# Heat transfer - generator losses and dissipation

1. Jul 22, 2011

### Turbo14

I am currently working on a small personal project.

It is a small under-water generator/ motor so the setup is as follows. The generator and gearbox are mounted on steel struts within an air-tight nacelle of sorts which is cylindrical and made of steel. The nacelle is submerged in cold water which will be flowing past. I am trying to calculate the heat within the nacelle and what natural cooling will occur knowing only material properties, dimensions and generator and gearbox losses. I am struggling to generally work out how to go forward and work out the temperatures over time. Any help would be great.

2. Jul 22, 2011

### edgepflow

Your heat loss from the surface of the nacelle is:

q loss = h A (Ts - Twater)

q loss = heat loss
h = convenctive heat transfer coefficient (more on this below)
A = surface area of nacelle
Ts = temperature on surface of nacelle
Twater = average water temperature

Try figuring h from a natural circulation correlation for a vertical cylinder. You can attack this with the Chruchhill and Chu, LeFevre and Ede, or Yovanovish correlation.

If you figure your q-loss from gearbox data, you find find out how hot your nacell will get by figuring Ts.