JJMIE Jordan Journal of Mechanical and Industrial Engineering

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1 JJMIE Jordn Journl of Mecnicl nd Industril Enineerin Volume 3, Number 3, September 009 ISSN Pes 8-35 Modelin nd Verifiction of Double Slope Sinle Bsin Solr Still Usin Lbortory nd Actul Solr Conditions K. Klids Muruvel, Kn. K. S. K. Cocklinm, K. Sritr b,. Deprment of Mecnicl Enineerin, Ntionl Enineerin Collee, Tmil Ndu, Indi. b Deprtment of Mecnicl Enineerin, Tirjr Collee of Enineerin, Mduri, Tmil Ndu, Indi. Abstrct A double slope sinle bsin, pssive type, still it bsin re of 1.75 m is fbricted nd tested under lbortory conditions. Te solr rdition et is simulted by usin kw electricl resistnce eter plced belo te inner bsin. Te et supply is vried usin control circuit. Te still is tested for vryin input condition to simulte te ctul solr rdition condition it different minimum depts of ter in te bsin rnin from cm to 0. cm. Te experiment is lso crried out t differ ent constnt input conditions it constnt dept of ter. Te vrition of different prmeters it production rte s b een studied. It is found tt te production rte increses it te increses of ter nd lss temperture. But t ier opert in temperture, te production rte increses it te decrese in temperture difference beteen ter nd lss. A ne m odel is recommended for te still it sllo bsin. Te experiment is lso conducted it te sme still t ctul sunsine conditions nd compred it te model. Te experimentl vlues re in close reement it model vlues. Keyords: Solr Still; Lbortory Simultion; Minimum Dept; Modelin; Productivity Enncement. 009 Jordn Journl of Mecnicl nd Industril Enineerin. All rits reserved Symbols A Are (m C Specific et (J/k K Gr Gros of number Greek symbols ω dry ir. Specific umidity of ir, k of vpour/k of Emissivity of te lss, c Het trnsfer coefficient (W/m K e Evportive et trnsfer coefficient bsed on temperture difference (W/m K e Evportive et trnsfer coefficient bsed on pressure difference (W/m K f Ltent et of evportion of te ter (J/k Het trnsfer coefficient of te lss upper surfce to ir (W/m K k Terml conductivity (W/m K L c M m Lent (m Moleculr eit Mss production rte (r/min or k/m / Nu L P Nusselt number Perimeter (m p Pr Q Pressure (N/m Prndtl number Het trnsfer rte (W Q c Convection et trnsfer rte from ter surfce to lss (W Q e Evportion et trnsfer rte from ter surfce to lss (W R L Rylei number T o Temperture, C Subscripts Atmospere, ir b Bsin Glss Glss to tmospere s Sturtion condition Wter s Wter vpour t sturtion condition 1. Introduction A lot of orks ve been done on improvin te effectiveness of te simple solr still, ic converts te b rckis ter into fres ter, usin solr enery. Recently, te utors revieed te proress in improvin t e effectiveness of simple sinle bsin solr still [1]. Studies so tt bsin ter temperture is te sinificnt prmeter tt ffects te effectiveness of te st ill. Te bsin ter temperture is t mximum en te et cpcity of te bsin is less. Te et cpcity of te b sin depends on te dept of te ter in te bsin. For Correspondin utor. ponsty@otmil.com

