LAST/FIRST NAME: _________________ _________________ MEEN MEE N 207 EXAM-II EXAM -IIII
ELEMENT ELE MENTRY RY THERMODYM THER MODYMENI ENICS CS FALL 06
Q#1
A Carn! Carn! "a! "a! n$%n n$%n r&%' r&%' "a! a! 7(0 7(0 ) an* r+& r+&!, !, !" !" a,! a,! "a! ! ! !" n'%r n'%rn. n.n! n! a! 00 ) T" n!%r r !3! 4 !" "a! n$%n %, ,* ! *r%' Carn! r4r%$ra!r !"a! r.', "a! 4r. &5* ,3a& a! -1(C a! a ra! 4 00 8/.%n an* r+&!, %! ! !" ,a. n'%rn.n! a! 00 ) D!r.%n9 a !" ra! ra! 4 4 "a! "a! ,335% ,335%* * ! !" !" "a! "a! n$%n n$%n an* an* ; !" !!a5 ra! 4 "a! r+&!%n ! !" n'%rn.n!
Q#2
S!a. S!a. n!r, n!r, a*%a a*%a;a! ;a!%& %& !r;%n !r;%n ,!a*%5 ,!a*%5< < a! 7 M=a9 M=a9 (00C9 (00C9 an* ( ( ./,9 ./,9 an* 5a' 5a',, a! 100 =a an* 7( ./, I4 !" 3r !3! 4 !" !r;%n %, ( M> an* %,n!r3%& 44%&%n&< %, 77 ?9 *!r.%n9 a !" .a,, .a,, 45 45 ra! ra! 4 4 ,!a. ,!a. !"r !"r$" $" !r;% !r;%n n ; !" !.3ra!r a! !" !r;%n @%! & !" ra! ra! 4 4 n!r3< n!r3< $nra!%n $nra!%n *r%n$ *r%n$ !" !" 3r&,, 3r&,,
Q#
S!a. S!a. a! 6 M=a M=a an* (00 (00C C n!r, n!r, a !!-,!a ,!a$ $ a*%a;a a*%a;a!%& !%& !r; !r;%n %n a! a! a ra! ra! 4 1( $/, $/, 10 10 ? 4 !" ,!a. %, @!ra&!* a! !" n* 4 !" 4%r,! ,!a$ a! a 3r,,r 4 12 M=a 4r !"r , T" r.%n*r 4 !" ,!a. %, 4r!"r @3an** %n !" ,&n* ,!a$ an* 5a', !r;%n a! 20 =a D!r.%n !" 3r !3! 4 !" !r;%n9 a,,.%n$ a !" 3r&,, %, r'r,%;5 an* ; !" !r;%n "a, %,n!r3%& 44%&%n&< 4 ?
Dr =ana+ C"an*ra
1
MEEN 207 EXAM-III
ELEMENTRY THERMODYMENICS FALL 06
A#1
Analysis Ba T" &44%&%n! 4 3r4r.an& 4 !" Carn! r4r%$ra!r %, CO=R9C
1 =
1
(T H / T L )
1
−
=
( 00 ) ) /( 2(A ) )
1
=
61
−
-15 C °
T"n 3r %n3! ! !" r4r%$ra!r ;&., 00 8/.%n n#!9%n = QL = = 6(1 8/.%n W CO=R9 C
750 K
400 kJ/min
QH, HE HE
R
QL, HE
61
n#!9 2! "%&" %, a5 ! !" 3r !3! 4 !" "a! n$%n9 W
QH, R
300 K
T" !"r.a5 44%&%n&< 4 !" Carn! "a! n$%n %, *!r.%n* 4r. η !"9C
=1−
T L T H
= 1−
00 ) 7(0 )
= 060
T"n !" ra! 4 "a! %n3! ! !"%, "a! n$%n %, *!r.%n* 4r. !" *4%n%!%n 4 !"r.a5 44%&%n&< ! ; H 9 HE = W n#!9 ! = 6(1 8/.%n = 108.5 kJ/min Q 060
η !"9 HE
Bb T" !!a5 ra! 4 "a! r+&!%n ! !" a.;%n! a%r %, !" ,. 4 !" "a! r+&!* ;< !" "a! n$%n B Q L 9 HE an* !" "a! *%,&ar** ;< !" r4r%$ra!r B Q H 9 R 9 L 9 HE = Q H 9 HE −W n#!9! =10 ( −6( 1 = 8/.%n Q H 9 R Q
= Q L 9 R +W n#!9 %n = 00 +6( 1 = 6(1
8/.%n
an* A.;%#n! Q
= Q L 9 HE +Q H 9 R = +6(1 = 508.5
Dr =ana+ C"an*ra
kJ/min
2
A#2
Assumptions 1 S!a*< 3ra!%n$ &n*%!%n, @%,! 2 =!n!%a5 nr$< &"an$, ar n$5%$%;5 Analysis Ba T" 3r3r!%, 4 !" ,!a. a! !" %n5! 4 !" !r;%n an* !" n!"a53< a! !" @%! 4r !" %,n!r3%& &a, ar BTa;5 A-6
P 1 =
7 M=a h1 = 11 8/$
T 1 = (00° C s1 = 6A000 8/$) P 2 = 100 =a h2 s = 2666 8/$ s 2 = s1 = 6A000 8/$)
Steam, 7 Ma 500 C, 45 m/! °
T" 3r !3! %4 !" @3an,%n a, %,n!r3%& 5* ; a (000 > W W 6E > s
=
=
η T
077
Turbine
=
An nr$< ;a5an& n !" !r;%n 4r !" %,n!r3%& 3r&,, .a< ; ,* ! *!r.%n !" .a,, 45 ra! 4 !" ,!a.
