solar water heater analysis

7/23/2019 Solar Water Heater Analysis

1/8

Experimental Study on the Performance of Built-in Storage Solar Water

HeaterABSTRACT

This paper scribes experimental investigations on a built-in solar water heater in

Benghazi claimant. The heater was a rectangular in shape (1440 x 720 x mm! an"

manu#acture" locall$ #rom galvanize iron sheets with capacit$ o# 0 liters. The top

sur#ace o# the heater was painte" with blac% paint to per#orm the "ual #unction o#

absorbing the solar energ$ an" storing the heate" water. & glass sheet o# 2mm thic%ness

was use" to cover the top sur#ace The si"es an" bottom o# the heater were insulate" with

#iber glass wool to re"uce" the heat loses. 'xperiments have been carrie" out to test the

per#ormance o# the heater en"-"a$) hourl$ an" night cooling e##ect measurements. *t is

conclu"e" that the heater wor%s e##icientl$ un"er Benghazi con"itions. The maximum

water temperature o# the heater was 7 o+) obtaine" on bright "a$s. The "ail$ e##icienc$

varies #rom 4, to 7 ,. ight cooling e##ect on the heater was re"uce" b$ using a

woo"en cover or well-insulate" "rum.

Keyord! olar energ$) *solation) *nsulation) storage tan%) collector) temperature)

e##icienc$) cooling e##ect) latitu"e angle an" claimant con"ition.

"#TR$%&CT"$#

&t the present time solar energ$ is more attractive than ever as an alternate energ$

source) which can provi"e heating an" cooling) water "istillation an" electric power

generation at economicall$ competitive costs an" without environmental "egra"ation. *t has

been %nown that /ib$a has an i"eal location #or use o# solar energ$) since man$ hours o#

bright sunshine are reporte" in man$ locations 1) 2.

olar water heating #or "omestic use is at present the most attractive wa$ o# utilizingsolar energ$. This is largel$ "ue to regular "ail$ "eman" o# hot water at mo"erate temperature

resulting in an e##icient collection o# the inci"ent solar ra"iation without the necessit$ o# large

storage. &ll o# solar water heaters can be classi#ie" into t$pes collection an" storage in

separate units an" storage in a single unit. The collection an" storage in separate units

consists o# a gri" o# water carr$ing tubes bon"e" to the absorber plate. *t has been observe"

that a large temperature "i##erence between the collector plate an" tubes is a "rawbac%)

resulting in lower collection e##icienc$. oreover) the collection e##icienc$ "epen"s highl$ on

the bon" between the plate an" the tubes 3. The usual bon" metho" is either so#t sol"ering

or gas wel"ing. Both are expensive. &lso) the sol"ere" or gas wel"ing bon" ma$ "evelop

cra%es "ue to thermal stresses associate" with heating an" cooling. These crac%s cause

lea%age an" corrosion problems. *ncrease" cost "ue to separate storage tan% an" absorberunit as well as slightl$ lower e##icienc$ is the "emerits o# such solar water heater.

olar water heater o# built-in storage t$pe incorporating the storage volume an"

collector in a single unit is one attractive to tra"ition solar water s$stem. ince built-in

storage heater is a compact unit (collector an" storage tan% are one unit!) the cost o# the

heater is remar%abl$ re"uce". uch unit is wi"el$ use" in man$ countries such as *n"ia)

outh rica) apan) 5alestine an" +hina 4-6

*t has been stu"ie" b$ man$ researchers. or example) +hinnappa an" 8nanalingam

10 investigate" the per#ormance o# a built-in solar water heater un"er climate o# *n"ia.

+hauhan an" 9a"ambi 3 carrie" out an experimental stu"$ on the per#ormance o# built-insolar water heater o# about 70 litter capacit$ un"er #our "i##erent mo"es o# operation an" the$

1


2/8

'a( ')(

conclu"e" that it is economicall$ to operate this solar water heater un"er stea"$ #low

con"ition. +ollection e##icienc$) as high as 72,) was obtaine". 8arg an" 8upta 11

presente" theoretical an" experimental stu"ies on built-in storage solar water heater which

was "evelope" b$ 8arg in *n"ia. The$ observe" that the overall per#ormance is a"versel$

a##ecte" b$ signi#icant night cooling "ue to the absence o# separation #ull$ insulate" storage

tan%. The$ "emonstrate" that b$ using a removable insulation cover "uring the night) thecollector per#ormance can be improve" b$ 70,.

