Rob
Ansys Employee

The HTC is based on a reference temperature: that's in the Reference Values in Fluent. You may be better off looking at the different HTC reports: the solver will be correct (if converged) but the reference may differ making comparison difficult. 


Note, 50micron tubes are very small, so you may also be missing some physics in Fluent. This also assumes your experimental rig is accurate enough at this scale.