Page 51 - DJJ20063- Thermodynamics 1

DJJ20063- Thermodynamics 1

Feedback to Activity 2C

o
2.6 From the superheated table at 120 bar, the saturation temperature is 324.6 C.
Therefore, the steam is superheated.

o
o
Degree of superheat = 500 C – 324.6 C
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= 175.4 C

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So, at 120 bar and 500 C, we have
-2
3
v = 2.677 x 10 m /kg
h = 3348 kJ/kg

 From equation 8.6,

u = h – Pv

-2
3
2
2
= 3348 kJ/kg – (120 x 10 kN/m )(2.677 x 10 m /kg)
= 3026.76 kJ/kg

2.7 At 160 bar, hg = 2582 kJ/kg. This is less than the actual specific enthalpy of

3139 kJ/kg. Hence, the steam is superheated.

From the superheated table at 160 bar, the specific enthalpy of 3139 kJ/kg is located at a

o
temperature of 450 C.

o
o
The degree of superheat = 450 C – 347.3 C
o
= 102.7 C

3
-2
o
At 160 bar and 450 C, we have v = 1.702 x 10 m /kg

 From equation 2.6,

u = h – Pv

3
2
2
-2
= 3139 kJ/kg – (160 x 10 kN/m )(1.702 x 10 m /kg)
= 2866.68 kJ/kg
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