Dimensioning of Solarcombisystem

8/17/2019 Dimensioning of Solarcombisystem

1/40

of

solar

nsronrng

im

Com

bisystems

Chris Baltr, llilfgan,q

Srrtulttr,'lltottta: Let.:

iid l n.qt PLftt's

Solar combisystcnrs

ditler'liont putcly

solar dot]]esric

hot water

systcDts in

sevcral

key

aspccts.

rvhich

nrcans

thet

the dinrcnsioning

of

tl-rc,ur

diilers

in scr,er.al

u,lys.The

nrrin

drllelences

a1-r the extra

space

hc:rtlng load, r'csulting

rn a tot:rl

helr

derrrand

rhat

v;ir-ies

considcrably

duling

tl-rc'

yr.ar-,

and the fact thar

the ther-nul cncrsl is not

usually

sto,red

as

hor rvater usecl lbr

shorvcrs etc. Oonsequentll',

solar conlbisystenls

tend

to bc ruole conrplcx lnd

larger-than sol:rl donestic hot

rvater.systc'rrrs

and they

have

excess capacit,v durrng thc

sunrrrrer-. The tirsr

section

in

this

chapter

qivcx

generel guidelincs

on the dirIrensioning

ofsolar

conrbisystenrs.This

gives

some

r

ulcs

of

thr-rmb aud

important points

to corsider.

Much

of this

is

eqr-rally

rclcr-ent fbr solar

dorncstic

l-rot

w:tter

systenrs. No

dctailed dintcnsiouing guidcJines

for'1.turp5. p1p.t

ctc.

rs

gir''cn,

as

the procedure

fbr

rhis is

the tame

as

tbr

any

hcating

systenr.

Thcrr:

arc a nulbcr

of

tcrms used in

this ch:ipter-that er-e

clcfincd clscrvhcr.c in

rhis handbook;

tl-re rtrost inrpoltlnt

uc dcscribcd brit'fly hele.

.

Systt'tirs

-rrudird

in

Thsk

26.

Each systcm hs

been given

l

specific number

ancl

is

descr

ibcd

in

detail

in

Section

.1.3.

.

I:ratirtrnl

errrigy

-ralirq-r.This

is the

firction

of c'ucrg1,.savcd

by

a

solrr

conrbis,vstem comparcd

to

thc Task 2(r refet-ncc

sysrerrr

rvithout

solar.

Thrc-e

diflerent

tetnrs arc defiled:-f

,.

,,..,

,,

incluclcs

ouly tl-rernral energry;f..,,..,

incluclc's

patasitic cnerqy

use

ofpunrps,

controllers, ctc.,

as u,c'11 as

rhclral

cnelg,v; l.rd-f, is

a vc'rsiori of-[,,,., rvith penalties

addcd

for

periods r',,hcn

rhe

solar

conlbis].stcn1 does not

meet

thc clcflied conrfirlt requireurents-

See

Section

6.2.

.

ReJircucc /ioii-v,r.

Four

diffclcut

referencc houses have

bccn used irr Trrsk

2(r

(see

Scction

6.1) and lur,'e the follos,ing

norrenclatur.e:

SFH 30, SFH

6{) ancl

SFH 100 for single firmily houscs

rvith ;r

30, 60 and 100 kWh/mr pcr

yc-ar

specrlic heating

load respectivc-Iy ibr

a

I20

mr

l.rouse loc:rted

in Zurich; and

MFH

fol

a

nrultr-liruily

house

rvith

t'ir.e

apartrlents

in

a

rour

The follorvrng

sections

give

nrore

infolnation

abolrt the toois

that ar.e

ar,-ailable for.

plannir-rg

lnd

designing solar corrrbisystenrs,

as rvcll:rs

those

lor

doing nrorc

cletailed

simulation

of the systctrrs. In Section

8.2 there is

an overvicrv of plalnilg

tools,

rncludrng

r tcol developcd

by Task

26.

This nay

be

of interest to

I wide audience

lnd

givcs

advrce

as

to

rvhat types

ofrools are suitable

fbr

r.arious

situations. Section

8.3

gives

inibruration

on

mor

detailcd.

timc

dependent

sitnul:rtion

of

systems and


2/40

192 SOLAR HEATING SYSTEMS

FOR HOUSES: A DESIGN

HANDBOOK

FOR SOLAR COMBISYSTEN/ls

the nrain assunlptions used in the siDlul:rtion of

the Task

26

systerns. Tlrese

simul:rtion tools ilre of

morc interest

to thosc dc'signing or devc'loping systems as

rvcll as to lcscarchcrs. Finalll-, a scction is dcvorcd to the simulatlon models

used

in

the

rvork

ofTask

26.This

is gir,'cn

as

background

informirtion

;rnd

is mostly lelevant

to

rescarclrer-s

and those rvishing

to

simulatc conrbisysteDr usirg TRNSYS.

Finall1.,

i1

15 wolth noting

that it

is

rclatively

casy

to

gct a rough approxruratron

ofthc

pelfolmancc

ofa

solar cor.nbisystcm, but

it is

r''ely

diilicult

to

get

close to the

'realii-'

because of the

colnplex

Dature of corllbisystelDs. Details in the systcD')

desrgr-r, especrally lol the store and horv hcar is n:rnsti:rled to and fiom it, do make

a

signii-icar-rt diilelence to the

overall

systenr pedbrrrrance.

Thcsc

dilE:rcnccs can

only

be

sl-rou,n rrsing detailed

slmulation

tools or drrect rllersul'ements

(Driick

and

Hahne,

1998;

Par-rschinger ef

ai., 1998). System

per{ormance

can

be cataslophicaJly

reduced by bad design

(Lorer.rz

rt

a/., 1997), but the

systenrs

shorvn

in

this book

are

belicved to bc

ofgood

design.

Oleatlon

ofan accLlrlLte

sin-rulation model

ofa

systcnr

requires

detailed

nleasurenents :1s well

as detailed modelling,

both

needing

considerable effor t.

A

list

ofintelnet

addrcsscs fol

thc

simulation

plogmlns

mcntion.'d in

tl-ris chaptcr

can

bc

found

in

a speciirl

section

in

the

rcferences rt

the end

ofthe chapter.

8.1

DIMENSIONING

GUIDELINES

In this scction guidclincs arc providcd lor thc most inlportant componcnrs ofa solar

conrbisystem.

8.1

.1

Collector

slope

and

orientation

The

dependency ofthe solar-fraction

on

collcctor tilt angle and :Lzirnuth anglc

for

Systeru #19

is

shorvn in Figure 8.1.

The highest

sohr

fi"ction

is

achieved

with

southwald

olienration

(slightly

rvestwards)

and the

optinrurn

tilt

angle is

about

55o.

Ncvcthclcss, the decrease in perlorluance bc'nveen tilt anglc's fiom 30o to 75o and

fionr

azirrruths

from

30' east to 45o

west is

vely

small.

Most

of

the

solar collectols

can thertl'ore be

installed

in

the

roof

of

the building without

expcnsivc

and

lesthetically unattlactive collector array racks. It should

be

noted drat a collector

mounted verticirlly

or f, south

facing rvall

has

only

20%

less

fractional

savings

thll

an optilnally

nrounted

one and

h:rs

nruch

highcr'

ftactional. savings than a

horizontally mountcd onc. As the direct solar irmdiancc in

summer at

midday

on a

south

facing wa11 is

only

about 50% of the

radiation

or an

optimally tilted

sufacc,

wall-mounted

collectors

do not

have

big

problenrs

rvith

stagnarion

(see

belorv).

For

higher

{i-actional

energy

savings

the optinrunr inclination

of

the

collector

iner-eases

because ofthe

hisl.rer amount

of

winter

suu being used

(see

Figure 2.3).

Collector orientation

Collector

orientation can

vary

30o

fiom

south and fiom 30o ro 75o in slope u'itl.r

less than

a 11)% reduction

in energy savings for a centml European climate.Within

rhis

range

it is

generally

easy to

corrpensate

rvith

I slightly

hrger

collector

area.


3/40

DIMENSIONING

OF SOLAR

COMB 5Y5TEMS

193

Extended f.actionai

energy savings

(in

o/o

lrom maximum)

9- 50

g

3+o

trio

'90

-75

-60

-45

West

.:0

"15

0 15 l0

45

Collecaor a2imuth

l"l

60

75

90

East

95

90

85

80

75

70

65

60

55

50

Figure 8.7. Dependency af the extended lractianal energy savtngs an tilt

angle and azimuth

of

the

callector

(climate

central Europe. 140%:39%of f,,

",)

(Heimrath,2A02).

Seealsa calaur

plab

2A

5?

d,

g-

/

.^,-

'\

/

t'

'-,\

lr\

959o

\n"r" /

t

\

--

,---- I

-

gtly.

./ /

r

':

,--l I

\,,

\.}:

co//ecto.

