Download - Solution Chapter 4 (Rayner Joel)
Question No: 1
Given Data
Required:
Enthalpy, h
Volume, v
Density, ρ
Solution:
A. Enthalpy
a. From the steam table at , the saturation temperature is 263.9oC. The value for
specific volume , liquid enthalpy and enthalpy
of evaporation
B. Volume
C. Density
Question No: 2
Given Data
Mass of the Steam Present , m = 4.5 kg
Pressure of the steam, P = 20 bar
Temperature, t = 300oC
Required:
Enthalpy, H
Volume, V
Density, ρ
Solution:
A. Enthalpy can be find with two methods
a. From the steam table at 20 bar, the saturation temperature is 212.4oC. Thus the steam is in
superheated state. So from steam table at 20 bars and temperature of 300oC
The Enthalpy, h = 3025 kJ/kg,
b. Alternately, it can be find with
So
B. Volume
C. Density
Question No: 3
Given Data
Pressure of the steam, P = 18 bar
Temperature, t = 320oC
Required:
Specific Enthalpy,
Specific Volume,
Solution:
A. Specific Enthalpy,
a. From the steam table at 18 bar, the saturation temperature is 207.1oC. Thus the steam is in
superheated state. So from steam table at 18 bars and temperature of 320oC, we need linear
interpolation for enthalpy and specific volume
For the temperature of 320oC, which is not given in steam table we need to interpolate
between temperature of 300oC and 350oC for specific enthalpy.
So
b. Specific volume,
Again, for the temperature of 320oC, which is not given in steam table we need to
interpolate between temperature of 300oC and 350oC for specific volume.
So
Question No: 4
Given Data
Required:
Solution:
A.
a. Consider the surface condenser
Let
Condenser is a constant pressure system and energy transfers will therefore appear as
changes in enthalpy; (neglecting losses)
Or
Or
From the steam table at , the value for liquid enthalpy and
enthalpy of evaporation
Also, from the steam table at , the value for liquid enthalpy and
similarly, for temperature of and , the value of liquid enthalpy is
and respectively
So
Question No: 5
Given Data
Required:
Solution:
A.
B.
Specific enthalpy before throttling = Specific enthalpy after throttling
From the steam table at , the value for liquid enthalpy and
enthalpy of evaporation ; also at ,the saturation
temperature is 104.8oC the value for vapour enthalpy
The Enthalpy, h1 = 3095.1 kJ/kg,
C.
Question No: 6
Given Data
Required:
Solution:
A.
a. From the steam table at , the specific volume
For the specific volume with ,
Now for the mass,
For enthalpy at at dryness fraction of 0.72
For enthalpy at at full dry saturated
For the heat transfer
For total heat transfer for mass
B.
a. For work transfer at
So the percentage of heat transfer which appears as work transfer
C.
a. For enthalpy at
Where
So
Total Heat transferred
Question No: 7
Given Data
Required:
Solution:
A.
a. Consider the surface condenser
Let
Condenser is a constant pressure system and energy transfers will therefore appear as
changes in enthalpy; (neglecting losses)
Or
Or
From the steam table at , the value for liquid enthalpy and
enthalpy of evaporation
Also, from the steam table at , the value for liquid enthalpy and
similarly, for temperature of and , the value of liquid enthalpy is
and respectively
So
Question No: 8
Given Data
Required:
Solution:
A.
a. Specific enthalpy of the steam before throttling
From the steam table at , the saturation temperature is 212.4oC. The value for
specific volume , liquid enthalpy and enthalpy of
evaporation
Also, for the specific volume, v
Now, combining the above equations
B.
C.
Specific enthalpy of the steam before throttling = Specific enthalpy of the steam after throttling
From the steam table at , the saturation temperature is 188.0oC. The value for
specific volume , liquid enthalpy and enthalpy of
evaporation
Question No: 9
Given Data
Required:
Solution:
A.
a. From the steam table at , the saturation temperature is 212.4oC. So the steam is
superheated steam. From superheated steam table specific volume
For the specific volume after expansion,
Now, condition of steam
B.
a. For enthalpy at and
b. For enthalpy at
So
C.
