Klemetson 1985 Aquacultural-Engineering

7/28/2019 Klemetson 1985 Aquacultural-Engineering

1/18

Aquacu l tu ra l Eng ineer ing 4 (1985) 191-208

A q u a c u l t u r e P o n d T e m p e r a t u r e M o d e l in gStanley L. K lemetson

Department of Civil Engineering, Brigham Young University, Provo,Utah 84602, USAand

G ary L. R ogersUniversity of Hawaii, Hawaii Institute of Marine Biology, PO Box 1346,Kaneohe, Hawaii 96744-1346, USAA B S T R A C T

T h e p r e d i c ti o n o f a q u a c u l t u re p o n d t e m p e r a t u r e s t h r o u g h o u t t h e y e a r ise s sen t i a l to t he de s ign and eva lua t ion o f po t en t i a l aquacu l tu re s ite s. A s i t em a y o b t a i n t h e n e c e ss a r y h e a t i n p u t s f r o m t h e s u n , g e o t h e r m a l w e ll s o ri n d u st r ia l a n d p o w e r p l a n t w a s t e he at. T h e a m o u n t o f h e a t a d d i t io nneces sary i s de pe nd en t upon c l ima t i c and env i ron me n ta l f ac to r s a t t he s ite .

T h e M . A P T ( M a i n te n a n c e o f A q u a c u l t u r e P o n d T e m p e r a tu r e s) m o d e lw a s d e v e l o p e d t o d e t e r m i n e t h e p o t e n t i a l f o r w a r m w a t e r a q u a c u l tu r e a tany s i t e i n t he wo r ld . Ho t w a te r sources and so la r rad ia t ion p rov ide d t h eh e a t i n p u t s t o t h e m o d e l w h i l e t h e h ea t s o f e va p o r a ti o n , c o n v e c t i o n a n drad ia ti on we re r e spons ib l e f o r t he hea t l o sses .

T h e m o d e l w a s u s e d t o c o n s i d e r a v a r i e ty o f h e a t lo ss re d u c t i o nm e t h o d s , h e a t t r a n sf e r m e t h o d s a n d p r o j e c t e d t h e p o n d t e m p e r a t u r e s a n dan ima l p roduc t ion rate s. I t has been ap p l i ed t o s eve ra l s i te s a roun d thew o r l d a n d p r o v i d e s a n i n e x p e n s iv e m e a n s f o r e v a l u at io n o f p r o d u c t i o npo ten t i a l w i thou t e x t ens i ve s i t e da ta co l l e c t i on .

INTRODUCTIONThe use of aquaculture ponds in temperate and subtropical climates ofthe world often requires the application of heat loss reducti on metho dsand the use of supplemental heat. The heat is most often available inthe form of power plant waste heat or geothermal hot water, althoughother sources may also be used. 191Aquacu l tu ra l Eng ineer ing 0144-8609/85/$03.30 Elsevier Applied SciencePublishers Ltd, England, 1985. Printed in Great Britain


2/18

192 S. L. Klemetson and G. L. RogersAn evaluation of factors affecting pond water temperatures, and

subsequently aquatic animal productivity, led to the development of acomputer model that predicts the temperature of the water for givenclimatic and site conditions. The model has been entitled Maintenanceof Aquaculture Pond Temperatures (MAPT) (Klemetson and Rogers,1981).

The model can be set up for climatic conditions anywhere in theworld and has been used to evaluate potential aquaculture sites inseveral parts of the world already. It can use geothermal or powerplant hot water to provide supplemental heat but these values can alsobe set equal to zero when no supplemental heat is provided. Theoptimum temperature for any aquatic species can be entered into themodel to determine productivity potentials. The model also allows thecomparison of various heat loss reduction methods.

For the purposes of this paper, specific operating conditions werechosen to use as an example. These consisted of a geothermal wellat a site located in Alamosa, Colorado. At this location, 37 30' N,105 52' E, the elevation is 7535 ft (2297 m). The freshwater Malaysianprawn Macrobrachian rosenbergii was chosen as the aquatic species.The opt imum temperature range of 82-87F (26-30.5C) was used for100% productivity. The productivity was cut in half for each drop inthe temperature of 5F (2.6C).

The basic concepts of the model with sample data are shown in thefollowing sections. These will be followed by a brief discussion of theuse of the model for design and evaluations.

COMPUTER MODEL DEVELOPMENTIn this paper, quantities are given in Imperial units. These values can beexpressed in metric units using the conversion factors given in Table 1.Energy budget equa tionThe temperature of the water is determined by local climatic factors onthe basis of the following energy budget equation (Velz, 1970):

H= He + Hc +H ,- -H s- -H a (1)where : H = net heat loss, He = heat loss by evaporation, Hc = heat


3/18

Aquaculture pond temperature modelingT A B L E 1

I m pe r i a l - Me t r i c Conve r s i on Fac t o r sCustomary unit x Conversion factor = SI unitBt u 1 . 055 kJBtu lb -~ 2 .32 6 kJ kg -1Btu h -1 1.055 kJ h -1B tu h - 1 f t - 2 3.1 54 J m -2 s -1Btu h -1 f t -2 F -I 5.6 77 J m -2 s -1 C - lf t 3 s -1 0-028 32 m a s-1f t 3-048 mi n . 25 . 40 m mLang leys day -1 0 .485 J m -z s -alb f t -3 1.602 kg m -3m p h 1 . 60 9 k m h -x