2 9 009 Jordn Journl of Mecnicl nd Industril Enineerin. All rits reserved - Volume 3, Number 3 (ISSN iven solr intensity vrition, te still production rte is ier, en dept is t minimum [-6]. A Number of studies in te literture is vilble to exmine et trnsfer process of te still. Te most idely cceptble study s mde by Dunkle [7]. Since ten, most of resercers used te prosed Dunkle s [7] model for teir nlysis. But, te bove model is suitble for men bsin ter temperture of 50 o C. Clrk [8] conducted stedy stte experiment on solr still; nd exmined te vlidity of te vrious correltions, proposed erlier for evlutin te et trnsfer coefficients. Sqfe nd Frid [9] investited et nd mss trnsfer processes nd recommended ne correltions for internl convective et trnsfer coefficient. Kumr nd Tiri [] recommended to test nd model te fbricted still for vrious tmosperic conditions for predictin te performnce t prticulr plce. An experimentl still s been tested, nd nlysis ve been mde to study te ter to cover et trnsfers by Port et l. [11] nd correltion to clculte te production rte of te still is lso recommended [1]. Recently Tripti nd Tiri [3, 13] studied te effect of bsin ter dept on te internl et trnsfer coefficients. Te utors lredy conducted experiment it lbortory solr still, for lyer of ter it different bsin mterils; nd studied te performnce nd noted te peculir bevior of te still t ier bsin ter nd lss tempertures [14]. At loer depts, te bsin ter temperture is i, nd te production rte of te still is not in proportion it bsin ter temperture nd te difference beteen te bsin nd lss tempertures. Te objective of tis ork is to conduct tree experimentl orks to nlyze te performnce of te double slope sinle bsin solr still. To orks re crried out in lbortory conditions; one it vryin et input condition. Here, te experiments re crried out it vryin depts rnin from cm to 0. cm. Tis ill elp in studyin te effect of solr insultion on productivity. Te second experiment is conducted it constnt et input condition to study te vrition of production rte it vrious tempertures. Hence, constnt dept of 1 cm is lso mintined. A ne model for te still is proposed from te bove nlysis. Te model is verified by testin te still t ctul solr rdition condition for minimum depts of ter in te bsin. For te still t ctul sunsine condition, te eter is tken out, nd te bottom is leveled it cement concrete. Tis concrete lyer stores excess et durin noon nd releses et durin evenin nd nit. Tis increses te nocturnl production.. Internl nd Externl Het Trnsfer Processes Te modes of et trnsfer inside te still beteen te ter surfce nd te lss cover re convection ccompnied it evportive mss trnsfer in te form of ter vpour nd rdition. Te rdition et trnsfer is very smll if compred it oter to et trnsfers, nd te production of te still is not ffected sinificntly by tis et trnsfer. Te evportive et trnsfer is responsible for te trnsporttion of ter mss from ter surfce to cover. Tis evportive et trnsfer increses it te vpour pressure difference beteen te ter nd lss; nd is responsible for bulk motion of ir inside te still. Tis bulk motion increses te convection et tr nsfer. Hence te convection nd evportion et trnsfer inside te still re interrelted. Dunkle [6] used te folloin correltion developed by Jkob [15] to estimte te convection et trnsfer coefficient inside te still, (Reltion.1 c ( p p = T p Te convective et trnsfer is iven by [7], Q c = A b c Te evportive et trnsfer coefficient s per te detiled derivtion iven by Mli k et l. [16] is iven by, M p f e = c M C ( p p ( p p (3 p Dunkle [6] ssumed tt te p nd p re considerbly smller tn te totl pressure p, nd te men opertin o temperture is 50 C nd estimted te vlue of e s, / = c e (4 In eqution (3, te vlues p nd p re considerbly smller tn p for loer rne