please give us the mathematical equation between relative humidity and difference of wet and dry bulb temperature

 

Probably, can create a calculator in Excel, in an afternoon. Here's the link to equations:

"www.ageng.ndsu.nodak.edu/envr/PsycEqns.htm
":http://www.ageng.ndsu.nodak.edu/envr/PsycEqns.htm

The description is a bit dry.

 

i hope this article helps you!

Water Vapor Myths:
A Brief Tutorial by Steven M. Babin, MD, PhD

"meto.umd.edu/~stevenb/vapor/index.html":http://meto.umd.edu/~stevenb/vapor/index.html .

 

> please give us the mathematical equation between relative humidity and difference of wet and dry bulb temperature

Here's a short BASIC program for calculation of enthalpy from dry bulb temperature and releative humidity.

10 REM ENTHALPY CALCULATION
20 REM Assumes standard atmospheric pressure (14.7 psi), line 110
30 REM Dry-bulb temperature in degrees F (TEMP)
40 REM Relative humidity in percentage (RH)
50 REM Enthalpy in BTU/LB OF DRY AIR (H)
60 T = TEMP + 459.67
70 N = LN( T ) : REM Natural Logrithm
80 L = -10440.4 / T - 11.29465 - 0.02702235 * T + 1.289036E-005 * T ^ 2 - 2.478068E-009 * T ^ 3 + 6.545967 * N
90 S = LN-1( L ) : REM Inverse Natural Logrithm
100 P = RH / 100 * S
110 W = 0.62198 * P / ( 14.7 - P )
120 H = 0.24 * TEMP + W * ( 1061 + 0.444 * TEMP )

Hope this helps.

Zvi Marcus
[email protected]

 

> Water Vapor Myths: A Brief Tutorial by Steven M. Babin, MD, PhD
>
> http://meto.umd.edu/~stevenb/vapor/index.html

Yes that is a very interesting and informative article on the nature of humidity and vapor pressure. But he errs in his belief that the temperature of the air has nothing to do with humidity. While air and water vapor are not in solution as such, they co-exist at the same temperature. Consequenty the water vapor is subject to the gas laws and these determine how much water can be in a vapor state as "humidity" not the temperature of the liquid from which the water is evaporating.

Regards
Erich Mertz
[email protected]

 

If a high accuracy solution is required this can become rather involved. The solution requires; partial pressures, steam table algorithms, etc.
We have developed our own software for the solution. Please contact me if you would like further details.

John Catch
http://inflowinc.com
e-mail: [email protected]