%ES"*# $+ B&",T-"# ST$RA*E WATER HEATER

The solar water heater consists o# a rectangular 2mm thic%ness galvanize" iron tan%

with "imensions o# 1440: 720:0 mm with capacit$ o# 0 liters. The outer top sur#ace o#

the tan% was painte" b$ matt blac% paint to wor% as plate collector to the heater. The

collector-storage tan% was reste" in a box whose s%eleton was ma"e o# steel angles an"

covere" b$ galvanize" iron sheet 2 mm thic%ness. The bulging o# the tan% un"er water

pressure was re"uce" b$ using angle iron #lats bolte" on the si"es o# the box. The top sur#ace

o# the tan% was covere" with a single glass win"ow cover o# 3mm thic%ness. The air space

gap between the collecting plate an" the glass cover was 20mm. The whole assembl$ wascarrie" b$ a stan" which incline" at 32o#rom the horizontal (accor"ing to the latitu"e o#

Benghazi cit$! an" was oriente" "ue to south to collect maximum solar ra"iation. *nlet) outlet

an" "rain pipes were wel"e" to the storage tan%. The storage tan% was insulate" with #iber

glass wool) 10 mm at the bottom sur#ace an" ; mm at the si"es. &ll the connection pipes were

insulate" with ; mm o# #iber glass wool. igure 1(a an" b! shows the photograph an"

schematic "iagram o# the heater respectivel$.

+igure 'a and )(. 'a( a photograph of the heater and ')( a !chematic diagram of the heater

2


3/8

/EAS&R"#* TECH#"*&E

5rovision was ma"e to measure the temperature variation along the tan% an" in

transverse "irection. Temperature was measure" b$ a thermistor (thermocouples! that can be

inserte" insi"e the storage tan% to the re


4/8

'a(')(

*n the night cover scheme) the water was allowe" to heat up "uring the "a$ without

"raw o##. &t 1700 pm) the heater was covere" with night cover a#ter recor"ing the water an"

ambient temperatures an" then le#t it over the night. *n the next morning) it was remove" an"

water temperature o# the storage tan% an" air were again recor"e". *n the insulate" "rum

scheme) at the en" o# the "a$) the hot water was "raine" #rom the heater into the insulate"

"rum. The "rum was then le#t overnight an" in the next morning the water is "rain o## b$opening the outlet valve o# the heater a#ter recor"ing its temperature.

RES&,TS A#% %"SC&SS"$#

The heater was teste" experimentall$ in the perio" #rom &ug. 1) 200 to ar. 7 2007.

The measurements inclu"e" solar ra"iation) ambient temperature an" mean water temperature

in the storage tan%.

Performance cur2e!

igure 4(a an" b! shows a t$pical examples o# hourl$ measurement #or a sunn$ "a$ on ep. 6)

200 an" clou"$ winter "a$ on an. ;) 2007 respectivel$. *t is clear #rom the ig. (4.a! that

the solar ra"iation increases rapi"l$ #rom earl$ morning to reach its maximum value (7;;w>m2! at 12 am an" then starts to "ecrease to reach it its minimum value (300 w>m2! at

1700 pm. The main water temperature o# the storage tan% alwa$s increases "uring the "a$

time to reach its maximum value (7= o+! at 1700 pm. The ambient temperature appears to be

approximatel$ constant "uring the "a$ time with main value about 30 o+. This manner o# the

curve has been observe" #or all the bright "a$s.

*n ig. (4.b!) the solar ra"iation #luctuates "uring the "a$ time with maximum value o# 700

w>m2at 1000 am where as the mean water insi"e the storage tan% increase slowl$ "uring the

"a$ time to reach its maximum value o# 40 o+ at 300 pm. The ambient temperature was

about 1= o+#or all "a$ time.

+igure 3 'a and )(. Hourly 2ariation of !olar radiation inten!ity4 am)ient and mean ater

temperature5 'a( !unny day ')( cloudy day

4


5/8

%ay-end Temperature

igure ; shows the variation o# "a$-en" mean water temperature o# the heater "uring

the perio" #rom &ug. 1) 200 to ar. 7 2007. *t can be observe" that the temperature

#luctuations roun" its mean value because the heater is "irectl$ a##ecte" b$ climaticcon"itions. &lso) it is clear that the #luctuation is more pronounce" "uring the winter season

an" minimal in summer season. ?uring the summer the maximum temperature reache" was

7= o+ on &ug. 22) 200) while the minimum was in 32 o+ on an. ;) 2007

+igure 6. 0ariation of day-end mean ater temperature for the period fromAug5 4 1778 to /ar5 14177955

%aily efficiency

The e##icienc$ o# the heater is "e#ine" as the ratio o# total energ$ gaine" b$ water to

the solar energ$ inci"ent on the absorber plate "uring the "a$. athematicall$ can be

expresse" b$ the #ollowing e%g-o+!) AT is increase

in water temperature (o+! an" * is the *nsolation (solar ra"iation w>m2!.

igure shows the variation o# "ail$ e##icienc$ o# the heater "uring the perio" #rom

&ug. 1)200 to eb. 1) 2007. *t can be seen that the e##icienc$ #luctuates aroun" its mean

value (about ;= ,!. The maximum e##icienc$ was 7, an" the minimum was about 4=,

;


6/8'a( ')(

+igure 8. The daily efficiency 2er!u! day!5

Effect of night cooling

The main "rawbac% o# the built-in solar water heater is the heat loss "uring the night

hours. This is clear #rom the ig. 7) which shows night cooling e##ect. The temperature "rop

overnight was 14 o+.