--

".uhuth

t6l


4/40

194 SOLAR HEATING SYSTEMS FOR HOUSEST A DESIGN HANDBOOK FOR

SOLAR COMBISYSTE,VS

8.1.2 Collector and store size

Figrues

8.2 and 8.3 shorv the

influencc

of

collector

sizc

lnd

srorc'

volunrc

on

thc

extended lractional cnergl'ser.ings

({.,..,)

lo,

Systeru

#19

and

all

clinutes. Onc

in'rportant obscrvatiorr that

can

bc m:rdc is that

lbr- solal

conrbisystenrs

s,ith

lelativcly

sma11 collcctor arcas, a snlall

\\,:rtc'r

store'

is

sut-licient. Bigger stores do not

40

:F

30

25

,,

Stockholm

0 5,

100 150 200 250 300 350 400 4JO

Specifrc store

volLrrne

lll.n'zl

Ftgure

6.2.

lnfluence

af stare

volume

and collectar area on the extended fractlanal

energy

savings

(f....,,)

fat

the

Zuich

and

Stackholm cltmates

(System

#19, MFH). The

salid

lines are

fot

dtflerent, fxed collectar arcas whercas the dotted

(nearly

vertical)

lines

arc

far

different, fixed

sLarc

valLlmes

r-

35

30

,ri9i

50 100 150 200 250 300 350 400

450

Speciiic slore voiuine

Jl/m:l

Jm-

15 oi

2ilah


5/40

DIMENSIONING

OF SOLAR

COMB

SYSIEMS

195

Catpentras

0

50 100 150 ?00 250 300 350 400 450

Specilic

store

volume

[/n1:]

Figure 8.3. lnfluence of store valume and callectar arca

an

Lhe

extended fracttanal energy

savings

(f.,

,.)

far the Carpentras climate

lsystem

#19, MFH)

incrcasc pcrforrnancc sigr-rificlntly and car even decrease

the

fr:crionll

cner-gry

savings

as

a

r-esr,rlt

ofthe increasing heat losscs ofthc storc as

thc

sizc incrtascs.This

is generally

true

lor

all climates and all

corubisystenrs investig:rted.

lncreases

in store

volume

Incrcased

store

volume does not necess:rrily lesult in increased

savings

(sct-

Figures

[3.2

ancl 8.3).

For

all climatcs end systcDl sizcs for Systcnr #19, the savings dccrcasc

rvid-r

l

speciiic volunre xbove 150

l/nrr es a

result

of incrc:rsed

store

losses.

The

results

for

rlrany

other

systen$

:rrt

similar

A

rough

ruie

of

thunrb

lbr

the

store

voluulc

is 5(l 1(X)

liues

1br

every

squar-e

nietle

of

t-l:rt

platc

collector

alex.

Collector

size

The

'best'

collector size is

depenclent oD thc uscr's ptiolities:

eltergy

\.r rngs,

ccononl),

or space requircnlcnrs. No genelal

guideline

is possible.

Sruall aleas are

conlnlon i1l the Netl-rcrlands rvhile

large altas are co11t11ton

in

Austria.

Both

cottrrrr

t.r lt.rvc

rrr.rrrl

h.rpp1 orr rrcrr

Figure

l'i.-l

shorvs

the

srzc

of

collecror

r-ecluired

to:rchieve

a

lange

of

fi'actiond

enersv savings for thlee drlTelent

types

ofcollector

and tu,o collector-

slopes. It can

be lcadil,v seen th;rt

a

higher

slopc is advantageous, espccially

:rt higher ti-acrional

savings.

Thc evacuated-tube collcctor requires nearly

t\,\ro rhirds

the iperturr-

trea

conpared

to thc flat-plate collector in

ordcl to achieve

25% fractional

energyl

savings, but only slightly

nore

thaD

half thc

area for

45% savings. The

ratio

betr,veeli requir-ed

lreas

for

the ev:lcuated trrbe

ald

Lord

Adapted

(LA)

collectols

remains

thc

sanle over the

wholc

r:rngc

ofsavings.Thc

calculations rvere

carricd

'-

5o

:45

40

0


6/40

196 SOIAR

HEAT

NG

SYSTEN/]s

FOR HOUSES: A DES

GN HANDBOOK

FoR SOLAR COMB SYSTEMS

E

o30

o

20

Flal P ate 30'

Evacuated

Tube 30'

Fv..",to.l T

'ha

7n'

+Load

Adapted

30'

-1...

Load Adapted

70'

--1:

4

--1

.4.=

20

25 30

35

40 45

50

55

f"",

tv"l

Figurc 8.,1.

Camparisan af

callectot apefture

areas that are

requtred

[or

three callectar

ty'pes

ta

aihieve

a

range of fractional

eneryy savings

The

date are valid fot a well

stratified syslen)

tn

Stockhalm

The

dtlferent

types af

collectot are

genertc

and arc nat

speciftc cammercial

units.

For

each callector,

[,1/o

lines are

shawn lot

slapes

af 3A'

balid

ltne)and

70"

(dashed

line)

out

for

a Srvedish

solar

coDrbisysterD

$'ith

ertclnal hcat

cxcl-rlDg5crs

lor botl-r

collectol

circuit ancl

dorncstic

hot rvatcr

prep.ultion lud are

Itot fol

the

specilic

condrtions

ofTask

26

(Lorenz

cl a/.,2000).The

LA collcclor

(sce

Frgrrrc

ll.5) uscs

rcl'lcctors

insrde the

collcctor

in

older

lo reduce

costs ancl to

give

it vlrying

optical

ploperties during

thc

year. lt is designcd

to

rvolk

e{licrcutly

cluring

most

of

t1.re

yeal ap:ut

fiolu rhc sun1lncr,

lhus avoidrng

utrnecessaty

ovcrheatitrg

in the

coilector

circuit

rvl-retr

thcrc

is

ttsulli-v

excess

clplcit,v

(Nordlandcr

lud

Rcinnclid,

2()()1).

Figure

8.5. Simphflecl

dlagftm

af the

principle

of a

U

callectat

Far

law solar allitudes, all

rays

rcach the

absorber, whereas

for high solar altitudes

same are tellected

aut

10

60

50

E

H

+l


7/40

DIN/ENS ONING OF SOLAR COMBISYSTEIV]s

197

8.1.3 Climate and

load

L.r

Figure

i'1.6,

the three deiined Ii-actional euelgy

savings lor

Sysrcm

#19

and

all

clillllLtes

ale

shorvn.

Thc

C:uperltras climate

has

much

llighe|

fi'actional

cncrgy-

srvings

than the

clirnate

in thc

other

trvo locations. I\esuits for Stockholm urd

Zurich ale quite siruilar despite the

lalge geoglaphic sepamtion in latitr-rde. It can

irlso be seen

that therc is a significant difTerence

in values ful the thcrr.nal (1.,,,,,) ar.rd

extended

(1,...,)

fiaction:rl

energy

savings. This ditTerence

is due

to diffelences in

pllasitic

electrical enelgy

usage of

the solar and

referetrce

systerns.

It

is, horvever,

possiblc

to

h:rve Iorver parasitic energy

consulrlption

in

thc solar

hcatir-rg

systerl if

lorv-ener-1ry'

prllnps arc used insread

ofthe

more con\.entional

ones.

Chorcc

oflorv-

cnerg)- Pumps can

lllake

an

imPortrull contribution

to

overall

savirlgs.

This

is,

of

colr\c.

Jl.o crue lor corrrcntion.rl

h-.lUng

\y\tcrll5.

-sr""kh"tr."l

]n

2,,'icr,

E Carpeniras

20v"

104/"

ah

Ftgure 8.6. Vanatian af

fractianal energy savings with cllnate

(Systen

#19 with 100 m'

calleclat and

5

5 m, stare)

Figure

ll.7

shorvs

the

virtiation

of

therm:rl

savings

Q.',, (kwh)

:rnd

lhcmral

fi'actional cncrgy- savings-f

,.,r,

(%)

t'br one solar conrbisystem of

l

fixed collector

alca

fur

three cLimires on three ditlercnt buildings.

Tivo

observations

can be made:

.

For

a chosen climate,

an incrcasc of the load due to a less

rvell

insulatcd

housc

(SFH

100 conrpared

to

SFH 30)

leads to hrgher encrgy savings,

but

to lo\'ver

fiactionll

energy-

savings.

[n

orher

words.

the higher the

]oad,

the

more'eftciendy'

thc solar

loop

rvorks,

but also

tl.re

highcr the auxiliary energy needs

arc.

*

30%


8/40

198 SOLAR HEATING SYSTEMS FOR

HOUSES

A DESIGN

HANDBOOK

FOR

sOLAR

COMBISY5TEM5

6>

>=

o.tr

F

C

o l

Eo

.9

IL

00%

90./"

B0%

7A.k

60%

50./.

40%

30%

2A%

10%

0'/a

Figure 8.7. lnfluence of climate an the savtngs

and

the

thermal

fractianal

energy savtngs

for

System

#9b

with

a 10 m'

collectot area

.

For

wcll

insulated

houses,

errer-gy

s:rvings

do

not

changc ruuch

rvith

the climate,

rvhich is not the

case

for-Ii-actional enelgy- savings.Thc satne cotnbisystetl

installed in ar.r

'identical'

r.vell insulated house rvill

providc

r11ore or less the same

energl, s:rvings and consequerrtly

the samc moncy savings. f)iffel:nces betrveen

clinlates beconle

greater lbl houscs

rvith

greater heatir-rg loads. In other words, it

is

as prot'itablc

to

install

combisystems anyrvhere

ir-r

Eruape.

8.1.4

The

boiler

and the

annual

energy

balance

The

savings achieved

by

any solar

heatinllsystenl

are

very dependent on tluee other

key

parameters:

.

the

boiler

eiliciency

.

the tenlperxture ofthe auxiliary heated

pxt

ofthe store

(thermostlt

setting for

stole charge)

.

the volLrme heated

by

the

auxiliary

heatet.

SFHl OO

SFHl

OO


9/40

Thc

boilcr elllcic'rcy

is

an obvio,s

f:rctor,

bLlt

oue rhAt is

sol'r'rctinrcs

underestirnated

in

solar l-rcating

systenN.The

other t\\,o

arc less

obvior-rs

factors,

but

thesc

ar-e

cqually

irnportant.

