ChemE 260

Phase Equilibrium and Thermodynamic Data Tables

Dr. William Baratuci

Senior Lecturer Chemical Engineering Department University of Washington TCD 2: C & D CB 2: 5+ April 1, 2005

Thermodynamic Data Tables

• • • Baratuci ChemE 260 April 1, 2005

Four Tables in a Complete Thermodynamic Data Table

– Saturation Temperature Table – Saturation Pressure Table – Subcooled Liquid Table – Superheated Vapor Table

Cengel & Boles Outline

– Steam Tables, SI & AE – R-134a , SI & AE – I will provide ammonia tables if and when you need them

Thermo-CD

– Steam Tables, SI & AE – R-134a Tables, SI & AE – Ammonia Tables, SI & AE

Baratuci ChemE 260 April 1, 2005

Single Interpolation

Baratuci ChemE 260 April 1, 2005

Double Interpolation

VLE Nomenclature

• Mole Fraction: • Water / Air

y i

• Partial Pressure: • Ideal Gases:

P i P i



y P i

• Vapor Pressure:

P i *

• Condensable and non-Condensable Species • Evaporation: Baratuci ChemE 260 April 1, 2005 • Boiling:

P total P i *

 

P i * T liquid

  

T liquid P total

 

P i

Baratuci ChemE 260 April 1, 2005

Humidity and Saturation

Baratuci ChemE 260 April 1, 2005

Next Class

• Equations of State – A relationship between P, V and T – Your favorite: IG EOS: PV = nRT – Many other better EOS’s exist – We will consider 5 others • The Virial EOS • The Van der Waals EOS • The Redlich-Kwong EOS • The Soave- Redlich-Kwong EOS • The Compressibility Chart Graphical EOS

Example #1

• • • •

Specific Volume of Saturated Mixtures

– Calculate the specific volume for the following situations: • Water at 200 o C and 80% quality • Freon 12 at -60 o C and 90% quality • Ammonia at 500 kPa and 85% quality

Ans.:

V = 0.1022 m 3 /kg

Ans.:

V = 0.57476 m 3 /kg

Ans.:

V = 0.21435 m 3 /kg Baratuci ChemE 260 March 29, 2005

Example #2

• The temperature of 10 lb m of water is held constant at 205 o F. The pressure is reduced from a very high value until vaporization is complete. Determine the final volume of the steam in ft 3 .

• Ans.: V final = 307 ft 3 Baratuci ChemE 260 March 29, 2005

Example #3

• • R-134a is contained in a sealed glass vessel at 50 o C. As it is cooled, droplets are noted condensing on the sidewalls at 20 o C. Find the original pressure in the vessel.

Ans.:

P 1 = 658 kPa Baratuci ChemE 260 March 29, 2005

Example #4

• Determine the volume occupied by 10 kg of water at a pressure of 10 MPa and the following temperatures: • T = { 5, 200, 400, 800, 1500, -10 } o C •

Ans.:

V(5 o C) = 0.009957 m 3 • •

Ans.:

V(200 o C) = 0.011482 m

Ans.:

V(400 o C) = 0.26436 m 3 • •

Ans.:

V(800 o C) = 0.48629 m

Ans.:

V(1500 o C) = N/A Baratuci ChemE 260 • March 29, 2005

Ans.:

V(-10 o C) = N/A 3 3

Example #5

• Determine the missing property values in the table below for a system that contains pure H 2 O.

a.) b.) T ( o C)

65 244

P (kPa)

25.03

226

V (m 3 /kg) U (kJ/kg)

2300

H (kJ/kg) X (kg vap/kg tot)

Baratuci ChemE 260 March 29, 2005

Example #5 – Answers

• Determine the missing property values in the table below for a system that contains pure H 2 O.

a.) b.) T ( o C)

65 244

P (kPa)

25.03

226

V (m 3 /kg) 5.736

1.107

U (kJ/kg)

2300

2721.3

H (kJ/kg) 2443.6

2958.0

X (kg vap/kg tot) 0.926

Superheated

Baratuci ChemE 260 March 29, 2005

Example #6

• A small rigid cylindrical vessel contains 1 kg of humid air at 80 o C under a total pressure of 1 bar. The humid air inside the vessel contains 0.150 kg of water vapor. Determine the relative humidity of the air in the container.

•

Ans.:

h r = 46.7% Baratuci ChemE 260 March 29, 2005

Example #7

• An unknown amount of water and 5 kg of a non-condensable gas (Molecular Weight = 40) are produced in an industrial plant at a temperature of 70 o C. These products are sent to a rigid storage tank. The pressure and relative humidity in the tank are 2 atm and 65% respectively. Determine the mass of water present in the tank. Assume that the gas behaves as an ideal gas.

•

Ans.:

m H2O = 250 g H 2 O Baratuci ChemE 260 March 29, 2005