of bsin ter nd lss temp ertures. Wen te still is it sllo bsin, te men ter nd lss tempertures re ier tn 50 o C; nd te eqution (4 cn not be used. At ier te mpertures, te prtil pressure vlues re considerbly ier, nd te eqution (4 ill not yield constnt vlue. Te evportive et trnsfer is iven by [16], Qe = Ab e ( p p (5 Te mss trnsfer rte of ter vpour is iven by [ 16], Q m = e (6 f At ier bsin ter temperture, te ter is more susc eptible to evportion nd te ter mss proportion in te still ir is i. Te percente of mss of ter v pour present in te ir inside te still is iven s by ssumin te ir s sturted, percente of vpour = ω s 1+ ω s ( x 0 (7 ere ω s is te k of vpor present in te one k of dry ir t sturted condition nd it is iven s [17], p s ω s = (8 p ps

3 009 Jordn Journl of Mecnicl nd Industril Enineerin. All rits reserved - Volume 3, Number 3 (ISSN Fiure 1. Sinle bsin double slope lbortory still. Te increse in p s it temperture is exponentil. Hence, t ier bsin nd ter temperture, te productivity depends on rte of et trnsfer from te lss cover to te tmospere. Te effect of te temperture difference beteen te ter nd lss, ic is te drivin force for te bulk motion of ir inside te still on condenstion nd trnsporttion of ter mss from bsin to lss, is less sinificnt. Te evportive et trnsfer coefficient, e bsed on te temperture difference beteen te ter nd lss cn be clculted usin folloin reltion, Q e = m f = Ab e T (9 Te mount of et trnsfer from t e lss upper surfce to te tmospere is iven by: 4 Q + 73 = A{ T + [ ]}... In most of te studies tis vlues is tken s constnt of 4.5 W/m K s recommended by Duffie [18] includin te rdition effect for no freeze condition. In tis ork, te ctul convection et trnsfer coefficient of te inclined surfce s clculted usin te procedure iven by Incroper nd Devitt. [19]. Te reltion for vere Nusselt number for te lss cover for entire rne of Rylei number s been recommended by Curcill nd Cu [0] nd is of te form: (Reltion.11 Nu 0.387R 1 + (0.49/ Pr L L = = L k c ( (11 ere L A c = = 1.18 m. P Te overll et trnsfer coefficient of te lss surfce, includin te rdition et trnsfer to tmospere nd itout considerin sky rdition, cn be clculted s: Q = A T (1 ( 3. Lbortory nd Solr Still A sinle bsin double slope solr still s been fbricted it mild steel plte, s son in Fiure 1. Te overll size of te inner bsin is.08 m 0.84 m m, nd tt of te outer bsin is.3 m 1m 0.5 m. Te p beteen te inner nd outer bsin is pcked it rice usk s insultion mteril. Te top is covered it to lsses of tickness 4mm, inclined t 30 o on bot sides, u sin ooden frme. Te outer surfces of te still re covered it lss ool nd termo cool insultion. Te co ndensed ter is collected in te V-sped drine provided belo te lss loer ede of te still. Te condenste collected is continuously drined trou flexible ose nd stored in jr plced on te electronic eiin mcine on bot side of te still. A ole in te b sin side ll llos insertin te termocouples for te m esurement of te bsin ter, still, nd condenste temperture. To mesure te bsin temperture, four termocouples ere plced t te bsin t different loctions. To termocouples ere dipped into te ter in te collectin drine on eiter side. Te ole is closed it insultin mteril to void te et nd vpour loss. One termocouple is exposed to tmospere to mesure te tmosperic temperture. Tis termocouple is plced in sdo re to prevent te vrition in temperture due to incidence of sun rdition on te termocouple.