193

l os s b y c o n v e c t i o n , H r = h e a t l os s b y r a d i a t i o n , H s = h e a t g a in b y s o l a rr a d i a t i o n a n d H a = h e a t t r a n s f e r b y a d v e c t i o n .Evaporative losses, IE v a p o r a t i o n f r o m t h e w a t e r s u r f a ce w i ll c a u s e a lo ss o f h e a t f r o m t h ew a t e r b o d y t o a d e p t h o f a b o u t 1 0 f t (3 m ) . T h i s e v a p o r a t i o n w i l l o c c u rn a t u r a l l y w h e t h e r t h e p o n d s a r e u s e d f o r a q u a c u l t u r e o r n o t ; it a ls og iv e s a m e a s u r e o f t h e w a t e r b a l a n c e f r o m t h e s y s te m . T h e e v a p o r a t i o ne q u a t i o n i s :

I = C 1 (1 + 0 .1 W ) (V w - - V a) ( M e y e r ' s f o r m u l a f o r e v a p o r a t i o n ) ( 2 )w h e r e : I = e v a p o r a t i o n f r o m n a t u r a l w a t e r b o d i e s ( in m o n t h - i ) , W = m e a nw i n d v e l o c i t y ( m p h a t 2 5 f t ) , V w = s a t u r a t e d w a t e r v a p o r p r e s s u r e a ts u r f a c e w a t e r t e m p e r a t u r e s 1 f t b e l o w s u r f a c e ( in H g ) , V~ = s a t u r a t e dw a t e r v a p o r p r e s s u re t i m e s r e l a t i v e h u m i d i t y a t 2 5 f t a b o v e s u r fa c e( i n H g ) , 6'1 = e m p i r i c a l c o n s t a n t ( = 1 0 f o r l a rg e d e e p l a k e s a n d r e s e r -v o i rs , 1 4 f o r f l o w i n g s t r e a m s o f m o d e r a t e d e p t h , 15 f o r s h a l l o w p o n d sa n d s u r fa c e a c c u m u l a t i o n s ) .Evaporative heat los ses , HeT h e e v a p o r a t i v e h e a t lo ss , H e , is d e t e r m i n e d b y m u l t i p l y i n g t h e ev a -p o r a t i v e l o ss e q u a t i o n , I , b y t h e l a t e n t h e a t o f v a p o r i z a t i o n , H v . T h e


4/18

194 S. L. Klemetson and G. L. Rogersevaporative heat loss equatio n is:

He = 0.007 22Hv C~(1 + 0-1 W) (Vw -- Va) (3)where: He = evaporative heat loss (Btu h -1 ft -2 of wate r surface) andHv = heat of vaporiza tion (Btu lb -1 of water evaporated). Sample data:H, = 1044-6 Btu lb -~ at 87F (Velz (1970) , page 283) , C1 = 15, W = 9-3mp h average, Vw = 1-28 in Hg at 87 F (Velz (1970) , page 289), andV~ = 0-097 in Hg 0-715 = 0.0 69 in Hg at 17F and 71-5% relativehumidity (Velz (1970), page 289).

He = 0-00722 (1044.6) (15)[1 + 0.1(9.3)1 (1.28 --0.069)= 264.4 Btu h -1 ft -2

Convective heat losses, HcConvection is a major source of heat loss within the pond. It is depen-dent upon the wind velocity, the mixing of the water within the pond,and temperature gradient between the pond and ambient air (Velz(1970), page 282).

He = (C3 + C2(W/2)) (Tw -- Ta) (4)where: Hc = convec tive hea t loss (Btu h -~ ft-2) , C2 = const an t (= 0-16for quiescent water body, 0.24 for most water bodies, 0.32 for flowingstream), C3 = convective losses from flat surface (= 0.5 Btu h -1 ft -2 F -afor Tw --Ta = a few F, 0.8 Btu h -1 ft -2 F -1 for typical range, 1-0 Btuh -l ft -2 F -1 for Tw --Ta = 50-100F) , l+' = surface wind velocity(mph at 25 ft), Tw = surface water temperature (F), Ta = ambient airtempe ra tur e (F). Sample data : C2 = 0.24, C3 = 1.0, W = 9.3 mph ,Tw = 87F, Ta = 17F (Jan uary mean), Hc = [1 .0 +0 -2 4( 9. 3/ 2) ](8 7- -1 7 F) ,H c = 148.1 Btu h -1 ft -2.Radiation heat losses, HrThe pond water acts as a warm body which radiates heat to the colderatmo sphe re during most of the year. This radiation loss in Btu h -1 ft -2can be co mpu ted using the St efa n-B olt zma nn law in the form Hr =0-173 10 -8 (Tw + 460) 4. However , a linear ap pro xim at ion of thisformula is given by (Velz (1970), page 285):

Hr = (Tw -- Ta) (5)where: Hr = radiation hea t loss (Btu h -1 ft-2), Tw = tempera tur e of


5/18

Aquaculture pond temperature modelingwater (F), Ta = temper atur e of air (F). Sample data:Ta = 17F, Hr = (Tw -- Ta) = 87- - 17 = 70 Btu h -~ ft -2.

195Tw = 87F,

S o l a r r a d i a t i o n h ea t g a i n s , H sWhile all of the other factors considered have removed heat from thewater body, the energy from the sun adds heat to the water (Velz(1970), page 75).

