A mass of 2.5 kg of saturated water vapor at 100 kPa is heated at constant pressure until the temperature reaches 200°C. Calculate the work done by the steam during this process. Use steam tables.

Respuesta :

Answer:

the work done by the steam during this process = 119.575 kJ

Explanation:

From the information given:

At state 1

Let obtain the specific volume of the saturated vapor from the Saturated water- Pressure table A-5 at the pressure of 100 kPa

[tex]v_1 = v_{g \ 100 \ kPa)[/tex]

[tex]v_1 = 1.6941 \ m^3 /kg[/tex]

where [tex]v_1[/tex] is the specific volume of the saturated vapor at state 1.

At state 2:

From the tables A-6 of Superheated water at the pressure of 100 kPa or 0.1 MPa and at the temperature of 200°C, the specific volume [tex]v_2 = 2.1724 \ m^3 /kg[/tex]

where [tex]v_2[/tex] is the specific volume of the superheated water at state 2.

The workdone by the steam during the process can be expressed by the formula:

[tex]W = P(V_2 -V_1)[/tex]

[tex]W = mP(v_2-v_1)[/tex]

where;

m = mass of the saturated water vapor

P = pressure of the saturated water vapor

[tex]V_2 =[/tex] volume of the superheated water at state 2

[tex]V_1 =[/tex] volume of the saturated water at state 1

Replacing our values ;

W = 2.5 (100) ( 2.1724 -1.6941)

W = 250(0.4783 )

W = 119.575 kPa.m³ [tex]\times \dfrac{1 \ kJ}{1 \ kPa.m^3}[/tex]

W = 119.575 kJ

the work done by the steam during this process = 119.575 kJ