increment in temperature of two-phase flow
 

Hello every one
I’m trying to simulate the evaporation of R410a in fluent.
These are some information about my case:
A 2-d axisymmetric smooth tube,
Refrigerant enters to the tube, diameter=9.52mm & length = 3000mm
inlet vapor quality = 0.2
Constant heat flux on the wall = 15 kw/m2
VOF multi-phase model,
turbulence model: k-e standard,
transient method, & time step = 1e-04
I put the liquid and vapor state of R410 in fluent material library. I used DuPont released information of R410.
when I plot temperature in outflow, there is a huge increment in temperature of mixture while the vapor quality is 0.4, it means that before all refrigerant transfer to vapor, the temperature began to increase, & as all we know that is impossible in reality.
Actually I repeated the simulation with water liquid and vapor instead of R410, but the result was same.
Does anyone have any idea why is this happening?
regards