F [6] F. [7] [8] F F. F F F F. F. F F. F [9] F 1. 1. F F F. F F. F F. 2 . F Spalding [4]. F Mass Transfer Processes. F Reynold Flow Modified Reynold. Flow Spalding [ 5 ].
2 27-29 $ 2549 '' ( ) *(
(A Study of Pyramid Like Solar Water still) + 1 2 + -3 1
/0 11',( '' 3 (*, '' ) 456, 10140 '.02-4530167 - : M_niramit @ hotmail.com 2 )-,( '' 3 (*, '' ) 456, , 10140 ' 02-4708622 '( 02-4708555 - : pichai.nam @ kmutt 3 )-,( '' 3 L '' , '' 56, 6 , 10140 '.02-4708902 '( 02-4279802 - : rattanachai.pai @ kmutt Niramit Meemark1 Pichai Namprakai2 Rattanachai Pairintra3 1
Master student in Technology Program, School of Energy and Material , King Mongkut Z s University of Technology Thonburi Bangkok 10140 Tel 01-4512675 Email : M_niramit @ hotmail.com 2 Assistant Professor Pichai Namprakai ,School of Energy and Material , King Mongkut Z s University of Technology Thonburi Bangkok 10140Tel.02-4708622Fax: 02-4708555 Email : pichai.nam@kmutt 3 Assistant Professor Rattanachai Pairintra, school of Bioresorces and Technology , King Mongkut Z s University of Technology Thonburi Bangkok 10140Tel.02-470980202 Fax : 024279623 Email : rattanachai.pai@kmutt
) *4b /0c/ ( 5 L b ( +- ) +466 d4 d( ef666 *4 * d4 e
g/ h1)6 ( +-d
4 i *4j ek * 4h1 * '*d4 d() e f6 + 6 ( d b * 6 * 490 + x 490 + * 6 b d (k 20 + *4 b / 0 + ( 60 40 ( ) d4+ * (* n* 6 b66 *66 40 d4+ * 66 60 3 3-4
- gi+- 4 ( +- o 12.8 )k ++ ++ ( 5 L(k (* ( 3 50 - gi+- 4 ( 22 )k ++ ++ g/ 66 *4
* ( ) 1.67 ) 6+ n ++ 03k b66
* ++ 3Lk n b6n ) 6( +Abstract This research study aim is to investigate the improvement of solar stills. As to the prototype conventional solar still with a single slope acrylic cover has a problem with shading of the side of the still in the morning and evening. We use the pyramid-like solar still to solve this problem. Using acrylic and glass as a transparent cover, the absorber has surface dimensions of 490 mm x 490 mm and water depth in the basin is 20 mm. The angle of inclination of a cover was varied as 60O, 40O(acrylic), According to the comparison between the two stills ( 60s , 40s angle inclination ) it was found that pyramid-like 40s solar still could produce more distillation rate than 60s solar still about 3-4
percents using mean solar radiation of 12.8 MJ.m-2day1. The highest efficiency of two stills is 50 percents (22 MJ.m-2.day-1) which is 1.67 times greater than those of the conventional stills. Important still parameters that affects distillation rate were the pyramid shape of still, temperature difference between evaporating and condensing surface, saturated wet air volume within the space of the still and the angle of inclination of the transparent cover. 1. 6b
b*4 ( +- e 5 / g/ b ( + - d4 d 4 e '- )d4'-d 'g g 64 e +4 g/ + + b d4d *4 + ( - d4 * (+ c/ 6 'L ) *4) d4 vvw[1] b d4 b n + *4 n + *4/ 6 e c/ h 1 b * * b (* d * 6 i z kd (- b)* )/ *4b ( +- * 66 * e*d4)d *4 d * e 5 / n ( +( *4 +4 ( 6b 0
5 d4 k 3L b *4)
6 3Lkd 3{- +| b* [2] g/ d4 (d) ) d ) 66 * d* + / 0 b 66 *4 * [3]66 ( *4[4] /0 d4 (* )(+ ef6[5] + 6 ( d4k 6*b[6] (* d4b [7] *6 b* 6 [8] g/ 66 * ) 4*4 6 ( +-)*44 + d+ 4 + i (k1 ( b + + n *4 *4 d + g/ ) *4 / 0k * )+ [9] *4j6 * k 1
k 1 b66} * g/ e4h16 ( +-* )k / ( + ( c en *4 '*d4 (+ e ( * f 6+ 6 ( '* )d4(+ (4 ek * 2 .89:;?@ Spalding [4] db + b d b ( +-g/ e Mass Transfer Processes '* )d4~0$ Reynold Flow Modified Reynold Flow Spalding [ 5 ] db+ b 6 '* e )3c n ( n( b6 g/ ( c(* *4* m* = g * ln(1 + B )
m* g* B
(1)
+ b, kg/m2.s Mass Transfer Conductance, kg/m2.s Driving force
b 3 driving force(B) *4)( B=
mH 2O, S − mH 2O ,G
1 − mH 2O, S
(2)
mH 2 O , S mH 2O ,G
)b b n b d (mass fraction n ) )b b n )(mass fraction n + )
b 3 )b b n b mH 2O, S )(
mH 2O , S =
ωS 1 + ωS
(3)
Sci Gr
ρ
b 3 )b b n ) mH 2O,G ) ( mH 2O ,G =
ωG 1 + ωG
D
(4)
β µ
)b b n b, kgH2O/kgdryair )b b n ), kgH2O/kgdryair
ωS ωG
g
∆T Tav
b 3 )b b n b ωS )( ωS =
0.622 Pw Patm − Pw
(5)
3.D?E
b 3 )b b n ) ωG ) ( ωG =
0.622 Pg
(6)
Patm − Pg
*6Ld66, kPa * + n b, kPa * + n ), kPa
Patm Pw Pg
(b6 )3 Mass Transfer Conductance (b6 c 46 n 6d * ( g/ *4)* [5] g* = 0.095(Gr.Sci )0.33
'*
Gr =
ρD L
L3 ρ 2 g β∆T
µ2
2.5 0.926 (Tav + 273) −6 D= × 10 101.325 ( T + 518) av
β=
1 Tav + 273
L
Scimidt number (b6 bd Grashof number bn( , kg/m3 ( ( 5 ) b d ( ( 5 + '* + , K-1 Absolute Viscosity bn( , kg/m-s ) '4 c ', m/s2 ++ 3Lk n b 3Lk n ), oC 3Lk o 3Lk n b 3Lk n ), oC o n 3-6 n 6 3-, m
3.1D?E 03 b *4 ( + - 66 * (* * k 2,3 ) 03 ek * 40 60 '*d4(+ b 3 + + d4 6) b b )(+ (+ n 6 ( d4 * ( ( *b*4 g/ * 490*490 + *6 b(k 2 g+ + d4( +-( n)g/ /*+ *6' (
+ ( b*20*40 +k 6| e d4 b (k *44 2 (b 6 + i 6 b * 6 )4 o 'v 30 + 6 b* 25.4
(7)
(8)
(9) k 2 66 b 40
3.5
(kg/m^2-d)
3 y = 0.2466x - 1.0024 2 R = 0.9082
2.5 2
y = 0.2717x - 1.3922 R2 = 0.9523
1.5 60
1
40 ( 40 )
0.5
k 3 66 b 60
8
5.1 = GJ=
