This is from Fundamentals of Engineering Thermodynamics, 6th edition. Chapter 7,
ID: 1816398 • Letter: T
Question
This is from Fundamentals of Engineering Thermodynamics, 6th edition. Chapter 7, problem 22. Exergy analysis of a closed system.Here is the full problem:
Refrigerant 134a vapor initially at 1 bar and 20oC fills a rigid vessel. The vapor is cooled until the temperature becomes -32oC. There is no work during the process. For the refrigerant, determine the heat transfer per unit mass and the change in specific exergy, each in kJ/kg. Let T0=20oC, p0=0.1MPa and ignore the effects of motion and gravity. Here is my problem: The solution is given on this site. I'm stuck on Step 3, when it gives values for specific volume/internal energy/ and entropy. It says that they get the values from R134a tables, and I see the "f" values on table A-10, but I don't know what the "fg" values are or where they got them from. I know that in later steps those are used for determining the quality of the mixture at T=-32C, but where did that value come from to begin with (and what is it?) Thank you.
Refrigerant 134a vapor initially at 1 bar and 20oC fills a rigid vessel. The vapor is cooled until the temperature becomes -32oC. There is no work during the process. For the refrigerant, determine the heat transfer per unit mass and the change in specific exergy, each in kJ/kg. Let T0=20oC, p0=0.1MPa and ignore the effects of motion and gravity. Here is my problem: The solution is given on this site. I'm stuck on Step 3, when it gives values for specific volume/internal energy/ and entropy. It says that they get the values from R134a tables, and I see the "f" values on table A-10, but I don't know what the "fg" values are or where they got them from. I know that in later steps those are used for determining the quality of the mixture at T=-32C, but where did that value come from to begin with (and what is it?) Thank you.