Figure

ll.8

slror,vs

that the

setting

of

the

the,rmostat for.

tire

auxiliary

heating

of thc

storc greatly

allccts

the

cnetgy

savir-rgs

for

a sl.stetrr,

in

this

case

Systcm

#11 rvith

au

oil

boilcr. IJigh

scrtings

r.esuit

in large

hcat

losses

rs tht,

collcctor

must r.vork

at

high

tenlper.etul.es

befor.e

thc

usc of rhe

auxiliary

heater. is

avoided (set

tcrlpcraturc

ercc'ecled in

the

store). FIowever.,

at low

settings

the

dcsired ther-nral

cor,fort nray

11ot

be

:rchie'cd.

This

lorv

ther'rai

conrfort

is sec.

hcre

fi-onr

the declease

ir.i

thc

indicator-./,

(sc,e

Section

(r.2)

at a tenrperatur-e

of

60oC-

At

e

setting

of

60"C

the hot

rvatcr

derrrand

is not

lully

rlret

on certain

occasioDs

during

the,vc'ar.

Signi6carlt

illtplovtDlc.tlt{

Il

\\.stcD1

p.rfortDancc

can be

achicved

by

rt-ducinq

the

requir-enlcnrs

ibr

thcr.mal

conrfort,

espccially for-

hot

rvatcr.

This

rn

practice

nleans

that

on occasions

ollc 1l1ust

havt,

a

slightly

sl-rorter

shower.

or

l

bath lvith

less rvater

in it.

Sinrilarl1,,

the volunre

that

is hcxted

by

thc

luriliary

also

at't'ects

botl-r therrrral

courlbrr

tnd savings.

A

larqcr heatcd

volumc

cllsr-r1es gr-cate1

the rul

comfort

btrt

t...sultr

in lorvqr..

in(s

ThLr,

i:

tltt.

altt,a1,s

a

trarlc-t)i

bttt|tctt

tlrc lertl

Ltl-ltnmriccd

tlunnl

anlittt

and

tltc cnc \

sain :.

D

MENSIONING

OF SOTAR

COMBISYSTEMS

199

I

os

zo

3

t

ov.

un[

+

t

60

75

80

Store charge

thermostat

setting

['C]

Figure

8.8. lnfluence

of the setting

af the

thermastat

cantralling

the

charging

af the starc

by

the

auxiltary

heatea

fot

System #

/ 7 ustng

an otl batlet

as

auslta4

heater

Thls

sittno

affects the

tenoprat

t

e

AI

the

d.,,,.

"q

ken1o

pol

at

.b-

-tot-

Low

thermostat setting

Alrv:ys

set

the the'nuostat

controlling

the

auxihar y

hcating

ofthe

store to

the Iorvest

ralue

that

rvill

give

thc

thermal

cornfort

and hygicne

that rhe

uscr rlesires.Too

higlr

a sctting

rcsults

in snullcr

energ)- savings

rvithout

any

extn

benclit

to

tite

usel. Note

that

if the domestic

hot uater

is preparcd

in

a

scpatatc,

store

or

i1-i r Lrnk_rn

tank

store,

this

setting is recornurended

in

many

countrics

to

be

60.C

or

highet

because

of

pote.rtial

problerrrs

with

bacterial

grorvth.

A

snall

uolu,L,

hcakd

ltv tltt arrxiriart,

also

leads

to

improved

s:rvings

but possibly

to

lower

thernral

cornfor.t.

]


10/40

200 SOLAR

HEATING

SYSTEMs

FOR HOUSES: A DES GN

HANDBOOK

FOR SOLAR

COMB

SYSTEMS

During

sunrmer, v,hen therc' is ofren a nearly 100% coverage

of

the

load

by so1ar,

thc boiler does

not

supply

nruch uselul eucrgy- to the systeru. Horvever,

it

still

has

significant losses to the environrrrent.Tl-ris

is especially tlue fol oldel boilcrs that do

nor

mrn otTcon'rplerely and

autoDaticdly

rvhen

not

lequiled,

and

in

thrs c.rsc

it

c.rn

be

advantageous to turn off

the

boilel niarually during

the

sunrnrer.

An

electrical

heater can be used

instead,

or

alternatively

thc boiler

can be turned

on

manually

for

the

lew

times that

ir

is lequired. Figule 8.23 shorvs that

during

sulnrner both

the

gas

and

oil boilcr

have

efficiencies

much less than

.l0%.

Figure 13.9 shor,vs the annual energy

balance fi:r System #11 fol tl.rc Zurich

clirnate and the SFH 60 house, resulting

iu

a

total

load

of

1 1,600 kWh. This annual

erergy

use

is epproxirnately the sanre

as

the

solrt

radiatio[

on

the 10 n']r ofcollcctor

during the

year.26t/u

of

tl.re

enelgy

lalling on the collector

is

delivered

to

thc'store

:rnd

thc

remaining 74% is lost due

to

pipe and collector

losscs during opL-I.rtron.

Figure 8.9. The eneryy balance far System

#11 with

gas

bailea

1A m2

callectar,

Zutich

chmate

and

SFH

6a hause.

All

values are

/n

kwh

The

value

far

parasitic

electflcity

is

given

as

pnmary

energy and thus a factar

af

2.5

grcatet

than the electrical eneryy used

TBANSFER,

STORAGE

CONTNO' O'O

O'"''""O*


11/40

D

l\/]ENSION

NG

OF SOLAR COMB SYSTEMS

2O,I

periods

of insut-iicient

t-adiation

to u:rke thc collectol

hotrel.tl.ran

the

storc

and

pcliods lvhen

rhe collector Ioop purnp

is sr.r,itched

olf because

the store is already

fully

charged.The

boiler

uses gas

rvith

a

fuel

encrgy

contenr

(final

cnergy-

deurand,

E,.,,

,

)

of 10,1{li)

kWh,

of

rvhiclr

785 kwh

is

lost

during

operation

ar.id

stand-by.

This

loss

is

uearly exactly

the

sanlc as

the

losses

from the well

insulated

score.

Neither

ofthese

losses

is tre'ated

as

g:rins

to

the house

in

the sirnulatior-rs.

Of thc

plimary

energl'E.,,, 1791t

kWh

(7ll)

kWh

clEtricrl. l.(,,)

is rcquircd for.

palasitic

usage lor pumps,

conrlollers rnd r.rlv


12/40

2o2

SO AR HEATNG SYSTEMS

FOR

HOUSEST

A DESIGN

HANDBOOK

FOR SOLAR COMBISYSTEIV1S

8.1.5.1 Stratification

The

l-rottcr the

watel the

lower the

densiry of the

wlter. Hot

water thus naturally

and

stably

finds

its

rvay above layers

of

cold

rvater.

Tl-ris

phenotrlerlon

makcs

it

possible to

have

stratification,

rvith

zones

ofditTcrtrt

tcnlperatr-uc

in one

physicd

store.Thc

zones indicatc'd

ir

Figure

13.10 can lhcrcfore

bc

at dill-erent

tenlperatures.

and

mole

specifically

:rt

the

tenlperatures

required

of

thc

loads

for

dorrrcstic hot

wxtcr- ancl space

heating.

Stratillcation

allorvs

an oPtilllal

use

of the

stolc

r'vith

limited

l-reat

losses and. in additron,

can

bc used to ensurc

that

the collectot

inlet

tenrperature

is

as

lorv as possible.

Horvcver',

it

is

not obvious oL casl

to nraint'lin

good stratification

in lhc

stort.

In

fact, the

telllls

stlatifled

and

stratilying

ale used

ibr

slightly

ditTetent

pl.renonrela

:rnd

apptoaches.

The

t'bllorving diagr':rms

aud

dcscriprions

shor,v

importatt

differences

in

horv the stole

can

be

cl-rargcd.The

satlle

distinctions

can be

applied to

dischatging

lhe

storc.

To

maintain

stratiflcation, all

chalging

and

discharging

must be

done iIr such

a rvay

as

to

illrplnve

or

rn.ritrt.rin

the stratitication.

If only

one

heat

soulcc

or sink

causes siguificlnt

rllixing.

it c.rrr

destr-oy

thc bencfit

ofthc

stlatjficetion

cre;Ltcd

by

otllel sotlrces/sinks.

Heat

source

Unaffected

.l

r

SharD

t

bou:10ary

Unaffected

Figure 8-11.

Charying

using an

intenal

heat exchanget

lleft)

and

with

diect

cannectians

light)

Tie zone at

the top at'

the tank with

direct cannecttons

will be affected

if

the

tnlet temperature

is higher than

the

temperaturc

at the

tap af

the tank

Figure

i3.11

shorvs

schematic;rlly

what

happens

rvithir.r

rhe

stole

when

it

is

cl1erged

with an

intcrnal

heat exchanget

and

rvith dilect

conneclions

The

rvater heated

by

the

internal heat

exchanget

starts

to

rise

and

nlixes rvith tl-re surrouncling

watet.In

this

rvay the heat

is

transfcrred

to a

large

volume o1t

rvater,

rvhich

is

helted

slowly.

The net

result is usually

a

zone

ofuniform

terrPemture

above

the

heat exchangcl.

This zone extends

as

far

as another

zone rvith higher

tempcratule,

if one

exists.

Once

tl-re telrlpelature

of this

l-ighcr zone

is reaclied, both

zoncs

will

be

heated

uniforr-nly

at the

sarne

temper-aturc.

