Chemical Engineering - Heat Transfer - Discussion

Dittus boelter equation used for turbulent.

Dittus boelter and seider tatte equation both are used for turbulent flow but only difference between both two is that dittus boelter does not account for viscosity change due to wall temperature whereas seider tatte does.

Sieder-tate equation is being used for turbulent flow.

For a fluid to be heated flowing through pipe requires a contact time between the heat source and the fluid (whose temperature is to be raised). Now if the flow is highly turbulent; the contact time between the flowing fluid and the source is almost negligible so the convective heat transfer coefficient does not get affected.

One should also keep in mind that the use of baffles in heat exchangers is practiced to increase the contact time between hot and cold fluids. This also leads to increase in heat transfer coefficient.

Yes @Sandeep you right Dittus bolter equation use in turbulent & reverse it sieder-tate equation for laminar.

Nu is constant, In the case of laminar flow in a tube so the answer must be laminar.

@Yash Sieder Tate equation is for <2000 Re so it is laminar regime. Dittus bolter equation is use for > 4000 Re it's turbulent regime. So you are wrong.

@Aksh.

There is a Sieder-Tate equation for turbulent Re>6000 where Nu = 0.027(Re^0.8)(Pr^1/3)(mu_b/mu_w)^0.14.

It should be laminar because Russell's number is independent of the tube length-to-diameter ratio in a circular pipe.