Oil Reservoir Heat Loss

[enirwin]

I need to size a heater for a small aluminum oil reservoir. It will be operated indoors with minimal air circulation. The shape is roughly square. I need a rough approximation of heat lost to the air from the tank. Does anyone have a rule of thumb value for the convection heat transfer coefficient, based on experience?

Thanks.

 

[saxon]

enirwin, From an old Crane Engineering Data Manual a liquid to gas free convection transfer shows a U value of approx. 1-3 btu/hr/ft^2/deg.F.

Hope this helps.
saxon