From the steam table at , the value for specific volume ,
liquid enthalpy and enthalpy of evaporation
D.
a. For enthalpy at
b. For enthalpy at
So
Question No: 10
Given Data
Required:
Solution:
A.
Specific enthalpy of the steam before mixing = Specific enthalpy of the steam after mixing
a. Specific enthalpy of the steam before mixing
As the steam is in superheated state; so from superheated steam table at 40 bars and
temperature of 375oC (By interpolating between 350oC and 400oC)
The Enthalpy, h1 = 3155.4 kJ/kg,
b. Now for the wet steam after mixing, h2
Now, the mass of the output steam is
B.
Now, the internal diameter of the steam pipe is
Question No: 11
Given Data
Required:
The heat transfer during compression,
Solution:
A.
a. From the steam table at , the value for specific volume
Now the quality,
B. The heat transfer during compression,
a. For specific enthalpy at
b. For specific enthalpy at 8 bar
Now, the heat transfer
Total heat transfer
Question No: 12
Given Data
Heat Capacity of superheated steam, Cp = 2.1 kJ/kg K
Required:
Solution:
A.
a. Specific enthalpy of the steam before throttling
From the steam table at , the saturation temperature is 217.2oC. The value for
specific volume , liquid enthalpy and enthalpy of
evaporation
Specific enthalpy of the steam after throttling
From the steam table at , the saturation temperature is 104.8oC. So the steam
is superheated steam. From superheated steam table specific enthalpy at 109.6oC
(Using double linear interpolation between saturation temperature
and 150oC)
Now, combining the above equations for enthalpy before and after throttling
B.
Question No: 13
Given Data
Required:
The change in the specific internal energy of the steam,
Solution:
A. Quality of the steam mixture, x
a. From the steam table at , the value for specific volume , liquid
enthalpy and enthalpy of evaporation
Also, from the steam table at , the value for specific volume ,
liquid enthalpy and enthalpy of evaporation
Now the quality,
B. Density of the steam
C. The change of specific internal energy of the steam,
a. For specific enthalpy at 1.5 bar
b. For specific enthalpy at 7 bar
Now, the change in internal energy
Question No: 14
Given Data
Required:
Solution:
A.
a. Specific enthalpy of the steam before throttling
From the steam table at , the saturation temperature is 217.2oC. The value for
specific volume , liquid enthalpy and enthalpy of
evaporation
b. Specific enthalpy of the steam after throttling
From the steam table at , the saturation temperature is 104.8oC. So the steam
is superheated steam. From superheated steam table specific enthalpy at 109.6oC
(Using double linear interpolation between saturation temperature
and 150oC)
Now, combining the above equations for enthalpy before and after throttling
B.
Question No: 15
Given Data
Required:
Solution:
A. Quality of the steam mixture, x
a. From the steam table at 30 bar, the saturation temperature is 233.8oC. Thus the steam is in
superheated state. So from steam table at 30 bars and temperature of 250oC
The Enthalpy, h1 = 2854.8 kJ/kg,
b. Now for the wet steam, h2
Now, net enthalpy of the mixture is
c. The steam after mixture is also at 30 bar, so then
B. Density of the steam
Question No: 16
Given Data
Required:
Solution:
A.
From the energy flow equation (neglecting change in kinetic and potential energies)
a. From the steam table at , the saturation temperature is 250.3oC. Thus the steam is
in superheated state. So from steam table at and temperature of 350oC
The Enthalpy, h1 = 3095.1 kJ/kg,
b. Now for the steam at exhaust, h2
Now, change in enthalpy here is given as work done (also neglecting any heat transfer loss)
c. The theoretical output power from the turbine
B.