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Thread: Formula / Code for r410a

  1. #1
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    Formula / Code for r410a

    In school for software engineering, and playing around at the house with some raspberry pi products trying to make a “garage digital gauge” basically. Won’t be used in the field or anything.

    My formula doesn’t seems to work right to get saturated temperature from pressure.

    T = P(V) / nR

    Works spot on with are base line at 75*f or 25*c but drastically drops or increases with pressure.

    Anyone with a formula or code for R410A?

    I’m using python to write everything.

  2. #2
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    Mar 2018
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    I haven’t ever plotted 410 PT but I’m guessing since the formula doesn’t work it’s not linear. Plot the pt chart in excel then add a trend line with the best r value and use that formula.
    "I think Quantum tunneling would work great... "

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  3. #3
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    Quote Originally Posted by JayMan7 View Post
    I haven’t ever plotted 410 PT but I’m guessing since the formula doesn’t work it’s not linear. Plot the pt chart in excel then add a trend line with the best r value and use that formula.
    I was messing around with a similar project in Python a few years ago and this is how I went about it.

    Saturated_Temperature = ((-0.00000000000005945075 * float(Refrigerant_Pressure) ** 6)
    + (0.00000000012222562999 * float(Refrigerant_Pressure) ** 5)
    - (0.00000009952385989983 * float(Refrigerant_Pressure) ** 4)
    + (0.00004124614025621030 * float(Refrigerant_Pressure) ** 3)
    - (0.00954589335695664000 * float(Refrigerant_Pressure) ** 2)
    + (1.49598421107793000000 * float(Refrigerant_Pressure))
    - 54.37257646747130000000)

    This is the polynomial algorithm that I generated in excel that got me close enough for a working proof of concept (I had to search up a really old reddit post that I made almost 3 years ago on a deleted account to find this, lol). It's close enough, but I think I remember that it got quite inaccurate at extremely high pressures. Probably not the most efficient code either. There is an engineering program called REFPROP by NIST that generates accurate polynomial formulas for most refrigerants and has Python libraries - but it being engineering software it is quite expensive if you're just trying to use it for a DIY project, around 325$.

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