Theory 15/Prandtl Number/Heat exchangers
Fouling Depends on Prandtl
The claim
Fouling rate in a heat exchanger is set by the Prandtl number at the wall, so a fluid with high thermal diffusivity fouls differently at the same velocity.
01Mechanism
Deposition requires the wall to be cool enough for precipitation while the boundary layer transports material; the ratio sets both.
02Prediction
Fouling should track wall Prandtl.
03Refutation
Fouling tracking velocity would remove the ratio.