Belorv the

heat exchanger,

lhc

storc is

{Jniform

temperature


13/40

DIMENSIONING

OF SOLAR

COMB

5Y5IEM5

203

un:r{fected. Therc

is a small temperature

gradient in

the store at the

sanle

height

;rs

tl-re l-reat

exchanger. An

electric

elenlent

i1-r

the

store

acts

rn

l

sir.uilar way, but as a

result

ofthe

rclatively high

por,,,er

and small heat transfer

area,

rhe heirted

water

does

not mix fully

rvith

the

sutlounding

store

s,ater., r.est

ting

in a

snuli

tenlper:rtLue

gradient

(stratification)

above

the heater.

With a

direct connection

there 1s solne

luixing in the srore

at the inlet.The

degrce

of

rrrixing

is dependent on the inlet

velociry

and the difference

in

temperature

benveen

thar of d-re incoruinq

rvater and that

ofthe store xt the

inlet.The

zone above

the

inlet

will be unafected

bv

rhe incol'r1ing

water

if

the Iatter

is colder.

Beneath

the

inlet, the

store

water

is

pushed

dorvn

and out

tllough

the

outlet.

There

is

usually a

sharp boundary

benveer]

the

hot water,

at

r-rca{

the

samc teDlpemtule

as that

entering

through

the

inlet, and

the

origin

store

\,\rarcr.

This

boundary

moves

downrvards

during

the charge. Holvevel, if

the incor-ning water

is hotter th;rn

the

uppcr zone,

then hclt rvill be

transferred into rh:rt zone,

causing r . i-xing therc,

as

well

as

into the r,'olurrrc belorv

the inLct. A

large

volurue

is thus

affected and the

teulpcraturc

below

the

inlet will bc

sigrificantly

lower

than

that

ofthe wrtcr enrerrng

rhe store.

Thc teDlpemtLlrls

of

the

inlet watcr from

both the collector. and

the

space

heating circuits v:rry

in

time,:urd

there

rvill

be tirtres

rvhen the

incoming

w-rrer

rs

hotter

than the wxtcr

in

the

store

it

the iDlet. arrd

other times it

rvill

be colder.

Charging

rvith

direct

conncctiolls tl-rus tends to

enhancc stratificatioll,

wlth the

volulne

of

the zone ilcreasing

dur-ing charging.

In

contrast,

charging

rvith

an

lnternal

hc.rt

cxchangcr tends

to desrroy

str:rtific:rtion.

In thc

store of

a solar

conrbisystcrn,

there

lr-e several

hcat

sourccs ls

rvell

as sioks,

and so

the flows

and

stratilicatior-r are

complex.

Nerther

the

intcrnal

heat cxchanger

nor

the dircct

inlet

is pcrfcct

fot creating

stratification, so dillerent

nlethods havc been applied

to

improve

stratification. Thc

first,

arid

sinrplest,

is to increirse

the numbet of inter.nal

heat exchangers,

:rs

illrrstrated in

the storc on the left of Fisure

8.12.This

errangcnlcllt

cfcates nrore

Figure

8.72.

Three

differ,.nt methads af causing

strattftcatian

with

intemal

heat

exchangerc..

sevetal internal

heat exchange6

(left),

strctitting Iube

(middle),

and stratifying unit

wilh

multiple autlets

(right)

The sttatifying unitcan

be used with

an

intenal

heat

exchanger or far

other tnlets that

vary

in temperature


14/40

204

SOIAR

HEAT

NG

SYSTEMS FOR HOUSES: A DESIGN

HANDBOOK

FOR SOLAR

COMB

SYSTEN.4S

zolcs bctween thc

heat

exchangers and thus l

gr-eatel degree

of stlatific;rtiorr.

Ilorvever', the rvhole ofeach zone is heated/cooled by the

heat

erchangets, and the

tenlperature

in

the

zones does not changc rapidly In order to create a variable-

r,'olume zone thrt can be

heated/cooled

quickll',

several

nranufactulers have

added

a stratifying

tube to

the inrcmal heat

exchanger, as

illustrated

in

the

nricldle

store

of

Figure 8.12.This

tube

acts in a

similar

rvay to a

direct inlet. Horvever, the florv

rn the tube and thus the

telrpenture

at the outlet of the tube

is

dependent on

rhe

terllperatures

in

the

stole

as

rvell

ls

those ofthc hcat sourcc, as the florv is the result

ofnarr-rral convec[ion.This

florv can

var-y

consrdclably dcpending or-r the conditions

rvithin the store.Thus,

rvith

this

r-r-rethod,

the

water enteling thc storc frorn the tube

can

be

either hotter

or

coldel

than the

surrounding

w:ller.

Another method

is

to

usc

a

stratirying

unit

rvith

several

outlets, rs

illusuated

in

the

righrhand

store

ofFigule

[J.12.This arr lqement allows rvatcr

to exit

the

unit

at the

helght

that has approximately

the

sxme

telrperature in

the stol'e, thr-rs

maxirnizing strrtiflcation.

This

nrcthod is

bettc[

tl]an the

othcr

two,

but

requires

careful attention.The ilorv

in the rube should be lvithin a lir ted range; othenvise

the

watcr

comes oLrt xt an

incorrect

height- In

addition,

it is

imporernt

to l nuruzc

drarving

in

of

wlter

through

outlets into

the

passing

florv

in

the

tube,

becausc

this

rvoulcl

lead

to mixing

o11 the way

up, l:sulting in

lorver outlet

tenlper.rtures- Such

stratifying

r.urits

have been succcssfi:lly used

rvith

both

internal

and external

heat

exchangers

in

rhe solar

circuit

and

for

the

rcturn fioru

rhc

sp:rcc

hcating loop.

Stlatifing

tubcs and

r.rnits

lvith intern:rl

heat

exch:ingers

rvork

rvith narural

con:ection as

nlentiolred lbovc. It is

ilrlportant that the pressure drop through thc

tubc/uuit, the

heat exch:rngcr's ctlcctivcncss ancl the expected

heat

trarlsfer

r:rte.lrc

matched

so

that the

flow in

the tube

is

similar

to thar in

the collectot circuit,

thtts

c'nsuring

1ol, tempelrlules

to

the

collcctor- and

high outlet

teinpcr:ltules. Both

stratiEing tubes and units can be

uscd advantagcously

in

1ow-flow systen$.

Figure 1,l.13 shorvs horv

a

good

stutti6cation

unir rvorks u,hen the tenrpcrrlurE

itl

the tube

is

benveen that

at

the top

and at

the

botton

of

tl-rc

storc

ir-r

fact, betu,een

Lh.rt .r(

tlrc

'.,

ond

rrrd rhrrd outlrt..

8.1

.5.2 The

collector

Thc

collector

circuit

usually

has :rn :rntiftcczc/rvater nixture

as the

heat tlansler

fluid.

A heat

exchanger

is

ther-efor-e

requir.ed lbr heat transli:r to the storc.

An

exception

to this arc systcms that use the drainback principle, such

as

Systeru #9b.

The

input to the

collector

should ahvays be as

cold

as

possible, ir.r

order

to keep rrs

eiliciency

high. Therefore, thc

connecting tube

to

the collector

is

mounted

at the

bottom of thc

store,

rvhere

the

coldest rvater

is.

The

height

of

rhe

input fronr

the

collector

into

the stole

vanes rvith

drflerent applicarions.

For

so-called

high-flow

systems,

with

flow in the

collector

circuit of

approxir-nately 50 1/h per nrr of collector area, the teruperaturc rise

in

the collecror

is ofthe

order

of 10oC.The input into the store for these high-flow systems should

be

near

the bottom of

the stor-e, and the store is heated slowly from the bottom to

the top. An exception to

tlis rule

is

for

stores rvith

more than

one heat exchanger

in

dre collector loop,

for

example

System

#12.


15/40

DII\IENS ON]NG OE SOIAR CON4BISYSTEI\,4S

205

Figurc 8.7 3. Stratiinng unit

far hot water stares shawtng autlet into the middle af the stare

(Saurce

Salvis, Germany).

See

alsa calaur

plate

21

For so

callecl

low-flow

systens

rvith

a

specific

collector florv

of

1(}11

5

l/h

per-

nrr

of

collector

area,

the tenlperltrue

risc

in thc

collcctol is

of tl.rc

ordcr

of4(1 50'(1.Thc

iliput to tl.rc

stort

in low-t'lorv

s,vstclns

should be

highel

up

than

ir

the

higl.r florv

systerr,

the best

height

dcpending on the

flow

and

systenl design. It

can

bc

ad\antxgeous to use a strati4'ing

unit to Drakc sule that thc heat 6oD1 the collectol-goes

to thc. f

ight

lc-r'cl rn

thc

storc. Lo\\r

florv

should

not in

lleneml

be used

lvith intelnal

heat

cxchanger-s, as these

c:rnnor

f-111y

utilizc

the

high

temperatr.rre built up

in the

collcctor', lnd

the

resulting

telrlperatulc

in

thc stort

is

rruch lolvcr

because

thc'water

in

the

stol-c' is

mlred

rapidlyr

Modeute tlows

can be

used.

bur irr rhis

case

rhc inteinal

helr erch:rrrgcl should

har-e

r gre:1ter-

vel-tical extert than rvhen high llou,s

nt'c uscd.

8.1 .5.3 The auxiliary

heater

The

rnput

tubc fl-on'r thc

auxihary

hearer

should be

on

dre

top of thc tank.

