A

I saw this formula in this forum, but this was put it here two years ago:

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Here's a short BASIC program that calculates the enthalpy using dry bulb temperature and releative humidity.

10 REM ENTHALPY CALCULATION

20 REM Assumes standard atmospheric pressure (14.7 psi), see 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 )

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But the problem is that

According to the formula, the results that I get are not acurate,

maybe

I'm putting something wrong when I calculate the "L" I check everything, But I don't get it.

Can somebody help me?

The air inlet that I have is 100°F and the humidity is 40%RH.

The enthalphy is sopposed to be in 42.9 BTU/LB according to the machine results, but I'm getting 24 BTU/Lb with this formula, what could be wrong????

Does anybody has another formula to calculate the enthalphy of the air to avoid using the psychometric char????