Chemical Reactions

15.5 Adiabatic Flame Temperature
Adiabatic Flame Temperature = Maximum limit of combustion
gas temperature of each Air – Fuel mixture
(Adiabatic Flame Temperature = Combustion Temperature)
Q cv =0,W cv =0 ,∆KE=,
KE=∆PE=0 :
1 st law
_
_
Qcv
+ ΣNi
hi
= Wcv
+ ΣNe
he
ΣN
R
{
_
o
h f
_
ΣN
i
_
o
_
h
+ ( h−
h )}
i
= ΣN
R
e
= ΣN
_
h
P
e
{
_
o
h f
To Calculate the adiabatic flame temperature, T P
1. Write the combustion equation
2. Apply energy balance (1 st law)
3. Solving by trial-and
and-error technique by assume a value of T P
get values…and
and
substitute in (2) ….LHS = RHS ..if not try new T P
….. (in good procedure we can
interporate the former value to get the right value of T P
_
_
o
+ ( h−
h )}
P
• What is your first guess of T
• What should be the 2 nd trial.
• How about the 3 rd , 4 th ......
• When/how to interporate
a
b
Trail and error procedure
LHS - RHS = Error
T
T 2
T c
Interporation
T b
T a
c
T 2
E 2
T a -E a
T b -E b
T 2
0.0
T c +E c
T 2 = 342 o C
m i =1.263 kg
-E a -E b E = 0
+E c
Error
18