The

outlct

position

to thc'ruxilialy

heatel

rs

deterniined by

seveIal

lactols:

There should

ahvays be enough

hot u,atcr in rhe storc

to

fullill the

hear

deruands. The

peak

heat demnncl in singlc'- or double-family houses occurs

rvhcn

a

bath tub

is

fillcd

(about 25

kW).

Therefore,

thc rccommcndcd volumc

for

thc

DHW can

bc

calculated fioru this denrand and the porvcr ofthc

luxilirry

heater.

Additionally

it

nlust

be

possible

to

deliver

heat

from the

auxiliar.,

heater

to

the

space

heating

system as

rvell. Ther

elbr e,

the outlc't

position nrust be below the DHW and the

space

heating outlet.

The auxilialy

heater

olten

needs a n-rinimum

lunnlng time

(especially

solid

rvood

burners).The

volume

betrveen

auxiliary heater inlet

and outlet

must

be

suf'licienr to prtvent overhextjng during fiis mininrunr running tilr1c.

:,

E

:tE.;ta

%


16/40

206 SOLAR

HEATING SYSTEMS FOR HOUSES:

A

DES GN HANDBOOK

FOR

SOLAR COMB SYSTEMS

.

The

outlet

to the

auxiliary

heater should be as

high

as possible

(limited

by tl.re

above

factors) in

ordel

to lcavc as latge a

volume

as possible for the solar

collector-.

8.1.5.4

Domestic hot water

(DHW)

The DHW outlet

most

olten

needs the higl-rest tempcrature of thc cornbisysteni

(50

60'C).

Therefole,

it

is located at thc top of

the

tank.The fresh

rvater

(or

the

water

from

a

heat

exchangel

fol

DHW

production)

is ah,vays

the coldest

part

and

therelbre

Iocated at the bottom.

The

volume heated by the auxiliary

nrust

be big

enough

to

gualantee thar all denrand

for

DHW

can be

met

(i.e.200

litres at

40'C

for a hot bath).

8.1.5.5

The space heating system

TI-re tempelaturcs in

the

space heating systerr

range

between

the

IlJins w.rter

tcnrper-ature and that necessar-y

for

l)HW

Consequentll,,

the zone

for

the hcating

system is positioned in the

middle

of

the tank. During thc heating season, space

heating

is

the dominant

heat

sink.

Thclclble,

the volulne

for this is

kept rclativcly

large.

8.1.6

Design

of

the collector circuit

ln

most countries

witiin Eulope, the collecror

circuit

needs to

be

such

that

it can

tolerate

periods

ofirost.The

nrost cornruon

rllethod

ofprotection is usc

of

an

anti-

fi'eeze lnixturc of

propylene

glycol

and

watcr.

[n

addition, the most

contDron

collectol circuit Jayouts ale also

subject to pcriods ofstagnation when thc collector-

pur.up is sr,vitched off because

the

storc is fully chaged. This is rnore courmon

in

solal

conrbisysterns

than

in solar donrcstic

hot

water systen$. Section 7.2 describes

sone

of

rccent

rvort carried out on what

happens

during st:Ign2rtion-

In many

systeD)s,

the

pressure

in

the

collectol

cir-cuit is

kept

belor,v

3

bar.

Durng

\tagrlatrorl

tl-re collector

flnid

evapotatc's alid

is for-ced dorvn

into

the expansion vcsscl. Figure

iJ.14 shorvs trvo

possible l.rydraulic scherlcs. [n the top scheme

(Case 1),

the

increasing vapoul pressure ibrres all liquid our of the

collector

as the

increased

pressule pushes thc liquid dor,vn

equally

on both

sides.There

is no vapour-in

the

connccting tubes because

only

the

liquid is

transported thr-ough them

during

tl-re

emptying of the collector.

In

the lorver schenre

(Case

2), if

tlre

pressure is

equal on

both sjdcs, all

liquid

in

the'U'has to be evaporated because

it is'trapped'in the

collector.

The

stearl

is forrced

into

the

tubes and has

to

be

condensed

in

the

heat

exch:rr-rger to thc

hcat sink.Very

high telnperatures occur-in

the

whole

collector

cirtuit. Additior.rall)',

thele

is

an

increased degradatior.r of

the propylene glycol

and

the corrosior.r inhibitors,

because ofthe

high tenlperature

in

the collector.Therelore

Case

1 is

reconrnrended lor

the

collector

layout. The rest

of

the

hydrlulic florv

scheme of the collectol circuit must allorv for the liquid ro be draited liom both

sides of rhe collector to the

expansion

device.

Figure

8.15

shorvs one

possible

hydraulic florv schene.


17/40

DIMENSIONING

OF SOLAR COMB SYSTEMS

207

Normal

operation

siart

of stagnal:on

Liqlrid"

Normal

operation

Figure

8.11

Hydrauhc

collectot flaw scheme farcing steam aut af the collector dunog

evaparatian,'tap

Case

1,

baltom

Case

2.

(Source.

Streichet, 2002b)

Dlainback

systems,

rvhele

the collector is drained

of t-luid r,vhen rt

rs rlor nr

operation,

arc

conurron

in

the

Netl-rerlands, as

described

in

Section 7.2. Evelr more

dctails can be found

in

the ploceedings

of

the

fifth

industry workshop

ofTask

26

(Weiss,

20{)1). This llethod is used for

prctection

fiom both

Iiost

and overhearing.

The Dutch

designs

havc shorvn

that

it

rs

possible

to

design reliable collectors

ancl

stores for this method. However, it is still possible for-the

pipes to be insralled in

an

incorrect

rvay, leading

to

problems.

In

practicc',

hor'vever, this docs

not

occur-in the

Nerhellands.

See

Chapter 7

for

morc

dctails.

Another ruethod ofoverheating protection involves keeping

the collector circuit

putup

in operation

lnd

dumpilrg heat

in

the

qround

or sonle other heat sink.

Some

systcnN even cool the

store at

night

so

that thc

risk of

or,-erheating rhe

next day is

reduced. A system design that carr rvithsrand high pressures (up

to 9 bar) in the

Start of slagnation

;t t;:

il

Lll

l,,l

I 1

ll^^ll

ilLJil

l-l

Oscillating liquid

phase

water hammer

-t

+"


18/40

208 SOLAR

HEATING SYSTEMS

FOR HOUSES:

A

DESIGN

HANDBOOK FOR SOLAR

COIV]BISYSTEN,']S

Fllling

valve

Val e

Manofieter

+

lhe.mo

eter

Collector

pump

Valve

Filllng

valve

Safety valve

One-way

valve

Expaasron

from both

sides,n

expansion device

possib

e

_...>

Drscha.ge

valve

'T#;:""

Figure B.l5

Hydraulic llow scheme

of

the

pump,

the

ane'way

valve

and

the expanstan

device

allawing

the

flaw

frcm

both sides

af the

callectar

(Source:

Strcichet, 20A2b)

collcctor

circuit

cnables the

fluid to

remain

in

the collectol at all

times.

Ho'uvever,

this approach

can lead to

rapid

detcrioration

in

the

glycol

and

is

not to

be

leconunended

lbr systems

with stagnation tenlPelatLrrcs

over 140'C-

8.2 PLANNING

AND DESIGN

TOOLS

Planning or design tools

can be split

ntto

tltce atcgorics: rules of

thurnb, where

the

rvhole

design

is

ptoduced using simple rules

of thulb based or.r

pooled

knorvlcdge;

diagtam-based

tools,

where simple calculatior.rs are

perforured

rvith

the

aid

of diagrams and

simple equations; and

cornputer-based

tools

r,vl.rere

detailed designs can

be rrade

using

specially designed computer

programs.

The

lattcr

can

be

split

into

several

sub

categorles

with

varying

deglees

of

detail

and

complexiry In addition

thcic

are lrlo /clcl-r

rf',/cs1grr,

from the overall sizing

ofthe

ettirc systcut,

principally the

collector and store, to detailed

sizing of snrcllcr

cottl])otletrts

such

:rs

pumps

and

pipes. The dctailed level

is, in plinciple, lhe saule as

for

other

types

of

heating s),stelr and

thc methods for design and

sizing

o{

thcse

small

cornponents

are

rvell knor'r,n.Thete

arc, of

coll$e,

a

number

of

difli:r'ent

tools

or

rules available, most

ofthem

being

lor

specilic countries

or

regions

because

of

varying

plurlbing practiccs and tr aditions.

Thcsc aIe

not

discusscd

hcr-e.


19/40

DIMENS ONING

OF SOtAR COMBISYSTEMS

209

Rules of thuurb ue vcry siruple for an1'one to undcrstand and

can

give

a

good

first

estirlrate lor system design. Thcy

often do

not

cover

the

ftill range of possible

:rpplicalions, or arc possibly

not

applicable fot

all

countries.They

may

also

valy

fi-om

systeln

to

svstelrl.

They

are,

however,

very

useful

as

overall guidelines

;rnd,

rvhere

possible,

rules of thumb havc bcen included

1n

the previous

section.There art

vely

Grv corumonly uscd di:rgr:rrl-b:rsed rools

for

solar combisystems. A nomogram

has

been cleared

rvithin

the rvork olTask 26 ancl is described in Section 8.2.1,

but

it is

restricted to the systems simulated in Task 26. Anorher

nontogranl including borh

solar conlbis),stenr

and

ho[

water systems

tvas created

as patt

ofa

Europe,It

prolect

(Karlsson

irnd

Zinko, 1997).

