillate podution The Fig.5 epesents the daily evolution of the distillated wate podution vesus time. We note that the ondensate podution ineases steadily and the maximum quantity obtained eahes 800 ml at 15 PM and 14 PM, espetively duing the days of 30/06/2010 and 06/07/2010. In fat, we onluded that the distillate podution is influened by the pesene of wind duing the day of 30/06/2010. We obseved that the extenal paamete has deeased the ate of podution duing the moning, so the podution ate emains onstant fom 13 PM to 14 PM in ompaison to the day of 06/07/2010. Fig.5.Vaiation of the distillate quantity vs. time (a)30/06/2010 et (b) 06/07/2010

7 Hanane.Abuideh et al. / Poedia Engineeing 33 ( 2012 ) Effet of the tempeatues evolution The Fig.6 pesents the esults of the measuements elated to the physial intenal paametes aoding to time. The evolution of diffeent tempeatues vesus time suh as: sea wate tempeatue; inne glass tempeatue T ig ; oute glass tempeatue T og ; vat tempeatue T b, ; mixtue ai/ Vapo tempeatue; ambient tempeatue T a and the insulato tempeatue T is obtained duing the two days of expeimentation indiate that the tempeatues inease and eah the maximum ate then it diminishes fom 15 PM. We an note a stong vaiation in the tempeatues of the sheet of wate, the ai/ Vapo zone and the extenal glass; this favous the evapoation and the ondensation poesses. It is found that the distillate podution ineases when the diffeene between wate and glass tempeatues deeases. Fig.6. Vaiation of the diffeent tempeatues as funtion of time (a) 30/06/2010 and (b) 06/07/2010 To ay out the wate quality analysis, the value of two paametes: eletial ondutivity and ph wee measued befoe and afte the distillation poess. Theefoe, the values of the ioni ondutivity and ph ae taken by sampling evey 1 hou to study the vaiation of these paametes duing the distillation poess. The Fig.7and 8 pesent the esults of the measuements of the eletial ondutivity and the ph values, espetively. One an note that the vaiation of the eletial ondutivity eveals a faily apid and emakable diminution fom 9 AM to 13 PM, then it emains onstant until 16 PM. On the othe hand, the ph deeases with time within the 5 ph 6 ange fo day 30/06/2010, see Fig. 8. The dop in ph is due to abon dioxide CO 2 dissolves in wate [15, 16]. The esults of measuements demonstate that the level of wate ph podued duing the above expeiments was between the value of 5 and 6, whih is simila to the value of ph in dinking wate.

8 482 Hanane.Abuideh et al. / Poedia Engineeing 33 ( 2012 ) Fig.7.Vaiation of the ondutivity e vs. time (30/06/2010 and 06/07/2010) Fig.8.Vaiation of the ph vs. time (30/06/2010 and 06/07/2010) 4.4. The study of the vaiation of the global effiieny vesus (Tw -Ta)/ Ig The obtained measuements enable us to pesent expeimentally the evolution of the global effiieny vesus (Tw -Ta)/Ig as illustated on the following figue elated to the day 06/07/2010. The global effiieny η and intenal effiieny η of the sola still ae expessed by the elation: i g η g Q ΣmL u v = = Q ΣA. Ig in...(1) η = α. η...( 2) g t i ( ) Q =Α. α. Ιg U. A T T u t l w a L v is the latent heat of evapoation at the wate tempeatue and m ate of the distillate.

9 Hanane.Abuideh et al. / Poedia Engineeing 33 ( 2012 ) [ w ] L v is given by: L = ( T ) v η = α U g t l T w T a Ig...(3) η g = A + B. X...(4) Fom the theoetial and expeimental equations we get: U L =A, α t =B. The onstants A and B of the (4) equation ae espetively the absoption oeffiient (Optial pefomane) of wate and the fato of the global losses of the sola still. The behaviou of the global effiieny follows a linea law, the egession line slope is positive expessing the fato of the total losses by analogy about U L =2.76W/m 2 C. In ompaison, the expeimental esults agee with those found in liteatue, whih ae of the ode 3 to 4 W/m 2 C. By ontast, the losses fato is elatively low ompaed to the theoetial value estimated U L =5.12W/m2 C. Conening the fitive absoption oeffiient t of the wate mass is found expeimentally 0.16, this optial pefomane of the still seems vey low in ompaison to the theoetial value 0.85, this an be explained by the pesene of an impotant mass of salt deposit at the bottom of the vat. The pefomed analysis enable us to examine the evolution of the global effiieny vesus sea wate tempeatue duing the loal time inteval fom 10 AM to 14 PM fo the day of 06/07/2010. The evolution of g obeys to a linea law of the positive slope. In fat, we eoded a apid inease of these haateistis. When the sea wate tempeatue ineases, we noted that the yield ineases in time inteval fo high tempeatues eahing 70 C to 107 C (Fig.9 (b)). Fig.9. Vaiations of the global effiieny fo the day of 06/07/2010 (a) as funtion of (Tw -Ta)/Ig,(b) as funtion of sea wate tempeatue 5. Conlusion A double slope sola still was manufatued and tested unde the sola adiation. This expeimental study pemits to examine the influene of some intenal and extenal paametes on the opeating system and thei tempoal evolution. Aoding to this analysis, the sea wate desalination poess by sola distillation seems to be influened by the diffeent effets that have an impat on the onsideed still yield as, the sola enegy, the distilled wate tempeatues, the thikness of the wate laye and the salts deposit.