4 Jordn Journl of Mecnicl nd Industril Enineerin. All rits reserved - Volume 3, Number 3 (ISSN Fiure. Sinle bsin double slope solr still. Anoter ole is provided for ter inlet. Trou tis ole, smll tube is inserted to supply r ter continuously to te bsin from store tnk trou flo reultor to keep te mss of ter in te bsin lys constnt. Te etin coil of 000 W is plced belo te inner bsin to supply necessry et enery to te bsin. Te input to te eter is iven trou control circuit, ic controls te input electricl enery. An enery meter is fitted it te circuit to mesure te input enery. To convert te lbortory still into n ctul solr still, t e eter nd poer supply nd mesurement systems ere rem moved. Te inner bsin is lso removed. Te bottom of te still is leveled it 5 cm tick cement co ncrete to minimize et loss trou te bsin nd to spred te minimum dept of ter uniformly, son in Fiure. Te concrete surfce is blck pinted to improve t e rdition bsorption cpcity. Te distillte output s record ded it te elp of mesurin jr. Te solr intens sity s mesured it te clibrted PV type sun meter. 4. Experimentl Procedure Te experiment s crried out in te fbricted lbortory still t Stem Lbortory, Ntionl Enineerin Collee, Kovilptti (9 o 11 N, 77 o 5 E, city in soutern Indi durin December 005 to Februry 006. In te lbor tory still, te et input is iven to te solr still usin etin coil trou control circuit. For iven const nt dept of bsin ter condition, te input to te ete r is vried for every 15 minutes from W/m bete en 6 AM n 1 noon nd from W/m bete en 1 noon nd 6 PM to mtc it te locl ver e solr rdition condition [8]. Durin nit, te ete r supplies no et. For iven dept, ll te obser vtions re tken for 4 ours durtion, strtin from 6 AM. Te temperture of te tmospere, bsin ter, nd t e condenste re noted for every 15 minutes. Te enery meter redins nd condenste collected on bot side of te still re lso noted. Te experiments ere co nducted for cm, 1.5 cm, 1 cm, 0.5 cm nd 0. cm de ept of ter in te still bsin for sme solr condition itout freeze. For experimenttion it dept of ter 0..5 cm nd 0. cm, lit blck cotton clot is used to spred te ter trou te entire re of te bsin. Te co ndenste temperture is tken s te temperture of te l lss cover. Fiure 3 sos enery input iven to te l bortory still t vrious times nd correspondin v rition in tmosperic temperture. Poer, W /m Input enery in Wtts Atmosperic temperture Locl time, Fiure 3. Input enery nd tmospere temperture vrition in t e simulted solr still. Te still is lso te sted under vrious constnt input conditions it different depts of ter in te bsin. Het is supplied by te eter until te still reces stedy stte co ndition. Ten poer is cut off nd te still is lloed to co ol don nturlly to rec equilibrium stte it tmospere. Te redins re tken for every 15 minutes fr om te time te still strts to deliver ter production until it delivers sinificnt mount of output. Te experiments re crried out for te constnt input poers from 300 W to 1500 W. Te experiments it solr still t ctul sunsine co nditions ere conducted durin Februry to April Temperture, o C

5 009 Jordn Journl of Mecnicl nd Industril Enineerin. All rits reserved - Volume 3, Number 3 (ISSN for vrious depts rnin from cm to 0.5 cm. Te observtions re tken for 4 ours durtion, strtin from 6 AM. Te totl rdition on orizontl plne, te tempertures of te tmospere, bsin ter nd condenste nd te mss of condenste collected re noted for every 30 minutes. beteen te lss nd tmosperic tempertures is t mximum en te production rte is t mximum. Ten ll ter nd lss tempertures nd difference in tempertures strt to decrese it production rte. Te vrition of te internl evportive et trnsfer coefficient nd overll et trnsfer coefficient for lss it locl ours re in reltion it production rte, son in Fi ure 5. Tis vrition is similr for different depts of ter in te bsin. Fiure 4. Vrition in tempertures nd production rte for lbortory still it vryin input set I. Fiure 5. Vrition in et trnsfer coefficients nd production rte for lbortory still it vryin input 5. Results nd Discussion 5.1. Anlysis of Lbortory