Page 386 - Advanced thermodynamics for engineers

16.7 CONCLUDING REMARKS 375

100
Residual
80 fraction
Pressure (bar) 60 40 0.050
0.100
0.150

20

-50 0 50 100 150
Crankangle (deg atdc)

FIGURE 16.20
The effect of residuals (exhaust gas recirculation (egr)) on cylinder pressure.

3000

2500
Temperature (K) 2000

1500
burned, res = 0.05
burned, res = 0.10
1000 burned, res = 0.15
unburned, res = 0.05
500 unburned, res = 0.10
unburned, res = 0.15

-40 -20 0 20 40 60 80 100 120 140
Crankangle (deg atdc)
FIGURE 16.21
The effect of residuals (exhaust gas recirculation (egr)) on burned and unburned gas temperatures.

16.7 CONCLUDING REMARKS

Having spent the initial chapters of this book developing thermodynamic theory the reader has at last
been introduced to actual ‘hardware’. Brief descriptions of engine combustion chambers have been
given, and analysed to examine the basic principles that have affected their design. It has been
demonstrated that the thermodynamic engineer has to try to manipulate the real world to achieve the
aim of high efficiency along with reduced emissions.
This chapter has brought together the theoretical developments in Chapters 3 and 15. It shows how
actual cycles differ from the heat engine cycles and even air-standard cycles that form the basis of much
fundamental thermodynamic analysis. While pointing the engineer in the right direction these under-
estimate the influence of the extraneous influences. An excellent demonstration of this is that an engine