Closed pressure vessel heat transfer.

[CRF59]

I am working with a 6AL-4V Titanium pressure vessel that has an ID of 11 inches, an OD of 12 inches and an interior length of 48 inches. The vessel contains a 12 inch long device which consumes 850 W of power. Assuming all of that power is radiated as heat I am looking to calculate heat buildup in the cylinder with the following assumptions:
Medium surrounding the pressure vessel is seawater at 28 degrees C and the seawater flow across the vessel is about 1 m/s. I know this is much more complicated than a simple UA(Th-Tc) problem so would appreciate any help. The vessel will either be filled with an inert gas (Nitrogen) or Flourinert. Additionally, based on calculation results I may added fins for heat transfer on both the electronics housing and the exterior of the vessel. Can I assume that simply using the area of the vessel's interior and exterior surfaces, the transfer coefficient of the material, and then calculating the heat removal by the seawater will get me there? My goal is to know what the equilibrium temp is in the vessel with and without Flourinert and added fins for dissipation.

 

[IRstuff]

If you cannot ensure that the heat dissipated is evenly distributed throughout the pressure vessel walls, then you cannot use the total surface and must use something smaller.

Since your device is less than 1/4 the length of the vessel, you'll need to revisit the surface area question.

You've also not indicated how hot your device is allowed to get and/or how much heat can be removed for a given surface temperature at the device.



TTFN

 

[CRF59]

Thanks. After further review of the drawings, I determined there are isolation bulkheads at either end of the package such that the effective length of the vessel surrounding the package is 14 inches. So, and I know this is not rigorous, I want to assume that all of the heat is radiated from that 14 inch long section.

Your second question I don't quite understand. Further detail on the electronics package; 12 inch cylinder with aluminum housing (1/8 inch thick 6000 series shell) and an outer diameter of 4 inches. I want to remove as much heat as is possible from the device but there are no real specifications on maximum heat from the manufacturer. The device (a 532 nm wavelength laser) is normally not contained in pressure vessels, hence my scrambling to find information. I am looking for a worst-case buildup using my original assumptions. I know this is not the best information to work with.