Still t Vrible Input Condition Te evportive et trnsfer coefficients re clculted usin eqution (9, nd te overll et trnsfer coefficient of te lss surfce to te tmospere is clculted usin equtions ( to (14. Fiure 4 sos te vrition of ter nd bsin tempertures, ter-lss tempertures difference, nd lss-tmosperic tempertures difference, nd ter production rte it time for lbortory still it dept of 0.5 cm nd under vryin input condition. Te vrition of ll prmeters it production rte is norml nd s expected. Te vrition of difference in temperture beteen ter nd lss is lso different ere. Initilly, durin mornin ours en te input poer is less, te production rte increses it tis temperture difference. Wen ter temperture exceeds 50 o C, tis temperture difference reces mximum vlue nd strts to decrese tere fter. Te still production rte continues to increse until te difference in temperture beteen lss nd tmospere increses. Te difference Fiure 6. Vrition in tempertures nd production rte for lbortory still it vryin input set II. Te vrition of te ter nd lss temperture nd difference in ter-lss nd lss-tmosperic tempertures, re similr for te still it different loer depts rnin from cm to 0. cm. Te strtin time nd t e durtion in ic te production rte increse it te decrese of te temperture difference beteen ter- Fiure 6 sos te vrition of tese prmeters for still it 1 cm dept. For tis still te peculir bevior lss. st rts round 1 Noon nd lsts up to round PM. For te st ill it 0.5 cm dept, te peculir bevior occurs durin PM nd 1 PM [Fiure 4]. For iven solr intensity vrition in loer dept still, tis peculir bevior strts erly nd lsts loner durtion n d for ier dept, nd strts erly nd lsts for sorter d urtion. For deep bsin still, durin loer solr intensity v ritions in dy, te still my not experience tis peculir opertion. If still experience tis peculir bevior for loner durtion, te production per dy ill be i. 5.. Anlysis of Lbortory Still t Constnt Input Condition Te vrition of te different prmeters of te l bortory still t constnt input of 1500 W is son in te Fiure 7. Te production rte of te still increses it te increse of ter nd lss tempertures durin et su pply period. Also te production rte increses it te in crese in ter-lss temperture difference durin tis period. Te production rte decreses it tese p rmeters durin coolin. Tis is te norml opertion of te still. Durin etin period, te production rte increses it te decrese in ter-lss tempertures difference. It is te peculir bevior of te still. Durin etin, te rte of decrese of ter-lss temperture difference is miniml, nd te correspondin rte of increse in production rte is ier. Tis peculir bevior is

6 Jordn Journl of Mecnicl nd Industril Enineerin. All rits reserved - Volume 3, Number 3 (ISSN Fiure 7. Vrition in tempertures nd production rte for lbortory still it 1500 W constnt input. Fiure 9. Vrition in tempertures nd production rte for lbortory still it 100 W constnt input. Fiure 8. Te vrition in et trnsfer coefficient nd production rte for lbortory still it 1500 W constnt input. observed only durin etin. Durin coolin, norml bevior is observed. Fiure 8 sos te vrition production rte, internl evportive et trnsfer, nd te externl overll et trnsfer coefficient of te lss cover it for te still. Te vritions of tese prmeters re in reltion it te vrition of production rte. For te lbortory still it constnt input, te vritions of different prmeters re similr for different constnt input poers. For ier input poer, rte of temperture rise for ter nd bsin is ier, nd production strts erly. Te ter-lss tempertures initilly increse it production rte for loer ter nd lss tempertures s son in Fiure 7. Wen te ter temperture is round 55 o C, tis difference temperture ttins mximum vlue ten strts to decrese. Similr vritions re observed for te still it 100 W input lso s son in Fiure Modelin of Still To study te production rte vrition it ter nd lss tempertures, ter-lss nd lss-tmospere temperture differences, correltion plot is drn by usin te observtions of te still under vryin opertin conditions s son in te Fiure. Bot ter nd lss