Hs = SR X 0.1535 X f (6a)where: H~ = solar rad iat ion gain (Btu h -~ ft-2 ), SR = solar radi atio n(langleys day -I), f = absor ption coeffic ient at surface.Alternative equat ion:

Hs = SR f/ 24 (6b)Sample data: SR = 201 langleys da y- X, f = 0.95 (Velz (1970), page 75),H~ = 201 x 0.1535 x 0.95 = 29.3 Bt u h - l f t -2.A d v e c t i o n h e a t t r a n s f e r , H aThe water mov emen t into and out of the pond from the surroundingsoil also carries heat with it. However, this heat transfer is consideredinsignificant and therefore has been neglected.

Assume no significant net advection.To t a l h ea t l o ss , HThe total heat losses and gains would be summarized utilizing eqn (1).

n = H e + H cH = 0.007 22Hv C~( 1 + 0.1 W) (Vw -- Va) + (C3 + C2 (W / 2 ) ) (Tw -- Ta)

+ (Tw --Ta) + (SR) (0.1535)(f).H = 264-4 + 148.1 + 70.0 -- 29.3

= 453.2 Btu h -1 ft -2.H o t w a t e r v o l u m e s r e q u ir e dAssuming an adequate water quality, the water from a geothermal wellor power plant cooling system can be exchanged directly with the waterin the aquaculture ponds or it can be passed through a heat exchangeunit to extrac t its heat. The direct exchange of water is more efficient,


6/18

196 S . L . K l em e t son and G . L . Roger su s e s l es s w a t e r , a n d p r o v i d e s m o r e h e a t t o t h e p o n d s . E a c h o f t h e s em e t h o d s w i ll b e d i s c u ss e d .

H e a t b a l a n c esT h e a m o u n t o f h o t w a t e r r e q u ir e d w i ll d e p e n d u p o n t h e h e a t b a la n c ew i t h i n t h e p o n d a n d t h e q u a n t i t y o f w a t e r f lo w i n g i n th e s y s t e m .A s s u m i n g t h a t t h e p o n d s a re f u ll a n d t h a t t h e b o d y s t a y s a t a c o n s t a n te l e v a ti o n , t h e w a t e r e n t e r i n g f r o m t h e w e l l m u s t e q u a l t h e w a t e rf l o w i n g o u t o f t h e p o n d s a n d t h e w a t e r e v a p o r a t in g f r o m t h e p o n d s .R a i n f a l l a n d s n o w m e l t h a v e b e e n n e g l e c t e d i n t h is a n a l ys i s , b u t t h e yw o u l d i m p r o v e t h e w a t e r b a l a n c e i f t h e y w e r e i n c lu d e d .

T h e h e a t b a l a n c e r e la t e s t h e t o t a l h e a t c a p a c i t y o f t h e h o t w a t e rm i n u s t h e h e a t c a p a c i t y o f t h e w a t e r l e av in g t h e p o n d s to th e n e t h e a tl os s e s c o m p u t e d i n th e p r e v i o u s s e c t io n . T h e r e f o r e , t h e h o t w a t e rq u a n t i t i e s r e q u i r e d c a n b e c o m p u t e d d i r e c t l y w h e n t h e d e s i re d l ev e l o fn e t h e a t l o s se s a r e k n o w n . T h e c o m p u t a t i o n s w i t h i n t h e m o d e l ar eb a s e d o n t h e t o t a l h e a t c a p a c i t y w i t h i n t h e s y s t e m .

D i r e c t e x c h a n g e w a t e r r e q u i r e dT h e n e t c a p a c i t y o f t h e w a t e r c o m i n g i n t o t h e s y s t e m v ia t h e h o t w a t e rs o u r c e a n d t h e l o ss o f h e a t c a p a c i t y f r o m t h e w a t e r le a vi ng th e p o n d a ta g iv e n p o n d t e m p e r a t u r e c a n b e c a l c u l a te d o n t h e b a si s o f f lo w ra t ea n d c h a n g e s in w a t e r t e m p e r a t u r e s a s s h o w n b e l o w :

q = Qw 3 ' (Thw - - Tpw) (7a )w h e r e : q = m a x i m u m a v a il a bl e h e a t e n e r g y ( B t u h - l ) , Q w = fl o w ra t eo f g e o t h e r m a l w a t e r s ( f t 3 s - l ) , 3" = av e r a g e s p e c i f i c w e i g h t o f w a t e r( lb f t -3 ) , T hw = t e m p e r a t u r e o f h o t w a t e r ( F ) , T pw = t e m p e r a t u r e o fp o n d w a t e r ( F ) .A l t e r n a t i v e e q u a t i o n :

Q w ( f t 3 s - 1 a c r e - 1) = 2 7 7 . 7 8 q ( m i l B t u h - 1 a c r e - 1)3'(Thw --Tpw )S a m p l e d a t a : 3' = 6 1 . 3 8 l b f t - 3, T hw = 1 4 0 F , T p w = 8 7 F .

/ m i l B t u ] ( 3 6 0 0 s ]q = ( Q w ) ( 6 1 - 3 8 ) ( 1 4 0 - 8 7 ) ~ ] - ~ B ~u / k - - -- h - -- /

( 7 b )


7/18

Aquaculture pond temperature modelingq = 1 1 . 7 1 Q w

Q w ( f t3 s - l ) = 0 . 0 8 5 4 q ( m i l B t u h - X ) .

