This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: PROBLEM ll?
KNOWN: 'I'utal tleet' space and vertical distance between tleui‘s let a square. tlat i'net‘huilding. FINI): [a] lixpi‘essiun t‘ei' width et‘htiilding which minimises heat less. [h] Width and number ot‘tleei's
which minimixe heat loss liar a prescribed tlimJ‘ space and ilistnnce between tlnnt's. tfni‘i‘espmttling heat hiss. percent heat luss reduction ti'unt 2 Hours. SCI IlthNI‘IC': .’\S§il.ll\ll"l'l{)NS: Negligible heat loss te ground.
.’\N.:\l.\'$§: [a] To minimise the heat less at. the exterior sui‘t‘ace area. As. must he minimized. From
Fig. [a]
A5 = w? — JAR"H = tit'3 + 4WN ['H [s
where Nf = Alf/W3
Heneet At. = w? +4tt"Ay H 1» / w? = W3 — 4st H {/w The optimum value et‘W eoi‘iespends to. (1W w 2 L'.‘[' '14 _. .1..
X’s0P = (2AI~H1\_} < The competing effects ent‘W en the areas et‘the i'eet‘and sitleik'alls. and hence the basis for an optimum. is
shewit schematically in Fig. [b]. 7
[b] For Af= 32.768111" antl Hf= 'l nt‘  .].3
j
W. = 2x32..7(~.2<m”><41n) =h4in < Continued PROBLEM 3.1? (Cont) Hence
1
Af 32.?63m“
NT“ 2 j: .—1 Z x
W ' {\ 1’14 [11)“
and
9 9 4/12 Than? \4111 n
q = LJAQAT = ] W/m‘  K_ [(14111)‘ I 251" = 30.1300“:
‘  Min
For Nf= 3
W = [ Af.ijll"'3 = (312.7(wa 1113.3)":2 = [IX [11
')
\ ' “" Th — ' q=1W/n'121< [12Hm_}2  251‘ =512.mmw IEXm '.'u reduction in q = [5 13mm— 31}?.3{I{}j.5 1 2mm = 40‘11'. (UNIMEN'I‘S: Even the minimum heat Jess is excessive and [:0qu be ['CLIUCCLI by reducing LJ. ...
View
Full Document
 Spring '10
 LEE,J.S.
 Redox, Heat Transfer, Negligible heat loss, percent heat luss, heat loss liar, square. tlat i'net‘huilding, 'l nt‘

Click to edit the document details