Sigma Programmable Object - What formula is used to calculate Enthalpy?

Issue

How is Enthalpy calculated in Sigma?

Product Line

Satchwell Sigma

Environment

Programmable Object

Prog Point

Enthalpy

Cause

Customers request for this information.

Resolution

A Programmable Object calculates Enthalpy using the following formula.


I = 1.006 * t + x * (2501 + 1.8 * t) where

t is the temperature and  

x = 0.62198 * (í * pdm / (p - í * pdm)) and at p = 101.325 kPa =>

x = 0.62198 * (í * pdm / (101.325 - í * pdm))    


where   í is relative humidity and    

pdm = p` = 101325 * 10A   where  


A = A0 - A1/T - A2*logT - A3*10(-T/A4) + A5*10(A6/T)   where


A0 = 20.82648355  

A1 = 2948.997118  

A2 = 5.02808  

A3 = 29811.33781  

A4 = 32.923061  

A5 = 25.21934913  

A6 = 1302.8503  


T = absolute temperature = 273.15 + t