1 97

H e a t e x c h a n g e u n i t w a t e r r e q u i re dT h e u s e o f a h e a t e x c h a n g e r f o r th e t r a n s f e r o f h e a t f r o m t h e h o t w a t e ris l es s e f f i c i e n t t h a n t h e d i r e c t e x c h a n g e o f w a t e r , b u t i t d o e s p e r m i t t h eu s e o f lo w e r q u a l i t y h e a t e d w a t e r . W a t e r is s ti ll e v a p o r a t e d f r o m t h ep o n d s y s t e m , w i ll h a v e t o b e m a d e u p f r o m o t h e r s o u rc e s , a n d s o m em a k e u p w a t e r is n e e d e d t o r e d u c e s a l in i ty b u i l d u p . I t is a s s u m e d t h a tt h is s y s t e m w o u l d n o t h a v e a d i sc h a rg e o r t h a t t h e q u a n t i t y o f w a t e rd i s c h ar g e d w o u l d b e r e d u c e d a n d a t r e a t m e n t p r o c e s s w o u l d b e u s e d o nt h e r e c y c l e d w a t e r . W h e n t h e h e a t e x c h a n g e r c a n b e i n s ta l le d i n th es a m e s h e l t e r a s t h e p o n d s , a n y h e a t l o s t f r o m t h e e x c h a n g e r a s a r e s u l to f i n e f f i c i e n c y w i ll st il l b e c o n t a i n e d w i t h i n t h e s h e l te r . S i n c e t h is l o ssis t h e r e f o r e b e i n g u s e d t o h e a t t h e s y s t e m , 1 0 0 % h e a t t r a n s f e r e f f i c i e n c yc a n b e a s s u m e d f o r t h e h e a t e x c h a n g e u n it . T h e h e a t t r a n s f e r r a t e o f t h eh e a t e x c h a n g e r i s b a s e d o n t h e l o g - m e a n t e m p e r a t u r e d i f f e r e n c eb e t w e e n t h e h o t w a t e r a n d t h e c o l d w a t e r . A s s u m i n g a h o t w a t e r dis -c h a rg e t e m p e r a t u r e 1 0 F a b o v e t h e p o n d te m p e r a t u r e , t h e fo l l o w i n gr e l a t i o n s h i p h a s b e e n d e r i v e d :

q = Qw 3'[- ( T h w - - Tp w ) - - ( T p w + l o - - T o w )Thw - - Tpw ) (8a )k I n ( Tp~+ l o --Tp--ow

w h e r e : q = a v a il a b le h e a t e n e r g y ( m i l B t u h - l ) , Q w = f l o w r a t e o f h o tw a t e r ( f t 3 s - 1 ) , 7 = a v e r a g e s p e c i f i c w e i g h t o f w a t e r ( l b f t - 3 ) , T h w = i n i ti a lh o t w a t e r t e m p e r a t u r e ( F ) , T pw = p o n d w a t e r t e m p e r a t u r e ( F ) ,T pw +lo = h e a t e x c h a n g e r d i s c h a r g e t e m p e r a t u r e ( F ) .A l t e r n a t i v e e q u a t i o n :

Q 2 ( f t 3 s -1 a c r e - l ) = q ( m i l B t u h -1 ac r e - 1 )

/] [ \ T p w + lo - - T p w ]

S a m p l e d a t a : 3 ' = 6 1 .7 1 lb f t - 3 , T h w = 1 4 0 F , T o w = 8 7 F , T p w + l O = 9 7 F .


8/18

198 S. L. Klemetson and G. L. Rogersq = ( a w ) ( 61 -7 1 ) F ( 1 4 0 - 8 7 ) - ( 97 - 8 7 ) - ]

/L( 1 B t u ] { m i l B t u ) ( 3 6 0 0 s )

X \ l b F / \ 106t------ ~= 5 .7 3 Q w

Q w f t3 s-1 = 0 . 1 7 4 6 q (m i l B t u -1 h -1)

C O M P U T E R M O D E L I N GM odel input and opt ionsC a l c u l a t i o n s t h a t c a n b e d o n e m a n u a l l y c a n b e d o n e f a s te r a n d m o r ea c c u r a te l y w i t h a c o m p u t e r m o d e l . T h e m o d e l d e v e l o p e d t o u ti li ze t h ep r e v io u s e q u a t i o n s h a s b e e n e n t i tl e d M a i n t e n a n c e o f A q u a c u l t u r e P o n dT e m p e r a t u r e s ( M A P T ) ( K l e m e t s o n a n d R o g e r s, 1 9 8 1 ). H o w e v e r , s ev e ra lo f t h e c o n c e p t s an d e q u a t i o n s m u s t b e m o d i f i e d to a s su re c o m p a t i b i l i t yo f o p e r a t i o n w i t h i n t h e c o m p u t e r m o d e l . T h e b a si c o p e r a t i o n o f t h em o d e l a n d a n y s i g n if i c a n t m o d i f i c a t i o n s o f a p p r o a c h w i ll b e n o t e d i nt h e f o l l o w i n g s e c t i o n s .

