Density of Saturated Vapor R-134a

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Discussion Overview

The discussion revolves around calculating the thermodynamic properties of R-134a, specifically focusing on the saturated vapor properties. Participants explore various methods and resources for achieving accurate calculations, including equations of state and existing data sources.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant is developing a program in Octave to calculate thermodynamic properties of R-134a using equations from a Dupont properties booklet, noting that their results for liquid density and saturated pressure are close to published data.
  • Another participant provides a link to a NIST resource for saturated properties of R-134a but expresses uncertainty about the differences between standard R-134a and the Dupont version.
  • A participant mentions they can effectively use tables to find properties at specific conditions but seeks a programmatic method for calculation.
  • One suggestion involves using an equation of state published in a referenced paper to calculate the properties.
  • A later post indicates a need for clarification on using the MBWR equation of state, particularly regarding the calculation of volume and the potential use of a guess and check routine to achieve acceptable error margins.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the best method for calculating saturated vapor properties, with multiple approaches and resources being discussed without resolution.

Contextual Notes

There are limitations regarding the assumptions made in the calculations, the dependence on specific equations of state, and the potential need for iterative methods that remain unresolved.

Who May Find This Useful

This discussion may be useful for individuals interested in thermodynamics, particularly those working with refrigerants and seeking to understand or calculate their properties programmatically.

Nugget_Mon
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Hi all,

Just for fun I am writing a program in Octave for calculating the thermodynamic properties of R-134a. I am using the equations in the Dupont properties booklet.
http://www2.dupont.com/Refrigerants/en_US/products/Suva/Suva134a.html

My functions for calculating the liquid density, liquid volume(of course), and the saturated pressure are less than 0.5% off of the published data.
My question is what am I missing to calculate the saturated vapor properties?

Thank You,
MON
 
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You can find the saturated properties of "regular" R134a here: http://webbook.nist.gov/chemistry/fluid/, but I'm not sure what the difference is between standard R134a and the dupont one, which seems to be made to function more effectively as a replacement in R12 systems.
 
Right, I have that link as well.
I can use the tables effectively, and I have found the properties at the conditions I needed (55/100)degF. My question is one of curiosity at this point. How to calculate it programmatically.
 
Using an equation of state such as what is published in this paper - http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JPCRBU000023000005000657000001&idtype=cvips&prog=normal
 
Last edited by a moderator:
Bump.
 
What, our answers weren't good enough? Don't just bump the thread, elaborate what it is you're still looking for
 
I guess I must have a subscription at work for the link I provided earlier, but a quick google search reveals that http://www.nist.gov/srd/PDFfiles/jpcrd480.pdf. Again, that is the equation of state for R134a that several computer programs use for property data.
 
Sorry about the delay. My question with the MBWR equation of state was determining the Volume from inside the summation. I can't directly solve for it, so I am assuming I need to put it into a guess and check routine until the error falls into an acceptable range?
 

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