Task

26

has

developed a new

di:rgralr tool

using

the

FSC method developed u,ithin

Task

26. lt

is essentially

r diagram

based tool

made

iuto a

computer progr:rm

for

t'lexibiliry

It

is described

in

Section

8.2.2.A variation

of dragran-r-based tools is

forl'n

shccts,

r.vhere

one c:rn

go

through thc

sheet :rnd

mlke

simple calcr.rlations to arrive at sizes for conlpone[ts. This

approach can even

inclr-rde more detailed siziug.

Rules of thumb, manufacturers'

guidelines

and diagram

tools

Rules

of

thurnb, rnanufacturers' guidelines

and diagram

tools

are

sir.nple,

and give a

rough

approximation

of system

pcrlornurlcc

and required sizc for :i

given location

and

user'.

They arc

good

for

preplanning

and lor detelmining the

overiill

size

ofa

factory

made system

for

singlc-

or nvo-family

houses.The methods

ale

not

ahvays easy to apply to all locations and

cases.

Cornputer-based tools vary

gl'eatly in

conrplexitl-.

The

siruplest

programs

nuke

rough

calculations using

a

mixture

of

rules

of thr-urrb

and simple

cquations.

These

can be based on spleadsheets

or

on

a

calculation plograDl that is part

ofthe

tool and arc generally sir.nple to

use. The

level

of

detail var-ies

considerabiy

fiom

those that

give

only ror.rgh sizilig infomratiou to thosc'rhat give suggestions fol the

choice ofcomponents and ar1 economic suuunary.Thcsc tools do not make

detailed

tine-dependent simulatior.rs,

although they

do take into

account

tlte v:uiarion of

the

clirlate

ud

load over the

yerr'.

However, few

ofthese

cover solar combisystellrs.

Thc

lesults ar-e usually

in

the

lorm

of

annual and sorlletinles

nontbly values.

Tl1ey

do not simulate the dynanric behaviour ofthe systcm and

;rre theleforc sorlletirlles

referred

to as static calculation rools.An example

ofsuch a tool that car-r be used

for

solar combisystems is F-chalt liom tl.re

USA. It was the first of its kind,

being

developed in 1975.

F-chart

uses

its o\vn internal

comput:tional routines

based on

a special mcthod

of

the same

name

(Dul-lie

and

Becknun,

1991) and

is

quite

con-rplchcnsive r.vith

many

input paraDleters and scvelal

different system rypes.The

proglam,

it't

increlsiltgly

nlore

advanced

tbrms,

h:rs

been

available

for

ruany

year

s.

The desigr

program PSDMI, specific

to

Systen$ #1 and

#3 rvith

dilect solar floor

heating, is also available fiee

of chatge

lrom

the intcrnct.

The simplel

corirputer tools discr-1ssed abovc do not

take

into

account

the

dynan c behaviour

ofthe systent;rathcr Lhey r-nake usc

ofcorrelatiot-ls that are

often

empirical.

The lllore

detailed

simulatrol-i plogmnr,

however, can

take

inro

account

the

dynanric,

or

time

depeltdent, nature ofsystellls ro give more

accurxte rESLrlts

for

time periods

that are ofthc

same

order

of

r-nagnitude

as

the

tirlrc

co1$tants

ofthe


20/40

210

SOLAR HEATING 5Y5TEM5

FOR

HOUSEs:

A

DESIGN

HANDBOOK

FOR SOLAR COMB SYsTEMS

systenr

colnponents. These timc colls[ants rlrge fiolr secorrds for- tenrper-:rture

sensol-s

to hours

or-

days for- thc tl-rcr-mal storagc. Thcr-c ar'c two gr'ncric types of

dynamic

simulation

tools:

system-based lnd component-based tools.

Ststem

based

tools allorv

thc

Lrscr

to

choosc bctr,vccli

l

uunrber

of

drernativc

systenl coiligur:rtions,

and

thcn thc wholc systc-m is simulatcd. With

cornponent-

based tools

thc

L$c'r coDnects the

colrponcnts

of

the

system together atrd thfll

sinrul:rtes the u,holc group or systenl.This latter type oftool is much urore t'lexible

than the system-based one as any conliguration

can, in principle,

be

sirllulrted. TI1.

disadvantage is that the corlrpr-rtatiorl til11e is

olten

quite

long. as

the

tool has to be

robust enough to soh,e any

corubinarion

of components.

The

flcxibiliry;rlso

brings

with it

Adninistrative problems t'br the

user. It is

often more

difhcult to

keep track

ofrvhat

exactly

is

part

ofthe

systen and

to

make

sure

that all the vllues are as thel

shor-rld be. lt is thus rciatively

easy to

hive

errors,

in

the

fotm ofincorrect values lbr

par-ts

of

tl-re

systcm.This can also be true

for

systeru-based tools that

dlorv

the usel

to change l hrge nurrrber ofsystem

p:rlan-retels.

Computer tools

Sirnpler computer tools

allo\.

Drore detailed design of

the

systenr rvhile still

being

lelarively

casy to

use.A

variety

ofsystems and

a

lar-ge

numbet

oflocations

aud

loads

can bc simulated. Somc

morc

dctailed studies can be

calried out.They:lre

generally

suitable

fol

dinrelxioning

both

single- and

multi-lanrily

drvellings and

as

an:rid

in the design

plocess.

There are :i

lurDbcr of s.vsterrr-based

dynallric siD'tulation tools th:rt can simulatc

solar conlbisystcllls.

Examples

of

rhcsc arc

thc

conrrrcrcial

programs

Polysurr fr-olu

Slvitzcrland and

T-sol

fiom Ger-r'nany, and

the

utrrversrly-dcvcloped SHW-WIN

fiour

Austr-i;r. Polysun and T-sol are ar.ailable

in

several

l:inguages. including English

and Gernran. and

can sirnulate both solar dorucstic hot

water

systems ltnd

combisystems.They are botl-r easy

to use ald have signiEcant numbers

ofpatanletets

that thc

uscr can

vary'.

It

is also easy

to

inrport

lvcathcr data

Iiom

a rar-rge ofsources.

As

rhesc

plograms

use dilTerent

nrodcls, it is

not easy to

compare

,--esults

from

the

two

progr:r111s

with any

great irccuracy, cvcn

rvith thc

rcsults from Task 2(r. SHW-

WIN is

only

available

in Gernran,

but

is availablc fi'cc from thc internet.

Simulation

programs

Detailed sirnulation programs

require detailed

kr.rorvledge ofboth

the prograur

and the

physics

ofthe systen'r

to be

simulrted.They

are thus

genellily

only suitable

for

esperts

rvho

r.visir

to

clrry

orlt

detailed clevelopment

work

or

leseiuch.

Some

progralns c: n

generate.

based

on

the xdvanced lrodels, a simpler

tool

that can be

used b,v

non

expelts.

There is an

evcn

greatcr

mrrrrber

of conlponcut

o[

cqlration based dynamic

simulation tools

rhat

allorv simul:rtion

in

great

detail. All can in

principlc bc

uscd

to

simulate

solrr l-reating systems, but

in practice there

rre only

a Grv thlt

ar-e used

because it takes tinre to

build

databases

of

the

rclevant cornponents. Exanrples of


21/40

D MENSION NG

OF SOLAR COME]SYSTEMS

211

proglanrs

th:lt havc bt'en used

to

sinrulate

sollr hcaring systenrs

ilr-c Colsim, Sntilc,

IDA, M.rdab

Simulink and Dymola. Thcy each have

rheir own advantases

.rnd

disadvaotlges rvith respect

to

simuhting

sohl combisystc'ns,

but

none

ofthe111

was

uscd

\\,ithin

Task

26.

lnscead

Task

26

used

TRNSYS,

a

progl':rl.n

thirt

has

been

used

lor

over-25

yeirrs

lnd of

rvhich

there

is

a grcar

dc'al

of experiencc in

the solar'

he:rtinE

comnruniryWith TRNSYS

it

rs

possible

to take the

ver1.

dcrailed

s,vstenr

rnoclcl

and to cre.lte a simplc corrrputer application

rvith Grver v:rli:rbIes

open to the

user',;L so callcdTRNSED application. This can

be

used

by a

nruch

r,vidc.r gloup

of

people.

Morc dcrails ofT1\NSYS

can be

found

in Section 8.3.I .

SuruDariziirg, onc can s:1,v that the tools that

are sinlplc.st

to

use give thc' roughesr

cstinratcs and also tl-re le:rst

llexibility:.

At

drc other end of the

scale,

the

tools

otTer-ing

the greltest

accuracy

are

also

[u

mort

flerrble.

Horvcvc,r,

they tequrrc

cxpL-lt

knorvleclge

urd a grear

dcal

of et'Iort.

In

betu,een thcrc is :r r.vide langc

of

possibilitres allolving difeling degrees

of tlexibiliry

and ersc

of use.

8.2.1 The Task 26 nomogram

The hsk 26 nolrlogram

is

based

on thc FSC mcthod described

in

Section

(r.3

and

cin

be used

lbr

sizing l

giveD

systenl

or

cotrrp:rring different

systenrs.

It is

lintited

to

the

systems

:rnd clinratcs tiscd in Task

2(r,

but thc load can

be chosen

arbitmrily

The

nrethod

is described belolv,

togcthcr

rvich a small

version

of

thc

nonlollranr

(Frgurc

1,i.17).A copy of the nomogranl

can be downloadcd fiorn the Task 26

rvebsite

(http://r'r,rvrviea

shc.or

g/task26).

ln

Task 26, thc FS(l charlcteristics have

been

der-ived

fronr

the

results

of the

dctailcd sirnulations using

TRNSYS for

a

nurnbcr

of diffc'rcr-rr systcms.

A

list of thc systenrs

available in

the

nonroqr.lnr

rs

found in Table

8.'1.

