I've got what I think is a fairly simple problem that's got me stumped for some reason.
I am trying to calculate the outside temperature of an underground carrier pipe assembly carrying steam at 95 psi at 335°F. Layers in the cylinder are as follows:
[ol 1]
[li]Steam at 95 psi at 335°F[/li]
[li]10"Ø Schedule 40 seamless steel pipe[/li]
[li]~2" aerogel insulation[/li]
[li]~2" Polyurethane foam[/li]
[li]HDPE Jacket[/li]
[li]Earth at ~75°F[/li]
[/ol]
I'm not too concerned about the conditions of the earth- this varies from piece of steam pipe to piece, and I'll get the thicknesses down later. I can get all pieces of the puzzle, i.e. thermal resistance values quite easy. My concern is being able to find the convective heat transfer coefficient/inside fluid film coefficient (Btu/hr. ft. °F) for the steam-steel interface in the pipe. I'd like to calculate for the most conservative case, but I am struggling to find a table that lists different values of h for different steam velocities and different conditions (condensing, non-condensing, etc.).
Is this a value that I will need to calculate elsewhere, or is there a range of values out of which I can pick a conservative value? Thanks in advance.
I am trying to calculate the outside temperature of an underground carrier pipe assembly carrying steam at 95 psi at 335°F. Layers in the cylinder are as follows:
[ol 1]
[li]Steam at 95 psi at 335°F[/li]
[li]10"Ø Schedule 40 seamless steel pipe[/li]
[li]~2" aerogel insulation[/li]
[li]~2" Polyurethane foam[/li]
[li]HDPE Jacket[/li]
[li]Earth at ~75°F[/li]
[/ol]
I'm not too concerned about the conditions of the earth- this varies from piece of steam pipe to piece, and I'll get the thicknesses down later. I can get all pieces of the puzzle, i.e. thermal resistance values quite easy. My concern is being able to find the convective heat transfer coefficient/inside fluid film coefficient (Btu/hr. ft. °F) for the steam-steel interface in the pipe. I'd like to calculate for the most conservative case, but I am struggling to find a table that lists different values of h for different steam velocities and different conditions (condensing, non-condensing, etc.).
Is this a value that I will need to calculate elsewhere, or is there a range of values out of which I can pick a conservative value? Thanks in advance.