T h e d a t a i n p u t f o r e a c h s i te i n c l u d e s : w e l l f l o w r a t e , w e ll t e m p e r a -t u r e , p o n d d e p t h , p o n d a r e a , i n i t i a l p o n d t e m p e r a t u r e , a n d n a m e o fw e l l l o c a t io n . A n y s p e c if ic c o n d i t i o n s c a n b e e v a l u a t e d b y c h a n g i n g o n eo f t h e s e p r o g r a m i n p u t s . T h e m o d e l w i ll s e q u e n t i a l ly e v a l u a te a n u m b e ro f d i f f e re n t s i t es d u r in g t h e s a m e c o m p u t e r r u n .

T h e p r i n c i p a l f a c t o r s t h a t a f f e c t t h e h e a t l o s s c a l c u l a t i o n s a r e t h ew i n d s p e e d , a m b i e n t a ir t e m p e r a t u r e , r e la ti ve h u m i d i t y a n d s o l arr a d i a t i o n . T h e s e a r e s i te s p e c i f ic f a c t o r s t h a t m u s t b e o b t a i n e d f o r e a c hs i t e , o r a t l e a s t i n t h e g en e ra l l o ca l e .

A n u m b e r o f f a c t o r s m u s t b e c o m p u t e d f o r u s e in t h e h e a t lo sse q u a t i o n s . T w o o f t h e s e a r e v a p o r p r e s s u r e a n d h e a t o f v a p o r i z a t i o n .S i n c e b o t h o f th e s e f a c t o r s a re t e m p e r a t u r e d e p e n d e n t , i t w a s n e c e s s a ryt o d e v e l o p a n a p p r o x i m a t i o n e q u a t i o n f o r e a c h r a t h e r t h a n p u t t h ee n t ir e t a b le s o f d a t a in c o m p u t e r m e m o r y .

P l o t t i n g o f t h e d a t a f o r t h e l a t e n t h e a t o f v a p o r i z a t i o n , H v , a n a p p r o x i -m a t e l y s t r a ig h t l in e p l o t w a s o b t a i n e d w h i c h y i e l d e d t h e e q u a t i o n :


9/18

Aquaculture pond temperature modeling 199H v = 1 0 9 4 - - 0 . 5 7 ( ~ F) ( 9)

T h e p l o t o f th e s a t u r a t e d v a p o r p r e s s u r e d a t a v e r su s t e m p e r a t u r e y i e l d e da h i g h e r le v e l e x p o n e n t i a l c u r v e . T h e s i m p l i f ie d f o r m o f t h e e q u a t i o n is :V P = 0 . 0 4 9 8 e '3 7s ( 1 0 )

A n o t h e r f a c t o r , C 3 , w h i c h is r e l a t e d t o t h e c o n v e c t i v e l o ss e s f r o m f l ats u r f a c e s w a s e n t e r e d a s i n p u t d a t a b u t c a n b e c o m p u t e d u s i ng t h ee q u a t i o n :

C 3 = 0 . 5 + 0 - 0 1 ( F ) ( v a li d r a n g e , 0 - 5 0 F ) ( 1 1 )A b o v e 5 0 F t h e v a l u e i s s e t a t C 3 = 1 -0 , a n d b e l o w 0 F t h e v a lu e iss e t a t C 3 = 0 .5 .

T h e f in a l t e m p e r a t u r e o f t h e p o n d w a t e r is d e t e r m i n e d b y i te r a t i o nu s in g t h e n e t h e a t l os s es o f t h e p o n d c a l c u l a te d f r o m c l im a t i c c o n d i t i o n sa n d t h e n e t h e a t i n p u t f r o m h o t w a t e r . O n c e e q u i l i b r iu m is r e a c h e db e t w e e n t h e h e a t l o ss e s a n d g a i n s , t hi s t e m p e r a t u r e is u s e d t o i n it ia l iz et h e p o n d t e m p e r a t u r e f o r t h e n e x t m o n t h . T h e m o d e l a ls o c o m p u t e se v a p o r a t i o n w a t e r l o s s e s .E v a p o r a t i v e w a t e r l os s esW h i l e t h e s e d a t a a r e n o t e s s e n t i a l t o t h e c a l c u l a t i o n o f t h e h e a t l o ss e s ,t h e y a r e a v a i la b l e a n d m a y b e u s e f u l i n r e l a t e d w a t e r b a l a n c e c a l c u la -t io n s . E v a p o r a t i o n is d e p e n d e n t o n t h e s a m e c l i m a t ic f a c t o r s a s h e a tl os s . W h i le e v a p o r a t i o n o c c u r s n a t u r a l l y i n a ll b o d i e s o f w a t e r , it i si n c r ea s e d b y t h e h i g h e r t e m p e r a t u r e s r e q u i re d f o r a q u a c u l t u r e p o n d s .

S i n ce a r e a s o n a b l e l im i t t o p o n d t e m p e r a t u r e f o r a n im a l p r o d u c t i o nis 9 0 F ( 3 2 . 2 C ) , t h is t e m p e r a t u r e w a s u s e d as t h e m a x i m u m p o n dt e m p e r a t u r e f o r t h e c a l c u l a t i o n o f t h e e v a p o r a t i o n r a t e. A n y t e m -p e r a t u r e b e l o w t h is l e ve l y i e l d e d i ts o w n e v a p o r a t i o n r a te a n d w a sr e c o r d e d .A n i m a l p r o d u c t i v i t yT h e p r o d u c t i v i t y r at e f o r p r o d u c t i o n o f t h e M a c r o b r a c h i u m r o se n b e rg i ip r a w n h a s b e e n a s s u m e d t o b e e q u a l t o o n e f o r t e m p e r a t u r e s a b o v e8 2 F ( 2 7 . 7 C ) a n d t o d e c r e a s e b y 5 0 % f o r e a c h 5 F (2 - 8 C ) te m p e r a -t u r e d r o p . B e l o w 6 2 F ( 1 6 -7 C ) i t is a s s u m e d t h a t p r o d u c t i v i t y d r o p s t oz e r o . T h e s e v a l u e s a r e c o n s e r v a t i v e a n d c a n b e r e f i n e d a s a d d i t i o n a li n f o r m a t i o n is a v a i la b l e .


