Help with refrigeration properties table

In summary, the conversation discusses the discrepancies in enthalpy values for R-22 between a textbook and online sources. The blue values from the internet are considered to be correct, while the red values from the textbook are consistently lower by approximately 154 kJ/kg. The difference may be due to enthalpy being defined relative to a reference state, rather than an absolute value.
  • #1
VooDoo
59
0
Hey guys,

Just a bit stuck with getting enthalpy values off a table I have in a textbook.

If we look at R-22 for example, the textbook gives me different answers than what is available on the net. If I use the values that are given to me on the net I get the correct value.

The blue ones are what seem to be the correct enthalpys, the red is what my textbook has given to me. Why is there always a ~154kJ/kg difference for the enthalpies between my book and the correct answer?(for both saturated liquid and vapour and it seems the same for superheated vapour)
 

Attachments

  • Untitled.jpg
    Untitled.jpg
    17.6 KB · Views: 371
Engineering news on Phys.org
  • #2
enthalpy is defined relative to a reference state, it isn't the absolute value.
 

1. What is a refrigeration properties table?

A refrigeration properties table is a reference tool that contains data on the thermodynamic properties of various refrigerants at different temperatures and pressures. It is used by engineers and technicians in the design and maintenance of refrigeration systems.

2. How is a refrigeration properties table organized?

A refrigeration properties table is typically organized in a tabular format, with columns for temperature, pressure, enthalpy, entropy, specific volume, and other relevant properties. The rows correspond to different refrigerants or refrigerant blends.

3. What information can be found in a refrigeration properties table?

A refrigeration properties table contains data on the physical properties of refrigerants, such as boiling point, critical point, specific heat, density, and viscosity. It may also include information on the refrigerant's environmental impact and safety considerations.

4. How is a refrigeration properties table used?

A refrigeration properties table is used to determine the properties of a refrigerant at a specific temperature and pressure, which is necessary for the proper design and operation of a refrigeration system. It can also be used to compare different refrigerants and select the most suitable one for a particular application.

5. Are refrigeration properties tables available for different units of measurement?

Yes, refrigeration properties tables are available in different units of measurement, such as SI units (e.g. Kelvin, bar, kJ/kg) and Imperial units (e.g. Fahrenheit, psig, Btu/lb). It is important to use the correct units when using the table to avoid errors in calculations.

Similar threads

Replies
7
Views
759
  • Mechanical Engineering
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
6
Views
698
  • Mechanical Engineering
Replies
1
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
10
Views
1K
  • Materials and Chemical Engineering
Replies
10
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
3K
Replies
1
Views
3K
  • Materials and Chemical Engineering
Replies
10
Views
5K
Back
Top