HT-028_SOLUTION.docx

CHEMICAL ENGINEERING SERIES: HEAT TRANSFER SOLVED SOLVED PROBLEMS PRO BLEMS

Consider a composie !a"" #a inc"$des an %&mm #ic' #ard!ood sidin( )'* +,+-. /0m1234 .+& mm 56 78+&mm #ard!ood s$ds )'* +,79 /0m123 on +,9&m ceners !i# ("ass ;i5er ins$"aions )paper&;aced4 <% '(0m 83 )'* +,+8% /0m1234 and a 7<&mm "a6er o; (6ps$m )=ermic$"ie3 )=ermic$"i e3 )'* +,7> /0m123 !a"" 5oard, /#a is #e #erma" resisance associaed !i# a !a"" #a is <, m #i(# 56 9, m !ide )#a=in( 7+ s$ds4 eac# <, m #i(#3?

So$rce: F$ndamena"s o; Hea and Mass Trans;er 9 # ediion4 56 Incropera4 e a" SOL@TION:

Mode o; Hea Trans;er: cond$cion !i# resisances in series and para""e"  RT 

1

 R wall= 10

( ) 1

=

10

 RT 

 R T = R A + R¿ + R D

1

 RT = R A +

1

 R B

 R A =

 R B =

 x  A k  A  A  A

 x B k B  A B

+

=

=

1

+ R

 D

 RC 

0.008 m

 

(

0. 094 094

W  m ∙ K 

)

( 0.65 m x 2.5 m )

0.130 m

(

0.16

W  m ∙ K 

)

( 0.04 m x 2.5 m )

ENGR, RONNIE V, FLORES

=0.0524

= 8.125

K  W 

Pa(e 7

K  W 

CHEMICAL ENGINEERING SERIES: HEAT TRANSFER SOLVED PROBLEMS  R C =

 R D=

 x C  k C  AC 

=

 x  D k  D  A  D

(

=

 R T =0.0524

0.130 m

  0.038

W  m ∙ K 

(

0.17

K  W 

W  m ∙ K 

)

= 0.0434

( 0.65 m x 2.5 m ) 1

+

1

K 

+

W 

+ 0.0434

1 2.2433

K  W 

K  W 

10

K  W 

ENGR, RONNIE V, FLORES

W 

K  W 

W 

W 

 R wall= 0.18537

K 

 m ∙ K 

K 

1.8537

 R wall=

( 0.6 1 m x 2.5 m )

0.012 m

8.125

 R T =1.8537

)

=2.2433

Pa(e <