Enthalpy Calculation In fluent
 

Dear All,
I am simulating a natural convection problem.The results shows that the Area-weighted average enthalpy at temperature 300 K is 1861.89 j/kg. I got this value for enthalpy at inlets, at interior and even at adiabatic wall, at all these locations temperatures are 300 K. But I do not understand how did fluent calculate this enthalpy?
Please help me.
Thanks...