+igure 9. #ight cooling effect on the performance of the heater

&s a result o# this "rop) the heater can not be use" #or provi"ing hot water in the earl$

morning. &s mentione" previousl$) to overcome this "rawbac%) two metho"s were use". The

#irst metho" is to cover the glass with an insulate" cover. ig. =(a! shows the night cooling

e##ect on the per#ormance o# the heater with night woo"en cover . *t can be seen that the

water temperature insi"e the storage tan% raises up to 3 o+ at 1700 pm. This temperature

#alls to 40 o+ in the next morning when the heater was li#te" covere" "uring the night. Thesecon" metho" is b$ storing the hot water in an insulation "rum overnight. ig =(b! shows

the night cooling e##ect #or the heater with well insulate" "rum. *t can be observe" that the

temperature "rop overnight was 6 o+. *n the morning temperature overnight 47 o+ was

recor"e".


7/8

+igure :'a and )(. The effect of night cooling on the performance of the heater u!ing 'a(.

ooden co2er and ')(. ell in!ulated drum5

rom these two metho"s) it can be observe" that) both metho"s improve" the

per#ormance o# the heater signi#icantl$. Cowever) using well insulate" "rum showe" better

results then the night woo"en cover. These results are well agree with those obtaine" b$ 8arg

an" Dani =

C$#C,&S"$#S

5er#ormance stu"$) ma"e #or a built-in solar water heater "uring the perio" #rom &u.

1) 200 to ar. 7) 2007) showe" that the heater wor%s e##icientl$ un"er Benghazi

con"itions with maximum temperature o# 7= o+ in bright "a$s ) 4; o+ in clou"$ "a$s

an" maximum "ail$ e##icienc$ o# 7, .

ight cooling e##ect on the built-in solar water heater can be re"uce") hence improve

the per#ormance o# the heater) b$ using a woo"en cover or well-insulate" "rum.

RE+ERE#CES

1 aie") E.D. an" huaeib) . .) F tu"$ the per#ormance o# the solar water heater use" in

the houses o# ew Brega Town) /ib$aF 5rocee"ings o# the irst international +on#erence on

'nvironmental *mpact o# 'nerg$ an" water saving in TourismF) pp. 10=-120) a$ 30-31)

2007) '"it b$ *nternational 'nerg$ oun"ation )Tripoli ) /ib$a.

2 'l bag"a"i) . &. an" 8arsho) &)9.) F tu"ies on the uses o# olar energ$ in heating)cooling an" generate renewable energ$.F ) 5rocee"ings o# the irst international +on#erence

on 'nvironmental *mpact o# 'nerg$ an" water saving in Tourism) pp. ;0-;6) a$ 30-31)

2007) '"it b$ *nternational 'nerg$ oun"ation) Tripoli) /ib$a.(2007!.

3 +hauhan) D.. an" 9a"ambi) G.) F5er#ormance o# a collector-cum storage t$pe o# solar

water heaterF) olar 'nerg$) Gol. 1=) pp 327-3;;) (167!.

4 8arg) C.5.) FHear roun" per#ormance stu"ies on built-in storage t$pe solar water heater at

o"hpur. *n"iaF) olar 'nerg$) Gol. 17) p 17) (167;!.

; Hellot) .*. an" obat%a) D.) F&n investigation o# solar water heater per#ormanceF. Trans.&CD&' 70) 42;) (164!.

7


8/8

Cottle) C.+ an" @oertz) B.B) FThe per#ormance o# #lat-plate solar heat collectors.F Trans.

&') 4) 61. (1642!.

7 +lose) ?..)F The per#ormance o# solar water heater with natural circulation F) olar

'nerg$) Gol. ) 5. 33) (162! .

= 8arg) C.5. an" Dani. I.) FTheoretical an" 'xperimental stu"ies on +ollector > torage

t$pe solar water heaterF) olar 'nerg$) Gol. 26) 5 47) (16=2!.

6 Eng) 9..) F& #inite "i##erence metho" to evaluate the thermal per#ormance o# solar water

heaterF) olar 'nerg$) Gol. 1) 5. 137) (1674!.

10 +hinnappa) .+.G. an" 8nanaligngam) 9.) F5er#ormance at +olombo) +e$lon) o# a

pressurize" solar water heater o# combine" collector an" storage t$pe.J olar 'nerg$) Gol. 1;)

55. 16;-20;) (1673!.

11 8arg) C.5. an" 8upta) /.+.) FEptimizing the tilt o# #lat-plat solar collectors #or *n"iaF)ournal o# 'ngineering (*n"ia!) 5t. 8') 21) (167!.

=

solar water heater analysis

Documents