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dA   0 , then internal energy of
system increases and as result of
such compression temperature of

system goes up ,

This phenomenon, called adiabatic
heating, is uses extensively in

Figure 2.8.2 technique, for example, in diesel
engine. A diesel engine (also known
as a compression-ignition engine) is an internal combustion engine that
uses the heat of compression to initiate ignition to burn the fuel that has

been injected into the combustion chamber.
The operation of diesel engine is illustrated in
the fig. 2.8.3Air with vapour of flammable

liquid is quickly compressed by piston, the
temperature of air grows (adiabatic heating),
and the vapour of liquid catches a fire.

And well determine work A done
12
by ideal gas in adiabatic process from state 1

with parameters p 1 ,V 1 ,T to the state 2 with
1
Figure 2.8.3
parameters p 2 , TV 2 2 (fig.2.8.4).
If we take into account that internal energy of gas in state 1 is

U   C RT and in state 2 it is
1 V 1

U   C RT work A done by ideal
2 V 2 12
gas in adiabatic process from state 1 to the
state 2 is equal to the change of its internal

energy:

A   C  T  T 2  (2.8.2)
12
1
V

Rewrite this equation in the next form

Figure 2.8.4

 T 2 
A 12   C V T 1  1  (2.8.3)


 T 1 

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