Reply To: Energy conservation/balance in mixture multiphase

[Amir]

 

Boundary Conditions:

        The chamber and soil outter walls have zero thickness and zero heat flux.

        The rest of the walls (interior walls and those between soil and pipe, and pipe and fluid) have zero thickness and thermaly coupled.

        Internal fan has constant pressure jump profile with 60 Pa (pushes the fluid down from left and the flow gets circulated counter-clockwise).

 

        I repeated the simulation with all the fluid zones (chamber and inside the pipe) having same initial temp, and soil and pipe zones having the same initial temp. With Dry Air and Humid Air.

        For Dry Air there was no discrepancy: heat transfer was from hotter zones to the colder and at the end, Total Energy lost by hotter zones(soil and pipe) is equal to the total energy gained by the colder zones. Total Energy and Enthalpy were also same initially and at the end of simulation.

        For Humid Air, there was discrepancies: Total Energy lost by hotter zone was not equal to the total energy gained by the colder zone. Change in system total energy and enthalpy was the same, but they were not conserved!

        Two cases of Humid Air:

        1-Air at 15C with 80%RH and solid at 27C went to —->>>> Air at avg 26.3C and 7%RH and solid at avg 26.9C. 137.9g of Liquid Water was generated. The change for both Total Energy and Total Enthalpy was: -3.4e+08J.

        2-Air at 27C and 80%RH and solid at 15C went to—->>>> Air at avg 29.6C with 14%RH and solid at avg 15.22C. 535.3g of liquid water was generated. The change for both Total Energy and Total Enthalpy was: -7.2e+08J.