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,


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


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


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



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)


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.




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.




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


superheated state. So from steam table at 30 bars and temperature of 250oC


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


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.

solution chapter 4 (rayner joel)

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