[Hai-users] Temperature & Humidity sensor (fwd)

[Paul Whyte]

Looks like an uphill battle given the tool we have to work with (PC
Access!!!). I take it nobody has any creative code they wish to share that
deals with this issue (and overcomes HAI's programming limitations)?

Paul 

-----Original Message-----
From: hai-users-bounces at tssi.com [mailto:hai-users-bounces at tssi.com] On
Behalf Of Mike Nolan
Sent: November 1, 2005 10:09 PM
To: hai-users at romaine.tssi.com
Subject: Re: [Hai-users] Temperature & Humidity sensor (fwd)

> If anyone has access to an ASHRAE book the enthalpy chart is in there. 
> It's not a simple algorithm. If you see the chart you'll know why, 
> nothing linear about it. However, since memory is cheap these days and 
> with some constraints on the input variables (limit the temperature 
> and humidity inputs to reasonable values) you could probably come up with
a lookup table.
> Would take some time but you'd only have to do it once.

I haven't done thermodynamic calculations since I was an undergrad at
Northwestern.  :-)

I don't have the book, here's a paper that includes an enthalpy graph. 
It should be possible to pull several values directly off the table and
interpolate enough to build a simple table.

http://ohioline.osu.edu/aex-fact/0120.html

And here's a site that you can download a humidity calculation app from.
You will need IE with Active-X enabled:
http://www.thunderscientific.com/web_humicalc/index.php
--
Mike Nolan

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