Environmental Engineering Reference
In-Depth Information
(A)
w
converter
combustor
T , H , S
ad
ad
ad
, p
T , H , S
T , H , S
, p
Q
s
l
l
l
E
EE
0
0
surroundings
T , p ,
∆
S
s
0
0
(B)
combustor
T , H , S
Hl
T , H , S
Fr
Hl
Hl
Fr
Fr
Q
r
w
converter
regenerator
T , H , S
ad
ad
ad
, p
T , H , S
T , H , S
, p
Q
s
l
l
l
E
EE
0
0
surroundings
T , p ,
∆
S
s
0
0
(C)
combustor
T = T
Fc
C
w
1
converter I
Q
s1
T , H , S
CCC
T , H , S
Fc
Fc
Fc
w
regenerator
converter II
Q
r
T , H , S
, p
T , H , S
, p
Q
s2
E
EE
l
l
l
0
0
surroundings
T , p ,
∆
S
s
0
0
FIGURE 1.14
Steady flow models of heat engine: (A) ordinary combustion, (B) with a
regenerator, (C) with an isothermal combustor/converter.
efficiency of isothermal combustion is always higher than that of the isenthalpic
one; particularly, the former still remains considerably high efficiency when the
latter starts to fall. Actually, the efficiency of isothermal combustion reaches as
high as that of Carnot cycle in the temperature range when the thermal dissociation
in burned product is negligible. It is clear now that the contribution of heat-
recirculating combustion in raising thermodynamic efficiency is significant even
at low temperatures where the efficiency of isenthalpic combustion is not high,
although we tend to think that raising the maximum temperature is the only way
to get higher efficiency.
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