tempertures nd difference beteen lss nd tmosperic temperture re incresin it production rte. Te overll vrition of te difference beteen ter Fiure. Vrition of production rte it different tempertures for lbortory still. lss tempertures is different. Initilly tis vlue increses it production rte, ttins mximum vlue nd strts to decrese. Te mximum vlue of tis diffe rent corresponds to ter temperture round 55 o C. Te production rte is 5 /min en te temperture difference beteen ter nd lss is in te rne 5 o C to 0 o C. Similrly oter prmeters lso ve rne of vlues for prticulr production rte. At loer tempertures of ter nd lss, te ter vpour present in te ir inside still is in minimum proportion. Te ter mss proportion increses exponentilly it te still ir temperture, (equtions (7 n d (8. Hence, production rte of te still depends on bsin ter nd lss tempertures. At ier ter te mperture, ter is more susceptible for evportion, n d te ter vpour proportion in te still ir is i. Wen te lss temperture is i, bot et trnsfer from lss to tmospere nd te production rte re lso i. Wen te ter nd lss tempertures re ier, teir difference is less, nd te production rte is i. Tis is te reson for te peculir opertion of te still. Te mount of condenstion t te lss loer surfce m inly depends on te mss of ir circulted, nd in contct it te lss loer surfce. Tis circultion depends on te temperture difference beteen ter nd lss. If te lss temperture is ier or ter temperture is loer, tis difference ill be lo nd te production rte is lso lo. Hence te production rte is complex function of ter nd lss tempertures nd te

7 009 Jordn Journl of Mecnicl nd Industril Enineerin. All rits reserved - Volume 3, Number 3 (ISSN m = T T T T T 5 T T T ( T (15 Fiure 11. Comprison beteen ctul nd clculted vlues of production rte for lbortory still Fiure 13. Performnce of te solr still it loer dept. Fiure 1. Performnce of te solr still it medium dept difference beteen te ter-lss nd lss- tmosperic tempertures. Te observtion from lbortory still experiments t constnt dept it vryin constnt input nd it vryin dept it constnt vryin input re used to estblis reression eqution usin Mtcd-1 softre. To-dereeqution is obtined for te production rte of te still in fittin function is used. Te folloin k/m /. Te bove eqution (eqution 15 is tken s ne model. Usin tis model, te production rte is clculted usin te observtions of lbortory still experiments, nd te clculted vlues re compred it ctul vlues. Te Fiure 11 sos te comprison beteen te ctul nd clculted production rte vlues by usin te model. It is found tt most clculted vlues re closer to ctul vlues it correltion coefficient of Anlysis of te Still Under Solr Rdition Condition Te sme lbortory still is tested under ctul solr rdition condition for different depts of ter in te bsin. Bot Fiures No. 1 nd nd No. 13 so te performnce of te stills en te depts of ter re 3 cm nd 1cm. Te production rte of te still vries proportionlly it different ter, lss tempertures, Fiure 14. Comprison beteen ctul nd clculted vlues of production rte for ctul solr still nd difference beteen lss nd tmosperic te mpertures. Similr it lbortory still, for ctul still l so, te production rte increses initilly it te increse of te temperture difference beteen ter nd l ss, but t ier temperture en te bsin ter reces round 55 o C, tis difference is t mximum. But te production rte increses until te difference beteen te lss nd tmosperic tempertures strts to decrese. Hence te still, nd under ctul sunsine conditions, beves similrly to lbortory still it vryin input. Usin te observed vlues of different tempertures, te ne model is used to clculte te production rte for te ctul solr still it different depts of 4 cm, 3 cm nd 1 cm. Te ctul vlues nd clculted vlues re compred b y usin te ne model. Te Fiure 14 sos te comprison beteen te ctul nd vlues clculted, usin te ne model. Te most of te clculted vlues re close to ctul vlues it correltion coefficient of Te devition in vlues due to sky rdition effect nd ind velocity effect even tou, durin experiment time, no pprecible ind is observed.