100 ka 75 m/!
V 12 V 22 +W s h1 + h2 s + m = m 2 2 B( ./,:2 1 8/$ B7( ./,: 2 1 8/$ +6 11 8/$ + m m = + 266 6 8/$ 2 2 2 2 2 2 1000 . /, 1000 . /, = 6.886 kg/s m Bb An nr$< ;a5an& n !" !r;%n 4r !" a&!a5 3r&,, .a< ; ,* ! *!r.%n a&!a5 n!"a53< a! !" @%!
2 = m h2 + V 2 + W 2 2 2 2 B( ./,: 1 8/$ B7( ./,: 1 8/$ = + B6AA6 $/,: 11 8/$ + B 6 AA6 $/,: h + (000 2 2 2 1000 . 2 /, 2 1000 . 2 /, 2 h2 = 26A( 8/$
h1 + m
2
V 1
a
N9 !"r 3r3r!%, a! !" @%! ,!a! .a< ; ;!a%n*
P2 = 100 =a
T 2 = 103.7° C h2 = 26A( 8/$ s 2 = 7A17 8/$)
Bc S%n& !" !r;%n %, a*%a;a!%&9 !" n!r3< $nra!%n %, !" n!r3< &"an$ 4 ,!a. a, %! 45, %n !" !r;%n Dr =ana+ C"an*ra
$#n S
= m B s 2 −s1 : = B 6 6
$/,:B7 17 - 6000: 8/$) = 4.01 kW/K
A#3
Assumptions 1 T"%, %, a ,!a*<-45 3r&,, ,%n& !"r %, n &"an$ %!" !%. 2 )%n!%& an* 3!n!%a5 nr$< &"an$, ar n$5%$%;5 3 T" !r;%n %, a*%a;a!%& an* !", "a! !ran,4r %, n$5%$%;5 Properties Fr. !" ,!a. !a;5, BTa;5, A- !"r$" 6
P 1 = 6 M=a h1 = 21 8/$
T 1 = (00°C s1 = 6AA26 8/$ ⋅ ) P 2 = 12 M=a
h2 = 2E62A 8 / $ s2 = s1 s s − s f 6AA26 − 0A20 = = 0A((2 P = 20 =a x s = s fg 707(2 s = s1 h = h + x h = 2(12 + ( 0A((2 )( 2(7() = 2267( 8/$ s f s fg Analysis Ba T" .a,, 45 ra! !"r$" !" ,&n* ,!a$ %, 0 Em 1 ( 0E)(1( $/, ) 1( $/, m =
=
=
> !a !" n!%r !r;%n9 %n&5*%n$ !" &nn&!%n 6 M=a 3ar! ;!n !" ! ,!a$,9 a, !" ,<,!.9 "%&" %, a (00 C &n!r5 '5. ,%n& .a,, &r,,, !" ;n*ar< N!%n$ !"a! n 45%* ,!ra. n!r, !" !r;%n an* STEAM ! 45%* ,!ra., 5a'9 !" nr$< ;a5an& 4r !"%, 1( $/, ,!a*<-45 ,<,!. &an ; @3r,,* %n !" ra! 4r. I a, 12 M=a °
E − E %n 2!
=
Ra!# 4 n#! #n#r$< !ran,4#r ;< "#a!9 -r19 an* .a,,
STEAM 1( $/,
E ∆ ,<,!#.
0 B,!#a*<:
10?0?
I I 20 =a
=0
Ra!# 4 &"an$# %n %n!#rna59 1%n#!%&9 3!#n!%a59 #!& #n#r$%#,
E %n = E 2! Dr =ana+ C"an*ra
1h1 m
=
1 −m : h2 Bm
! W
+
h m
! W
=
1h1 − B m 1 −m : h2 m
−
h m
=
1 B h1 − h2 : + m B h2 m
+
−
h :
S;,!%!!%n$9 !" 3r !3! 4 !" !r;%n %,
! W
= (1( $/, )(21 − 262)8/$ + (1( $ )( 262 −2267()8/$ = 16,291
kW
Bb I4 !" !r;%n "a, an a*%a;a!%& 44%&%n&< 4 ?9 !"n !" 3r !3! ;&., a =η T W s = (0AA )(1692E1 > ) = 14,336 kW W
Dr =ana+ C"an*ra
(