10 484 Hanane.Abuideh et al. / Poedia Engineeing 33 ( 2012 ) The ealised expeiments, pemitted to note the modifiations elated to the evolution of the global effiieny suh as the global losses fato obtained expeimentally U L =2.76 W/m 2 C.This one agees with the esults epoted in the liteatue, whih is of the ode 3 to 4 W/m 2 C. The wind and the salts deposits deease elatively the ate of the distilled wate podution. The inidental sola adiation and the diffeene in tempeatue between sea wate and the ambiane tend to aeleate the physial phenomenon of the sola distillation between 12PM and 15PM. This qualitative study poves that sola distillation of sea wate is a good option fo wate teatment. The aveage yield of distilled wate obtained by sola desalination was 4 L/m 2 /day. Refeenes [1] Dunkle RV. Sola wate distillation: the oof type still and a multiple effet diffusion still. In: Intenational Developments in Heat Tansfe, Int. Heat Tansfe Confeene, Univesity of Coloado;1961, p Pat 5. [2] Pages J., C. Chaboub, F. Laloë, P. Sagna, I, Sow."Un Point d Eau Doue dans les Iles du Saloum? Examen des Possibilités des Distillateus Solaies. Revue Sénégalaise des Rehehes Agioles et Halieutiques ; 1989,Vol. 2 n 34. [3] Bouidiba M. ET AL : Etude d un distillateu solaie a effet de see de type asades ;1987, Jith, vol.2, pp [4] Eduado Rubio- Ceda,Miguel A. Pota-Gandaa, Jose L. Fenandez-Zayas. Themal pefomane of the ondensing oves in a tiangula sola still. Renewable Enegy 27;2002, [5] Imad A1-Hayek a, Oma O. Badan: The effet of using diffeent designs of sola stills on wate distillation. Desalination 169;2004, [6] Hikmet S. Ayba.Mathematial modeling of an inlined sola wate distillation system. Wate distillation system. Desalination 190 ;2006, [7] Cheaed L..Amélioation du Rendement d un Distillateu Solaie à Effet de See. Eneg. Ren. Valoisation ;1999, [8] Bilal A. Akash, Mousa S. Mohsen, Waleed Nayfeh. Expeimental study of the basin type sola still unde loal limate onditions. Enegy Convesion & Management 41;2000, [9] Al-Hinai H., M.S. Al-Nassi, B.A. Juban. Effet of limati, design and opeational paametes on the yield of a simple sola still. Enegy Convesion and Management 43;2002, [10] Hioshi Tanaka.Expeimental study of a basin type sola still with intenal and extenal efletos in winte. Desalination 249 ;2009, [11] Abdul Jabba N. Khalifa, Hussein A. Ibahim. Effet of inlination of the extenal efleto on the pefomane of a basin type sola still at vaious seasons.enegy fo Sustainable Development 13;2009, [12] Hioshi Tanaka, Yasuhito Nakatake. One step azimuth taking tilted-wik sola still with a vetial flat plate efleto. Desalination ;2009, 235:1 8. [13] Hioshi Tanaka, Yasuhito Nakatake. Inease in distillate podutivity by inlining the flat plate extenal efleto of a tilted-wik sola still in winte.mehanial Engineeing Depatment, Kuume National College of Tehnology, Komoino, Kuume, Fukuoka Japan. Sola Enegy 83 ;2009, [14] Velmuuga V., M. Gopalakishnan, R. Raghu, K. Sitha. Single basin sola still with fin fo enhaning podutivity.depatment of Mehanial Engineeing, Infant Jesus College of Engineeing, Thoothukudi , Tamilnadu, India. Enegy Convesion and Management 49 ;2008, [15] Gysi A. P. and A. Stefa nsson. Numeial modelling of CO 2 -wate-basalt inteation. Minealogial Magazine, Febuay 2008, Vol. 72(1), pp [16] Rahel M. Dunk. Sequestation of Cabon Dioxide in the Deep Sea: Dissolution Rates fom ph Measuements. Shool of Oean and Eath Siene, Southampton Oeanogaphy Cente, Univesity of Southampton, England. Mentos: Pete G. Bewe and Edwad Peltze Summe 2001.