Table

6

1 Lisl

at axes

fat

the faur dtagrams tn the namagram

X rxn

r)tgsL

t,I,:g4nNerer

Unit

I

2

3

I

Specilic collecror

l1)

I

m:/

Frr.rkrn.l

$hr

kwli .onnuDpdon

-

Fmctioml

energr'

srvings

l0'nrr/

Speclfic.rnnurl

kWh

elergl

sarings

111

'rrr/

Arnurl rel-ererce

kwh

consumptio.

-

Clnute

%

Srstenr

kWh/ml

The FSC

nonlogranl is designed for quick

estiluation of the ener-gy

savings, afrer

four pararrrctt-rs have

been chosen:

.

a system

.

a

climate

.

a

collector

area

.

a

Ieference

consuDlptiolt.

kwh


22/40

212

SOLAR HEAIING SYSTEMS

FOR HOUSES: A DES]GN

HANDBOOK

FOR SOLAR COMBISYSTEMS

The norrogram

is built witl.r lour dirgmms

(Figr.uc

8.16), connected together b)

conlnron axes, as

listed in Trble t3.1.Thc dilIcrcnt diagrarns and their

functions

are

as fbl1olvs:

.

l)iagram

l cdculates t1.re specific collector

arca

(,4/E,.,),

according

to

the

chosen collector area

and the chosen annual

tefetence consumption.

.

Di:rglanr 2 calculates the Fractional Sol:rr

Consurrptiou

(FSC),

;rccolding

to

th.'

specific collector area and the chosen climate.

.

Diagram

3 c:rlcuiatcs the

thermal

flacrional

energy s:Lvings (l-

.

,,,,,

,,),

:rccording

to

the

fi-:rctional solar

consumption and the

chosen

systern.

.

Diagranr

.1

c;Llculates

tl.re

annual energy

savings

({.,),

acco.di"g

to

the

specific

collector

area ancl

tl-re

thelnral

lractionll

energy

savings.

Alist of

the

intersections used in

thc

nonlogranr arid

their

meaning.

is givert in

Table 8.2.

Table

8.2.

Llst

of

intersectians used in the nomagtum and their neanlngs

Meaoins

b

d

f

g

h

i

j

k

I

kWh/r

10

I

m:/kWh

pcr

vclr

,L

Il.fcr.n.c

.o11\ur11ptrcn

Oigin ofth. s1rc(itl.

(ollectu

rrer uis

Specilic collcctor

erc'r

F

.rionrl Solir

(lonsunrptiorl

Fracrioml crcrg)

raringl

Annuil .nd.$ salings

8.2.1.1 Using the

nomogram

For

each step

thc

c\ample

values

lre

givclt

in

brackets

(see

Figure

lJ.1(r

for

dr.'

e\irinple

nomograrn

and

Figute

U.17 t'br an et'npry nonrograur pagc).

1. Cl.roosc an alurual reference consumption

E.i(a

=

22,(100 kwh).

The lefelerrce consLlmption

is

calculated according to

Tirsk 26 relerc'rrct

conditions:

-

Q,,+Q,,",'+Q

,,

''' 4r.",r,..

The

eficiencl'of

rhe reference

boilcr

is

0.85.The

yelrly

he:rt

losscs

ofthe

stolc'

are

calculated accordrng

to thc

daily

hot rvater

deurand

I/,

(litles/day),

in the

same

way

as

in ENV12977-2

(CEN,

1997)

(Table

8.3):

Q,,..,.,

:

(uA).,,,,.

.;(T.,,,*-7.,,,.

,,,r).i1760

in urrits

of

kwh/a

r.virh 7.,,,,.

:

52.5"C

(hor

rvarer renrperature) and

l.*.,,u

=

15'C

(:urbienr

teDlperatufe).


23/40

D MENSIONING

OF SOLAR

COMB SYSTEMS 213

Table

8.3 Calculated

yearly

heat lasses

Drilv

hor tvrrc.

d.DraDd I

(lioa'j/d)

llefer.encc

storc loscr

e.....

(kwh/r)

155

557

72n

TIJIJ

1r)l)

15i)

2r)(l

250

301)

2. l)rlrv

a

lirrc

fr-orrr point

a to the origin.

3.

(ll.roosc

r

collector

area

(c

=

28

nrr).

'{.

Dmrv

a holizontirl

line

Iionr

poinr

c until

r,on

meet

thr. seglllcr.rt

[ab]

xt

d.

5. Dlarv

r

verticJ

line fionr point

d uriril

,vou

nreet

thc diagonal

liuc

at e.

6. l)r'arv

a

hor-izontal

linc

liom

point

e

until

yoll

rlreer

the

vcrtical aris

at

f,

you

S'

t tlrc 'l'"''if,'

."llr'r"t

nt,n .l

\).

7. I)r au,

a

horizonral

line fr-orn point f

uutil

you

nlc.'t

the clirnate

cur-ve

(g

on

thc

cllrve

fbl

Zurich).

8.

l)r-arv

a

vcrtical

linc fiont poinr g

until

you nrect

the

horizontxl

axis at h; you

get

the

l'ractional

solar rorruirlprirrrr

(FSC

:

0.(r,i).

9.

I)r'arv:r

vertical

line

fiom

point

h until

1.ou

nrcct the

system clllve :rt i.

10. l)rarv

a

horjzontal

line &om point i

until

you

nteet

thc vertical

aris.rtj;

1ou

ect

thc

Jl'ddialnl

qrc

rg),

-r.lr,i

/iq-r

(f,,,t,,,,,,:

17%,).

11.

l)r

1r,,,

a

horizontal line li-onr pointj

until

you nrcet

thc vcrtical line

conrng

liom

e

at

point

k.

I 2.

I)mrv

a linc i}om

the

origin

b

to point

k.

and exrend rt if requircd.

Poir.it I at

the intelsection

of

this hne rvith

the cnctgl' savings

lxis

givcs

tl-re rprrlir

dinual ctlcr ),salrrlqs (kWh/rnr

per-

,vear)

corupared to

the

refer-encc

systc111

rvith mnual

boilcr-

elliciency

ol85%

(350

kWh/r'nr

pcr ycaf

.

Coloul ver-sions

ofboth

the c'xample

anci

the enlpt,v nonlograur

arc included

in

the

coloru- section.

8.2.2

The Task 26

design tool

Tl.rc Task

26

design tool, called

CourbiSun, is

b:rsed

on the FS(l mc'thod

descr

ibt'd

in

Sc'ction

(r.3.

The

FSC

value is dept'ndcnt

on the size

of the

collector, its

olientrtion

and

tl.re

total

load

ofthe

systent.lt is rhus possible

to csriluate

the stvings

ofan)

s)-ste1u using the FSCi

ch:u:rctelrstic ifone

knou,s the systcm

load:rnd

clinrate

as wcll :is

the

sizc ancl or_icnration

of thc

collectol-.

In

connast

to

the

lorlogr:urr,

this

tool

is

not

restrictcd

to

the

three

clinrates used

in

hsk

26.

as

it

conres

rvith

a

lxrger

d:itabase

of

difGlent

clinures.

Thc rool

can

be

dorvnloaded

i'j.cc of chargc

liour

tl,e Task 26 rvebsitc (hrtp:

//rvrvuriea-shc. or.g/task26,/).

Somc, of the derailed

TRNSYS

sirDulation nrodels

:uc avaihble llor1t

rheir-crc:rtors

asTrDsed

applicltions,

in rvhich

tl-re user. via

a sirnple inter{:rcc,

calr

vary

a limircd

number

of

the

m:rny

availrble pararucters.

CombiSun

is

aimed at :r

rvide

range

of user.s

and is desianed

pr

incip;r)ly

to

cnlble

users

to

nreke

a choicc

of thc

ovclall size ofthe systcur

for thc

gir.en

location

irnd


24/40


FOR HOUSES:

A

DESIGN HANDBOOK FOR SOLAR COIVIBISYSTEI'/S

s

{

I

I

f-l

Il

a

:

l

r :.

Qi

1

)/

:., .Lli

x


25/40

D MENSION NG OF SOLAR COMB SYSTEMS

215

'..i

R

\:

t,s

:i-

,ai

l ::

l3r.:

ir.

\;

l\

i',

I \E

l^.

1N \

a

a

l

s

\

9rr,

r.lr..r r :rrr3

l[r']

qo

*

-.a

,


26/40

216 SOLAR HEATING

SYSTEMS FOR HOUSES:

A

DESIGN HANDBOOK FOR SOLAR COMB

sYSTEN.4S

building

sizc. lt is rc':rlly a corrputet'ized

dirgrlrrl brsed rool nd is not proposcd;rs a

detailed desig[

tool- lt clll. horvever-, be used

to

colrpare

diIGr-enl systcn'l types lol the

sarne

conditions.

Several

of thc

systenr included in

the tool

arc

not

sold r'vith

ii

spccific

boiler:

rathe'r,

this

is

chosen by

tl.re

bu,ver

ol

instdler.This choicc grcatly

ailects

thc over-iill

slvings ofthc system.The boiiers

used

fbr-the sit'uulatioti ofthese

systeurs.

:rnd thus the basis of

thc

FSC characreristic,

r'r,ere

thc

stlndatd Task

26

boilels

(see

S,:'ction

(r.1.1

for mole- dctails).lt

is possible to estinute thc savings ofthese systems

using anothcl boiler'.

rf so desircd.The systems

inclucled in

(lombiSun

:uc those listed

inTablc 8..1.It

is possible to add ncrv systenls

to

the

pro€jr"r11

databasc'

as

long

as

thele

is an

FSC

characteristic

lot

the

system, r'elating

FSC

ancl Ii-actional

savings,

as

defined

by

Task

26.