10/18

200 s. L. Klemetson and G. L. RogersArea required for productionG i v e n a d e s i re d r a t e o f a n i m a l p r o d u c t i o n , t h e p o n d t e m p e r a t u r e i sd e t e r m i n e d a n d t h e r e f o r e t h e n e t h e a t l os s es a re d e t e r m i n e d . O n th isb a s is , i t is p o s s i b l e t o c a l c u l a t e t h e p o n d s u r f a c e a r e a t h a t c a n b es u p p o r t e d f o r e a c h h o t w a t e r s o u r c e a n d e a c h le v el o f p r o d u c t i v i t yd u r i n g t h e e n t i r e y e a r .M o d e l o u t p u tI t w a s a s s u m e d t h a t t h e p o n d s w o u l d b e e it h e r o p e n t o t h e e n v i r o n m e n to r c o m p l e t e l y e n c l o s e d . T h e e n c l o s e d c o n d i t i o n a s s u m e s t h a t th e r e isn o w i n d a n d 1 0 0% h u m i d i t y o v e r t h e p o n d s u r fa c e .

T h e s e d a t a i n c l u d e th e t e m p e r a t u r e p r o f i l e t h r o u g h o u t t h e y e a r , t h ea n i m a l p r o d u c t i v i t y r a t e s, a n d t h e a r e a o f p o n d t h a t c a n b e s u p p o r t e da t e a c h s i t e w i t h t h e e x i s t i n g f a c i li ti e s . T h e r e s u l t s a r e g i v e n f o r b o t hn o r m a l s it e w i n d c o n d i t i o n s a n d f o r n o - w i n d c o n d i t io n s w h i c h w o u l ds i m u l a t e t h e u s e o f a n e n c l o s e d s t r u c t u r e .

T h e o u t p u t ( T a b le 2 ) o f th e m o d e l i n cl u d e s t h e t e m p e r a t u r e p r o fi leo f t h e p o n d a t a s p e c if i c s it e t h r o u g h o u t t h e y e a r a nd f o r d i f f e re n tp o n d s iz e s. I n a d d i t i o n i t a ls o i n d i c a t e s t h e p e r c e n t o f t o t a l a n n u a lp r o d u c t i o n a v a il a bl e a t e a c h s i t e o n t h e b a si s o f 1 2 m o n t h s o f o p t i m u mp r o d u c t i o n r a t e .

T h e s e c o n d o u t p u t ( T a b l e 3 ) i s t h e p r o d u c t i v i t y p r o f i l e f o r t h e sa m es i te o n t h e b a s is o f 1 0 0 % p r o d u c t i v i t y i n a n y g iv e n m o n t h . A l s o p r o -v i d e d is t h e a n n u a l e v a p o r a t i o n r a t e ( in y e a r - I ) . T h e s e v a l u e s w e r ec o m p u t e d o n t h e b a si s o f t h e t e m p e r a t u r e d a t a in t h e p r e v i o u s o u t p u t .A l s o s h o w n i n th i s o u t p u t is th e t o t a l p r o d u c t i v i t y o n t h e b a s is o f ay e a r ' s p r o d u c t i o n p o t e n t i a l .

T h e t h ir d o u t p u t ( T a b l e 4 ) p r e s e n t s t h e p o n d s u r f a c e a r e a in a c r est h a t c a n b e s u p p o r t e d a t a g i ve n s i te f o r t h e in d i c a t e d p r o d u c t i v i t yr a t e . I t w i ll b e u s e d t o c a l c u l a t e a r e a s t h a t c a n b e u s e d in a m a n a g e m e n ts y s t e m a q u a c u l t u r e p r o d u c t i o n .

A P P L I C A T I O N T O H E A T L O S S R E D U C T I O NEvaporation suppressionI n o r d e r t o c o n s e r v e e n e r g y a n d i m p r o v e p r o d u c t i v i t y , s e v e ra l h e a t lo s sr e d u c t i o n m e c h a n i s m s w e r e e v a lu a t e d u t i li zi n g th e M A P T m o d e l . O n l y


11/18

TABLE2

CompePecooAq

ueP

TmpauenF

(Aq

ueP

TmpauePoeSmmayoDieE

oWaeP

HoSnAre

NmawnanmhmidyaJ

F

MaA

MaJ

JyA

S

ON

D

Po

Ta

tobpo

bowTm

DehA

#htoc{%)

(3s~[F

{?