8 Jordn Journl of Mecnicl nd Industril Enineerin. All rits reserved - Volume 3, Number 3 (ISSN Conclusion A double slope sinle bsin, pssive type, still it bsin fbricted; nd tested under lbortory conditions. Te et is supplied to te bsin usin electricl resistnce eter plced belo te inner bsin. Te et supply is vried usin control circuit. Te still is tested for vryin input condition to simulte te ctul solr rdition condition it different minimum depts of ter in te bsin rnin from cm to 0. cm. Te experiment is lso crried out t different constnt input conditions it constnt dept of 1 cm ter. Te vrition of different prmeters it production rte vrition s been studied. It is found tt te production rte increses it te increses of ter nd lss temperture. At loer ter nd lss tempertures, te production rte is proportionl it te temperture difference it ter nd lss. At ier opertin tempertures, te production rte increses it te decrese in temperture difference beteen ter nd lss until te difference beteen te lss nd tmosperic temperture increses. Tis is te peculir bevior of te still. Te reson for tis bevior is te ier proportion of ter vpour t ier still temperture. Te still overll production rte per dy ill be i en te still opertion in tis peculir bevior for loner durtion. A ne model is proposed for te still it sllo bsin. Te experiment is lso conducted it te sme still t ctul sunsine conditions. Te still under solr rdition condition it loer dept beves similrly to lbortory still. Te experimentl production rte vlues re in close reement it model vlues. Te proposed mode l cn be used to predict te production rte of te still it minimum dept of ter in bsin in te rne of cm to mm nd for te bsin ter temperture up to 80 o C. References [1] K.K. Muruvel, S.K. Cocklinm, K. Sritr, Proresses in improvin te effectiveness of te sinle bsin pssive solr still. Deslintion, Vol. 0, No. 1-, 008, [] P.I. Cooper, Diitl simultion of trnsient solr still processes. Solr Enery, Vol. 1, No. 3, 1969, [3] R. Tripti, G.N. Tiri, Terml modelin of pssive nd ctive solr stills for different depts of ter by usin te concept of solr frction. Solr Enery, Vol. 80, No. 8, 006, [4] R. Tripti, G.N. Tiri, Effect of ter dept on internl et nd mss trnsfer for ctive solr distilltion. Deslintion, Vol 173, No., 005, [5] S. Aboul-Enein, A.A. El-Sebii, El-Bily, Investition of sinle-bsin solr still it deep bsins. Reneble Enery, Vol. 14, No. 1-4, 1998, [6] N. Hussin, A. Rim, Utilistion of ne tecnique to improve te efficiency of orizontl solr deslintion still. Deslintion, Vol. 138, No. 1-3, 001, [7] R.V. Dunkle, Solr ter distilltion; te roof type still nd multiple effect diffusion still. Interntionl Developments in Het Trnsfer, ASME, Proceedins of Interntionl Het Trnsfer Prt V, University of Colordo, [8] J. A. Clrk, Te stedy stte performnce of solr still. Solr Enery, Vol. 44, No. 1, 1990, [9] A.T. Sqfe, M.M. Frid, Ne development in te t eory of et nd mss trnsfer in solr stills. Solr enery, Vol. 55 No. 6, 1995, [] S. Kumr, G.N. Tiri, Estimtion of convective mss trnsfer in solr distilltion systems. Solr enery, Vol. 57, No. 6, 1996, [11] M.A. Port, E. Rubio, J.L. Ferndez, Experimentl mesurement of te ter-to-cover et trnsfer coefficient inside sllo solr still. Applied Terml Enineerin, Vol. 18, No. 1-, 1998, 69-7 [1] E. Rubio, M.A. Port, J.L. Fernde, Cvity eomentry influence on mss flo rte for sinle nd double slope solr stills. Applied Terml Enineerin, Vol. 0, No. 1, 000, [13] R. Tripti, G.N. Tiri, Effect of ter dept on internl et nd mss trnsfer for ctive solr distilltion. Deslintion, Vol. 173, No., 005, [14] K.K. Muruvel, K.K. Cocklinm, K. Sritr, An experimentl study on sinle bsin double slope simultion solr still it tin lyer of ter in te bsin. Deslintion, Vol. 0, No. 1-3, 008, [15] Jcob M. Het Trnsfer. Ne York: Wiley; [16] Mlik M, Tir GN, Kumr A, Sod MS. Solr Distilltion. st 1 ed., Oxford: Permon press; 198. [17] Cenel Y. Termodynmics An Enineerin Approc. 3 rd edition. Indi: Tt Mc Gr Hill; 003. [18] Duffie JA., Beckmn WA. Solr Enery Terml Processes. Jon Wiley nd sons; 1974 [19] Frnk P. Incroper D, Deitt P. Het nd Mss Trnsfer. Sinpore: Jon Wiley & Sons (Asi Pte. Ltd.; 006. [0] S.W. Curcill, H.S. Humbert, Correltin equtions for lminr nd turbulent free convection from verticl plte. Interntionl Journl of Het nd Mss Trnsfer. Vol. 18, No. 11, 1975,