This charactelistic

cl.r.

in

prir.iciple, be

caicr-rlated

using resuks

fi'otn

iurl

simulation

tool.

Thcorcticalll,

it

is

dso

possiblc

to

derrr,'e

:t

charrcteristic

based

on

monitored data, but this

drta is

uriikcly

to spau a

rvide enoug;h r':rnge of FSC values.

Table

8-4. Generic systems that are

included tn the destgn taal Cambisun. These are the same

as

are available

in the Task 26

nomagram

#2

#3x

#11

#15

Hert

cxchrngcr

bcmcen

,

o1le1to. l{)(,p

rnd

sfr.. h.xr rg lt

op

(D.Dnu

rl

Adnnccd

durcc roll

uo.r

(l'ru.e)

I)HW

t.,,,k rs r \fr.. h.rrlng sromgc dcli.c

(I)cnmrrk)

Spti.e

herring sror. \\'rh

do,ble

l.,rrL

srle

l,ert

tr.hrrs.r 1;r l)HW

(Switz.rland)

S,,,,,11

I)HW

rink

r

spicc

hcrtrug

ruk

(Norsrv)

Stu.e

herrmc ror.

(rh

DIIW l,t(l

ridc

he.it e\(l)riSU(.).n)d.\t.nul

elNilierr boilcr

lilo srrit i.r\ u r

\.r.e

lertins \tonst tlrk Nirh rn csrcnral loar:l si.lc hc.t c\chuqer

i;l

I)HW

((;.rDaDr)

Tlble 8.5 shorvs the user

inpr-1ts to the

Prcliram

rvhile

Figure 8.18

shorvs the

interactiorr

of

CombiSun

rvith the nser.

TRr\SYS i-r tt-tcd lo

-r/rtttlarc

the btilditt.q

ot

f

.""

/

FSC

lnpul

paramet

COMBISUN

Nlo Ilhly

radiation

&

loads

TRNSYS

MODEL

FigLtre

8.78.

lnfarmattan flaw tn

the

destgn taol Cambisun

R eport


27/40

DIMENSION

NG OF SOLAR

COMB]SYSTEI\45

217

dn l/l) r\,

1)d5i:

dltl

fo

cdl.:'

dte

lr

ihndintiott

ott

fltt dklsctt

callitot

otittttatiou

T

he oulput

fiom this

T1INSYS

silrlul:rlion

is theu

uscd

by CombiSul

to caictrl:rte

the

FS(l

virhrcs loL l

range

of collecror

sizt's.

Thc'

colrcsponding

cnergry

savings

alc

then

calculrtcd

for-

thesc collector

alcas and

thc

chost-t-t

systcrll, bxsed

on

thr' systelll

FSC

charactelistic.

Thesc

lestllts

arc then

rvt-ittcll out

in table

folur and

c:rn be

plotted

on

a diagrlm

such

as Figut'e

8

19-

Scveral diilercnt

plots clln be

rrltcle

o'

thr.- s:l1llc

cliagra[r.

lor-diiIercDI

systellls

or other

\.]riations

in

r,rsc'r' rnput.

Thc cliagtlrD

can

bc'

scald

"r'r,l

.rpoltcd

:rs a

\ePalatc

lile so tl-rat

1l clrn

bc

illcorPol:rtcd

itrto

Ieports'

A

stendard

rc'poit

caD:Llso

be cre:ltcd:ind

priuted

out.

ft is

possible to

add

additiorul

climiites

to

thc-

clat:rb:rsc.

Table

8.5.

The

user

inputs to Cambisun

Clnr

te

Trpc ol builling

Slopc

DLIW

l(,id

The clirmte

lor

the

crlcr rtioll

6om

I

d]ttrb,s(

ofclnnrt$.

The

user

crn

choose

hour dre

thrce Trsk

26 rngle

fxnih house

cor)\tru'don\

(iN,ltr

dri.kne$)

Floor

.re,] or

tl1.

building

fhe

rzrnuLh

ofthc colltctor

Ueld

The slope

oathe colle.tor

tleld

The

DHw

lord

for rhc

.rlcuhtiotl

lner{v

S.vinqs

lkwl,Yenrl

t

{

;

,

Colleclor

Arealm'zl

Figure B

7g.

Example

output cJiagram

lrom Combisun

for

the

same system

wth

10 m: af

callectar but tuva

diflerent

azinuths

(saLtth

east

and

sauth)


28/40


FOR HOUSES: A DESIGN HANDBOOK FOR SOTAR COMB SYSTEMS

As CorubiSun

is b:rsed on

the FS(l rr

ethod,

sotue

rrrajot assurllptiolls,:lnd

thc

r-csults

ofT:rsk

26-

thelr' aie

scvcral

liuritations

to

thc

tool.

Thcse

ale

suDrnilfized

in

T:rb1c

8.6.

Table

8.6. Limitatians/assumpttons

af

CambtSun

and

their implicatians.

Llnit.rrui/r$uDrltron

Lnpli.xtrcn

FSC lrlidit\

Fixed s\1teDr

parim.tcrs

S.lurgs

rehtilc to Tr\k

26

Onh

\\1tenr Nith r dctuc(l FSC .h,rr,rl:teristi. cin be crl.uhtecl

-lhese

nr^r

bc

prrt oI thr

progranr

rtrtrbrrc

Thc FSC n.thod is t1ot u..Lr te tor,rll

lurirtioni

ofdre

irpur lrrixble Se.

S..trcn 6.3. .l he

t,rogrrni

.loes

not

rllo\\

lrlues

lor

$hich nre nrenrod

n

The FSC nrethod

h.r

l,eer

nlidrted ibr r L:rv svstcms rnd r rv c'nnge of

input

luiible\

Ir i\ noi .ertrin rhrt it

r vrl

olcr

thc srnrc

rrngc lor

rni

5\stcn}

thxt

xrc

.dded

to

the

progranr

The

FSC.hrncteri\ti.

\nr crlculrrtd brscd

on

fLrcd prruictcr ulLr$ $ith.

li)r

esrlpl..

r

.lenne.l relrtionship between collector

sizc rnd

storc

vohule.

Ahentlons

ofudiviLlLul pxrllict.rs .on..rnnrg of.mtion. hc.t lo$e\ ct(.

..lrnot

b..dnde.There

is

dus

lLmitcd flclb

itv

The crlcrlrted

slings rr. rliti\'. to

tlic

Txsk

26 rclercncc

srsteur.

rvhich

hrr

r

s.\

blrr)er

wirh

85'.r,

ein.iLar.

th(Nithout thc krr, lndeFerd.'r1t

oflou.l.

Sr\n)gs rehrive

to orher boilcLs

oL

LclcLuice svstenr rvoulcl

nerd to be

cllclrhtcd

s.p.rirelv u ng thc nionthlv vrlLrcs oflorcl\ crl.uLtted Lr\

TRNSYS

i-or th. LIiLlDg

in

question

The

results

crlculatcd

by

thc

tool

alc

sarings

rvith

rcspcct to the

Task 26 leference

syslcm.

Thcsc rcicrence

collditiolls

irrc

Llseful

ill

oldel to cortlpare systr-nls

on

ill

ea}lil basis. Holcvcr,

user_s

ar-e

likely to want to cstinl:tc savillgri

corllpalc(l

to

I

speciflc

systcm thclr own or their

clietlts'

systelrr. I[

ordcr

to do

lhis,

ihe

co1lsuD1ptio11 of

the

user

spe.lficd

syste[r

rle"^ds

to be esti]]lated by

divid1lig rhc

r11o

thl,v

Ioxds by thc ruouthly boiler-

eflicicncy

of

that systct-n, and thcn sr.rmnrin(

these

nronthlv corlsr.1mptio11s- ln:r similar

wa),

the s:rri[ s

call l]c cstimaled lor i1

different

boilel

in the

sohr

heating systenr.

8.3

SIMULATION

OF SYSTEM PERFORMANCE

Task 2(r has uscd TI\NSYS

(K1ein

rt al.. 1991t) as thc tool lor siuiulation ofsystenr

pelfolDrurcc-

lt is

just

one

of sevelal

possiblc

tools,:rs

discusscd itr lhe prevrous

scctiorl.

It is a

moclul:rl

ploglam

widl e:lch

nlodule represe[ting a

partic]-1lar

conlPollel1l Or

grcup

of colllporlerlts

i1l

the

s,vstenl.

These

ale

Proglinl1llcd

ul

Foltrlli

aud

the soulce codc is avaiiablc to the user-.

TRNSYS has

been

usecl

lbr

over 25

,\'eArs

lbr

rhc

sir-nu1:rtior-r

of

solar

heating

s.vstems,

xnd there

is

wide

range

oi

cornponr-nt lllodels thiit

have

beeD

\-:llidlrcd ovcr lhc

,vcurs.

Dctails oi the

cot11pol1crlt Dlodcls that \ver-e usecl

in Task 26

can be

lound in

Section

1J.,1.

In

morr- r'nodern sinlLrlalion

progranl

such

as

Il)A.

Snlile

lnd

M;rt1ab Simrlilk.

rhe

process

of

crlculariorr

rs cLili:rclt to

tlut rn TII.NSYS.

In these

prcgftu1N the

eclLr.ltion5 used to

deline

tht' beh:rviour of

rht- irrdividu;

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Dimensioning of Solarcombisystem

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