(a

05

10

35

05

05

10

35

10

05

10

35

50

05

10

35

10

05

10

35

20

05

10

35

50

05

10

35

10

808387808098949496848984

1

10

787570767581838183767579

1

70

5045515365677873666

5742

5

10

424041506863777160614441

4

18

474844575968727663594536

4

14

494744505362777167514534

4

15

454149555969756964574937

4

11

t~

aNomawnahmidyme

hnh

o

e

omehweeudnhscmpeays

bncehnmbomohwhempaueweea

apeeminsuvveoha

cspec

cncehpcooapo

oaeacmpeooapo

opbeomumempauemananoeey

t3


12/18

19

O 19

TABLE3

CmpePecooAmPovy(AcuePPovyPoeSmmayfoDeE

oWae

t~

FowTmDhA

J

F

MaA

MaJ

JyA

S

O

N

DEaTa

(31(F

((a

toapo

(ny1vyb

o~

051035

0510

01010101010101010101

02210~

051035

104459536889101010107362402481

051035

5000

00

00

001944656033

00

00

002723

05103510

00

00

00

00

0033545620

00

00

002514

0510352000

00

00

00

0029464719

00

00

002812t~

0510355000

00

00

00

0023424310

00

00

002619

05103510

00

00

00

00

0020404115

00

00

001517

t~

anceoae

aoe

eomwesuaey

bSmmaoomohya

camapo

vygeAvuo1

smamumpbeoy

cAvuo1ncehomumgowthempaueweoanospebneue


13/18

TABLE4

CmePecooPSaAeReoSeeAmPovyPSznAeTWiS

~

VoMohyPove

~

FowTmaDehPo

J

F

MaA

MaJ

JyA

S

ON

D

(3s1uF(

tvy

05103520a12131519392099c9991241513

05103550091010121936271531151109

"~

05103570070707081117

34

3116100807

05103510050505060710

15

1510070605

aPovysauoohpemaueacbseeoacspeusu

bncehnmoaeopaehcbmnanahdeemauewhhhewesue~

cncehnhweseeomnanpadeemaue

b9 O


14/18

204 s. L. Kleraetson and G. L. Rogersa brief presentation of information about heat loss reduction methodswill be presented to set the stage for utilization of the model. There arethree main classes of evaporation suppression (Magin and Randall,1960): (1) wind shear fences and shelterbelts; (2) surface covers andfilms; and (3) greenhouses. A four th alternative of reducing surface areaby constructing deep reservoirs or storing underground was not con-sidered in this study.

A review of the literature related to fences and shelterbelts (VanEimern, 1964) showed that they can reduce wind shear and evapora-tive losses. Wind speeds may be reduced by 80-20% of ambient windson the leeward side of a fence for a distance of ten times the height ofthe barrier. Evaporation rate may be reduced by 20% to ten times theheight of the fence downwind.

Surface covers and films include aquatic plants, floating plastic covers,floating balls, inflatable plastic structures and monomole cular films.Monomolecular films could be used if an adequate grid system wereconstructed for protection from wind and wave action (Nicholaichuk,1978). The chemical film would not affect growth of animals thoughsubmerged aeration and feeding may be required.

Greenhouses would provide the best alternative for maintenance ofpond water temperatures, although they can be expensive (Walker andDuncan, 1975). Conventional heating systems could provide back upfor extending the growing season and increasing productivity. Green-houses should find special application in hatchery and nursery facilitiesgenerally smaller than 1 acre in size. They could also be used inmultiple-use facilities for other cash crops like tomatoes or mushroomsin addition to prawn production.

Assumptions for model analysisThe wind shear fences reduced the wind speed to a minimum of about20% of the prevailing wind speed and evaporation rates by about 20%.Either rigid or fluid surface covers can be used on the ponds. Theinflatable plastic structures and the floating plastic covers reduce windspeeds to zero and increase humidity to near 100%. The monomolecularfilms provide about 25% reduction in evaporation, and the floating ballsystems reduce heat losses by about 75% and liquid losses by about87%.

A structural shelter or greenhouse, like the inflatable plastic struc-tures, reduces wind speeds to zero and increases the humidity to near


15/18

Aquaculture pond temperature modeling 2051 0 0% . A l t h o u g h t h e r e w a s i n s u f f ic i e n t i n f o r m a t i o n a v a il a bl e, it w a sa s s u m e d t h a t t h e i n s u la t in g c h a r a c t e ri s ti c s a n d th e in t e r i o r t e m p e r a t u r eg r a d i e n ts a b o v e t h e w a t e r s u r f a c e w o u l d s ig n i fi c a n tl y re d u c e t h e s el o s s e s .

A p p l i c a t io n s o f t h e c o m p u t e r m o d e l a r e p r e s e n t e d in Fi gs 1 - 4 .F i g u r e 1 g i ve s t h e r e s u l t s o f w i n d s p e e d r e d u c t i o n f o r a 1 a c r e ( 0 . 4 0 5 h a )

onE

I - -t -0n

F i g . 1 .

1 90 "

2 0 %7 0 f / ~ . ~ / \ ' ~ , ; 4 0 % CO6 0 %100%

J J I I I j I l I I IO F M A M O A S 0 N DEffect o f wind speed reduct ion o n the tem perature prof ile o f a 1-acreaquacu l t u r e pon d ( g eo t he r m a l 1 .0 f t 3 s- 1 , 100 F , 3 . 5 f t dep t h ) .

