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Absolute Humidity / Calculate "Power of x" in SIMPL+
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Hi there, does anybody have some experience with converting relative humidity to absolute humidity, using SIMPL+ and is willing to share? In the project at hand, a ventilation system is supposed to bring down humidity in an underground cellar. Since warm air can hold more water, blowing warm air into the cool cellar might actually lead to water in the warm air to condense in the cool cellar. Therefore the absolute humidity in grams per cubic meter has to be taken into account. Only if the absolute humidity outside is below the absolute humidity inside the fan should blow fresh air into the cellar. So far, I have installed two C2N-RTHS, one inside the cellar and one outside. So temperature and relative humidity are available. I also found a formula for MS-Excel that works fine there. But I have trouble to implement the formula in SIMPL+, as there is no "power of x" operator of function available. The Excel formula looks like this:
where aH is the absolute humidity, rH the relative humidity and T is the temperature in degrees Celsius. Does anybody have a module that does the conversion or can hint how to do the conversion in a Crestron system in general or how to implement the formula above in SIMPL+? Any help is appreciated! Thanks! Markus |
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Kool-Aid Drinker
S+ is not the right tool.
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Yes, you could in theory slog your way through calculating the result using Taylor-series, power-series, and associated limits methods. But it will be very slow and won't be worth your time unless you're an obsessive math geek. Only slightly easier would to use the log/anti-log symbols in Simpl... Use S#, or query a server, or build a big look-up table. On 21 Sep 2014 06:15:21 -0700, crestron@... wrote:
Hi there, |
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You can get close using fixed point math and Taylor series in S+, but it's not exactly straightforward. There's a thread on here from 2009 about calculating rH from temp and dew point, it looks like it would be similar.? If you're on 3 series, though, S# is a much better route.
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On the other hand, unless you are in this for a technical exercise to improve your skill rather than make money . . . It would probably be more straightforward to just build a lookup table for (13.233*10^x) since there are relatively few points to evaluate. ?The temperature in the cellar should be almost constant, the outdoor temperature should also fall into a relatively small range, and it would seem that the temperature need not be carried out to decimal places. ?Just run a big sheet in excel and use the values from it. ?If you use your rounding to err on the side of not letting the outside air in you should be able to ensure the conditions are met. From: "Jeremy Weatherford jweather@... [Crestron]" <Crestron@...> Reply-To: <Crestron@...> Date: Sunday, September 21, 2014 at 6:25 PM To: Crestron <Crestron@...> Subject: Re: [Crestron] Absolute Humidity / Calculate "Power of x" in SIMPL+ ?
You can get close using fixed point math and Taylor series in S+, but it's not exactly straightforward. There's a thread on here from 2009 about calculating rH from temp and dew point, it looks like it would be similar.? If you're on 3 series, though, S# is a much better route. On Sep 21, 2014 9:16 AM, "crestron@... [Crestron]" <Crestron@...> wrote:
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¿ªÔÆÌåÓýHi, Thanks everybody for your advice! :-) I went down the lookup table lane. My first attempt didn't work out, as the array seems to have been too big... the 41x71 array was too much. SIMPL+ would neither find an error nor put out a warning. It just didn't link the compiled file, while SIMPL Windows gave an error that the Crosscompiler might not be installed... Now that I have scaled ?down the integer array to 31x31 everything works as desired! Thanks again to everybody for your support! :-) Markus Von meinem iPhone gesendet
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