General equation for box prediction?

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General equation for box prediction?

Postby waterlubber » February 23rd, 2019, 8:23 pm

I'm wondering if anyone has worked out an equation that allows for a general solution of box temperature prediction. I've found that T = a + e^(b + cx) where x is time and T is difference from room temperature closely fits my recorded data; however, a, b and c appear to be unpredictable for starting conditions (volume and starting temperature.) I'm wondering if anyone knows of a solution that works for various temperatures of a specific volume or similar equations.

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Re: General equation for box prediction?

Postby MattChina » February 23rd, 2019, 8:58 pm

waterlubber wrote:I'm wondering if anyone has worked out an equation that allows for a general solution of box temperature prediction. I've found that T = a + e^(b + cx) where x is time and T is difference from room temperature closely fits my recorded data; however, a, b and c appear to be unpredictable for starting conditions (volume and starting temperature.) I'm wondering if anyone knows of a solution that works for various temperatures of a specific volume or similar equations.

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Re: General equation for box prediction?

Postby CookiePie1 » February 23rd, 2019, 9:04 pm

MattChina wrote:
waterlubber wrote:I'm wondering if anyone has worked out an equation that allows for a general solution of box temperature prediction. I've found that T = a + e^(b + cx) where x is time and T is difference from room temperature closely fits my recorded data; however, a, b and c appear to be unpredictable for starting conditions (volume and starting temperature.) I'm wondering if anyone knows of a solution that works for various temperatures of a specific volume or similar equations.

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As a general warning, DON'T rely on an equation. Bad idea; just do the trials. Invest your time in good results.
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Re: General equation for box prediction?

Postby rohans415 » February 24th, 2019, 8:20 am

You could always run multiple trials (multiple temps, different volumes) and create a regression formula via StatsCrunch or some other program.

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Re: General equation for box prediction?

Postby JoeyC » February 24th, 2019, 8:25 am

Equations can never fully capture the essence of your device because it's not ideal, is always changing, and its surrounding factors are so many that a single equation cannot adapt effectively. I tend to just derive my k value of my device (via multiple trials over different temperatures and time spans) and then use that, trial data, and gut feelings to intuit what the final temperature will be.
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Re: General equation for box prediction?

Postby TheChiScientist » February 24th, 2019, 10:11 am

JoeyC wrote:Equations can never fully capture the essence of your device because it's not ideal, is always changing, and its surrounding factors are so many that a single equation cannot adapt effectively. I tend to just derive my k value of my device (via multiple trials over different temperatures and time spans) and then use that, trial data, and gut feelings to intuit what the final temperature will be.

Note that there are always just too many variables to factor in. No simple equation would be capable of calculating temp accurately given all those variables. Only multiple tests of your device will provide an accurate estimation.
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Re: General equation for box prediction?

Postby CPScienceDude » March 7th, 2019, 10:56 am

TheChiScientist wrote:
JoeyC wrote:Equations can never fully capture the essence of your device because it's not ideal, is always changing, and its surrounding factors are so many that a single equation cannot adapt effectively. I tend to just derive my k value of my device (via multiple trials over different temperatures and time spans) and then use that, trial data, and gut feelings to intuit what the final temperature will be.

Note that there are always just too many variables to factor in. No simple equation would be capable of calculating temp accurately given all those variables. Only multiple tests of your device will provide an accurate estimation.

I use an equation and its never more than a 2 degrees off
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Re: General equation for box prediction?

Postby JoeyC » March 7th, 2019, 11:36 am

Until your ESes use a broken thermometer. ;)
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Re: General equation for box prediction?

Postby TheChiScientist » March 7th, 2019, 12:35 pm

JoeyC wrote:Until your ESes use a broken thermometer. ;)

That or they use a more calibrated and accurate thermometer than yours. Or the other way around... :roll:
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Re: General equation for box prediction?

Postby CPScienceDude » March 7th, 2019, 12:43 pm

TheChiScientist wrote:
JoeyC wrote:Until your ESes use a broken thermometer. ;)

That or they use a more calibrated and accurate thermometer than yours. Or the other way around... :roll:

Wouldn't it make a difference no matter how you do your prediction?
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Re: General equation for box prediction?

Postby JoeyC » March 7th, 2019, 1:25 pm

Precisely. About 1/2 of my Thermo experience has gone down like state above.
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