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' (t f 1 ' ' t  f 2 )  (t " f 1 ' t  f 2 )
t  , (6.7)
' t ' ' t 
ln f 1 f 2
" t ' t 
f 1 f 2

For the above formulas all symbols are given at the signatures of figures (Fig. 6.1).
For the diagrams of cross-flow and other more complex schemes of fluids flow the
average temperature difference is determined from the formula

Δt = ·Δt – for parallel, (6.8)

where  - is the amendment which is determined from auxiliary schemes
based on two auxiliary variables;
Δt – the log mean temperature difference for parallel fluid flow
' t f 1  " t f 1 " t 1 f ' t  f 2
R  , P  (6.9)
" t  ' t ' t ' t 
f 2 f 2 1 f f 2
The temperature of the hot fluid at the outlet of the heat exchanger

 t 1 f  T 4  273 2 , (6.10)
The temperature of the hot fluid at the outlet of the heat exchanger
q  G
r

t  f 1  t  (6.11)
f 1
W
The water equivalent of the fluid:
W  G  C pm (6.12)

The temperature of the cold fluid inlet and the heat exchanger
t p 2  T  273, 2 (6.13)
2
The temperature of the cold fluid outlet of the heat exchanger
q  G
t  f 2  t f 2  r (6.14)
W

6.6 The variables of the working fluid at the points 5 and 6 of a gas turbine cycle
with regeneration heat are determined by the following equations:
a pressure P 5 = P 1 = P 4 ; P 6 = P 3 = P 2

a temperature Т 5 = t  + 273,2 ; Т 6 = t  + 273,2
1 f f 2
T T
the specific volume   R 5 ;   R  6
5 6
P P
5 6
T T
the change of specific entropy S  C  ln ; S  C  ln 6
5
1 5 pm 2 6 pm
T T
1 2
6.7 According to the calculated parameters, to put points 5 and 6 on the working and
heat diagrams.

6.8 Using the found temperatures build the circuit flows in the heat exchanger on a
sheet of graph paper size A4 (Fig.6.1).

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