# Nusselt Number Correlation

1. Dec 6, 2016

### cruckshank

I am looking for a Nusselt number correlation that will work for a shell & tube heat exchanger in the Re < 3000 region, i.e. extremely laminar flow (for a lab experiment).

I've been searching for a while now, but can only find empirical correlations for Re > 3000, and was thus hoping that someone could point me in the right direction.

2. Dec 6, 2016

### BvU

Slightly annoying. First it posts the same thing three times, then it deletes the first while I 'deleted' 2 and 3. Great.

http://www.itcp.kit.edu/deutschmann/img/content/Doppelrohrwaermeaustauscher.pdf page 9 (Hausen 1959)
http://www.zogg-engineering.ch/MVTTVT/Buch_WuS.pdf page 29 (Stephan 1959)

Both occur in my Waermeatlas (1984 ! ) where there is also Schluender (1972) $$\operatorname {Nu_0} = \sqrt[\uproot{4} \leftroot{-4} \scriptstyle 3]{ \; 3.66^3 + 1.61^3 \, \operatorname {Re}\,\operatorname {Pr}\,d_i/l \; }$$

All in German, all for flow through pipes

3. Dec 7, 2016

### Staff: Mentor

The equation BvU gives a good approximation for laminar flow heat transfer in a tube, including both the thermal entrance region and for distances beyond the thermal entrance region. This equation applies to a constant wall temperature.