If given a current temperature and relative humidity, I am interested in how to determine the relative humidity at a 2nd temperature, assuming all other relevant factors e.g.: dew point, absolute humidity, etc. remain constant.
Example: If T = t1 and RH = rh1, and temperature changes to t2, what then is rh2? (again, assuming nothing else changes that might affect RH in general.)
Yes there are formulas out there. Iâd have to do a lot of digging to find my old formulas. We used the formulas to determine enthalpy in the air. Then compare inside vs outside to see which is lower to determine going into economizer control. (Use of outside air to control the temp usually mixed air temp) if I recall it was a rather long formula.
lolâŚI am a bit red-faced (usually it is just my buttocks after a session). But your flagrant use of the word âenthalpyâ got me wound upâŚI honestly didnât think doing a search on the bulky, ambiguous set of terms âhow can I determine new relative humidity from current temperature and relative humidityâ would return anything helpful, but it did (although Iâve no way to validate accuracy of results:
There exists a formula for a reasonable approximation from about freezing to a few hundred degrees. I think it is cited in some ASHRAE standards. Way back in the windows 3.11 days, I worked for a company that wrote software to do manual J calculations, DoE energy loads and similar. I had worked on the âtoolboxâ program that had a lot of these little calculators built in, and back in â94 had actually found some of the references online. Sadly, a couple of years ago I was looking for the same thing, and had no luck finding it.
Hmm. Some of what you are looking for might be here:
There are a lot of different processes you can do to air, and while you are asking a valid question, it probably isnât in the top 10 from a HVAC engineer perspective. It almost might be more readily apparent from a meteorological study of psychrometrics, in that they usually arenât heating/cooling the air mechanically.