1 O 0

90

~ 7 0 F i l mnNormal

6 0

F ig . 2 . C o m p a r i so n o f p o n d t e m p e r a t u r e s w i t h a n d w i t h o u t m o n o m o l e c u l a r f il mon su r f ace o f 1 - ac r e pond ( a s sum e 25% r educ t i on i n evapor a t i on r a t e , geo t he r m a l

1 .0 f t 3 s -x , IO 0F, 3 .5 f t de pth ) .


16/18

206 S. L. Klemetson and G. L. Rogers9 0 ,

8 0 o

~ 70EI - -" U-.g. Bo

F i g . 3.

~ G r e e n h o u s eOpen Pond

Compar ison of pon d tem peratures wi th and wi tho ut greenhouse cover(no wind, 100% hu m idity in greenhouse, geothermal 1-0 f t 3 s -z, 100F , 3.5 f t depth ).

9 0

8 0

~ 7 o"0-g. eo

JF i g . 4 .

G r e e n h o u s e sF e n c e sM o n o m o l e c u l a ril mNormal c o n d i t i o n s

s , , , , , ~ j 0 , jF M A M J J S N DProjected pond temperature prof i les as a funct ion of heat loss reduct ionme chanism at Alam osa (geotherm al 1-0 ft 3 s -z, IO 0F, 1 acre).

a q u a c u l t u r e p o n d 3 . 5 f t ( 1 .1 5 m ) i n d e p t h w i t h a g e o t h e r m a l h o t w a t e rf l o w o f 1 . 0 f t 3 s -1 ( 0 . 0 2 8 m 3 s - l ) a n d a t e m p e r a t u r e o f 1 0 0 F ( 3 7 - 8 C ) .T h e p o n d w a t e r t e m p e r a t u r e i m p r o v e m e n t w a s a p p r o x i m a t e ly 5 - 8 F( 2 . 8 -4 - 4 ( 3 ) f o r e a c h m o n t h o f t h e y e a r . S im i l ar a n a ly s is fo r m o n o -m o l e c u l a r f i lm s a s s u m i n g 2 5 % r e d u c t i o n o f e v a p o r a t i o n ( F ig . 2 )


17/18

Aquaculture pond temperature modeling 207suggests that the water temperature may be improved by about 3-5F(1-7-2-8C) each month. Figure 3 presents the expected pond watertemperature for each month of the year under the same conditions withor wi thout a greenhouse. The greenhouse could improve the pond watertemperature by as muc h as 6F (3.3C). Greenhouses, fences and mono-molecular films are compared in Fig. 4. The greenhouse would be thebest alternative for reducing heat losses.

CONCLUSIONSThe use of heat loss reduction methods can be worth considering forthe development o f any site. The following conclusions were reached inthis evaluation:

1. Wind shear fences and monomolec ula r films can achieve the same6F (3.3C) improvemen t in pond temperatu re (Figs 1 and 2).

2. Monomolecular films require some wind and wave protection .3. Structural shelters, inflatable shelters and greenhouses are feasible

methods of covering the ponds and can achieve 5-8F (2.8-4-4C)improvement in temperature. Further study is needed to deter-mine the total degree of effectiveness.

4. Fixed film or plastic surface covers should be considered as aviable solution to both the heat loss and water loss problem.Subsurface aeration may be required.

5. Floating ball systems are questionable until more study is com-pleted concerning their effect s on the aquatic animals.

ACKNOWLEDGEMENTThis work was funded in part by the Southern Colorado EconomicDevelopment district under Grant FCRC No. 292-399-104-8, DocumentNo. 109-50104.

REFERENCESHanson, J. A. & Goodwin, H. L. (1977). Shrimp and Prawn Farming in the Western

Hemisphere, Dowden, Hutchinson and Ross Inc., Stroudsburg, Pennsylvania.


18/18

208 S. L. Klemetson and G. L. RogersKawaratani , R. K. (1978). State of the Art: Waste Heat Utilization for Agriculture

and Aquaculture, Tennessee Valley Authori ty.Klem etson, S. L. & Rogers, G. L . (1981). De velopm ent of geothermal-aquaculture

system in Colorado ut i l izing the Macrobrachium rosenbergii prawn, KlemetsonEngineering Report to Coury & Assoc., Denver, Colorado.Ling, S. W. & Cotel low, T. J . (1976) . Status and problems of Macrobrachiumfanning in Asia, Food and Drugs from the Sea Conference, Puer to Rico, pp .6 6 - 7 1 .

Magin, G. B. & Randall , L. E. (1960). Review of Literature on Evaporation Sup-pression, Geological Surv ey Professional Paper 272-C, US Gov ernm ent PrintingOffice, W ashington DC .Nicholaichuk, W. (1978). Evaporat ion control in farm-size reservoirs, J. Soil andWater Conservation, 33 , 185-8 .

Van Eimern, J . (1964) . Windbreaks and Shelterbelts, World MeteorologicalOrganizat ion, Tech. N ote 59 , Geneva, Sw itzerland.Velz, C. T. (197 0) . Applied Stream Sanitation, Joh n W iley and Sons, New York.Walker, J. N. & Duncan, G. A. (1975). Environmental equipment and tradit ional

energy considerations for heating systems, in: Greenhouse Vegetable Workshop,Tennessee Valley Authori ty Bullet in Y-94, pp. 53-63.

Date post:	03-Apr-2018
Category:	Documents
Upload:	jorge-rodriguez
View:	216 times
Download:	0 times

Klemetson 1985 Aquacultural-Engineering

Documents