Page 240 - Advanced Thermodynamics for Engineers, Second Edition
P. 240
228 CHAPTER 10 THERMODYNAMICS OF COMBUSTION
Combustion equation is (Eqn (10.30))
þ U P T s :
U P T P ¼ ðQ v Þ þ U R T R U R T s
s
Conditions at start of combustion
k
V 1 1:4
p 2 ¼ p 1 ¼ 1:2 10 ¼ 30:142 bar:
V 2
k 1
V 1 0:4
T 2 ¼ T 1 ¼ 400 10 ¼ 1004:75 K:
V 2
Reactants energy [U R (T R ) U R (T s )] is
Constituent C 3 H 8 O 2 N 2
u 1004.7 106,690.3 23,165.0 22,013.6
u 298 12,911.7 6032.0 6025.8
Difference 93,778.7 17,133.0 15,987.9
n 1 5.882 22.12
nu 93,778.7 100,776.1 353,651.4
½U R ðT R Þ U R ðT s Þ ¼ 548206:2kJ:
Products energy at standard temperature, T s ,is
Constituent CO 2 H 2 O O 2 N 2
7041.6 7223.3 6031.7 6025.8
u 298
n 3 4 0.882 22.12
nu 21,124.8 28,893.2 5320.0 133,290.7
U P ðT s Þ¼ 188628:7kJ:
U P ðT P Þ¼ 46440 ð12 3 þ 8Þþ 548206:2 þ 188628:7
¼ 2043360:0 þ 548206:2 þ 188628:7
¼ 2780194:9kJ:
Assume T P ¼ 3100 K.
Constituent CO 2 H 2 O O 2 N 2
u 3100 143,420.0 114,194.9 84,974.72 79,370.95
n 3 4 0.882 22.12
nu 430,260.1 456,779.6 74,947.7 1,755,685.0
U P ðT P Þ¼ 2717672:4kJ:
